Metal porous materials are composed of a multitude of directional or random holes dispersed throughout the material. These holes vary in diameter, ranging from 2 micrometers to 3 millimeters. The design of these holes can take different forms, such as foam, lotus, or honeycomb types. Depending on the shape of the holes, porous metal materials can be classified into two categories: independent hole type and continuous hole type.
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There are different classifications of metal porous materials, including powder sintered porous materials, metal fiber sintered porous materials, wire mesh porous materials, and foam metal materials. Among these, powder sintered porous materials are created by utilizing metal or alloy powder as a raw material. The process involves forming the powder into a rigid structure and sintering it at high temperatures. This results in a porous material with a significant number of interconnected or semi-connected pores. The pore structure is formed by stacking regular and irregular powder particles, with the size and distribution of the pores and porosity depending on the particle size composition and preparation process.
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Commonly used materials for powder sintered porous materials include bronze, stainless steel, iron, nickel, titanium, tungsten, molybdenum, and refractory metal compounds. Traditional preparation processes for these materials involve compression molding and sintering, isostatic pressing, loose sintering, powder rolling, powder plasticizing extrusion, and slip casting. Additionally, new preparation technologies such as centrifugal deposition, injection molding, 3D printing, laser rapid prototyping, and electron beam rapid prototyping offer alternative methods for creating powder sintered porous materials. -
Centrifugal deposition technology utilizes a porous metal tube with large pore sizes as a support structure. The process begins by preparing a metal powder slurry, which is then placed into the support tube and subjected to high-speed rotation. Under the influence of centrifugal force, the powder particles in the slurry are graded and deposited on the inner wall of the support tube, resulting in a gradient film structure. Subsequent drying, sintering, and other treatments yield a porous membrane tube. This technique is suitable for producing microporous metal films using powders such as titanium, titanium alloys, stainless steel, nickel, and nickel alloys. By employing sub-micron and nano-scale particle sizes, it is possible to create microporous metal films with corresponding pore sizes. -
Metal injection molding (MIM) is another method for preparing powder sintered porous materials. In this process, the powder is mixed with an organic binder and formed using an injection molding machine. The binder is then removed from the formed blank, and the resulting product is sintered to achieve the desired final properties. MIM technology offers high precision, uniform structure, excellent performance, and cost-effectiveness, making it suitable for manufacturing porous materials from bronze, stainless steel, titanium, nickel, and their alloys. -
