JPH0413866A - Manufacture of open-cell structure - Google Patents

Abstract

PURPOSE: To rapidly and economically produce an open cellular structure having a high surface area ratio by depositing part of the required amt. of metals by arc evaporation on a network synthetic resin substrate and further depositing the remaining metals by spray evaporation thereon, then subjecting the substrate to pyrolysis and sintering.

CONSTITUTION: The thermally decomposable substrate made of the network synthetic resin subjected to openwork is coated with the metals, etc., by arc vapor deposition. The arc vapor deposition is executed by arranging an electrode made of the metals, etc., in proximity to the substrate, reducing a pressure and evaporating the electrode by an arc discharge. At this time, a part of the whole requirement amt. is deposited by evaporation. Then, the remaining metal is spray deposited by evaporation with spray on the coating describe above. The substrate is thereafter removed by pyrolysis to form an openwork framework consisting of the metals, etc. This framework is then sintered to aggregate. The open cellular structure having the high surface area/volume ratio is thus obtd.

COPYRIGHT: (C)1992,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing openwork bodies, i.e. bodies with a high surface area, volume ratio, and in particular a high degree of internal 6. Concerning structures of this type with roughness and thus surface activity.6 The present invention relates in particular to structures of this type made from metals, but also semiconductor or ceramic structures and similar methods. and are particularly intended to be self-supporting and are composed of the latter materials, which contain a certain content of the specified substance per unit area or volume of the structure to be manufactured. This relates to a structure that must be zero.

The invention further relates to battery electrodes produced from structures of this type, battery products formed from or utilizing a single TI3A of this type, and batteries 111
BACKGROUND OF THE INVENTION U.S. Co-pending Application No. 0772-8 , No. 886 (Japanese Patent Application No. 64 15441 +1), the inventor explained that fence-like metal structures have hitherto been produced for a number of purposes. For example, structures of this type may be conductive networks suitable for use as supports in batteries, where active substances are applied and held in place by supports in brackets, or It can be provided that it is formed on the support. This type of porous IFI structure can also be used as a sieve, screen, etc. ``They can be used as catalytic materials and can promote reactions between various phases. Generally, they have been characterized by having a relatively high surface area per unit volume or weight of their support.

Inventor's U.S. co-pending application No. 1) 7/'208.88
Prior to the method described in No. 6, materials of this type were produced in a variety of ways. These include chemical vapor deposition, electroless plating, and even fiber! Electrodeposition onto it-like supports, such as non-woven fabrics or needled fabrics, is included. The fibrous support can be destroyed by pyrolysis, leaving behind the network structure wood.

Further, the above U.S. co-pending application notes that these systems have various drawbacks and that, in general, these systems have a large number of sharp edges or angular surfaces or irregularities that are It has been pointed out that it is desirable, especially if a specific activity is the primary function of the fabricated structure.

Inspired by the above-mentioned co-pending U.S. Application No. 07/208, 8.
In No. 86, the inventor proposes that a structure of this kind, in particular one made of metal and having a high porosity, supports a continuum of reticular metallic phase and an openwork continuum in σ. A manufacturing method utilizing arc evaporation obtained using a pyrolyzable foam structure as a body is described.

Essentially, the method according to that application involves low-temperature arc deposition on a pyrolysable openwork structure, preferably a pyrolysable foam consisting of a synthetic resin material.

The method is to produce a reticulated tree by applying a coated lug of at least one material, generally a metal, but also a semiconductor or a ceramic. In this way, the coating produced on the support will produce a transparent structure, which will persist against thermal decomposition! In other words, the coated product undergoes pyrolysis (i.e., it loses one of the plastic supports while producing a web of metal; for example, this is then sintered to make it mechanically stable). A highly porous and branched structure with a cohesive and irregular surface could be obtained.

In class 1 and higher low temperature arc deposition processes as described in earlier co-pending applications and patents, the rate of deposition of a metal or other material is the rate at which the material is deposited from a vapor state onto a support. It is a function of speed. Although this speed varies depending on the metal or substance, it is nevertheless relatively slow, and one foam, one foam, and one resin
It is not unusual for a deposition time of 60 g per square foot to be deposited on a surface and inside the surface to require 1+f hours or even more [objectives of the invention]. The primary object is porous transparent ellipsoids, U.S. Application No. +47 2I', +8.88
As a result of extending the principle of No. 6, it is possible to create a manufacturing method that can produce products that are approximately the same in quality as those obtained by the method of this application at a faster rate.

It is an object of the present invention to provide an improved method for producing relatively quickly metal porous openwork 3ia bodies with high metal content per unit area or volume.

Another object of the present invention is to provide an improved method for manufacturing article 4.1 having a high surface area to volume ratio that is more economical than previous methods.

Furthermore, it is an object of the present invention to provide an improved method for producing battery electrodes with high activity and mechanical strength.

Furthermore, another object of the present invention is an improved reticulated or fretwork structure, particularly a metal tR structure, which can be utilized for a variety of purposes and which can be very economically remold and SUMMARY OF THE INVENTION 1 The inventor has now discovered the following. It is US EIJi Application No. 07 by the present inventor. '21:18, No. 886, at least some of the materials to be deposited by low-temperature arc deposition can be applied in at least one step, and optionally in multiple steps, in a spray deposition process. This means that they can be replaced by the same substance.

As long as the fused material is in contact with the coating applied by cold arc deposition, whether before or after subsequent sintering, the resulting metal structure wood will be similar to that of bodies prepared exclusively by cold arc deposition. It is completely unexpected that it will have the desired one-kiness property.

Advantageously, the spray-deposited metal is applied to the support or to a previous arc-deposited coating, or is coated with an arc-deposited coating, with a binder forming a pyrolyzable material, especially a foam. The objective is to provide a thermally decomposable material that may be the same as the thermally decomposable material that is used.

If the spray deposition operation is carried out using a mixture of metal and pyrolyzable synthetic resin, the pyrolysis step should be carried out subsequent to the application of the spray deposited layer.

The pyrolysis process in the latter case may, of course, be identical to the pyrolysis process for removing the foam structure 1 wood, as described in US application Ser. Step 1 is similarly utilized here.

The metal flake process, which utilizes a metal powder that has been ground into pieces, particularly sharp edges, uses the metal powder as a support and eventually an arc-deposited layer to fill the pores of the arc-deposited layer with metal. It is quite unexpected that it can be used for filling and bonding without eliminating the openwork structure, and that this can be used even if an arc-deposited coating is applied, and a spray-deposited coating is performed. There is.

US time (related application No. 07/CA8.88) by the inventor
As described in No. 6, the support is an openwork foam plastic capable of undergoing low temperature pyrolysis;
This may then be pretreated, for example in a surface active field, for example in an electron beam field, or by exposure to solvent vapor, in order to promote the adhesion of the material to be applied.

The openwork foam plastic support is manufactured in an arc evaporation process by having a pair of electrodes close to the support through the entire thickness of the support, while connecting a direct current source between the electrodes;
By bringing one electrode into and out of contact with the other, a low voltage, high current arc is created between the electrodes, and the electrodes carrying the coating material are rendered relatively cathodic. Surprisingly, the support material is not destroyed or melted by this deposition method, even though it is very sensitive to heat.

The low temperature arc evaporation coating is preferably carried out in a vacuum space maintained at a pressure of less than 11)-month·L, and preferably within the range of 1++-3-H'l-6 Torr. This space may contain an inert or reactive gas atmosphere, the latter being the case when depositing arsenic materials such as semiconductors or ceramics. The power supply applies a voltage of 20-+50 volts between the electrodes. and the power supply should be capable of delivering 4 (+-51) amperes.

At least one of the electrodes is at least one of the substances to be deposited.
It should be composed of an element, for example nickel, and it is advantageous to have both poles composed of nickel, which is progressively evaporated to change the metal into a vapor state by cathodic arc discharge. As a result, spray vapor deposition coating, in which the metal is vapor-deposited on the support using the vapor, can be performed with a spray gun etc. commonly used when spraying polyurethane foam, and of course when used, .

The means is used to supply metal particles to the sprayed foam.

Advantageously, about 20-25°6 of the metal deposited and in the final product should be constituted by the metal applied by low temperature arc deposition in one or more coatings, whereas The remaining 75-80% is comprised of spray deposited 15" I powder metal.

The powdered metal may have a particle size of 3 to 20 microns.

The foam used preferentially as a support should be a material that can be thermally decomposed relatively easily. The inventor has found that a 11 polyurethane foam of reticulated flexible ester tights provides effective results and that a foam mixed with this 19 powder as a binder can have the same composition. By foaming, the pore τ1 method can be controlled over a wide range, 10-100 pores per linear inch. This product can have a density that is not related to pore size, and it may be about 1,75 Bond, 1 cubic foot, which exceeds this range.

Although the thickness of the foam to be coated will depend largely on the thickness of the product to be prepared, what is entirely unexpected is that the two-phase coating process of the present invention results in a completely unexpected R
In this way, it is possible to apply a uniform deposited layer of material to a substrate of considerable thickness. For example, 1
Foams can be coated with thicknesses ranging from 1I11 to 3 hm or more.

Preferably, the foam is of the type described in U.S. Pat. No. 4,670,477 and prepared by the method described in that patent or U.S. Pat. No. 4,656,192. It is.

A polyvinyl chloride reticulated foam in which the polyurethane foam described above is coated with the polysalt 1-hibinyl to retain its open pore structure can also be used. The inventors may also use polyurethane foams such as those described in 1. Permanently compressed reticulated foams that are prestressed to increase density.

The above-mentioned US Intermediate Time 1 Series Application No. 1 Noah 7.2+) 8.88
As in No. 6, following sintering, the open cell network can be compressed to a desired thickness that is less than the initial thickness of the metal support and support foam. The compaction process thins the sheet of structure to be produced, so that the total density increases.6 To the best of the results that we can measure, we have used gas flow through a transverse body as a test, This compaction allows for the preparation of thin catalyst sheets, such that the porosity of the compacted crossbody is not substantially reduced compared to the porosity of the structure prior to compaction.

Although it is preferred that the spray-deposited material be the same as the material applied by cold arc deposition, the spray-deposited material may be different as long as it is compatible with the layers to be present thereon, and their During this period, no rK eclipse phenomenon or thermal deformation phenomenon occurs.

The method has been found to be particularly suitable for the production of nickel electrical W structures, especially for use in nickel-cadmium and alkaline batteries.

However, it would also be advantageous to provide structures other than nickel or structures that combine nickel and other metals in various proportions. It has been found by the inventors that it is possible to select compositions of metals deposited by low temperature arc evaporation with relative ease, for example, by a variety of methods. One approach is to provide a sacrificial electrode with the composition to be deposited so that it is preferentially evaporated. Ike's approach utilizes the polarity switching technique of the aforementioned application so that the electrodes establish a cathodic arc from which evaporation occurs selectively. In addition to the arc-igniting electrode, it is possible to provide a light source, which is vaporized by the arc. The other electrode may be made of a metal that should be alloyed with nickel, which is one of the arc ignition electrodes.

Pyrolysis occurs best in the presence of air in an electric furnace, which can be fed at a rate sufficient to allow combustion and thermal decay of the polyurethane foam. There is no residue or only a small amount of residue is present.

For sufficiently thin supports, for example coatings on the order of a few millimeters, a temperature of about 351)'C1 and a residence time of about 2 minutes are sufficient. - Longer layer times and higher temperatures are applicable for thicker coatings or supports.

The sintering is preferably carried out in a vacuum furnace, with the exclusion of oxygen, in an inert or reducing gas atmosphere at a temperature below the melting point of the metal used, but this does not sinter the metal without applying an applied pressure of 1". For example, in the case of nickel, nickel-cadmium or nickel for alkaline batteries, in the manufacture of battery electrodes, temperatures ranging from 750°C to 125°C can be used.
θ° C. and a time on the order of 15 minutes can be used.

For reference to IJF applications with nickel and other metals,
Nickel and other metals which have been found to be advantageous in combination with nickel for various purposes, e.g. in catalyst systems, batteries etc., e.g.
Combinations of weight 9≦ may be included. Such other metals may include, for example, cobalt.

It will be appreciated that the combination of arc evaporation coating and powder spraying can be carried out in a variety of ways, depending, for example, on the thickness of the foam support to be coated.

For example, for a support having a thickness on the order of 1/16th of an inch of the composition described above, there is no need to coat both sides of the support since penetration of the coating through the foam is practically uniform. .

For supports having a thickness of 178 or more inches,
Advantageously, the arc deposition coating is carried out from both sides.

Although the powder spray need only be applied to one side, it has often been found advantageous to apply the powder spuffle to both sides of the coated article or support.

Application of the powder and coating can be done in any order and with a wide variety of variations depending on the desired layer deposition.

Preferred implementation MPAs of the invention include:

(a) Powder deposition on a foamed support followed by pyrolysis and sintering of the arc deposited coating.

(b11 Foam supported arc evaporation coaching, this is part 5
>Things that are not deposited, continue to undergo thermal decomposition and sintering.

(c) arc evaporation coating of a foamed support, followed by powder coating, followed by further arc evaporation coating, pyrolysis and sintering; and (d) arc evaporation coating;
This is followed by pyrolysis, powder deposition and sintering.

The objects, features, and effects of the above and ponds of the present invention are attached in Appendix 1.
It will become clearer from the following description with reference to one drawing.

DETAILED DESCRIPTION Referring initially to FIG. It will be appreciated that the six-structure interconnected pores are designated by 52 and are comprised of structure 5I, and structure 5! Sintered on top is powder dust 53 when applied with a tan binder.
However, the binder will be removed in the pyrolysis process.

In the method sequence of FIG. 1, designated by the reference numeral 11, a polyurethane foam is used, as indicated at 11, and as described in the aforementioned U.S. application and in FIG. A related first step 12 is a low temperature arc deposition as shown. Further, as shown with respect to FIG. 1 of the present application, the metal-coated product is subjected to pyrolysis at 13 and finally sintered at 15, and further rolled or compacted at 16. Cooling and winding of objects 1
You may continue at 9. Sequence 10 and U.S. Application No. 07/2+ by et al., which is hereby incorporated by reference.
The difference with the method described in connection with Figure 1 of No. 8.886 is the metal spray step 14, where pyrolysis is followed and the metal spray is applied to a particle size 3-2υ in an expandable liquid polyurethane binder. The polyurethane may be made of micron nickel particles, but this polyurethane can be eliminated in the sintering step 15.

In FIG. 2 of the method sequence 20, a metal spray is applied directly to the foam 21 at 24 and arc deposition is performed at 22 to the sprayed layer. In a pyrolysis step 23, the foam binder and foam support are destroyed and the openwork product can undergo sintering at 25 and compaction at 26 to obtain product 29.

FIG. 3 shows a method sequence according to the invention, designated at 30, in which, as in FIG. 1, a foam 31 is subjected to direct arc deposition at 32. However, the metal spray is applied directly to the arc deposited coating at 34 and the coated body then undergoes pyrolysis at 33 to destroy both the metal powder and the binder for the polyurethane support wood. Sintering and rolling are carried out at 35 and 36 as has been described to obtain three products.

The sequence 40 shown in FIG. 4 is such that the polyurethane foam support tree at 41 is coated by arc evaporation at 42 and by metal powder spray at 44 before the polyurethane foam support tree at 41 is coated at 44 by metal powder spray. This composite ellipse is then processed in a sequence generally similar to that of FIG. 3, except that it receives another coating by arc deposition at 47 utilizing the coating apparatus shown in FIG. The number of bodies is 48
The openwork body is sintered at 45 and compacted at 46 to obtain the product at 49.

[1 tool, 1 row] A nickel openwork structure for use as an electrode material in a nickel-cadmium battery is made of an open pore flexible reticulated ester type foam with 80 pores/inch and a density target 1.75 bonds/cubic foot and thickness approx.
/16 inch by low temperature arc evaporation in a vacuum chamber using nickel electrodes and a vacuum of 10 Torr applied.

The applied voltage is 4 volts and the arc current is about 75 amperes.

This process is carried out until the support is coated to its maximum thickness and a deposited layer of approximately 60 grams of nickel per square foot of support is applied. The coating time is approximately 75-1+10 hours.The foamed support was coated with metal coated polyurethane foam in an electric furnace at a temperature of 350°C in the presence of air, and analysis of the air passing through said furnace revealed that carbon dioxide and monoxide It is destroyed by subjecting it to pyrolysis until it no longer produces carbon, thereby indicating complete decomposition of the polyurethane structure.

The crossbody is then sintered at 950 DEG C.-1250 DEG C. in a vacuum oven at about 1100 DEG C. for a period of 561) minutes, preferably about 15 minutes. This nickel structure has a porosity of up to 95-6 and U.S. Application No. 07/20
No. 8.886, it has a framework structure as shown in the scanning electron microscope photograph of FIG.

This process is carried out by low-temperature arc evaporation for about 20 hours.
and the balance of nickel metal to 60 g/sq. ft. is deposited by spraying nickel particles in the 5 to 10 micron cryometry onto the arc deposited coating in a pyrolyzable liquid polyurethane binder at pyrolysis temperatures. All terms and conditions, which are the same as those set forth above, except as applicable to coaching, shall apply. This product after sintering is particularly indistinguishable from products prepared solely by arc evaporation coating.

[Brief explanation of the drawing]

1 [2I-FIG. 4 is a block-type work flow diagram showing four different sequences in the method according to the invention;
FIG. 5 is a schematic cross-sectional view enlarged to R and intended to illustrate the result. 50 ・ Openwork body, 51 ・ Network structure, 53 ・ Powder layer. 52 ... interconnected pores,

Claims (20)

[Claims] (1) (a) applying a coating of at least one substance selected from the group consisting of metals, semiconductors and ceramics onto and into an openwork synthetic resin pyrolyzable support by arc evaporation; , at least one of which is comprised of at least one element of said material, are brought into close proximity, said electrodes are advanced into contact, an electric arc is ignited between said electrodes, and said element is by evaporating from said one of said electrodes and carrying out vapor deposition of said substance on said support and depressurizing the space in which said support is in close proximity to the electrode, thereby finally (b) depositing a portion of the total amount of said material in the form of said coating to form said open-pore structure; (b) on at least one of said support and said coating in at least a spray deposition operation; (c) after at least one of step (a) and step (b), pyrolyzing said support to essentially and (d) sintering the framework into an agglomerate constituting the open-pore structure. Method for manufacturing a pore structure. 2. The method of claim 1, wherein said spray deposition operation comprises spraying said material in a mixture with a thermally decomposable binder, and step (c) follows step (b). (3) said spray deposition operation (b) precedes step (a), and said arc deposition step (a) is carried out on a layer of said material applied directly to said support in said spray deposition operation. The method according to claim 2. 4. The method of claim 2, wherein said spray deposition operation (b) follows step (a). (5) said spray deposition operation (b) precedes step (a), and said arc deposition step (a) is carried out on a layer of said material applied directly to said support in said spray deposition operation. The method according to claim 1. 6. The method of claim 1, wherein said spray deposition operation (b) follows step (a). 7. The method of claim 6, wherein another arc deposition deposits an additional portion of the material on the material deposited by the spray deposition operation. 8. The method of claim 1 further comprising the step of compressing the metal open pore structure to a reduced thickness while preserving its porosity. (9) step (a) is characterized in that a vacuum at a pressure of less than 10-3 torr is applied to said step and a voltage of 2 is applied between said electrodes;
2. The method of claim 1, wherein the method is carried out by applying 0 to 150 volts and providing an arc current of 40 to 150 amperes. (10) The method according to claim 1, wherein the support is a reticulated synthetic resin foam material. 11. The method of claim 10, wherein the foam material is polyurethane foam. 12. The method of claim 1, wherein the element is a metal capable of forming an electrode for an electrochemical cell. (13) The method according to claim 12, wherein the metal is nickel. 14. The method of claim 1, wherein said pyrolysis is carried out in the presence of air at a temperature of about 350° C. for a time sufficient to substantially completely remove said support. (15) The sintering is performed in a vacuum furnace in the absence of air, or in an inert gas or reducing atmosphere at a temperature of approximately 950°C.
15. The method of claim 14, wherein the method is carried out at a temperature of 1250 DEG C. for a time sufficient to sinter the body into a structurally self-supporting state. 16. The method of claim 1, wherein said total amount is 20 to 70 grams per square foot of metal deposited on said support. 17. The method of claim 2, wherein said binder is a synthetic resin material that is thermally decomposable under the same thermal decomposition conditions that are thermally decomposable to said support. (18) A porous openwork metal structure prepared by the method according to claim 1. (19) A battery electrode in the form of a porous nickel openwork structure, characterized in that it is prepared by the method of claim 1. (20) arc deposition, spray deposition operations, pyrolysis and sintering are performed successively on the continuously advancing web of said support to successively produce said web of open pore metal structures; 2. The method according to claim 1, wherein the method comprises: