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 ℃.