Bearing is a kind of sliding parts commonly used in mechanical industry, and its material is different from metal, nonmetal and composite materials.Learn More
1. Binderless natural graphite powder can be cold-pressed under the pressure of 5~20 MPa. The density and strength of the mold increased with increasing pressing pressure, while the porosity and appearance change after heating at 1200 ° C decreased with increasing pressing pressure.
2. After the graphite mold is used, it can still be used after removing impurities, crushing, screening and repressing. When repressing, apply a small amount of new powder on the end face of the indenter to restore its good release.
3. Coating a thin layer of resin, such as polymethacrylate, on the surface of the mold can improve the strength of the mold surface, change the characteristics of the adhesiveless surface is too soft, and improve the assembly performance of the mold.
Graphite has excellent mechanical and thermal properties at high temperatures and is widely used in chemical, metallurgy, aviation, aerospace and reactor fields. Graphite is divided into artificial graphite and natural graphite. Artificial graphite is made of anthracite, coke, asphalt and other products. After crushing, screening, molding and firing. Natural graphite is a kind of non-metallic ore, and high purity graphite can be obtained by crushing, grinding, flotation and chemical purification. China has abundant natural graphite resources, mainly flake graphite, but artificial graphite is currently widely used in industry. Graphite molds for powder metallurgy are generally made of artificial graphite. It has high mechanical strength at high temperature, but it can not be used again after damage, so it has to be abandoned. Considering the good cold-pressing performance of natural graphite and the characteristics of low mechanical strength requirements for applications such as liquid phase sintering, this study used domestic natural graphite powder to make molds by non-binder cold-pressing method, and studied the possibility of continued use of waste molds after impurities removal, crushing, screening and re-pressing.