Tungsten-Cobalt Carbide Alloy Powder Preparation for Spraying

Cobalt tungsten carbide series is widely used as one of the most important wear-resistant coating materials with excellent properties at medium and low temperatures. Many developed countries such as the United States, Russia and the United Kingdom have carried out a lot of research work in this direction. They have formed many kinds of materials preparation methods, such as electrofusion crushing, sintering crushing, polymerization, coating and so on. Cobalt tungsten carbide coatings with different grades and different applications have been designed and prepared.

tungsten-cobalt carbide alloy powder preparation for spraying image

At present, the nominal cobalt content of commonly used tungsten carbide/cobalt coating materials at home and abroad is 12% or 18%, such as METCO in the United States and STELLITE series products in the United Kingdom. The highest cobalt content in China is about 20%. The common problem is that the bonding strength with the matrix material is slightly poor.

In order to improve the bonding strength, some scholars have proposed a preparation method of tungsten-cobalt carbide powder for spraying. The steps include:

Using ordinary tungsten carbide powder and cobalt as basic materials, mixing and grinding uniformly by conventional process, pre-sintering for 2 hours at 1300 C under argon atmosphere, then sintering at 1300 C for 15 hours, crushing and powder making, and testing products. The composition of the powder is 25% CO, the remaining WC and the fineness of the powder are as follows: 7% of the powder less than 0.030mm, 90% of the powder from 0.030mm to 0.063mm, and 3% of the powder from 0.063mm to 0.160mm. The prepared alloy powder was sprayed on TA15 titanium alloy. The bonding strength of the coating was 81 MPa and the hardness HV5 was 620.

In general, the level of cobalt plays an important role in the properties of materials and coatings. Increasing the cobalt content in the tungsten carbide cobalt material will give the coating a better bonding strength, which is an important direction of this kind of material. It has been found through extensive experiments that only by finely controlling the fineness of the alloy powder can the originality be maintained. At the same time of the wear resistance of the alloy powder, the strength of the alloy powder is increased in combination with the matrix, and the coating process is good.