Powder metallurgy after sintering treatment

Powder metallurgy after sintering treatment

The further treatment of metal powder after compaction and sintering is called posttreatment.There are many types of post-processing, which are generally determined by the requirements of the product.Several commonly used post-processing methods are as follows.
1. Impregnation the capillary phenomenon of porosity of sintered parts into various liquids.For example, for the purpose of lubrication, can be immersed in lubricating oil, ptfe solution, lead solution;In order to improve the strength and corrosion resistance, copper solution can be dipped;For surface protection, soak in resin or paint, etc.Macerating may be done under atmospheric pressure or under vacuum.
2. In order to improve the dimensional accuracy of parts and reduce the surface roughness, surface cold extrusion can adopt shaping;In order to improve the density of parts;Recoverable recovery pressure;In order to change the shape of parts, precision pressing can be used.Parts after re – pressing often require re – burning or annealing.
3. Cutting transverse groove, transverse hole, and axial dimensional accuracy of the surface.
4. Heat treatment can improve the strength and hardness of iron-based products.Due to the existence of pores, products with porosity greater than 10% shall not be heated by liquid carburizing or salt-melting furnace to prevent the salt solution from immersing into the pores and causing internal corrosion.In addition, gas carburizing of low-density parts is easy to penetrate into the center. For products with porosity less than 10%, the same heat treatment methods as ordinary steel can be used, such as integral quenching, carburizing quenching, carbon and nitrogen co-quenching and so on.Vulcanization can be used to seal pores in order to prevent the possible adverse effects of plugging pores.It is better to use oil as the quenching medium, high-density products, if in order to cool the need for speed, also use water as the quenching medium.
5. Surface protection treatment is very important for instrument, military and powder metallurgy products with anti-corrosion requirements.The existence of pores in powder metallurgy products makes surface protection difficult.At present, can be used to use the surface protection of steam blue treatment, oil, sulfur and annealing, paint dip, zinc after electroplating, phosphating, anodizing treatment!