JPS6153417B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel and simple method for manufacturing a porous metal body having a three-dimensional network structure.

As a conventional method for manufacturing a three-dimensional network metal porous body, there is Japanese Patent Publication No. 10524/1984. As shown in Figure 1, this method involves treating a reticulated foamed synthetic resin with carbon or graphite to make it conductive, and then applying a metal such as Ni to an electrically conductive layer in a plating bath. After being deposited, the electrodeposited metal is fired to burn out or partially burn out the internal synthetic resin, thereby forming the electrodeposited metal into a skeleton of the porous body. This method is still used today as the first effective and practical method for producing three-dimensional mesh porous metal materials, but on the other hand, a conductive treatment is essential in order to electrodeposit the metal. There were problems with the process and equipment, such as the need for a power source and electrodeposition equipment such as a plating tank. In addition, the electrodeposition speed is determined by many factors such as the resistance value of the surface of the reticulated foamed synthetic resin due to conductive treatment, power supply voltage, metal ion concentration in the plating solution, current density, and plating time. There were also problems such as the complexity of process control in that the amount of metal electrodeposited could not be adjusted without adjusting everything, as well as the inability to obtain a product consisting of an alloy of two or more types.

The present invention eliminates the drawbacks of the above-mentioned conventional methods and provides a novel method for producing a porous metal body that is simple and easy to control the process. That is, as shown in the process diagram of FIG. 2, the method of the present invention is similar to the conventional method in that a reticulated foamed synthetic resin is used as the starting base material, but the process and process control of the conventional method are complicated. Without using conductive coating treatment or electrodeposition treatment,
As an alternative, heat treatment can be performed after application by dipping or spraying a kneaded mixture of an organic polymer binder and metal particles onto the base material, thereby burning out the base material and the binder, and removing the metal. It uses a process of sintering microscopic bodies to form a skeleton.

Hereinafter, the present invention will be explained in detail with reference to the illustrated embodiments.

Example 1 A polyurethane foam having a three-dimensional network structure (trade name: Everlite Scotto, manufactured by Bridgestone Tire KK) was used as a starting base material. A kneaded product obtained by mixing the composition of Composition Example 1 below in a ball mill for about 1 hour was uniformly applied to this urethane skeleton by spraying. Leave the application at room temperature for 15 minutes and
After drying at 120°C for 10 minutes, it was baked at 380°C for 50 minutes.

Composition example 1 Binder (urethane varnish) 33% by weight Microscopic metal (Al powder) 42 Additives (Aerosil, hardening agent, thinner)
25 Then, by firing in a hydrogen stream at 520° C. for 2 hours, an Al metal porous body having a three-dimensional network structure as shown in FIG. 3 was obtained. Third
In the figure, 1 is a skeleton and 2 is a hole. When this surface was observed with a scanning electron microscope, a phenomenon as shown in the schematic diagram of FIG. 4 was observed. That is, before firing in a hydrogen stream, the Al powder particles 3 are only densely dispersed as shown in Figure 4a, but after firing, as shown in Figure 4b, ,Al
Powder particles 3 sinter each other at the interface
It was found that they were connected at the network part 4.

Al metal porous bodies are essentially Al-plated (electrodeposition)
However, with the method of the present invention, it is possible to produce an Al porous body with a three-dimensional network structure. This has the advantage of being possible.

Example 2 Using the same polyurethane foam as in Example 1, a mixture of Composition Example 2 below was kneaded in a ball mill for about 1 hour, the viscosity was adjusted, and the mixture was applied by dipping. After drying the coated material at 120℃ for 20 minutes, it was dried at 180℃ for 30 minutes and in a vacuum of 10 ^-5 torr.
After firing at 600°C for 2 hours, a three-dimensional network porous body having the structure shown in Figure 3 was obtained.

Composition example 2 Binder (polyester varnish) 25% by weight Microscopic metal (Fe-Ni powder, Al powder) 58 Additives (hardening accelerator, silica, thinner)
17% by weight When the surface of this material was observed using a scanning electron microscope in the same manner as in Example 1, it was found that the particles were sintered together by sintering, as in the case of Fig. 4b. After constructing the structure and performing X-ray analysis, it was found that at the interface between Fe-Ni powder and Al powder, atoms of both particles diffuse into each other due to firing in vacuum.
It was found that Fe-Al alloy was formed.

Next, the bending workability of the two types of porous metal bodies produced in Examples 1 and 2 was examined. When both plates were prepared in the form of a plate with a thickness of 5 mm and bent at an angle of 60° to the horizontal plane, no cracks were observed in the bent portions, indicating that they had good bending workability. .

By the way, as the binder made of an organic polymer compound used in the present invention, in addition to the urethane and polyester varnishes used in the examples, melamine, acrylic, epoxy, polyethylene styrene, etc. can be used. A varnish-like product prepared by dissolving an initial polymer of an organic polymer compound in a solvent is easy to use.

As the microscopic metal, powdered metals such as those used in the examples are suitable for kneading with a binder, but other shapes such as microscopic fibrous or whisker-like metals may also be used. Furthermore, any kind of metal or alloy may be used.

As the synthetic resin foam having a three-dimensional network structure, the polyurethane foam used in the examples was
Although it is the most common and highly available on the market, the same porous metal body as in the example can be obtained by using other synthetic resins with open cell structures, such as silicone, vinyl chloride, styrene, and polyester. In order to apply the kneaded mixture of binder and microscopic metal to this synthetic resin foam skeleton, general coating methods such as spray coating, dipping, and flow coating may be used. A uniform porous metal body can be obtained by controlling the process by controlling the viscosity of the coating material and the amount of coating. By the way, when baking the coated article, an atmosphere such as air, oxygen gas, or inert gas may be used. In this case, the synthetic resin skeleton may be completely burnt out, half burnt out, or carbonized and remain. However, when bonding (sintering) microscopic metals to each other through subsequent heat treatment, sintering is difficult and brittle if done in an oxidizing atmosphere such as air. Therefore, as in the examples, it is necessary to carry out the process in a non-oxidizing atmosphere such as a hydrogen stream, an inert gas, or a vacuum.
In this case, in the embodiment, the microscopic metals are bonded using sintering and diffusion bonding, but even if a low melting point metal such as a brazing material is used,
Bonding may also be done by liquid phase sintering.

As explained above, the process involves kneading the microscopic metal, which is the main material, into a binder mainly consisting of an organic polymer compound, and applying the kneaded material to the skeleton of a synthetic resin foam having a three-dimensional network structure. process, a process in which the coated material is heat-treated to burn off, semi-burn off, or carbonize the skeleton of the synthetic resin foam and the organic polymer compound that is the binder; and a process in which the metal particles are removed by heat treatment in a non-oxidizing atmosphere. The method for producing a porous metal body of the present invention, which includes a sintering step, not only allows a porous metal body having a three-dimensional network structure to be obtained by a simple and easy-to-manage method, but also enables the production of a porous metal body that is not obtainable by conventional methods. I couldn't help it
It is also possible to obtain one made of Al or an alloy of two or more types. Therefore, it is an extremely advantageous method for producing various metal porous bodies.

[Brief explanation of the drawing]

Figure 1 is a diagram of the conventional manufacturing process for porous metal bodies;
The figure is a manufacturing process diagram of the metal porous body of the present invention, and FIGS. 3 and 4 are schematic diagrams showing the porous body obtained by one example of the present invention. 1 is a skeleton, 2 is a hole, 3 is a particle, and 4 is a joint. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A step of kneading a microscopic metal as the main material into a binder mainly consisting of an organic polymer compound, a step of applying the kneaded material to the skeleton of a synthetic resin foam having a three-dimensional network structure, and a step of applying the applied material to the skeleton of a synthetic resin foam having a three-dimensional network structure. A step of heat-treating the synthetic resin foam skeleton and the organic polymer compound as a binder to burn out, semi-burn or carbonize it, and a step of sintering the microscopic metal by heat treatment in a non-oxidizing atmosphere. A method for producing a porous metal body, characterized in that: