Attention Should Be Paid To Spraying Distance And Substrate Temperature

       

We should pay attention to spraying distance and substrate temperature. First

of all, we should know the cating and technology characteristics.

Coating structure characteristics. The structure of oxyacetylene flame powder spraying coating is also layered, and the coating contains oxides, pores and a small amount of particles with insufficient deformation. The coating and substrate belong to mechanical bonding. The porosity and bonding strength of the coating are greatly affected by the spraying material and spraying process. The porosity is generally between 5-20%, and the bonding strength is between 10-30mpa.

Technical characteristics of the process. Oxyacetylene flame powder spraying is one of the most widely used spraying processes

1) The equipment is simple, easy to operate, low cost and convenient for site construction.

2) The spraying process is simple and easy to master, which is widely used.

3) It can spray metal, alloy, composite powder, ceramic, plastic and other materials.

4) The porosity of the coating is large and the residual stress of the coating is small.

Main process parameters

(1) Heat source parameters. In the process of machining, it is necessary to correctly use and control the performance of flame, that is, neutral flame or micro carbonization flame should be used when preheating and powder spraying, so as to avoid oxygen on the surface of workpiece and powder. In general, powder flame spraying mostly relies on flame to accelerate the spray particles. When the oxygen acetylene with larger flow rate is used, the power and intensity of the flame flow are high, and the flight speed of the spray particles is high. The prepared coating has high bonding strength and density.

(2) Spraying distance. The distance between the spray gun and the spraying surface of the workpiece is generally controlled at 150-200 mm. The specific value should be determined according to the model of the spray gun, the power and the length of the flame straightness. The best distance is to put the brightest part of the alloy powder in the best heating state in the flame on the surface of the workpiece.

(3) Matrix temperature. When spraying, the workpiece should be preheated first. The preheating temperature of steel parts is 80-120 ℃. During spraying, the overall temperature of parts should not exceed 250 ℃.