U.S. patent number RE33,366 [Application Number 07/253,819] was granted by the patent office on 1990-10-02 for rigid, water-resistant phosphate ceramic materials and process for preparing them.
This patent grant is currently assigned to Armstrong World Industries, Inc.. Invention is credited to Jeffery L. Barrall.
United States Patent |
RE33,366 |
Barrall |
October 2, 1990 |
Rigid, water-resistant phosphate ceramic materials and process for
preparing them
Abstract
The present invention concerns rigid, water-resistant phosphate
ceramic materials which may be prepared from components comprising
metal oxide, calcium silicate, and phosphoric acid. By prereacting
a portion of the metal oxide with the phosphoric acid and/or by
adjusting the temperature of the acid solution when it is combined
with the other ingredients, the character of the resulting product
can be controlled to give foamed or unfoamed phosphate ceramic
material.
Inventors: |
Barrall; Jeffery L. (Lancaster,
PA) |
Assignee: |
Armstrong World Industries,
Inc. (Lancaster, PA)
|
Family
ID: |
27400725 |
Appl.
No.: |
07/253,819 |
Filed: |
October 6, 1988 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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351753 |
Mar 2, 1982 |
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274156 |
Jun 16, 1981 |
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Reissue of: |
378522 |
May 18, 1982 |
04375516 |
Mar 1, 1983 |
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Current U.S.
Class: |
501/84; 106/602;
501/111; 501/123; 501/127; 501/153; 501/85 |
Current CPC
Class: |
C04B
28/342 (20130101); C04B 28/342 (20130101); C04B
14/043 (20130101); C04B 14/30 (20130101); C04B
20/0048 (20130101); C04B 22/10 (20130101); C04B
38/02 (20130101); C04B 40/0028 (20130101); C04B
40/0082 (20130101); C04B 28/342 (20130101); C04B
14/043 (20130101); C04B 20/0048 (20130101); C04B
22/064 (20130101); C04B 24/005 (20130101); C04B
38/02 (20130101); C04B 40/0028 (20130101); C04B
40/0082 (20130101); C04B 2103/40 (20130101); C04B
2103/40 (20130101) |
Current International
Class: |
C04B
28/34 (20060101); C04B 28/00 (20060101); C04B
021/00 () |
Field of
Search: |
;501/84,85,111,123,127,153 ;106/85,86 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Dixon, Jr.; William R.
Assistant Examiner: Group; Karl
Parent Case Text
This is a continuation-in-part of my copending application Ser. No.
351,753, filed Mar. 2, 1982, which is a continuation-in-part of my
copending application Ser. No. 274,156 filed June 16, 1981, both
now abandoned.
Claims
I claim:
1. A process for manufacturing rigid, water resistant phosphate
ceramic material, said process comprising the steps of:
preparing a metal oxide comprising from about 11 to about 65 parts
by weight calculated on an anhydrous basis of at least one metal
oxide selected from the group consisting of Al.sub.2 O.sub.3, MgO,
CaO or ZnO or the hydrates thereof,
preparing a reaction solution comprising a portion of said metal
oxide and from about 80 to about 190 parts by weight of a
phosphoric acid solution comprising the equivalent of from about 35
to about 75% by weight of phosphorus pentoxide based on the weight
of the acid solution, the water of hydration of said metal oxide
being included when calculating the phosphorus pentoxide
content,
preparing a mixture comprising the remainder of said metal oxide
and about 100 parts by weight of calcium silicate,
adjusting the temperature of said reaction solution to a desired
value,
proportionally intermixing said mixture with said reaction
solution, and
placing the resulting intermixed material in a desired
configuration and allowing the components thereof to interact,
the amount of metal oxide used to prepare the reaction solution and
the temperature of the reaction solution being selected so as to
approximately predetermine the point in time at which said
intermixed material becomes rigid relative to the point in time at
which vaporization of the water occurs.
2. The process according to claim 1 hereof comprising from about 13
to about 26 parts of metal oxide, about 100 parts of calcium
silicate, and from about 90 to about 150 parts of phosphoric acid
solution comprising the equivalent of from about 40 to about 70%
phosphorus pentoxide.
3. The process according to claim 1 hereof comprising from about 15
to about 22 parts of metal oxide, about 100 parts of calcium
silicate, and from about 100 to about 130 parts of phosphoric acid
solution comprising the equivalent of from about 45 to about 65%
phosphorus pentoxide.
4. The process according to claims 1, 2, or 3 hereof wherein the
temperature of the reaction solution is from about 35.degree. to
80.degree. F.
5. The process according to claims 1, 2, or 3 hereof wherein the
temperature of said reaction solution is from about 38.degree. to
45.degree. F.
6. The process according to claims 1, 2 or 3 hereof wherein the
temperature of said reaction solution is about 40.degree. F.
7. The process according to claims 1, 2, or 3 hereof wherein the
particle size of said metal oxide is not larger than 325 mesh
(Tyler Standard) and the particle size of said calcium silicate is
not larger than 200 mesh (Tyler Standard).
8. The process according to claims 1, 2, or 3 hereof wherein said
metal oxide is aluminum oxide trihydrate.
9. The process according to claims 1, 2, or 3 hereof wherein said
metal oxide is magnesium oxide.
10. The process according to claims 1, 2, or 3 hereof wherein said
metal oxide comprises a mixture of aluminum oxide trihydrate and
magnesium oxide.
11. The water resistant phosphate ceramic product of the process
set forth in claims 1, 2, or 3 hereof.
12. The products according to claim 11 hereof wherein said products
have a foamed structure.
13. The products according to claim 11 hereof wherein said products
have an unfoamed structure.
14. The products according to claim 13 hereof wherein said products
comprise a filler.
15. The process according to claims 1, 2, or 3 hereof wherein said
reaction solution comprises a surfactant.
16. The process according to claims 1, 2, or 3 hereof wherein said
mixture comprises fibrous reinforcing material.
17. The process according to claims 1, 2, or 3 hereof wherein said
intermixed material comprises a foaming agent.
18. The process according to claim 17 hereof wherein said foaming
agent is a carbonate selected from the group consisting of
MgCO.sub.3, CaCO.sub.3, ZnCO.sub.3 or Li.sub.2 CO.sub.3.
19. The process according to claim 17 hereof wherein said foaming
agent is a fluorinated hydrocarbon having a boiling point lower
than the temperature at which said intermixed material becomes
rigid.
20. A process for manufacturing rigid, water resistant phosphate
ceramic material, said process comprising the steps of:
preparing a mixture comprising .[.from about 11 to about 65 parts
by weight calculated on an anhydrous basis of.]. at least one metal
oxide selected from the group consisting of Al.sub.2 O.sub.3, MgO,
CaO, or ZnO or the hydrates thereof and about 100 parts by weight
of calcium silicate,
preparing a reaction solution comprising .Iadd.at least one metal
oxide from the group consisting of Al.sub.2 O.sub.3, MgO, CaO, or
ZnO or the hydrates thereof and .Iaddend.from about 80 to about 190
parts by weight of a phosphoric acid solution comprising the
equivalent of from about 35 to about 75% by weight of phosphorus
pentoxide based on the weight of the acid solution, the water of
hydration of said metal oxide being included when calculating the
phosphorus pentoxide content, .Iadd.the total of metal oxide in
said mixture and in said reaction solution being from about 11 to
about 65 parts by weight calculated on an anhydrous basis,
.Iaddend.
adjusting the temperature of said reaction solution to a desired
value,
proportionally intermixing said mixture with said reaction
solution, and
placing the resulting intermixed material in a desired
configuration and allowing the compounds thereof to interact,
the temperature of the reaction solution being selected so as to
approximately predetermine the point in time at which said
intermixed material becomes rigid relative to the point in time at
which vaporization of the water occurs.
21. The process according to claim 20 hereof comprising from about
13 to about 26 parts of metal oxide, about 100 parts of calcium
silicate, and from about 90 to about 150 parts of phosphoric acid
solution comprising the equivalent of from about 40 to about 70%
phosphorus pentoxide.
22. The process according to claim 20 hereof comprising from about
15 to about 22 parts of metal oxide, about 100 parts of calcium
silicate, and from about 100 to about 130 parts of phosphoric acid
solution comprising the equivalent of from about 45 to about 65%
phosphorus pentoxide.
23. The process according to claims 20, 21, or 22 hereof wherein
the temperature of the reaction solution is from about 35.degree.
to 80.degree. F.
24. The process according to claims 20, 21, or 22 hereof wherein
the temperature of said reaction solution is from about 38.degree.
to 45.degree. F.
25. The process according to claims 20, 21, or 22 hereof wherein
the temperature of said reaction solution is about 40.degree.
F.
26. The process according to claims 20, 21, or 22 hereof wherein
the particle size of said metal oxide is not larger than 325 mesh
(Tyler Standard) and the particle size of said calcium silicate is
not larger than 200 mesh (Tyler Standard).
27. The process according to .[.claims.]. .Iadd.claim .Iaddend.20,
.[.21, or 22.]. hereof wherein said metal oxide .Iadd.in the
reaction solution .Iaddend.is aluminum oxide trihydrate.
28. The process according to .[.claims.]. .Iadd.claim .Iaddend.20,
.[.21, or 22.]. hereof wherein said metal oxide .Iadd.in the
mixture .Iaddend.is magnesium oxide.
29. The process according to claims 20, 21, or 22 hereof wherein
said metal oxide comprises a mixture of aluminum oxide trihydrate
and magnesium oxide.
30. The water resistant phosphate ceramic product of the process
set forth in claims 20, 21, or 22 hereof.
31. The products according to claim 30 hereof wherein said products
have a foamed structure.
32. The products according to claim 30 hereof wherein said products
have an unfoamed structure.
33. The products according to claim 32 hereof wherein said products
comprise a filler.
34. The process according to claims 20, 21, or 22 hereof wherein
said reaction solution comprises a surfactant.
35. The process according to claims 20, 21, or 22 hereof wherein
said mixture comprises fibrous reinforcing material.
36. The process according to claims 20, 21, or 22 hereof wherein
said intermixed material comprises a foaming agent.
37. The process according to claim 36 hereof wherein said foaming
agent is a carbonate selected from the group consisting of
MgCO.sub.3, CaCO.sub.3, ZnCO.sub.3 or Li.sub.2 CO.sub.3.
38. The process according to claim 36 hereof wherein said foaming
agent is a fluorinated hydrocarbon having a boiling point lower
than the temperature at which said intermixed material becomes
rigid.
39. A process for manufacturing rigid, water resistant phosphate
ceramic material, said process comprising the steps of:
preparing a metal oxide comprising from about 11 to about 65 parts
by weight calculated on an anhydrous basis of at least one metal
oxide selected from the group consisting of Al.sub.2 O.sub.3, MgO,
CaO or ZnO or the hydrates thereof,
preparing a reaction solution comprising a portion of said metal
oxide and from about 80 to about 190 parts by weight of a
phosphoric acid solution comprising the equivalent of from about 35
to about 75% by weight of phosphorus pentoxide based on the weight
of the acid solution, the water of hydration of said metal oxide
being included when calculating the phosphorus pentoxide
content,
preparing a mixture comprising the remainder of said metal oxide
and about 100 parts by weight of calcium silicate,
proportionally intermixing said mixture with said reaction
solution, and
placing the resulting intermixed material in a desired
configuration and allowing the components thereof to interact,
the amount of metal oxide used to prepare the reaction solution
being selected so as to approximately predetermine the point in
time at which said intermixed material becomes rigid relative to
the point in time at which vaporization of the water occurs.
40. A process according to claim 39 hereof comprising from about 13
to about 26 parts of metal oxide, about 100 parts of calcium
silicate, and from about 90 to about 150 parts of phosphoric acid
solution comprising the equivalent of from about 40 to about 70%
phosphorus pentoxide.
41. A process according to claim 39 hereof comprising from about 15
to about 22 parts of metal oxide, about 100 parts of calcium
silicate, and from about 100 to about 130 parts of phosphoric acid
solution comprising the equivalent of from about 45 to about 65%
phosphorus pentoxide.
42. The process according to claims 39, 40, or 41 hereof wherein
the particle size of said metal oxide is not larger than 325 mesh
(Tyler Standard) and the particle size of said calcium silicate is
not larger than 200 mesh (Tyler Standard).
43. The process according to claims 39, 40, or 41 hereof wherein
said metal oxide is aluminum oxide trihydrate.
44. The process according to claims 39, 40, or 41 hereof wherein
said metal oxide is magnesium oxide.
45. The process according to claims 39, 40, or 41 hereof wherein
said metal oxide comprises a mixture of aluminum oxide trihydrate
and magnesium oxide.
46. The water resistant phosphate ceramic product of the process
set forth in claims 39, 40, or 41 hereof.
47. The products according to claim 46 hereof wherein said products
have a foamed structure.
48. The products according to claim 46 hereof wherein said products
have an unfoamed structure.
49. The products according to claim 48 hereof wherein said products
comprise a filler.
50. The process according to claims 39, 40, or 41 hereof wherein
said reaction solution comprises a surfactant.
51. The process according to claims 39, 40, or 41 hereof wherein
said mixture comprises fibrous reinforcing material.
52. The process according to claim 39, 40 or 41 hereof wherein said
intermixed material comprises a foaming agent.
53. The process according to claim 52 hereof wherein said foaming
agent is a carbonate selected from the group consisting of
MgCO.sub.3, CaCO.sub.3, ZnCO.sub.3 or Li.sub.2 CO.sub.3.
54. The process according to claim 52 hereof wherein said foaming
agent is a fluorinated hydrocarbon having a boiling point lower
than the temperature at which said intermixed material becomes
rigid.
55. A composition suitable to provide a rigid, water-resistant
phosphate ceramic material, said composition comprising:
from about 11 to about 65 parts by weight calculated on an
anhydrous basis of at least one metal oxide selected from the group
consisting of Al.sub.2 O.sub.3, MgO, CaO or ZnO or the hydrates
.[.8.]. thereof .Iadd.divided between two sets of
components.Iaddend.;
.Iadd.the first set of components being said oxide and
.Iaddend.from about 80 to about 190 parts by weight of phosphoric
acid solution comprising the equivalent of from about 35 to about
75% by weight of phosphorus pentoxide based on the weight of the
acid solution, the water of hydration of said metal oxide being
included when calculating the phosphorus pentoxide content; and
.Iadd.the second set of components being said oxide and
.Iaddend.about 100 parts by weight of calcium silicate.
56. The invention according to claim 55 hereof wherein said
composition comprises from about 13 to about 26 parts of metal
oxide, about 100 parts of calcium silicate, and from about 90 to
about 150 parts of phosphoric acid solution comprising the
equivalent of from about 40 to about 70% phosphorus pentoxide.
57. The invention according to claim 55 hereof wherein said
composition comprises about 15 to about 22 parts of metal oxide,
about 100 parts of calcium silicate, and from about 100 to about
130 parts of phosphoric acid solution comprising the equivalent of
from about 45 to about 65% phosphorus pentoxide.
58. The invention according to claims 55, 56 or 57 hereof wherein
the particle size of said metal oxide is not larger than 325 mesh
(Tyler Standard) and the particle size of said calcium silicate is
not larger than 200 mesh (Tyler Standard).
59. The composition according to claims 55, 56 or 57 hereof wherein
said metal oxide .Iadd.in the first set of components .Iaddend.is
aluminum oxide trihydrate.
60. The invention according to claims 55, 56 or 57 hereof wherein
said metal oxide .Iadd.in the second set of components .Iaddend.is
magnesium oxide.
61. The invention according to claims 55, 56 or 57 hereof wherein
said composition comprises a mixture of aluminum oxide trihydrate
and magnesium oxide.
62. The invention according to claims 55, 56 or 57 hereof wherein
said composition comprises a surfactant.
63. The invention according to claims 55, 56 or 57 hereof wherein
said composition comprises a fibrous reinforcing material.
64. The invention according to claims 55, 56 or 57 hereof wherin
said composition comprises a foaming agent.
65. The invention according to claim 64 hereof wherein said foaming
agent is a carbonate selected from the group consisting of
MgCO.sub.3, CaCO.sub.3, ZnCO.sub.3 or Li.sub.2 CO.sub.3.
66. The invention according to claim 64 hereof wherein said foaming
agent is fluorinated hydrocarbon having a boiling point lower than
the temperature at which said intermixed material becomes
rigid.
67. A rigid, water-resistant phosphate ceramic material obtained by
reacting
(1) from about 11 to about 65 parts by weight calculated on an
anhydrous basis of at least one metal oxide selected from the group
consisting of Al.sub.2 O.sub.3, MgO, CaO or ZnO or the hydrates
thereof;
(2) from about 80 to about 190 parts by weight of a phosphoric acid
solution comprising the equivalent of from about 35 to about 75% by
weight of phosphorus pentoxide based on the weight of the acid
solution, the water of hydration of said metal oxide being included
when calculating the phosphorus pentoxide content; and
(3) about 100 parts by weight of calcium silicate.
68. The invention according to claim 67 hereof comprising from
about 13 to about 26 parts of metal oxide, about 100 parts of
calcium silicate, and from about 90 to about 150 parts of
phosphoric acid solution comprising the equivalent of from about 40
to about 70% phosphorus pentoxide.
69. The invention according to claim 67 hereof comprising from
about 15 to about 22 parts of metal oxide, about 100 parts of
calcium silicate, and from about 100 to about 130 parts of
phosphoric acid solution comprising the equivalent of from about 45
to about 65% phosphorus pentoxide.
70. The invention as set forth in claims 67, 68 or 69 hereof
wherein said ceramic material is obtained by reacting a reaction
solution and a component mixture, said reaction solution comprising
said phosphoric acid solution and at least a portion of said metal
oxide, and said component mixture comprising said calcium silicate
and the remainder of said metal oxide.
71. The invention according to claims 67, 68, or 69 hereof wherein
the amount of metal oxide used to prepare said reaction solution
and the temperature of said reaction solution are selected so as to
approximately predetermine the point in time at which said
intermixed material becomes rigid relative to the point in time at
which vaporization of the water occurs.
72. The invention according to claim 71 hereof wherein the particle
size of said metal oxide is not larger than 325 mesh (Tyler
Standard) and the particle size of said calcium silicate is not
larger than 200 mesh (Tyler Standard).
73. The invention according to claim 71 herein wherein said metal
oxide is aluminum oxide trihydrate.
74. The invention according to claim 71 hereof wherein said metal
oxide is magnesium oxide.
75. The invention according to claim 71 hereof wherein said metal
oxide comprises a mixture of aluminum oxide trihydrate and
magnesium oxide.
76. The invention according to claim 71 hereof wherein said ceramic
material comprises a surfactant.
77. The invention according to claim 71 hereof wherein said ceramic
comprises a fibrous reinforcing material.
78. The invention according to claim 71 hereof comprising a foaming
agent.
79. The invention according to claim 78 hereof wherein said foaming
agent is a carbonate selected from the group consisting of
MgCO.sub.3, CaCO.sub.3, ZnCO.sub.3 or Li.sub.2 CO.sub.3.
80. The invention according to claim 78 hereof wherein said foaming
agent is a fluorinated hydrocarbon having a boiling point lower
than the temperature at which said intermixed material becomes
rigid.
Description
The present invention relates to rigid, water-resistant phosphate
ceramic materials and more particularly to rigid, water-resistant
phosphate ceramic materials which do not require subsequent thermal
curing.
BACKGROUND OF THE INVENTION
Refractory metal phosphates have long been recognized as useful
building and insulating materials. Compositions comprising
phosphoric acid, a metal oxide, and metal silicates are known in
the art; however, compositions comprising these constituents and
having adequate strength are extremely difficult to prepare. For
example, mixtures of aluminum oxide and 85% phosphoric acid are
viscous and difficult to handle. If such mixtures are diluted with
water, the ease of handling is greatly improved; nevertheless, when
silicate, e.g. calcium silicate, is added and the resulting
phosphate is thermally cured to drive off excess water, the
refractory material obtained has relatively poor tensile strength.
Alternatively, if all of the components are mixed together at once
without using additional water, a rapid reaction ensues which
cannot be handled under normal manufacturing circumstances.
THE PRIOR ART
Various phosphate compositions and processes for preparing them are
found in the prior art. For example, U.S. Pat. No. 2,992,930, dated
July 18, 1961 to William Wheeler et al. discloses compositions
comprising powdered zirconium or aluminum oxides, calcium silicate
for foam stabilization, phosphoric acid, a silica sol bonding agent
and a blowing agent, the composition being prepared by blending the
dry ingredients, adding the silica sol, stirring the mixture with
phosphoric acid and allowing the resulting foam to become rigid.
U.S. Pat. No. 3,148,996, dated Sept. 15, 1964 to Mark Vukasovich et
al. discloses compositions which set into a rigid mass without
heating and which may be rendered porous by incorporation of gas
bubbles. These compositions consist of water, an acid phosphate
consisting of phosphorus pentoxide and calcium, aluminum or
zirconium oxides, and finely divided calcium silicate. They are
formed by preparing a viscous solution of water, phosphorus
pentoxide and an appropriate metal oxide, adding calcium silicate
to the mixture and allowing it to partially harden. Foaming is then
induced by adding an internal foaming agent or by mechanically
introducing gas bubbles. U.S. Pat. No. 3,330,675, dated July 11,
1967 to Jules Magder discloses compositions comprising acidic
aluminum phosphate, the carbonate, oxide, hydroxide or silicate of
magnesium or zirconium, and organic or inorganic gas producing
materials. Similarly, other patent references disclose related
phosphate foams in which a powdered metal is incorporated into the
acidic mixture, thereby inducing foaming through the release of
hydrogen gas.
Although it is evident from these references that substantial
effort has been extended to develop useful phosphate foams, many
problems still exist. Most of the prior art foams have poor bond
strength, thereby rendering them unusable as building materials.
Some are moisture sensitive, many require heat curing to improve
bond strength, and most contain other additives designed to
circumvent weakness problems. In addition, most commercially
manufactured foams contain blowing agents which can increase the
cost of the product and sometimes contribute to bond weakness.
Accordingly, one object of the present invention is to provide
strong, moisture-resistant phosphate ceramic materials which can be
prepared without the use of external heat.
Yet another object of the present invention is to provide processes
for the preparation of rigid phosphate foams without the use of
added blowing agents.
Still another object of the present invention is to provide
processes for the convenient and continuous production of phosphate
foam whereby slumping of the foam is avoided.
These and other advantages of the present invention will become
apparent from the description of the invention which follows.
SUMMARY OF THE INVENTION
The present invention concerns rigid, water-resistant phosphate
ceramic materials which may be prepared from components comprising
metal oxide, calcium silicate, and phosphoric acid. By prereacting
a portion of the metal oxide with the phosphoric acid and/or by
adjusting the temperature of the acid solution when it is combined
with the other ingredients, the character of the resulting product
can be controlled to give foamed or unfoamed phosphate ceramic
material.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
In one embodiment, the process of the present invention comprises
the steps of (1) selecting at least one metal oxide from the group
consisting of Al.sub.2 O.sub.3, MgO, CaO or ZnO or the hydrates
thereof, said metal oxide comprising a total of from about 11 to
about 65 parts by weight calculated on an anhydrous basis; (2)
preparing a reaction solution comprising a portion of said metal
oxide and from about 80 to about 190 parts by weight of a
phosphoric acid solution comprising the equivalent of from about 35
to about 75% by weight of phosphorus based on the weight of the
acid solution, the water pentoxide of hydration of said metal oxide
being included when calculating the phosphorus pentoxide content;
(3) preparing a mixture comprising the remainder of said metal
oxide and about 100 parts by weight of calcium silicate. The
temperature of said reaction solution is adjusted to a desired
value and the mixture is proportionally intermixed with said
reaction solution. The resulting intermixed material is placed in a
desired configuration and the components thereof are allowed to
interact. The amount of metal oxide used to prepare the reaction
solution and the temperature of the reaction solution are selected
so as to approximately predetermine the point in time at which said
intermixed material becomes rigid relative to the point in time at
which vaporization of the water occurs.
In a second embodiment the process of the present invention
comprises the steps of (1) preparing a mixture comprising from
about 11 to about 65 parts by weight calculated on an anhydrous
basis of at least one metal oxide selected from the group
consisting of Al.sub.2 O.sub.3, MgO, CaO or ZnO or the hydrates
thereof, and about 100 parts by weight of calcium silicate; and (2)
preparing a reaction solution comprising from about 80 to about 190
parts by weight of a phosphoric acid solution comprising the
equivalent of from about 35 to about 75% by weight of phosphorus
pentoxide based on the weight of the acid solution, the water of
hydration of said metal oxide being included when calculating the
phosphorus pentoxide content. The temperature of the reaction
solution is adjusted to a desired value and the solution is
proportionally intermixed with said mixture. The resulting
intermixed material is placed in a desired configuration and the
components thereof are allowed to interact. The temperature of the
reaction solution is selected so as to approximately predetermine
the point in time at which said intermixed material becomes rigid
relative to the point in time at which vaporization of the water
occurs.
In a third embodiment the present invention comprises the steps of
(1) selecting at least one metal oxide from the group consisting of
Al.sub.2 O.sub.3, MgO, CaO or ZnO or the hydrates thereof, said
metal oxide comprising a total of from about 11 to about 65 parts
by weight calculated on an anhydrous basis; (2) preparing a
reaction solution comprising a portion of said metal oxide and from
about 80 to about 190 parts by weight of a phosphoric acid solution
comprising the equivalent of from about 35 to about 75% by weight
of phosphorus pentoxide based on the weight of the acid solution,
the water of hydration of said metal oxide being included when
calculating the phosphorus pentoxide content; and (3) preparing a
mixture comprising the remainder of said metal oxide and about 100
parts by weight of calcium silicate. The mixture is proportionally
intermixed with said reaction solution and the resulting intermixed
material is placed in a desired configuration where the components
thereof are allowed to interact. The amount of metal oxide which is
used to prepare the reaction solution is selected so as to
approximately predetermine the point in time at which said
intermixed material becomes rigid relative to the point in time at
which vaporization of the water occurs.
In a fourth embodiment the present invention comprises a
composition suitable to provide a rigid, water-resistant phosphate
ceramic material, said composition comprising (1) from about 11 to
about 65 parts by weight calculated on an anhydrous basis of at
least one metal oxide selected from the group consisting of
Al.sub.2 O.sub.3, MgO, CaO or ZnO or the hydrates thereof; (2) from
about 80 to about 190 parts by weight of a phosphoric acid solution
comprising the equivalent of from about 35 to about 75% by weight
of phosphorus pentoxide based on the weight of the acid solution,
the water of hydration of said metal oxide being included when
calculating the phosphorus pentoxide content; and (3) about 100
parts by weight of calcium silicate.
In a fifth embodiment the present invention comprises a rigid,
water-resistant phosphate ceramic material obtained by reacting (1)
from about 11 to about 65 parts by weight calculated on an
anhydrous basis of at least one metal oxide selected from the group
consisting of Al.sub.2 O.sub.3, MgO, CaO or ZnO or the hydrates
thereof; (2) from about 80 to about 190 parts by weight of a
phosphoric acid solution comprising the equivalent of from about 35
to about 75% by weight of phosphorus pentoxide based on the weight
of the acid solution, the water of hydration of said metal oxide
being included when calculating the phosphorus pentoxide content;
and (3) about 100 parts by weight of calcium silicate.
The components used to practice the present invention are all
commercially available. Calcium silicate (100 parts by weight) is
preferred in practicing the present invention although other
silicates may also give satisfactory results. Calcium silicate
occurs naturally and is referred to as wollastonite. Suitable
foamed or unfoamed products can be obtained when this material is
used in powdered form as described below. For making foams, the
particle size will preferably be sufficiently small that most of
the silicate passes through a 200-mesh Tyler Standard sieve.
A number of metal oxides such as aluminum oxide, magnesium oxide,
calcium oxide and zinc oxide may be used to obtain satisfactory
phosphate ceramic material. These oxides are used in powdered form,
with finer particle-size oxides on the order of 325 mesh (Tyler
Standard) of smaller giving generally superior results. Hydrated
forms of the oxide may also be used and in many instances are
preferred. In the event that a hydrate is used, the water of
hydration must be taken into account so as not to provide excess
water for the reaction. This may be conveniently done by including
the water of hydration when calculating the phosphorus pentoxide
content of the phosphoric acid solution.
From about 11 to about 65 parts by weight of metal oxide,
calculated on an anhydrous basis, in relation to 100 parts of
calcium silicate may be used to practice the present invention;
however, from about 13-26 parts of metal oxide is preferred and
from about 15-20 parts is especially preferred. The amount of oxide
which is used will depend on whether it is in hydrated form and/or
on its reactivity.
Anhydrous magnesium oxide reacts much more rapidly with phosphoric
acid than does anhydrous aluminum oxide. For example, the former
will react within minutes whereas the latter may required hours,
depending on the temperature of the acid solution. If hydrated
forms are used, however, the disparity in the reaction times is
dramatically diminished. Hydrated magnesium oxide reacts more
quickly than does anhydrous magnesium oxide, and it also reacts
much more quickly than hydrated aluminum oxide. Nevertheless,
hydrated aluminum oxide is substantially more reactive than
anhydrous aluminum oxide for it reacts with the phosphoric acid
solution within a matter of minutes, rather than hours. The
implications of the reaction times will be set forth more fully
below.
Suitable products can be obtained using any of the indicated
oxides, alone or in combination, but anhydrous magnesium oxide
(calcined) and hydrated aluminum oxide are particularly preferred
to practice the present invention. Magnesium oxide tends to
increase the strength and moisture resistance of the final product
whereas aluminum oxide tends to provide superior setting
characteristics.
Phosphoric acid is available in a variety of concentrations, 85%
being the most common concentration for ortho-phosphoric acid.
Other compositions, such as polyphosphoric acid, which will yield
phosphoric acid upon dilution with water may also be satisfactory
to practice the present invention, provided that the overall water
content of the reaction system is not too high. Too much water must
be avoided because products will be obtained which, even though
water resistant, will have poor strength. On the other hand, too
little water is also detrimental, not only because intermixing of
the materials is difficult to achieve, but because, in the case of
foamed products, only high density foams are obtained.
As a general rule, the phosphoric acid will be suitable if it
contains the equivalent of from about 35 to about 75% by weight of
phosphorus pentoxide based on the weight of the acid solution.
Preferably, the equivalent of phosphorus pentoxide will be about
40-70%, and more preferably about 45-65%. The remaining portion of
the acid solution comprises water including, for purposes of
calculation, any water of hydration from the metal oxide. From
about 80 to about 190 parts by weight of the acid solution may be
used in practicing this invention but preferably from about 90 to
about 150 parts will be used, and more preferably from about 100 to
about 130 parts of acid will be used.
Although the components used to practice the present invention have
long been used in the art, the advantages to be derived when these
components are combined as disclosed herein have never been
recognized. It has been discovered that if the manner in which the
ingredients are combined is controlled and excess water is avoided,
a product will be obtained which requires no heat curing and is
water resistant. While applicant is not bound by any theory as to
the nature of the reactions involved in the present invention, two
separate yet related phenomena are apparently occurring; namely,
vaporization of the water and bonding of the materials. Heat
generated by the reactants vaporizes the water present whereby the
water vapor can act as a foaming agent. During approximately the
same time span, bonding or setting occurs which results in the
formation of a rigid ceramic-like material. These two phenomena
will be referred to herein as "vaporization" or the "vaporization
stage," and "setting" or the "setting stage," respectively.
To practice the present invention a reaction solution is preferably
prepared by adding a desired portion of the metal oxide to the
phosphoric acid solution. In addition, liquid additives such as
surfactants may also be incorporated into the reaction solution.
The remainder of the metal oxide and all of the calcium silicate
are then combined and mixed with any solid additives, such as
reinforcing fibers, thickeners, coloring matter and the like. The
temperature of the reaction solution is preferably adjusted to a
desired value and the solution is proportionally mixed with the
remaining dry ingredients. The intermixed material is then placed
in a desired configuration and the components of the system
interact. The products which are obtained do not require heat
curing and may be placed in boiling water without adverse effect.
Nevertheless, they are not heat sensitive for samples have been
heated to 1600.degree. F. without significant loss of strength.
It has been discovered that the relative points in time at which
vaporization and setting occur will dictate the nature of the
product which is obtained. For example, if the vaporization stage
is reached before the setting stage, the water vapor will cause the
mixture to foam before the mass becomes rigid. Conversely, if
setting occurs first, the material is unable to foam and the water
vapor escapes through the interstitial spaces. The implications of
the latter sequence of events will be set forth in more detail
below, but in either case a product can be obtained which does not
require heat curing, yet is resistant to water.
Two factors which contribute to the aforementioned events are the
amount of metal oxide which is prereacted with the phosphoric acid
and the temperature of the reaction solution at the time it is
combined with the remaining dry ingredients. If only one of these
factors is controlled, a ceramic-like material can still be
produced. Nevertheless, it is preferable to control both parameters
to facilitate handling and to obtain a superior product.
How these factors may be varied will be seen from the following.
Generally speaking, if relatively less of the metal oxide is
prereacted with the phosphoric acid relatively more foaming will
occur during the subsequent mixing step before the mass of
materials become rigid, provided that the temperature of the acid
solution is not too low. Conversely, if relatively more of the
metal oxide is prereacted with the phosphoric acid, less foaming
will occur before the mass becomes rigid. If enough metal oxide is
prereacted, essentially no foaming will occur. This result is
apparently obtained because the preaddition of the metal oxide
tends to lengthen the duration of the exothermic reaction or
reactions which vaporize the water.
The temperature of the reaction solution during the subsequent
mixing step can also significantly affect the resulting product.
The higher the temperature of this solution, the more vigorous is
the evolution of water vapor and the sooner water vaporization
occurs when the reaction solution is mixed with the remaining dry
ingredients. Thus, if the temperature is too high, the greater the
likelihood of obtaining foams which contain voids or which foam
rapidly and then slump. This effect may be mitigated somewhat,
however, by including a surfactant in the reaction solution.
If the temperature is too low, the exothermic reaction may be
suppressed so that no foaming will occur. Furthermore, too low a
temperature may be detrimental because the material which is
obtained might have relatively weak bonding strength. The optimum
temperature of the reaction solution can vary depending on the
reactants, but generally it has been found that a temperature range
of about 35.degree. to about 80.degree. F. will give satisfactory
results. When making foams, the preferred temperature range is
about 38.degree.-45.degree. F., and most preferably 40.degree. F.,
unless a foaming agent is added as hereinafter set forth.
In practice, other factors in addition to the amount of prereacted
material and the temperature of the acid solution must be
considered, many of which are dependent on the type of product to
be produced. When making foams, the objective is to cause the foam
to reach a desired height at about the time setting occurs. In
essence, the water vaporization which causes the foaming should be
timed so that it yields a uniform cell size in a product which is
the right height and density after setting is complete. Cell size
is affected by the rate at which the water vapor is given off and
by the viscosity of the acid solution. The viscosity, in turn,
depends on the type of oxide or oxides used, the particle size of
the oxide, and the temperature of the acid solution.
Solutions having different viscosities are obtained when the
various oxides are dissolved in phosphoric acid. For example, when
increasing amounts of magnesium oxide are added to one aliquot of a
standard strength (e.g. 85%) acid solution, viscosities are
observed to vary from ca 50 cp to 1,000 cp at 72.degree. F.
However, when comparable molar amounts of aluminum oxide are added
to a second aliquot of the same acid solution at 72.degree. F.,
viscosities of from ca 50 cp to only 400 cp are observed. To make
superior foams, it is preferred that the viscosity of the acid
solution at the time of intermixing with the remaining ingredients
not exceed about 400 cp. Thus, it will be seen that a second
limitation to the use of magnesium oxide, aside from its tendency
to vigorously cause foaming, is the viscosity of the reaction
solution which results when it is used.
The higher the viscosity of the reaction solution the poorer the
mixing of the ingredients and the poorer the foam quality of the
product that is obtained. For that reason, it is often desirable to
use more than one oxide. Thus, one oxide could be used to prepare
the reaction solution and another could be combined with the
calcium silicate. Alternatively, the oxide could be used as a
mixture, both for forming the reaction solution and for mixing with
the calcium silicate. A variety of possibilities exist; therefore,
it is intended that all such possibilities be included within the
scope of the present invention, and the present invention should
not be limited to these two illustrations.
The density of the final product will depend to a great extent on
the amount of metal oxide which is used to form the reaction
solution; namely, the more of the metal oxide, the greater the
density. As a general rule, in the absence of added foaming agents,
if from about 0 to about 0.3 part of metal oxide for each one part
of P.sub.2 O.sub.5 in the acid solution is used to form the
reaction solution, foams having densities of from about 40 down to
about 15 pounds per cubic foot will be obtained. However, if more
than about 0.3 part of metal oxide is used, a non-foamed ceramic
will be anticipated. Nevertheless, practical considerations, such
as viscosity, affect the upper limit of prereacted material; thus,
usually not more than 50% of the metal oxide can be conveniently
prereacted.
Other considerations which affect the foams are particle size,
surface properties and reinforcing materials. A small and uniform
particle size is much preferred to practice the present invention
because of the tendency of such material to promote fine cell
structure. As previously noted, metal oxides which pass through a
325-mesh Tyler Standard sieve and calcium silicate which passes
through a 200-mesh Tyler Standard sieve are preferred.
Cell size also depends on the surface properties of the material
and it is often helpful to include one or more surfactants to
promote cell stability. Virtually any surfactant which is not
affected by the phosphoric acid may be used. One surfactant which
has been found particularly satisfactory is .[.dimethylccoamine.].
.Iadd.dimethylcocoamine .Iaddend.oxide which is sold by Armak under
the name Aramox DMC. Care must be taken in handling this material,
however, because it is a skin and eye irritant.
Because foams are of a porous nature, they tend to have lower
tensile strength than unfoamed materials. Accordingly, it is often
advisable to add fibrous reinforcing material to strengthen the
foam. Polyester, glass, polypropylene and nylon, among others, have
been used with success, although the conditions under which the
final product will be used may influence the selection of fiber.
For example, for a high temperature application, glass fibers would
be much more stable than would organic fibers. Generally, fiber
lengths of from 1/8" to 1" will be suitable, with approximately
1/2" fibers being especially suitable.
When preparing unfoamed phosphate ceramics, factors such as
particle size, viscosity, temperature and surface properties become
much less important because cell structure is not a concern.
Accordingly, coarser particle-size materials and a higher viscosity
of the reaction solution may be permissible, subject only to
constraints imposed by the handleability of the reactants. A much
higher temperature for the reaction solution may also be used
because the unfoamed material will not slump. Furthermore, no
surfactant will be required because there is no cell stability
problem.
Aside from these considerations, the objective in preparing an
unfoamed ceramic is comparable to that of preparing a foamed
material, the major difference being that, with unfoamed materials,
it is necessary to postpone the vaporization stage until the mass
has become rigid, thus preventing expansion of the phosphate
material. This is conveniently accomplished by prereacting a
greater amount of the metal oxide. However, care must be taken to
ensure that the water can escape from the unfoamed material. If the
internal pressure of the structure becomes too great due to water
pressure, the rigid ceramic can be cracked. For this reason, when
preparing unformed phosphate ceramics, it is often desirable to
include porous fillers which provide passageways through which the
water vapor can escape. Examples of fillers which are satisfactory
are vermiculite and perlite.
Surprisingly, I have also discovered that satisfactory foamed
products may be produced by combining the techniques of the present
invention with foaming agents taught by the prior art. The prior
art contains references to the use of carbon dioxide or carbon
dioxide-producing materials and hydrogen or hydrogen-producing
materials, as well as other organic or inorganic gas-producing
materials, during the production of phosphate products. Such agents
may also be used to advantage in producing the rigid,
water-resistant phosphate ceramics of the present invention.
Although virtually any prior art foaming agent may be employed, the
results that may be obtained are exemplified by the use of various
carbonates. Carbonates such as MgCO.sub.3, CaCO.sub.3, ZnCO.sub.3,
Li.sub.2 CO.sub.3 and the like, or mixtures thereof, which produce
relatively insoluble phosphates are preferred; however, MgCO.sub.3
is especially preferred because it typically produces a foam having
a relatively uniform cell size and a generally suitable density.
Other carbonates such as Na.sub.2 CO.sub.3 and K.sub.2 CO.sub.3
will produce relatively soluble phosphate salts may also be
employed where leaching of the phosphate from the resulting
phosphate ceramic when it is exposed to water will not be
detrimental.
When using dry foaming agents, it is usually desirable to mix them
with the other dry ingredients comprising the calcium silicate and
a portion of the metal oxide; however, these foaming agents may
also be added separately. Because the foaming obtained in the
presence of such agents is not provided by water vaporization, it
is undesirable to have the exotherm occur prior to setting. For
that reason, it is usually necessary to prereact a greater portion
of the metal oxide with the phosphoric acid solution. Often this
will cause an undesirable increase in the viscosity of the acid
solution. Accordingly, when using an added foaming agent, it may be
necessary to dilute the acid solution somewhat in order to control
the viscosity. However, care must be taken to avoid using excess
water because the combination of using additional water and
prereacting more of the metal oxide tends to lower the temperature
of the exotherm, thereby increasing the possibility of producing a
phosphate ceramic with unsatisfactory performance
characteristics.
As an additional consideration, the temperature of the reaction
solution at the time of intermixing with the dry components can
often be higher when foaming is achieved using dry foaming agents
rather than using water vaporization because setting must occur
prior to the occurrence of the exothermic reaction. Thus, when
using dry foaming agents, it is often desirable for the reaction
solution to be within a preferred temperature range of about
50.degree. to 60.degree. F. rather than the preferred range of
about 38.degree. to 45.degree. F. referred to earlier in connection
with the water vaporization foaming process.
Of course, it is also possible to use a liquid foaming agent such
as a fluorinated hydrocarbon having a boiling point lower than the
temperature at which setting of the foam occurs. Examples of such
hydrocarbons are Freon-11 or Freon-113 sold by duPont. Hydrocarbons
of this type may be added to and mixed with the acid solution, or
they may be added separately at the time of intermixing with the
solid ingredients. Non-fluorinated hydrocarbons having an
appropriate boiling point may also be used, but they are much less
desirable because of the inherent risk of fire associated with
their use.
The manner of adding these foaming agents, whether wet or dry, may
be a matter of choice to the artisan or it may depend on various
factors such as the type of product desired and/or the type of
equipment utilized. In certain circumstances, the method of use may
be controlled by the nature of the foaming agent. For example, the
carbonates react chemically with the acid solution; thus, they
cannot be added to the acid solution at a point too early in the
reaction sequence. Conversely, fluorinated hydrocarbons produce
foaming by passing from a liquid to a gaseous state; thus, they may
be maintained in contact with the acid solution if the temperature
of the mixture remains sufficiently low. In the latter case,
however, it must be recognized that fluorinated hydrocarbons form a
two-phase system with the acid solution. Therefore, care should be
taken to ensure that the two-phase system is uniformly mixed prior
to intermixing with the solid ingredients.
Because the art discloses a wide variety of materials which may be
employed in various ways to produce the phosphate ceramics of the
present invention, the term "foaming agents," as used herein, is
intended to encompass all such materials, provided that they
produce phosphate ceramics having the characteristics previously
set forth.
The following examples, in which all parts are expressed by weight,
will be illustrative to demonstrate the advantages of the present
invention.
EXAMPLES
Example 1
A phosphate foam was prepared from the following components:
______________________________________ Parts per Component Weight
(g) 100 parts CaSiO.sub.3 ______________________________________
Al.sub.2 O.sub.3.3H.sub.2 O 14.42 36.04 85% H.sub.3 PO.sub.4 41.58
104.0 (61.6% P.sub.2 O.sub.5) CaSiO.sub.3 40.0 100 Surfactant 0.04
0.1 ______________________________________
If these relationships are calculated by placing the metal oxide on
an anhydrous basis and including the water of hydration as part of
the acid solution, the following is obtained:
______________________________________ Parts per 100 Component
Parts CaSiO.sub.3 ______________________________________ Al.sub.2
O.sub.3 23.56 75.9% H.sub.3 PO.sub.4 116.5 (55% P.sub.2 O.sub.5)
CaSiO.sub.3 100 Surfactant 0.1
______________________________________
The reaction solution was prepared by adding 1.04 parts of Al.sub.2
O.sub.3.3H.sub.2 O to 104 parts of phosphoric acid and stirring the
mixture with moderate agitation for approximately 15 minutes until
a clear solution was obtained. The surfactant (0.1 part) was added
to the reaction solution, which was then cooled to 40.degree. F.
The remaining dry ingredients (100 parts of calcium silicate and 35
parts of aluminum oxide trihydrate) were mixed together and fed
into a Readco continuous processor. The reaction solution was also
fed into the Readco mixer through a different addition port. The
ingredients were proportionally mixed therein, discharged onto a
moving belt covered with a scrim material and leveled. Foaming
began in approximately 1.5 minutes and the mass of material became
rigid in approximately 2 minutes. A continuous block of foamed
material 1" thick and 5" wide was obtained in this manner. The
foamed material had a fine cell structure and a density of 18
pounds per cubic foot. The compressive strength of this material
according to ASTM D1621 was 60 psi. The modulus of rupture
according to ASTM C209 was 70 psi. No evidence of cracking was
detected when 20-g cubes of the product were either placed in
boiling water for 1/2 hours and allowed to dry, or wetted with 50 g
of water at room temperature and allowed to dry.
Example 2
A phosphate foam was prepared from the same components used in
Example 1. The reaction solution was prepared by adding 1.04 parts
of Al.sub.2 O.sub.3.3H.sub.2 O to 104 parts of phosphoric acid and
stirring the mixture with moderate agitation for approximately 15
minutes until a clear solution was obtained. The surfactant (0.1
part) was then added to the reaction solution. The remaining dry
ingredients (100 parts of calcium silicate and 35 parts of aluminum
oxide trihydrate) were mixed together and fed into a Readco
continuous processor. The reaction solution at room temperature,
72.degree. F., was also fed into the Readco mixer through a
different addition port. The ingredients were proportionally mixed
therein, discharged onto a moving belt covered with a scrim
material and leveled. Foaming began in approximately 42 seconds and
the mass of material became rigid in approximately 50 seconds. A
continuous block of foamed material 1" thick and 5" wide was
obtained in this manner. The foamed material had a coarse,
irregular cell structure and a density of 17 pounds per cubic foot.
The compressive strength of this material according to ASTM D1621
was 50 psi. The modulus of rupture according to ASTM C209 was 50
psi. No evidence of cracking was detected when 20-g cubes of the
product were either placed in boiling water for 1/2 hour and
allowed to dry, or wetted with 50 g of water at room temperature
and allowed to dry.
EXAMPLE 3
A phosphate foam was prepared from the following components:
______________________________________ Parts per Component Weight
(g) 100 parts CaSiO.sub.3 ______________________________________
Al.sub.2 O.sub.3.3H.sub.2 O 11.44 30.1 MgO (calcined) 3.0 7.9 80%
H.sub.3 PO.sub.4 43.56 114.63 (58.0% P.sub.2 O.sub.5) CaSiO.sub.3
38 100 Surfactant 0.3 0.79 1/2" Polyester Fiber 0.2 0.53
______________________________________
If these relationships are calculated by placing the metal oxide on
an anhydrous basis and including the water of hydration as part of
the acid solution, the following is obtained:
______________________________________ Parts per 100 Component
Parts CaSiO.sub.3 ______________________________________ Al.sub.2
O.sub.3 19.7 MgO (calcined) 7.9 73.3% H.sub.3 PO.sub.4 125.05
(53.2% P.sub.2 O.sub.5) CaSiO.sub.3 100 Surfactant 0.79 1/2"
Polyester Fiber 0.53 ______________________________________
The reaction solution was preapred by adding 1.15 parts of Al.sub.2
O.sub.3.3H.sub.2 O to 114.63 parts of phosphoric acid and stirring
the mixture with moderate agitation for approximately 15 minutes
until a clear solution was obtained. The surfactant (0.79 part) was
added to the reaction solution, which was then cooled to 40.degree.
F. The remaining dry ingredients (100 parts of calcium silicate,
28.95 parts of aluminum oxide trihydrate, 7.9 parts of magnesium
oxide and 0.53 parts polyester fiber) were mixed together and fed
into a Readco continuous processor. The reaction solution was also
fed into the Readco mixer through a differnt addition port. The
ingredients were proportionally mixed therein, discharged onto a
moving belt covered with a scrim material and leveled. Foaming
began in approximately 57 seconds and the mass of material became
rigid in approximately 1 minute 51 seconds. A continuous block of
foamed material 1" thick and 5" wide was obtained in this manner.
The foamed material had a fine cell structure and a density of 19
pounds per cubic foot. The compressive strength of this material
according to ASTM D1621 was 100 psi. The modulus of rupture
according to ASTM C209 was 80 psi. No evidence of cracking was
detected when 20-g cubes of the product were either placed in
boiling water for 1/2 hour and allowed to dry, or wetted with 50 g
of water at room temperature and allowed to dry.
Example 4
A phosphate foam was prepared from the following components:
______________________________________ Parts per Component Weight
(g) 100 parts CaSiO.sub.3 ______________________________________
Al.sub.2 O.sub.3.3H.sub.2 O 16.0 40.0 85% H.sub.3 PO.sub.4 40.0
100.0 (61.1% P.sub.2 O.sub.5) CaSiO.sub.3 40.0 100.0 Surfactant
0.04 0.1 ______________________________________
If these relationships are calculated by placing the metal oxide on
an anhydrous basis and including the water of hydration as part of
the acid solution, the following is obtained:
______________________________________ Parts per 100 Component
Parts CaSiO.sub.3 ______________________________________ Al.sub.2
O.sub.3 26.15 74.7% H.sub.3 PO.sub.4 113.85 (54.1% P.sub.2 O.sub.5)
CaSiO.sub.3 100 Surfactant 0.1
______________________________________
The reaction solution was prepared by adding 5 parts of Al.sub.2
O.sub.3.3H.sub.2 O to 100 parts of phosphoric acid and stirring the
mixture with moderate agitation for approximately 15 minutes until
a clear solution was obtained. The surfactant (0.1 part) was added
to the reaction solution, which was then cooled to 40.degree. F.
The remaiing dry ingredients (100 parts of calcium silicate and 35
parts of aluminum oxide trihydrate) were mixed together and fed
into a Readco continuous processor. The reaction solution was also
fed into the Readco mixer through a different addition port. The
ingredients were proportionally mixed therein, discharged onto a
moving belt covered with a scrim material and leveled. Foaming
began in approximately 1 minute 45 seconds and the mass of material
became rigid in approximately 2 minutes 5 seconds. A continuous
block of foamed material 1" thick and 5" wide was obtained in this
manner. The foamed material had a fine cell structure and a density
of 29 pounds per cubic foot. The compressive strength of this
material according to ASTM D1621 was 120 psi. The modulus of
rupture according to ASTM C209 was 120 psi. No evidence of cracking
was detected when 20-g cubes of the product were either placed in
boiling water for 1/2 hour and allowed to dry, or wetted with 50 g
of water at room temperature and allowed to dry.
Example 5
A non-foamed phosphate ceramic was prepared from the following
components:
______________________________________ Parts per Component Weight
(g) 100 parts CaSiO.sub. 3 ______________________________________
Al.sub.2 O.sub.3.3H.sub.2 O 18.4 40.89 85% H.sub.3 PO.sub.4 39.6
88.0 (61.6% P.sub.2 O.sub.5) CaSiO.sub.3 45.0 100
______________________________________
If these relationships are calculated by placing the metal oxide on
an anhydrous basis and including the water of hydration as part of
the acid solution, the following is obtained:
______________________________________ Parts per 100 Component
Parts CaSiO.sub.3 ______________________________________ Al.sub.2
O.sub.3 26.73 73.2% H.sub.3 PO.sub.4 102.16 (53.1% P.sub.2 O.sub.5)
CaSiO.sub.3 100 ______________________________________
The reaction solution was prepared by adding 9.78 parts of Al.sub.2
O.sub.3.3H.sub.2 O to 88 parts of phosphoric acid and stirring the
mixture with moderate agitation for approximately 15 minutes until
a clear solution was obtained. The remaining dry ingredients (100
parts of calcium silicate and 31.1 parts of aluminum oxide
trihydrate) were mixed together and fed into a Readco continuous
processor. The reaction solution at room temperature was also fed
into the Readco mixer through a different addition port. The
ingredients were proportionally mixed therein, discharged onto a
moving belt covered with a scrim material and leveled. No foaming
occurred and the mixture set into a solid mass in 2 minutes 10
seconds. The hard ceramic-like material had a density of 60 pounds
per cubic foot.
Example 6
A phosphate ceramic was prepared from the following components:
______________________________________ Parts per Component Weight
(g) 100 parts CaSiO.sub.3 ______________________________________
Al.sub.2 O.sub.3.3H.sub.2 O 17.44 38.76 72% H.sub.3 PO.sub.4 40.56
90.13 (52.18% P.sub.2 O.sub.5) CaSiO.sub.3 45 100 Vermiculite 4
8.89 (6#/ft.sup.3) ______________________________________
If these relationships are calculated by placing the metal oxide on
an anhydrous basis and including the water of hydration as part of
the acid solution, the following is obtained:
______________________________________ Parts per 100 Component
Parts CaSiO.sub.3 ______________________________________ Al.sub.2
O.sub.3 25.34 63% H.sub.3 PO.sub.4 103.55 (45.4% P.sub.2 O.sub.5)
CaSiO.sub.3 100 Vermiculite 8.89
______________________________________
The reaction solution was prepared by adding 7.65 parts of Al.sub.2
O.sub.3.3H.sub.2 O to 90.13 parts of phosphoric acid and stirring
the mixture with moderate agitation for approximately 15 minutes
until a clear solution was obtained. The remaining dry ingredients
(100 parts of calcium silicate, 31.11 parts of aluminum oxide
trihydrate and 8.89 parts of vermiculite) were mixed together and
fed into a Readco continuous processor. The reaction solution at
room temperature (72.degree. F.) was also fed into the Readco mixer
through a different addition port. The ingredients were
proportionally mixed therein, discharged onto a moving belt covered
with a scrim material and leveled. No foaming occurred and the
mixture set into a solid mass in 2 minutes 30 seconds. The hard
ceramic-like material had a density of 59 pounds per cubic
foot.
Example 7
This example illustrates the use of a prior art dry foaming agent
in combination with the present invention to produce a phosphate
ceramic material. A phosphate foam was prepared from the following
components:
______________________________________ Parts per Component Weight
(g) 100 parts CaSiO.sub.3 ______________________________________
Al.sub.2 O.sub.3.3H.sub.2 O 8.97 17.94 68% H.sub.3 PO.sub.4 56.03
112.06 (49.3% P.sub.2 O.sub.5) CaSiO.sub.3 50.00 100.0 MgCO.sub.3
2.0 4.0 MgO (calcined) 7.0 14.0 Talc Filler 10.0 20.0
______________________________________
If these relationships are calculated by placing the metal oxide on
an anhydrous basis and including the water of hydration as part of
the acid solution, the following is obtained:
______________________________________ Parts per Component 100
parts CaSiO.sub.3 ______________________________________ Al.sub.2
O.sub.3 11.72 64.4% H.sub.3 PO.sub.4 118.27 (46.7% P.sub.2 O.sub.5)
CaSiO.sub.3 100.0 MgCO.sub.3 4.0 MgO (calcined) 14.0 Talc Filler
20.0 ______________________________________
The reaction solution was prepared at room temperature by adding
17.94 parts of Al.sub.2 O.sub.3.3H.sub.2 O with stirring to 112.06
parts of phosphoric acid solution. The resulting clear solution was
cooled to 55.degree. F. The remaining dry ingredients (100 parts of
calcium silicate, 4.0 parts of magnesium carbonate, 14.0 parts of
magnesium oxide and 20.0 parts of filler) were mixed together and
fed into a Readco continuous processor. The reaction solution at
55.degree. F. was also fed into the Readco mixer through a
different addition port. The ingredients were proportionally mixed
therein, and discharged onto a moving belt covered with a scrim
material. Due to the presence of the acid in the mixture, foaming
was occurring as the material exited the mixer. The foaming
material was leveled and it solidified in approximately 1 minute 30
seconds, with an exothermic reaction occurring approximately 30
seconds thereafter as indicated by the evolution of steam. The
rigid foamed material had a fine cell structure and a density of 12
pounds per cubic foot. The compressive strength of this material
according to ASTM D1621 was 90 pounds per square inch and the
modulus of rupture according to ASTM C209 was 40 pounds per square
inch. This material floated when placed in water, indicating that
the water could not readily penetrate the foam matrix.
Example 8
This example illustrates the use of a liquid prior art foaming
agent to produce the phosphate ceramic of the present invention. A
phosphate ceramic was prepared from the following components:
______________________________________ Parts per Component Weight
(g) 100 parts per CaSiO.sub.3
______________________________________ Al.sub.2 O.sub.3.3H.sub.2 O
9.0 18.0 80.2% H.sub.3 PO.sub.4 53.0 106.0 (58.2% P.sub.2 O.sub.5)
CaSiO.sub.3 50.0 100.0 Freon-11 4.0 8.0 MgO (calcined) 5.0 10.0
Talc Filler 10.0 20.0 ______________________________________
If these relationships are calculated by placing the metal oxide on
an anhydrous basis and including the water of hydration as part of
the acid solution, the following is obtained:
______________________________________ Parts per Component 100
parts CaSiO.sub.3 ______________________________________ Al.sub.2
O.sub.3 11.8 75.8% H.sub.3 PO.sub.4 112.2 (55% P.sub.2 O.sub.5)
CaSiO.sub.3 100.0 Freon-11 8.0 MgO (calcined) 10.0 Talc Filler 20.0
______________________________________
The reaction solution was prepared at room temperature by mixing 10
parts of Al.sub.2 O.sub.3.3 H.sub.2 O with stirring to 106.0 parts
of phosphoric acid solution, after which the reaction solution was
cooled to 55.degree. F. The remaining dry ingredients (100 parts of
calcium silicate, 8.0 parts of aluminum oxide trihydrate, 10.0
parts of magnesium oxide and 20.0 parts of filler) were mixed
together and fed into a Readco continuous processor. The
ingredients were proportionally mixed therein, the Freon-11 being
added through a separate in-line mixer in order to obtain good
dispersion. The intermixed material exited from the mixer and
foaming occurred slowly over a 3-minute period. Solidifaction
occurred in 4 minutes, and the exothermic reaction occurred in 4.5
minutes. The resulting coarse-celled foam had a density of 19
pounds per cubic foot.
My invention is not restricted solely to the descriptions and
illustrations provided above, but encompasses all modifications
envisaged by the following claims.
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