Powder metallurgy technology is a process technology that prepares metal powder or uses metal powder as raw material, and then produces metal materials, composite materials and various types of products through molding and sintering. Compared with other traditional technologies, powder metallurgy can greatly improve energy utilization. Therefore, this technology has become a new technological means to solve new material problems and plays a decisive role in the development of new energy materials.

1. Categories of powder metallurgy materials

Traditional powder metallurgy materials

Traditional powder metallurgy materials mainly include iron-based powder metallurgy materials, copper-based powder metallurgy materials, cemented carbide powder metallurgy materials, etc. Among them, iron-based powder metallurgy materials are the most basic, most common and most critical among traditional powder metallurgy materials. Materials are currently widely used in the automobile manufacturing industry. With the advancement of technology, its application scope will be further expanded. Copper-based powder metallurgy materials have strong corrosion resistance and various types, and are widely used in the electrical appliance manufacturing industry. Cemented carbide powder metallurgy materials have a higher melting point, higher hardness and strength, and are widely used in high-end fields such as nuclear weapons manufacturing.

Modern powder metallurgy materials

Modern powder metallurgy materials mainly fall into the following categories:

1. Powder metallurgy materials used in the information field are mainly metal and ferrite materials;

2. Powder metallurgy materials in the field of new energy are mainly new energy materials and energy storage materials. The application of powder metallurgy technology and materials can greatly improve the utilization rate of energy and better develop new energy;

3. Powder metallurgical materials used in the biological field are generally divided into metallurgical materials and medical materials, which are of great significance for protecting people's health;

4. The application of powder metallurgy materials in the military field, such as the aerospace field, nuclear military field, etc. These fields have extremely high requirements for materials, which require strong stability, safety, high temperature resistance and other properties. Only in this way can we promote the development and progress of science and technology and military affairs and promote the improvement of their technical level.

2. Application of powder metallurgy technology in new energy materials

1. Application in wind energy materials

Wind energy is a new energy source that is abundant and clean. Wind energy can be used to produce power generation equipment using powder metallurgy technology. In the manufacturing process of wind energy power generation equipment, two materials using powder metallurgy technology are required, namely permanent magnet neodymium iron boron material and brake pad material. The application of these two materials can directly affect the safety and stability of wind energy power generation equipment. affect its operation.

Currently, the commonly used mechanical braking materials for wind turbines are copper-based powder metallurgy friction materials. Friction materials prepared using powder metallurgy technology have outstanding advantages in performance and quality. They are also extremely flexible in terms of component design and product diversification. It can change the composition of the material at will, so it can prepare friction materials with excellent performance in different situations. Copper-based powder metallurgy friction materials have small friction coefficients, good thermal conductivity, relatively stable friction coefficients, and good wear resistance. Their application in wind turbine braking systems greatly improves the stability of wind turbine operation.

NdFeB rare earth permanent magnets are the most important components of rare earth permanent magnet motors. They can replace traditional motors and move towards large capacity, excellent power generation quality, improved material utilization, noise reduction, cost reduction, and efficiency improvement. develop. NdFeB rare earth permanent magnet materials are prepared using powder metallurgy technology. The basic process is smelting - ingot casting - crushing - micro-pulverization - forming in a magnetic field - sintering - aging treatment - machining - surface treatment - magnetization.

2. Application in solar materials

The utilization of solar energy mainly includes photovoltaic, photothermal, photochemical conversion and photobiological conversion.

(1) Solar photovoltaic materials

There are many types of solar cells currently developed, but their photoelectric conversion efficiency is generally low. Especially for military and space applications such as military equipment and aerospace, photoelectric conversion efficiency is the most important indicator of solar cells. The development of new high-efficiency solar cell materials and improvements in preparation technology will help improve photoelectric conversion efficiency.

The application of powder metallurgy technology in the preparation of solar photovoltaic materials is reflected in the preparation of thin film solar cells.

The methods for polycrystalline silicon thin film solar cells include plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD), hot wire chemical vapor deposition (HwCVD), rapid thermal chemical vapor deposition (RTCVD), liquid phase epitaxy (LPE), sputter deposition method, etc. Amorphous silicon thin film solar cells are prepared using amorphous silicon semiconductor materials on glass, special plastics, ceramics, stainless steel, etc. as substrates. They are currently recognized as the best environmentally friendly solar cells. The preparation methods include reverse sputtering, low voltage Chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD) and hot wire chemical vapor deposition (HwCVD). The targets used in the preparation of these films are inseparable from powder metallurgy technology.

(2) Solar photothermal materials

Compared with photovoltaic power generation, solar thermal power generation has the advantages of low cost and suitable for large-scale power generation. However, its energy density after reaching the earth is relatively low. It brings certain difficulties to large-scale development and utilization, so its energy density must be improved for its promotion and use. The preparation of efficient solar selective absorption coatings is a key technology in solar thermal utilization and is crucial to improving the efficiency of collectors.

(3) Photothermal power generation

The application of powder metallurgy technology in the preparation of solar photothermal utilization materials is reflected in the preparation of solar energy selective absorption coatings. The main preparation methods for solar selective absorption coatings include coating method, electroplating method, electrochemical method, vapor deposition method and vacuum coating method.

The coating method requires mixing a powder with light absorption selectivity as a pigment and a binder to make a coating, and then applying the coating to the substrate through spraying, dipping, brushing, etc. on the substrate. Commonly used pigment materials include Si, Ge, PbS and some transition metal complex oxides.

The electroplating method uses electroplating to plate metal with selective light absorption on the substrate. Commonly used electroplating coatings mainly include black nickel coating, black chromium coating, black cobalt coating, etc.

Other methods are also widely used in thin film preparation. By changing the target material of magnetron sputtering, various thin films can be prepared. With the development of new material technology in powder metallurgy, new selective coatings have been applied, and the research and preparation technology of solar selective absorption coatings will also gain new development.

3. Application in hydrogen storage materials

Solid hydrogen storage is the most common storage method, but the application of powder metallurgy technology in solid hydrogen storage containers and under a certain temperature and hydrogen pressure can make hydrogen storage more stable, safe and effective.

Hydrogen storage alloy refers to an intermetallic compound that can reversibly absorb, store and release hydrogen in large quantities under a certain temperature and hydrogen pressure. The hydrogen storage mechanism is that hydrogen molecules are first adsorbed on the metal surface, then dissociated into hydrogen atoms, and then enter Hydride forms in the metal's crystal lattice. Hydrogen storage alloys have large hydrogen storage capacity, are pollution-free, safe and reliable, and have relatively mature preparation technology and processes. They are currently the most widely used hydrogen storage materials.

Metal-based hydrogen storage alloys generally include magnesium-based hydrogen storage materials, rare earth-based hydrogen storage materials, titanium-based hydrogen storage materials, etc. For advanced hydrogen storage alloys, powder metallurgy technologies such as mechanical alloying, hydrogenation combustion synthesis, and reduction diffusion methods are generally used. to prepare.

4. Application in fuel cell materials

A fuel cell is a device that can convert the energy of fuel gas and other substances into electrical energy. The application of powder metallurgy technology is mainly used for electrode materials and sealing components in fuel cells. The advantages of powder metallurgy technology can be greatly It can improve the performance, safety, stability, etc. of materials. In addition, it can also reduce material prices, which is of great significance to the development of fuel cell materials.

Due to its excellent electrochemical performance, Ni/YSZ cermet anode is currently the first choice for hydrogen-fueled solid oxide fuel cells (SOFC). Because of its cheap price and high stability, metallic Ni is often mixed with electrolyte yttria-stabilized zirconia (YSZ) to form porous cermet Ni/YSZ. Ni/YSZ is currently the most widely used SOFC anode material.

The fuel cell cathode material is porous strontium-doped lanthanum manganate (LSM), and the porous material can only be prepared using powder metallurgy technology.

5. Application in other new energy sources

In addition to its application in wind and solar energy, powder metallurgy technology also has an application effect that cannot be ignored in nuclear energy development and lithium battery manufacturing.

Taking the combination of lithium batteries and powder metallurgy technology as an example, the new electrolytes and energy density in lithium batteries are closely related to powder metallurgy technology. Using ultrafine powder to make nanocrystal materials and nanotubes can increase the charging speed of lithium batteries and extend the service life of lithium batteries.

In terms of nuclear energy development, powder metallurgy technology is also widely used. In terms of the preparation of beryllium, powder metallurgy technology can improve the quality of vacuum hot pressing and semi-finished product processing, and has an irreplaceable positive role. Powder metallurgy technology involves processes for producing powder from ingots (mechanical grinding or sputtering molten plating) and pressing processes such as vacuum hot pressing (VHP) and hot isostatic pressing (HIP).

In the development process of new energy, new energy materials play an irreplaceable and important role, guiding and supporting the development of new energy. As a new technology with many advantages, powder metallurgy technology can greatly improve energy utilization, improve the safety and stability of energy utilization, etc., and is of great significance to my country's industrial development and the application of new energy. With the advancement of powder metallurgy technology, more and more advanced new powder metallurgy materials will appear and be applied to energy materials, promoting the development and use of new energy and solving energy problems.