Introduction of Tungsten Carbide Spraying Process

       

Introduction of Tungsten Carbide Spraying Process

Thermal spraying is a general term describing all the methods by which droplets or semi-melted droplets form a coating. In thermal spraying, the material is transported in the form of powder, wire or rod into the flame generated by the spray gun, melted in the flame, and the formed droplets are accelerated to reach the substrate to be coated. The heat and kinetic energy of the flame can be generated by burning a mixture of fuel gas and oxygen, or by using a power source. According to the energy source, thermal spraying methods can be divided into plasma spraying method (atmospheric pressure plasma spraying method, vacuum plasma VPS method and low-pressure plasma LPPS method), combustion flame spraying method (plasma spraying), high velocity oxygen/air combustion method (super Sonic spraying tungsten carbide spraying/HVAF method), electric arc method (wire arc method), detonation method (D-Gun method), and the latest cold gas method (CGS).

 

Since the coating is formed by flat, rapidly solidifying droplets, speed plays an important role in obtaining the density of the layered structure coating. Flame temperature has a strong influence on suitable spray materials. Ceramic coatings are mainly prepared by atmospheric pressure plasma spraying, while temperature-sensitive materials such as cermets are more inclined to spray with a lower flame temperature.

 

Thermal spray coatings are usually for better corrosion resistance and wear resistance. Therefore, low porosity and good adhesion are the ideal properties of the coating. High-speed processes—especially high-speed oxy-fuel spraying—are the preferred method for preparing low-porosity, high-adhesion coatings.