The basic principle of powder sherardizing is to use the penetration and diffusion of metal atoms in the heated state. Under the condition that the temperature is lower than AC1 and the base metal has no phase change, the metal zinc is infiltrated into the surface of the steel material fasteners to form different Zn-Fe ratios. Alloy protective layer (referred to as infiltration layer or coating). The main purpose of powder sherardizing surface alloying is to improve and improve the corrosion resistance, surface oxidation resistance and wear resistance of the surface of steel fasteners.
The powder sherardizing anti-corrosion coating technology is based on the traditional powder sherardizing process, using the special thermal properties of the added composite material (CeO2, powder sherardizing La2O3, LaF3, etc.) sherardizing agent (high surface performance, high activity) , Metal atom diffusion process temperature is low) and chemical properties (high diffusion rate, which can realize the solid-state diffusion bonding and bonding of metal materials) and other characteristics, and the research and development can realize mechanized production and improve product performance. At the same time, it can realize multiple Composite (co-infiltration of zinc, aluminum, cadmium, chromium, oxides, etc.) powder thermal diffusion coating anti-corrosion technology.
Powder sherardizing consists of five layers of FeZn7+Zn, FeZn7, Fe11Zn40 zinc-rich layer, solid solution of Zn in Fe and steel matrix. If the surface dacromet coating is added, the salt spray resistance test time can reach more than 1000 h.