U.S. patent number 3,652,317 [Application Number 05/033,794] was granted by the patent office on 1972-03-28 for method of producing substrate having a particulate metallic coating.
This patent grant is currently assigned to S.A.E.S. Getters S.p.A.. Invention is credited to Paolo Della Porta, Tiziano A. Giorgi, Bruno Kindl, Mario Zucchinelli.
United States Patent |
3,652,317 |
Della Porta , et
al. |
March 28, 1972 |
METHOD OF PRODUCING SUBSTRATE HAVING A PARTICULATE METALLIC
COATING
Abstract
A method of producing a substrate having a particulate coating
of high surface area to mass ratio, said method comprising in
sequence the steps of: I. disposing particles between a substrate
and an intermediate body wherein the particles are harder than the
substrate; and the intermediate body is softer than the particles
but is harder than the substrate; Ii. compressing the substrate and
intermediate body, with particles therebetween whereby the
intermediate body pushes the particles into the substrate; and Iii.
removing the intermediate body from the particles leaving them
embedded in the substrate. The coating substrates produced by the
process of the present invention find utility as catalytic devices
to accelerate or retard chemical reactions, as getter devices to
sorb residual gases in closed vessels such as electronic tubes, and
with further processing as capacitors.
Inventors: |
Della Porta; Paolo (Milan,
IT), Giorgi; Tiziano A. (Milan, IT), Kindl;
Bruno (Milan, IT), Zucchinelli; Mario (Milan,
IT) |
Assignee: |
S.A.E.S. Getters S.p.A. (Milan,
IT)
|
Family
ID: |
21872470 |
Appl.
No.: |
05/033,794 |
Filed: |
May 1, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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527906 |
Feb 16, 1966 |
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Current U.S.
Class: |
427/194;
29/DIG.32; 29/423; 29/527.7; 252/181.7; 419/66; 419/69; 427/81;
427/123; 427/198; 428/555; 428/557; 428/614; 428/653;
502/527.24 |
Current CPC
Class: |
C23C
24/02 (20130101); Y10T 428/12486 (20150115); Y10T
428/1209 (20150115); Y10T 428/12076 (20150115); Y10T
29/49991 (20150115); Y10S 29/032 (20130101); Y10T
29/4981 (20150115); Y10T 428/12757 (20150115) |
Current International
Class: |
C23C
24/00 (20060101); C23C 24/02 (20060101); B05b
007/14 (); B44c 001/06 (); B44c 001/08 () |
Field of
Search: |
;29/191.2,420,423,527.7,DIG.32 ;264/111 ;117/1M,31,13R,22,16R
;252/181.7 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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5,774 |
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Dec 1915 |
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GB |
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198,085 |
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Jun 1967 |
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SU |
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Primary Examiner: Campbell; John F.
Assistant Examiner: Reiley, III; Donald C.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. application Ser.
No. 527,906 filed Feb. 16, 1966, now abandoned, the disclosure of
which is incorporated herein by reference.
Claims
We claim:
1. A mechanical method of producing a metallic substrate having a
metallic particulate coating of high surface area to mass ratio,
said method comprising in sequence the steps of:
I. disposing metallic particles between the metallic substrate and
an intermediate body wherein the particles are harder than the
substrate; and the intermediate body is softer than the particles
but is harder than the substrate;
Ii. employing a compressing means in order to compress the
substrate and intermediate body, with particles therebetween
whereby the intermediate body pushes the particles into the
substrate; and
Iii. removing the intermediate body from the particles leaving them
embedded in the substrate.
2. The process of claim 1 wherein the particles are placed on the
substrate, and wherein an additional amount of particles are placed
on a second intermediate body which is on the side of the substrate
opposite the first intermediate body in order to produce a
structure having particles embedded on both sides of the
substrate.
3. The process of claim 1 wherein the particles are susceptible to
cold welding to one another and to the substrate.
4. The process of claim 1 wherein the particles are of a size such
that they pass through a U.S. standard screen of 10 mesh per
inch.
5. The process of claim 1 wherein the substrate has a Vickers
hardness of 10 to 200 kg./mm..sup.2.
6. The process of claim 1 wherein the intermediate body has a
Vickers hardness of 100 to 300 kg./mm..sup.2.
7. The process of claim 1 wherein the metallic particles have a
Vickers hardness of 200 to 800 kg./mm..sup.2.
8. The process of claim 1 wherein the intermediate body has a
Vickers hardness at least 50 kg./mm..sup.2 less than the
particles.
9. The process of claim 1 wherein the substrate has a Vickers
hardness at least 40 kg./mm..sup.2 less than the intermediate
body.
10. A mechanical method of producing a structure of high surface
area having particles of metal embedded in a metallic substrate,
said method comprising in sequence the steps of:
I. disposing loose particles of metal between the metallic
substrate and a work hardenable intermediate body wherein the
particles are harder than the substrate; and the intermediate body
is softer than the particles but is harder than the substrate;
Ii. passing the substrate and intermediate body, with loose
particles therebetween, between the nip of two rotating rolls
wherein the distance between the rolls in less than the combined
thickness of the substrate the intermediate body and the mass of
loose particles; whereby the intermediate body undergoes plastic
deformation with the concurrent work hardening while effectively
pushing the particles into the substrate without substantially
reducing the total surface area of the particles; and
Iii. removing the intermediate body from the particles leaving them
partially embedded in the substrate.
11. The process of claim 1 wherein the distance between the
surfaces of the rolls is sufficiently small that the intermediate
body and the substrate both exhibit plastic deformation, but is not
so small as to substantially reduce the total surface area of the
particulate material.
12. A mechanical method of producing a getter device having
particles of a non-evaporable getter metal embedded in a metallic
substrate, said method comprising in sequence the steps of:
I. disposing particles of a non-evaporable getter metal between the
metallic substrate and an intermediate body wherein the particles
are harder than the substrate and the intermediate body is softer
than the particles but is harder than the substrate;
Ii. passing the substrate and intermediate body, with particles
therebetween, between the nip of two rotating rolls whereby the
intermediate body pushes the particles into the substrate; and
Iii. removing the intermediate body from the particles leaving them
embedded in the substrate.
13. The process of claim 12 wherein the non-evaporable getter
material is a zirconium-aluminum alloy.
14. The process of claim 13 wherein the zirconium-aluminum alloy
contains 5 to 30 weight percent aluminum balance zirconium.
15. A mechanical method of producing a getter device having
particles of a non-evaporable getter metal embedded in a metallic
substrate, said method comprising in sequence the steps of:
I. disposing loose particles of a non-evaporable getter metal
between the metallic substrate and an intermediate body wherein the
particles are harder than the substrate and the intermediate body
is softer than the particles but is harder than the substrate and
is in a work-hardenable condition;
Ii. passing the substrate and intermediate body, with loose
particles therebetween, between the nip of two rotating rolls
wherein the distance between the rolls is less than the thickness
of the substrate and intermediate body with loose particles
therebetween; whereby the intermediate body undergoes plastic
deformation with concurrent work hardening while effectively
pushing the particles into the substrate without substantially
reducing their surface area; and
Iii. removing the intermediate body from the particles leaving them
partially embedded in the substrate.
16. A mechanical method of producing a getter device having
particles of a non-evaporable getter metal embedded in a metallic
substrate, said method comprising in sequence the steps of:
I. disposing loose particles of a non-evaporable getter metal
consisting essentially of an alloy of 13 to 18 weight percent
aluminum balance zirconium between the substrate and a work
hardenable intermediate body wherein the intermediate body has a
Vickers hardness at least 100 kg./mm..sup.2 less than the particles
and the metallic substrate has a Vickers hardness at least 80
kg./mm..sup.2 less than the intermediate body;
Ii. passing the substrate and intermediate body, with loose
particles therebetween, between the nip of two rotating rolls
wherein the distance between the rolls is less than the thickness
of the substrate and intermediate body with loose particles
therebetween; whereby the intermediate body undergoes plastic
deformation with concurrent work hardening while effectively
pushing the particles into the substrate without substantially
reducing their surface area; and
Iii. removing the intermediate body from the particles leaving them
partially embedded in the substrate.
Description
Processes for producing substrates having thereon a particulate
metallic coating are notoriously well known in the art. However,
most prior processes require the use of a binder to hold the metal
particles to the substrate. In an effort to avoid the use of a
binder it has been suggested to place the metal particles on the
substrate to be coated and then pass these between the nip or
rotating rolls to embed the particles in the surface of the
substrate. However, such processes suffer from a number of
disadvantages. One disadvantage is the wear of the rolls which is
especially acute when the metal particles are hard. This wear of
the rolls necessitates their frequent replacement with a concurrent
expense. However, an even more troublesome effect of the wear of
the rolls is their inability to exert an even pressure on the
particles with the result that only a portion of the substrate is
coated or alternatively an uneven coating results. Another
disadvantage of the use of rolls in contact with metal particles is
that the action of the rolls on the particles substantially reduces
their total surface area. This is especially troublesome when the
desired coated substrate is one preferably having a high surface
area to mass ratio of the coating particles.
Many of the prior processes require the use of superambient
temperatures increasing expense and the necessity for elaborate
controls. Many other prior processes do not produce a coated
substrate having physical characteristics rendering it suitable for
the intended use. Examples of such physical characteristics include
among others a high heat transfer coefficient between the metal
particles and the substrate, a resistance of the coated substrate
to mechanical shocks, to ultrasonic vibrations, and to thermally
induced stresses such as are caused by heating the coated substrate
to high temperatures such as those of 1,000.degree. C. and higher.
Many of these coated substrates lack freedom from loose particles
which may be created by separation of particles of the metallic
coating from the substrate.
Because of the above described disadvantages such processes have
been found unsuitable for the production of getter devices,
catalytic devices, and capacitors.
It is therefore an object of the present invention to provide an
improved method for producing a substrate having a particulate
metallic coating thereon which method is substantially free of one
or more of the disadvantages of prior methods.
Another object is to provide an improved method which does not
require the use of a binder.
A further object is to provide an improved method which can be
practiced at ambient temperatures.
A still further object is to provide an improved method employing
rolls which are not subject to wear.
Yet another object is to provide an improved method for producing a
coated substrate such as those suitable to be used as catalytic
devices, getter devices, or capacitors.
Still another object is to provide an improved method for producing
a coated substrate which has the above described desirable physical
characteristics.
Still another object is to provide a method for producing an
improved getter device having a high surface area to mass ratio of
the getter metal and which is free of loose particles.
Additional objects and advantages of the present invention will be
apparent to those skilled in the art by reference to the following
detailed description thereof and drawings wherein:
FIG. 1 is a cross-sectional view with an enlargement of about 300
diameters of a coated substrate produced by the method of the
present invention wherein the coating has a thickness approximately
equal to one particle diameter and;
FIG. 2 is a cross-sectional view with an enlargement of about 300
diameters of a coated substrate produced by the method of the
present invention wherein the particulate metallic coating has a
thickness of approximately 3 particle diameters, this figure being
a drawing corresponding to a microphotograph representing the
structure taken along line 2--2 of FIG. 4 and;
FIG. 3 is a cross-sectional view with an enlargement of about 1,300
diameters of a coated substrate produced by the method of the
present invention wherein the original substrate comprised a hard
base having a softer metallic coating thereon and;
FIG. 4 is a schematic representation of an apparatus suitable for
practicing the method of the present invention.
In accordance with the present invention there is provided a method
of producing a substrate having a particulate metallic coating of
high surface area to mass ratio and usually greater than 2
cm..sup.2 /mg. The method comprises in sequence the steps of:
I. disposing metal particles between a substrate and an
intermediate body wherein the particles are harder than the
substrate; and the intermediate body is softer than the particles
but is harder than the substrate;
II. compressing the substrate an intermediate body, with particles
therebetween whereby the intermediate body pushes the particles
into the substrate; and
III. removing the intermediate body from the particles leaving them
embedded in the substrate.
Referring now to the drawings and in particular to FIG. 1 there is
shown a substrate 1 of stainless steel having an upper coating 2
and a lower coating 3 comprising metal particles of a zirconium
alloy partially embedded in the surface of the substrate 1. FIG. 2
shows an iron substrate 4 having coatings 5 and 6 wherein these
coatings 5 and 6 have a total thickness which is approximately
equal to three times the diameter of a single particle. As can be
seen the metal particles in contact with the substrate 4 are
partially embedded therein whereas the other particles are attached
to one another or held in place by small cold microwelds (not
shown) between the individual particles. FIG. 3 discloses a base 7
of iron having aluminum thereon which actually forms the substrate
8. The particles forming the coating 9 are partially embedded in
this substrate 8.
Referring now to FIG. 4 there is shown an apparatus 10 suitable for
practicing the process of the present invention. In the practice of
this process loose metal particles 11 and 12 are disposed
respectively between a substrate 13 and an upper intermediate body
14 and the substrate 13 and a lower intermediate body 15. Most
conveniently the metal particles 11 are placed on the substrate 13
whereas the metal particles 12 are placed on the lower intermediate
body 15 to form a composite structure which is passed between the
nip of two rolls 16 and 17 rotating respectively in the direction
of arrows 18 and 19. The apparatus 10 is provided with means for
maintaining the distance between the rolls less than the combined
thickness of the substrate 13, particles 11 and 12, and
intermediate bodies 14 and 15. In the preferred embodiment wherein
the intermediate bodies 14 and 15 are work-hardenable the rolls 16
and 17 press the intermediate bodies 14 and 15 with a force such
that the intermediate bodies 14 and 15 undergo plastic deformation
with concurrent work-hardening while effectively pushing the metal
particles 11 and 12 into the substrate 13 without substantially
reducing the total surface area of the metal particles 11 and
12.
The entire composite structure then leaves the nip between rolls 16
and 17 with the intermediate bodies 14 and 15 adhering to the metal
particles 11 and 12 which are embedded in the substrate 13 and are
welded to one another by cold microwelds. The intermediate bodies
14 and 15 are then removed leaving behind the coated substrate 20.
By virtue of the above described relationship in hardness between
the metal particles 11 and 12, the substrate 13 and the
intermediate bodies 14 and 15 the metal particles 11 and 12 adhere
substantially completely to the substrate 13 rather than to the
intermediate bodies 14 and 15. This relationship in hardness is
critical to the successful practice of the method of the present
invention. For example, if the intermediate bodies 14 and 15 are of
the same hardness as the substrate 13 the particles 11 and 12 will
be randomly embedded in the substrate 13 and the intermediate
bodies 14 and 15. On the other hand if the substrate 13 is harder
than the intermediate bodies 14 and 15 the particles will
preferentially embed themselves into the intermediate bodies 14 and
15. If the particles 11 and 12 are softer than either the
intermediate bodies 14 and 15 or the substrate 13 they will be
plastically deformed losing their surface area and will not become
embedded in the substrate 13.
The metal particles can be of widely varying particle sizes but are
generally those which pass through a U.S. standard screen of 10
mesh per inch and are preferably those which pass through a U.S.
standard screen of 100 mesh per inch and are retained on a screen
of 600 mesh per inch.
Broad and preferred ranges of Vickers hardness for the intermediate
body, the metallic particles and the substrate are given in the
following table:
Vickers Hardness Component Broad Preferred Example Range Range
(kg/mm.sup.2) (kg/mm.sup.2) (kg/mm.sup.2) Intermediate body 10-600
100-300 180 Particles 100-.infin. 200-800 400 Substrate 1-400
10-200 90
The values given in this table are non-limiting in the sense that
specific values within the above ranges must be chosen while
maintaining the herein-described hardness relationship. In a
preferred embodiment of the present invention the intermediate body
has a Vickers hardness at least 50 and preferably at least 100
kg./mm..sup.2 less than the particles; and the substrate has a
Vickers hardness of at least 40 and preferably at least 80
kg./mm..sup.2 less than the intermediate body.
The particles of the metal to be embedded in the substrate are
chosen with respect to the desired end use of the product. Thus if
a getter device is desired particles of a non-evaporable getter
metal are employed whereas if a catalytic device is desired
particles of a catalyst metal are chosen. Finally if a capacitor is
desired metallic particles are employed which are electrically
conductive. In the broadest aspect any prior known non-evaporable
getter metal can be employed in the production of getter devices.
Examples of suitable getter metals include among others zirconium,
titanium, tantalum, niobium, vanadium mixtures thereof and alloys
thereof with one another and with other metals which do not
materially reduce the gas sorptive capacity of these getter metals.
The preferred getter metal is an alloy of 5 to 30 and preferably 13
to 18 weight percent aluminum balance zirconium. When it is desired
to produce catalytic devices the metal particles are those which
have heretofore been found to catalyze the particular chemical
reaction. Examples of suitable catalytic materials include among
others platinum, zirconium, vanadium, and tantalum. Examples of
electrically conductive particles suitable for producing capacitors
include among others iron, silver, copper and preferably
aluminum.
The substrate and the intermediate bodies can be of any metal which
has the herein described hardness relationship. Examples of
suitable metals include among others soft iron, steel, and
stainless steel. It must be emphasized that the chemical nature of
the elements making up the alloys employed as substrates and
intermediate bodies is not critical. In fact it is conceivable that
alloys of identical chemical composition can be employed as both
provided that they have differing hardnesses. As is apparent to
those skilled in the art differing hardnesses can be imparted by
conventional metallurgical techniques such as heat treatment, cold
rolling and the like.
The invention is further illustrated by the following examples in
which all parts and percentages are by weight unless otherwise
indicated. These non-limiting examples are illustrative of certain
embodiments designed to teach those skilled in the art how to
practice the invention and to represent the best mode contemplated
for carrying out the invention.
EXAMPLE 1
This example illustrates the method of the present invention
wherein the resulting structure is a getter device.
Referring to FIG. 4 finely divided particles of a non-evaporable
getter alloy available from SAES Getters S.p.A. as "St 101" is
placed on an iron substrate 0.010 inches thick. The St 101 is an
alloy of 16 percent aluminum, balance zirconium and passes through
a screen of 100 mesh per inch and is retained on a screen of 600
mesh per inch. The particles of St 101 in their sheet form exhibit
a Vickers hardness of 400 kg./mm..sup.2. The substrate has a
Vickers hardness of 90 kg./mm..sup.2. A single intermediate body of
iron having a Vickers hardness of 180 kg./mm..sup.2 and a thickness
of 0.010 inches is placed on top of the metal particles and the
resultant composite passed between the nip of two rotating rolls.
The intermediate body is then removed leaving the particles
embedded in the substrate.
EXAMPLE 2
This example illustrates the process of the present invention
wherein the resultant product is a catalytic device.
The procedure of Example 1 is repeated except that the particles of
St 101 are replaced with platinum and the substrate is replaced
with one of aluminum having a Vickers hardness of 50 kg./mm..sup.2
and the intermediate body is replaced by one of iron having a
Vickers hardness of 170 kg./mm..sup.2. The resultant catalytic
device functions satisfactorily to increase the reaction rate of a
chemical reaction.
Although the invention has been described in considerable detail
with reference to certain preferred embodiments thereof, it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention as described above and as
defined in the appended claims.
* * * * *