U.S. patent application number 13/676386 was filed with the patent office on 2014-05-15 for inorganic fiber block.
This patent application is currently assigned to NICHIAS CORPORATION. The applicant listed for this patent is NICHIAS CORPORATION. Invention is credited to Tomohiko KISHIKI, Tetsuya MIHARA, Takashi NAKAJIMA, Yoshinori OCHI, Ken YONAIYAMA.
Application Number | 20140134444 13/676386 |
Document ID | / |
Family ID | 50681986 |
Filed Date | 2014-05-15 |
United States Patent
Application |
20140134444 |
Kind Code |
A1 |
OCHI; Yoshinori ; et
al. |
May 15, 2014 |
INORGANIC FIBER BLOCK
Abstract
An inorganic fiber block obtained by stacking blanket-like
products each including inorganic fibers, wherein the composition
of the inorganic fibers have the following composition: SiO.sub.2:
66 to 82 mass %, CaO:10 to 34 mass %, MgO: 0 to 3 mass %,
Al.sub.2O.sub.3: 0 to 5 mass %, and the total of SiO.sub.2, CaO,
MgO and Al.sub.2O.sub.3 is 99 mass % or more.
Inventors: |
OCHI; Yoshinori; (Tokyo,
JP) ; MIHARA; Tetsuya; (Tokyo, JP) ;
YONAIYAMA; Ken; (Tokyo, JP) ; KISHIKI; Tomohiko;
(Tokyo, JP) ; NAKAJIMA; Takashi; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NICHIAS CORPORATION |
Tokyo |
|
JP |
|
|
Assignee: |
NICHIAS CORPORATION
Tokyo
JP
|
Family ID: |
50681986 |
Appl. No.: |
13/676386 |
Filed: |
November 14, 2012 |
Current U.S.
Class: |
428/450 |
Current CPC
Class: |
F27D 1/04 20130101; F27D
1/0009 20130101 |
Class at
Publication: |
428/450 |
International
Class: |
E04B 1/78 20060101
E04B001/78 |
Claims
1. An inorganic fiber block obtained by stacking blanket-like
products each comprising inorganic fibers, wherein the composition
of the inorganic fibers have the following composition: SiO.sub.2:
66 to 82 mass % CaO: 10 to 34 mass % MgO: 0 to 3 mass %
Al.sub.2O.sub.3: 0 to 5 mass %, and the total content of SiO.sub.2,
CaO, MgO and Al.sub.2O.sub.3 is 98 mass % or more.
2. The inorganic fiber block according to claim 1, wherein the
inorganic fibers have the following composition: SiO.sub.2: 71 to
80 mass % CaO: 18 to 27 mass % MgO: 0 to 3 mass % Al.sub.2O.sub.3:
1.1 to 3.4 mass %, provided that the content of each of ZrO.sub.2
and R.sub.2O.sub.3 (R is selected from Sc, La, Ce, Pr, Nd, Sm, Eu,
Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y or a mixture of these) is 0.1
mass % or less, the content of an alkaline metal oxide is 0.2 mass
% or less, and the total content of SiO.sub.2, CaO, MgO and
Al.sub.2O.sub.3 is 99 mass % or more.
3. The inorganic fiber block according to claim 1, wherein the
inorganic fibers have the following composition: SiO.sub.2: 71 to
80 mass % CaO:18 to 27 mass % MgO: 0 to 3 mass % Al.sub.2O.sub.3:
2.0 to 3.4 mass %, provided that the content of each of ZrO.sub.2
and R.sub.2O.sub.3 (R is selected from Sc, La, Ce, Pr, Nd, Sm, Eu,
Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y or a mixture of these) is 0.1
mass % or less, and the total content of SiO.sub.2, CaO, MgO and
Al.sub.2O.sub.3 is 99 mass % or more.
4. The inorganic fiber block according to claim 1, which keeps its
original shape after heating at least at 1000.degree. C. for 8
hours.
5. The inorganic fiber block according to claim 1, which keeps its
original shape after heating at least at 1300.degree. C. for 8
hours.
6. A heat insulating structural body obtained by arranging two or
more inorganic fiber blocks according to claim 1 such that they are
adjacent with each other.
7. The heat insulating structural body according to claim 6,
wherein joint opening between the inorganic fiber blocks
constituting the heat insulating structural body or between the
blankets constituting the inorganic fiber block is 7.5 mm or less
after heating at 1300.degree. C. for 24 hours.
Description
TECHNICAL FIELD
[0001] The invention relates to an inorganic fiber block. In
particular, the invention relates to an inorganic fiber block used
as a refractory heat insulating material or the like for various
industrial furnaces.
BACKGROUND ART
[0002] Due to its excellent heat resistance, an inorganic fiber
block is used as a refractory heat insulating material for lining
of various industrial furnaces, for example. An inorganic fiber
block is obtained by compressing a stacked body of blankets each
formed of inorganic fibers and tightening by means of a band or by
sewing into a block shape. An inorganic fiber block is installed
onto a furnace wall or a furnace casing, and used as a heat
insulating structural body. In order to facilitate working, an
inorganic fiber block may contain a support fitting, a jig or the
like.
[0003] As the inorganic fiber used as the material for the blanket,
ceramic fibers are widely used. For example, Patent Document 1
discloses an inorganic fiber block obtained by stacking ceramic
fiber blankets and alumina fiber blankets.
[0004] A block prepared by using a blanket formed of ceramic fibers
may suffer occurrence of joint opening between blocks due to heat
shrinkage when used at high temperatures. Joint opening may damage
the wall of a furnace.
[0005] In order to suppress occurrence of joint opening, Patent
Documents 1, 2 or the like propose an inorganic fiber block
obtained by combining ceramic fiber blankets and alumina fiber
blankets. However, this technology involves a problem that alumina
fibers are significantly expensive.
RELATED ART DOCUMENTS
Patent Documents
[0006] Patent Document 1: JP-A-H09-156989 [0007] Patent Document 2:
JP-A-2006-76015
SUMMARY OF THE INVENTION
[0008] An object of the invention is to provide an inorganic fiber
block which can suppress occurrence of joint opening generated
between inorganic fiber blocks.
[0009] As a result of extensive studies, the inventors have found
that by adjusting the content of each oxide constituting an
inorganic fiber, i.e. SiO.sub.2, CaO, MgO and Al.sub.2O.sub.3, to
be a prescribed value, occurrence of joint opening between
inorganic fiber blocks can be suppressed. The invention has been
made based on this finding.
[0010] According to the invention, the following inorganic fiber
block or the like are provided. [0011] 1. An inorganic fiber block
obtained by stacking blanket-like products each comprising
inorganic fibers, wherein the composition of the inorganic fibers
have the following composition: [0012] SiO.sub.2: 66 to 82 mass %
[0013] CaO: 10 to 34 mass % [0014] MgO: 3 mass % or less [0015]
Al.sub.2O.sub.3: 5 mass % or less other oxides: less than 2 mass %.
[0016] 2. The inorganic fiber block according to claim 1, wherein
the inorganic fibers have the following composition: [0017]
SiO.sub.2: 71 to 80 mass % [0018] CaO:18 to 27 mass % [0019] MgO: 0
to 3 mass % [0020] Al.sub.2O.sub.3: 1.1 to 3.4 mass %, provided
that the content of each of ZrO.sub.2 and R.sub.2O.sub.3 (R is
selected from Sc, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm,
Yb, Lu, Y or a mixture of these) is 0.1 mass % or less, the content
of an alkaline metal oxide is 0.2 mass % or less, and the total of
SiO.sub.2, CaO, MgO and Al.sub.2O.sub.3 is 99 mass % or more.
[0021] 3. The inorganic fiber block according to 1, wherein the
inorganic fibers have the following composition: [0022] SiO.sub.2:
71 to 80 mass % [0023] CaO: 18 to 27 mass % [0024] MgO: 0 to 3 mass
% [0025] Al.sub.2O.sub.3: 2.0 to 3.4 mass %, provided that the
content of each of ZrO.sub.2 and R.sub.2O.sub.3 (R is selected from
Sc, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y or a
mixture of these) is 0.1 mass % or less, and the total content of
SiO.sub.2, CaO, MgO and Al.sub.2O.sub.3 is 99 mass % or more.
[0026] 4. The inorganic fiber block according to any of 1 to 3,
which keeps its original shape after heating at least at
1000.degree. C. for 8 hours. [0027] 5. The inorganic fiber block
according to any of 1 to 3, which keeps its original shape after
heating at least at 1300.degree. C. for 8 hours. [0028] 6. A heat
insulating structural body obtained by arranging two or more
inorganic fiber blocks according to any of 1 to 5 such that they
are adjacent with each other. [0029] 7. The heat insulating
structural body according to 6, wherein joint opening between the
inorganic fiber blocks constituting the heat insulating structural
body or between the blankets constituting the inorganic fiber block
is 7.5 mm or less after heating at 1300.degree. C. for 24
hours.
[0030] According to the invention, an inorganic fiber block which
can suppress joint opening between inorganic fiber blocks can be
provided. The inorganic fiber block of the invention is produced
from bio-soluble inorganic fibers. Therefore, when installing or
dismantling a heat insulating structural body formed of inorganic
fiber blocks, there is only small possibility that the worker's
heath is injured.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is a schematic perspective view of the inorganic
fiber block according to one embodiment of the invention;
[0032] FIG. 2 is a schematic perspective view of the inorganic
fiber block according to another embodiment of the invention;
[0033] FIG. 3 is a schematic side view of a heat insulating
structural body formed for a heating test, in which (a) shows the
state before the heating test, and (b) shows the state after the
heating test;
[0034] FIG. 4 is photographs of a heat insulating structural body
formed of inorganic fiber blocks prepared in Example 2, in which
(a) shows the state before heating, and (b) shows the state after
heating at 1300.degree. C. for 24 hours;
[0035] FIG. 5 is photographs of a heat insulating structural body
formed of inorganic fiber blocks prepared in Comparative Example 1,
in which (a) shows the state before heating, and (b) shows the
state after heating at 1300.degree. C. for 24 hours;
[0036] FIG. 6 is photographs of a heat insulating structural body
formed of inorganic fiber blocks prepared in Example 3, in which
(a) shows the state before heating, and (b) shows the state after
heating at 1300.degree. C. for 24 hours; and
[0037] FIG. 7 is photographs of a heat insulating structural body
formed of inorganic fiber blocks prepared in Comparative Example 2,
in which (a) shows the state before heating, and (b) shows the
state after heating at 1300.degree. C. for 24 hours.
MODE FOR CARRYING OUT THE INVENTION
[0038] The inorganic fiber block of the invention is a stack of
blanket-like products formed of inorganic fibers and the inorganic
fibers have the following composition: [0039] SiO.sub.2: 66 to 82
mass % (for example, 68 to 80 mass %, 70 to 80 mass %, 71 to 80
mass % or 71 to 76 mass %) [0040] CaO: 10 to 34 mass % (for
example, 20 to 30 mass % or 21 to 26 mass %) MgO: 3 mass % or less
(for example, 1 mass % or less) [0041] Al.sub.2O.sub.3: 5 mass % or
less (for example, 3.5 mass % or less or 3 mass % or less. Or, 1
mass % or more, 1.1 mass % or more, or 2 mass % or more) [0042]
Other oxides: Less than 2 mass % (or the total content of
SiO.sub.2, CaO, MgO, Al.sub.2O.sub.3 is 98 mass % or more)
[0043] If the content of SiO.sub.2 is in the above-mentioned range,
the heat resistance is improved. If the contents of CaO and MgO are
in the above-mentioned range, the bio-solubility of the inorganic
fibers before and after heating is improved. If the content of
Al.sub.2O.sub.3 is in the above-mentioned range, heat resistance is
improved.
[0044] As other oxides, an alkaline metal oxide (K.sub.2O,
Na.sub.2O or the like), Fe.sub.2O.sub.3, ZrO.sub.2, P.sub.2O.sub.5,
B.sub.2O.sub.3, R.sub.2O.sub.3 (R is selected from Sc, La, Ce, Pr,
Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y or a mixture of
these) can be given. The inorganic fiber block of the invention may
or may not contain one or more of these oxides. The content of each
of the other oxides may be 0.2 mass % or less or 0.1 mass % or
less. It is preferred that the total content of all alkaline metal
oxides be 0.2 mass % or less or 0.1 mass % or less.
[0045] The total content of SiO.sub.2, CaO, MgO, Al.sub.2O.sub.3
may exceed 98 mass % or exceed 99 mass %.
[0046] In the invention, it is preferred that the inorganic fibers
have the following composition: [0047] SiO.sub.2 70 mass % to 80
mass % [0048] CaO 18 mass % to 27 mass % [0049] MgO 0 to 3 mass %
[0050] Al.sub.2O.sub.3 1 mass % to 3.5 mass %
[0051] Further, it is preferred that the inorganic fibers have the
following composition: [0052] SiO.sub.2 71 mass % to 80 mass %
[0053] CaO 18 mass % to 27 mass % [0054] MgO 0 to 3 mass % [0055]
Al.sub.2O.sub.3 1.1 mass % to 3.4 mass %
[0056] The above-mentioned fibers normally do not contain
ZrO.sub.2. The content of ZrO.sub.2 is 0.1 mass % or less or less
than 0.1 mass %.
[0057] Further, normally, the above-mentioned fibers do not contain
R.sub.2O.sub.3 (R is selected from Sc, La, Ce, Pr, Nd, Sm, Eu, Gd,
Tb, Dy, Ho, Er, Tm, Yb, Lu, Y or a mixture of these). The content
of R.sub.2O.sub.3 is 0.1 mass % or less or less than 0.1 mass
%.
[0058] The alkaline metal oxide may or may not be contained. Each
of the alkaline metal oxides is contained in an amount of 0.2 mass
% or less, 0.15 mass % or less or 0.1 mass % or less. It is
preferred that the total content of all alkaline metal oxides be
0.2 mass % or less. Each of the alkaline metal oxides may be
contained in an amount of exceeding 0.01 mass %, 0.05 mass % or
more or 0.08 mass % or more.
[0059] K.sub.2O may or may not be contained. The content thereof
may be 0.2 mass % or less, 0.15 mass % or less or 0.1 mass % or
less. K.sub.2O may be contained in an amount exceeding 0.01 mass %,
0.05 mass % or more or 0.08 mass % or more.
[0060] Na.sub.2O may or may not be contained. The content thereof
may be 0.2 mass % or less, 0.15 mass % or less or 0.1 mass % or
less. Na.sub.2O may be contained in an amount exceeding 0.01 mass
%, 0.05 mass % or more or 0.08 mass % or more.
[0061] The above-mentioned fibers normally do not contain
TiO.sub.2. The above-mentioned fibers do not contain each of ZnO,
B.sub.2O.sub.3, P.sub.2O.sub.5 and SrO. SrO or P.sub.2O.sub.5 may
be contained in an amount of 0.1 mass % or less, or less than 0.1
mass %.
[0062] Fe.sub.2O.sub.3 may be contained in an amount of 0.1 to 0.3
mass %.
[0063] The total content of SiO.sub.2, CaO, MgO, and
Al.sub.2O.sub.3 is 99 mass % or more, 99.5 mass % or more or 99.7
mass % or more.
[0064] When Fe.sub.2O.sub.3 is contained, the total content of
SiO.sub.2, CaO, MgO, Al.sub.2O.sub.3 and Fe.sub.2O.sub.3 may be
99.7 mass % or more, 99.8 mass % or more, 99.9 mass % or more or
100 mass %.
[0065] If the content of SiO.sub.2 is 71 to 80 mass %, the fibers
have excellent heat resistance. If the content of SiO.sub.2 is too
high, the amount of cristoballite as a carcinogenic substance which
is generated after heating may increase. The content of SiO.sub.2
is preferably 71 to 77 mass %, more preferably 71 to 76 mass %.
[0066] If the content of CaO is 18 to 27 mass %, the inorganic
fibers have excellent bio-solubility, and the tensile strength of
the product is increased. The content of CaO is preferably 20 to 27
mass %, more preferably 21 to 26 mass %, with 23 to 26 mass % being
further preferable.
[0067] If the content of MgO is 0 to 3 mass %, the inorganic fibers
have excellent bio-solubility. If the content of MgO is too high,
the bio-solubility may be deteriorated after heating. The content
of MgO is preferably 0 to 1 mass %. Although the preferable content
is 0 mass %, normally MgO is contained in an amount exceeding 0
mass % due to the mixing of impurities.
[0068] If the content of Al.sub.2O.sub.3 is 1.1 to 3.4 mass %, the
heat shrinkage is lowered, whereby heat resistance is increased.
Further, in this amount range, the inorganic fibers have an
appropriate water solubility without impairing the fiber quality,
whereby the fibers can be processed easily. The preferable content
of Al.sub.2O.sub.3 is 1.3 to 3.0 mass %.
[0069] The amount of Al.sub.2O.sub.3 may be 1.3 to 1.95 mass % or
1.4 to 1.7 mass %. Further, the amount of Al.sub.2O.sub.3 may be
1.5 to 3 or 2 to 3 mass %. When the amount of Al.sub.2O.sub.3 is
2.0 mass % or more, each of the alkaline metal oxide may be
contained in an amount of 0.2 mass % or more (for example, 0.2 to
1.5 mass %).
[0070] By the above-mentioned composition, the fibers as mentioned
above have excellent bio-solubility, in particular, after heating.
Due to the excellent bio-solubility before heating, there is small
possibility that the health of workers is injured at the time of
production, installation or the like. Due to the bio-solubility
after heating, there is small possibility that the health of
workers is injured at the time of disassembling, dismantling or the
like after use in the heated environment.
[0071] The bio-soluble inorganic fibers are inorganic fibers of
which the solubility in a physiological saline solution at
40.degree. C. is 1% or more, for example. Solubility in a
physiological saline solution can be measured by the following
method, for example. Specifically, first, 1 g of a sample which is
prepared by pulverizing inorganic fibers to 200 meshes or less and
150 mL of a physiological saline solution are placed in an
Erlenmeyer flask (volume: 300 mL), and the flask is placed in an
incubator of 40.degree. C. Next, horizontal vibration of 120
rotations per minute is continuously applied to the Erlenmeyer
flask for 50 hours. Thereafter, the concentration of each element
(mg/L) contained in a filtrate is measured by an ICP emission
spectrometer. Then, the solubility in a physiological saline
solution (%) is calculated based on the measured concentration of
each element and the content (mass %) of each element in the
inorganic fibers before the dissolution. Specifically, if the
elements to be measured are silicon (Si), magnesium (Mg), calcium
(Ca) and aluminum (Al), the solubility C (%) in a physiological
saline solution is calculated by the following formula:
[0072] C(%)=[Amount (L) of
filtrate.times.(a1+a2+a3+a4).times.100]/[mass (mg) of inorganic
fibers before dissolution.times.(b1+b2+b3+b4)/100]. In this
formula, a1, a2, a3 and a4 are respectively the measured
concentration (mg/L) of silicon, magnesium, calcium and aluminum,
and b1, b2, b3 and b4 are respectively the content (mass %) of
silicon, magnesium, calcium and aluminum in the inorganic fibers
before dissolution.
[0073] The block produced from a blanket-like product produced
formed of the above-mentioned inorganic fibers has a small heat
shrinkage. As a result, in a heat insulating structural body formed
of a plurality of inorganic fiber blocks, joint opening between
inorganic fiber blocks which is generated by heat applied to a heat
insulating structural body during use can be suppressed.
[0074] The inorganic fibers having the above-mentioned composition
can be produced by a common method in this technical field.
Specifically, a molten product containing raw material oxides such
as SiO.sub.2, CaO, MgO, Al.sub.2O.sub.3 or the like such that they
satisfy the above-mentioned composition range is prepared. The
molten product is then formed into fibers. In order to allow the
molten product to be fiber, a spinning method in which a molten raw
material is flown onto a wheel which is rotated at a high speed, a
blow method in which compressed air is applied to a molten raw
material, or other methods can be used.
[0075] With the above-mentioned composition of the inorganic
fibers, it is possible to obtain fibers having a high quality by a
normal production method. Further, since a molten material used for
producing such fibers has a low viscosity, thin fibers can be
obtained at low temperatures. The diameter of the fiber can be made
small by spinning at high temperatures at a high speed. The average
fiber diameter is normally 2 to 6 .mu.m, preferably 2 to 4
.mu.m.
[0076] If the fiber diameter is small, the fiber feels smooth,
without giving itchy feeling. A small fiber diameter means that the
fibers tend to be dissolved easily in a living body, and that the
number of fibers per unit volume of a product is increased. Due to
the increased number, thermal conductance is lowered to enhance the
heat insulating effect. Further, in processing, it is possible to
obtain a processed product with a high density, whereby heat
insulating effects are enhanced. In addition, if the number of
fibers is large, the tensile strength (tensile strength of the
blanket) is increased. Accordingly, there are many advantages of
the small fiber diameter.
[0077] Regarding the evaluation of the inorganic fibers, reference
can be made to the Japanese Patent Application No. 2011-59354.
[0078] By stacking blanket-like products formed of the
above-mentioned inorganic fibers, the inorganic fiber block of the
invention is produced. The shape of inorganic fiber blanket-like
product includes not only that of common blankets which are
commercially available, but also board-like shape such as a
felt-like and sheet-like shapes. Hereinbelow, these shape may
comprehensively be referred to as blanket.
[0079] A blanket can be produced by a common method known in this
technical field. For example, inorganic fibers are stacked
continuously into a blanket-like shape, followed by a needle-punch
processing.
[0080] In addition to the above-mentioned inorganic fibers, the
blanket may contain an organic binder, an inorganic binder, an
inorganic compound or the like. As long as the advantageous effects
of the invention are not impaired, common binders or compounds can
be used. Examples of the organic binder include starch, acrylic
emulsion, pulp, a paper strengthening agent, organic fibers,
coagulants or the like. Examples of the inorganic binder include
colloidal silica, alumina sol, clay mineral, aluminum salt or the
like.
[0081] The blanket used in the invention may consist essentially of
the inorganic fibers mentioned above, and optionally, an organic
binder, an inorganic binder and an inorganic compound, consist of
these components. The "consist essentially" means that the
above-mentioned blanket is mainly made of inorganic fibers, and
optionally, an organic binder, an inorganic binder and an inorganic
compound. The content of the inorganic fibers may be 90 mass % or
more and 95 mass % or more.
[0082] The blanket may be subjected to a heat treatment. Although
no particular restrictions are imposed on the heat-treatment
temperature as long as it is equal to or lower than the highest
temperature at which the blanket is used, the heat treatment
temperature is preferably 300 to 1300.degree. C., more preferably
600 to 1200.degree. C., with 700 to 1100.degree. C. being further
preferable.
[0083] Although no particular restrictions are imposed on the
thickness of the inorganic fiber blanket, it is normally 3 mm to 60
mm.
[0084] The inorganic fiber block of the invention has excellent
heat resistance. Specifically, when heat treated at 1000.degree. C.
for 8 hours, it keeps its original shape without being molten. More
preferably, it can retain its original shape even after a heat
treatment at 1300.degree. C. for 8 hours.
[0085] Whether the block can retain its shape or not can be judged
by the heat shrinkage of the inorganic fiber block-shaped product
used in the block. In the invention, keeping the original shape
means that, in a sample after heating, a change in dimension before
and after the heating is within 10%, preferably 5%.
[0086] No restrictions are imposed on the method for producing a
block by stacking the blankets. A method known in this technical
field can be used. For example, a method in which a plurality of
pieces of a blanket which are obtained by cutting a long blanket
into pieces such that each piece has the same size are stacked, or
a method in which a long narrow strip-like blanket is folded in a
zigzag manner (i.e. like an accordion) can be given.
[0087] An adhesive may be used between each blanket. As the
adhesive, in addition to an acrylic resin, a commercially available
organic adhesive such as a styrene resin, a urethane resin, an
epoxy resin, a phenol resin and an imide resin may be used. Also,
colloidal silica, alumina sol, water glass, an inorganic adhesive
or the like may be used. One or two or more may be selected from
these.
[0088] FIG. 1 is a schematic perspective view of the inorganic
fiber block according to one embodiment of the invention.
[0089] An inorganic fiber block 1 of this embodiment is obtained by
stacking six pieces of blanket 11 which has been cut into an
approximately square shape so that the stacked blanket pieces have
a block-like shape. The pieces of blanket 11 may be adhered with
each other by an adhesive, or sewed or fixed with each other by
means of a tack pin or the like.
[0090] In this embodiment, the pieces of blanket 11 are bundled by
means of a bundle band 13. Further, a lateral plate 12 is used. In
substantially middle of the inorganic fiber block, a support
fitting 14 is provided.
[0091] FIG. 2 is a schematic perspective view of the inorganic
fiber block according to another embodiment of the invention.
[0092] An inorganic fiber block 2 of this embodiment is obtained by
folding a long narrow strip-like blanket 11 in an accordion-like
manner so that the folded blanket has a block-like shape. In this
embodiment, as in the case of the inorganic fiber block 1, the
blanket 11 is bundled by means of a bundle band 13. Further, a
lateral plate 12 is used. In substantially middle of the inorganic
fiber block, a support fitting 14 is provided.
[0093] No particular restrictions are imposed on the number of
blankets to be stacked. The number can be adjusted such that the
stacked blankets have a required shape of a block. In general,
about 1 to 30, preferably 3 to 20, further preferably 5 to 15
blankets are stacked.
[0094] Although no particular restrictions are imposed on the shape
or the size of the block, it is preferred that the block have an
appropriate rectangular parallelepiped shape or an appropriate
cubic shape. As for the size, in general, it is preferred that one
side have a length of about 2.5 cm to 150 cm, preferably 5.0 to 100
cm, and further preferably 5.0 cm to 90 cm.
[0095] The density of the inorganic fiber block may be
appropriately adjusted according to use. Normally, the density of
the inorganic fiber block is 80 kg/m.sup.3 to 300 kg/m.sup.3,
preferably 100 kg/m.sup.3 to 250 kg/m.sup.3, further preferably 100
kg/m.sup.3 to 200 kg/m.sup.3. The density can be adjusted by
adjusting the density of the blanket or by compressing the stacked
body of blankets.
[0096] In the inorganic fiber block of the invention, as in the
above-mentioned embodiments, a member which is commonly used in
this technical field, such as a support fitting, a bundle band (a
PP band or the like), a lateral board (reinforced corrugated
fiberboard or the like), or the like may be used.
[0097] For example, by arranging two or more inorganic fiber blocks
such that they are adjacent with each other, a heat insulating
structural body can be formed. A heat insulating structural body
can be used as a refractory heat insulating material for applying
in an inner wall of various industrial furnaces.
[0098] Between adjacent blocks, a sealing agent may or may not be
filled. As the sealing agent, one or two or more may be
appropriately selected from the inorganic fibers mentioned above,
alumina fibers, mullite fibers, unshaped materials and inorganic
adhesives.
[0099] The heat insulating structural body of the invention can
suppress joint opening between the inorganic fiber blocks or
between blankets constituting the inorganic fiber block.
Specifically, in the heat insulating structural body obtained by
stacking cubic blocks (one side: about 300 mm) in three rows and
three columns, joint opening before and after heating for 24 hours
at 1300.degree. C. is 7.5 mm or less. The details of the evaluation
of the joint opening are described in Examples.
EXAMPLES
Example 1
Preparation of an Inorganic Fiber Block Obtained by Stacking and
Adhesion
[0100] An inorganic fiber having an SiO.sub.2 content of 72 mass %,
a CaO content of 25 mass %, a MgO content of 0.3 mass % and an
Al.sub.2O.sub.3 content of 2 mass % was produced.
[0101] A blanket composed of this inorganic fiber was produced.
This inorganic fiber blanket had a density of 160 kg/m.sup.3 and a
thickness of 50 mm.
[0102] As for the heat shrinkage of the resulting blanket, after
heating at 1000.degree. C. for 8 hours, the heat shrinkage was
-0.1%, and after heating at 1300.degree. C. for 8 hours, the heat
shrinkage was 3.4%.
[0103] The above-mentioned inorganic fiber blanket was cut into a
rectangular shape with a dimension of 280 mm.times.300 mm. Six of
the blanket pieces were stacked. Adjacent blanket pieces were
adhered by an adhesive (acrylic resin).
[0104] The stacked body of the blanket pieces was compressed in the
direction of stacking such that the entire thickness became 275 mm,
whereby an inorganic fiber block was prepared.
[0105] An inorganic fiber having an SiO.sub.2 content of 66 mass %,
a CaO content of 30 mass %, a MgO content of 3 mass % and an
Al.sub.2O.sub.3 content of 1 mass % was produced, and by using the
thus formed fibers, a blanket was produced in the same manner as in
Example 1. The heat shrinkage of this blanket was measured. After
heating at 1000.degree. C. for 8 hours, the heat shrinkage was
-0.3%, and after heating at 1300.degree. C. for 8 hours, the heat
shrinkage was 21.9%. In the test at 1300.degree. C., the blanket
was almost molten.
Example 2
Preparation of an Inorganic Fiber Block Obtained by Stacking and
Sewing
[0106] An inorganic fiber blanket was prepared in the same manner
as in Example 1, except that the density and the thickness of the
inorganic fiber blanket were changed to 136 kg/m.sup.3 and 30 mm,
respectively.
[0107] The inorganic fiber blanket was cut into a 300 mm-square
piece, and 12 of the blanket pieces were stacked. The blanket
pieces were fixed to each other by means of a tack pin, a support
fitting and a band.
[0108] The stacked body of the blankets was compressed in the
direction of stacking such that the entire thickness became 275 mm,
whereby an inorganic fiber block was prepared.
Comparative Example 1
[0109] An inorganic fiber block was produced in the same manner as
in Example 2, except that ceramic fibers having an SiO.sub.2
content of 52 mass % and an Al.sub.2O.sub.3 content of 48 mass %
were used as the inorganic fibers.
[0110] As for the heat shrinkage of the ceramic fiber blanket,
after heating at 1000.degree. C. for 8 hours, the heat shrinkage
was 1.7%, and after heating at 1300.degree. C. for 8 hours, the
heat shrinkage was 4.1%.
Example 3
Preparation of an Accordion-Type Inorganic Fiber Block
[0111] An inorganic fiber block was produced in the same manner as
in Example 1, except that the density and the thickness of the
inorganic fiber blanket were changed to 100 kg/m.sup.3 and 25 mm,
respectively.
[0112] The inorganic fiber blanket that was a 300-width strip was
used. As shown in FIG. 2, the strip was folded into 16 layers in an
accordion-like manner. The blankets were fixed to each other by
means of a support fitting and a band.
[0113] The stacked body of the blankets was compressed in the
direction of stacking such that the entire thickness became 275 mm,
whereby an inorganic fiber block was prepared.
Comparative Example 2
[0114] An inorganic fiber block was produced in the same manner as
in Example 3, except that the same ceramic fibers as those in
Comparative Example 1 were used as the inorganic fibers.
[0115] As for the inorganic fiber blocks prepared in the Examples
and Comparative Examples mentioned above, the following heating
test was conducted.
[0116] As shown in FIG. 3(a), the inorganic fiber block 1 produced
in each example was prepared in a quantity of 9, and these blocks
were arranged in three rows and three columns in such a manner that
almost no opening (joint opening) was formed between the blocks,
whereby heat insulating structural bodies were obtained. The blocks
were arranged such that the inorganic fiber blankets were stacked
vertically. In FIG. 3, a vertical line shown in the inorganic fiber
block 1 indicates the interface between inorganic fiber
blankets.
[0117] This heat insulating structural bodies were heated for 24
hours at 1000.degree. C., 1200.degree. C. and 1300.degree. C. The
heat shrinkage of each block before and after the heating was
measured. The heat shrinkage was obtained by the following formula
taking the length of the block before heating as X mm and the
length of the block after heating as Y mm.
Heat shrinkage (%)={(X-Y)/X}.times.100
[0118] The measurement was conducted in the stacking direction of
the inorganic fiber blankets and in the direction orthogonally
crossing the stacking direction (referred to as the "longitudinal
direction"). Heat shrinkage was measured for the 9 blocks, and the
average value was taken as the heat shrinkage. The results are
shown in Tables 1 and
[0119] As shown in FIG. 3(b), by heating a heat insulating
structural body, a joint 21 is formed. Evaluation was made on the
generation of such joint. Specifically, the heat insulating
structural bodies were heated for 24 hours at 1000.degree. C.,
1200.degree. C. and 1300.degree. C. The dimension of the joint 21
before and after the heating was measured. As for the dimension of
the joint 21, of the joints formed between the blocks being stacked
up and down, the size of a joint which has the largest size in the
vertical direction was measured by means of a foot measure. The
joint dimension was measured at 6 locations, and the average value
was taken as the dimension of the joint.
[0120] The dimension of the joint was obtained by the following
formula taking the length of the joint after heating as X mm and
the length of the joint before heating as Y mm.
Dimension of joint (mm)=X-Y
TABLE-US-00001 TABLE 1 Shrinkage in the stacking direction (%) Test
temperature 1000.degree. C. 1200.degree. C. 1300.degree. C. Example
1 0.3 0.7 1.7 Example 2 0.3 0.9 2.1 Example 3 0.3 0.8 1.7 Com. Ex.
1 0.9 1.7 2.2 Com. Ex. 2 0.8 1.7 2.3
TABLE-US-00002 TABLE 2 Shrinkage in the longitudinal direction (%)
Test temperature 1000.degree. C. 1200.degree. C. 1300.degree. C.
Example 1 0 0.7 1.5 Example 2 0.3 1.0 1.7 Example 3 0.4 1.2 1.8
Com. Ex. 1 0.8 1.7 2.3 Com. Ex. 2 0.9 1.7 2.2
TABLE-US-00003 TABLE 3 Dimension of joint (mm) Test temperature
1000.degree. C. 1200.degree. C. 1300.degree. C. Example 1 0.7 2.7
5.5 Example 2 1.2 3.2 5.8 Example 3 0.7 3.0 4.2 Com. Ex. 1 2.8 4.6
9.5 Com. Ex. 2 2.6 4.9 7.8
[0121] As for the heat insulating structural body formed of the
inorganic fiber blocks prepared in Example 2, the photograph of the
structural body before heating is shown in FIG. 4(a) and the
photograph of the structural body after heating at 1300.degree. C.
for 24 hours is shown in FIG. 4(b).
[0122] As for the heat insulating structural body formed of the
inorganic fiber blocks prepared in Comparative Example 1, the
photograph of the structural body before heating is shown in FIG.
5(a) and the photograph of the structural body after heating at
1300.degree. C. for 24 hours is shown in FIG. 5(b).
[0123] As for the heat insulating structural body formed of the
inorganic fiber blocks prepared in Example 3, the photograph of the
structural body before heating is shown in FIG. 6(a) and the
photograph of the structural body after heating at 1300.degree. C.
for 24 hours is shown in FIG. 6(b).
[0124] As for the heat insulating structural body formed of the
inorganic fiber blocks prepared in Comparative Example 2, the
photograph of the structural body before heating is shown in FIG.
7(a) and the photograph of the structural body after heating at
1300.degree. C. for 24 hours is shown in FIG. 7(b).
[0125] From the photographs shown in FIGS. 4 to 7, it could be
confirmed that the heat insulating structural body formed of the
inorganic fiber blocks of the invention hardly suffered from
generation of joint opening after heating as compared with those in
Comparative Examples.
INDUSTRIAL APPLICABILITY
[0126] The inorganic fiber block of the invention can be used as a
refractory heating insulating material for lining of various
industrial furnaces or the like.
[0127] Although only some exemplary embodiments and/or examples of
this invention have been described in detail above, those skilled
in the art will readily appreciate that many modifications are
possible in the exemplary embodiments and/or examples without
materially departing from the novel teachings and advantages of
this invention. Accordingly, all such modifications are intended to
be included within the scope of this invention.
[0128] The contents of the above-mentioned documents and the
specification of Japanese patent application on which Paris
priority is claimed are herein incorporated by reference in its
entirety.
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