Surface Ceramic - Plasma Spraying and Self Propagation High-Temperature Synthesis

Plasma spraying produces a dc arc between the cathode and the anode. The arc disassociates the working gas into a high temperature plasma. The resulting plasma flame melts the powder into droplets.

The droplets are atomized by high speed air and sprayed onto the surface of the substrate to form a coating.

The advantage of plasma spraying is that the temperature of the spraying is very high, the center temperature can be up to 10000 K, and the ceramic coating of any high melting point can be prepared. The coating has good compactness and high bonding strength.

The disadvantage is that the spraying efficiency is low, the equipment is expensive and the one-time investment cost is high.

Self propagation high-temperature synthesis(SHS) is a technology to synthesize new materials by utilizing the self-conduction of high chemical reaction heat between reactants. It has the advantages of simple equipment, simple process, high production efficiency, low energy consumption and no pollution.

It is a kind of surface engineering technology which is very suitable for pipe inner wall protection.

The ceramic liner prepared by SHS has the characteristics of high bonding strength, high hardness and corrosion resistance, which can effectively prolong the service life of pipeline.

The main component of the common ceramic lining of the oil pipeline is Fe Al₂O₃. The process is that the iron oxide powder and the aluminum powder are mixed uniformly in the steel pipe in proportion, then the centrifuge is rotated at high speed and then ignited by the electric spark. The replacement reaction occurs during the combustion of the powder, and the melting layer of the Fe Al₂O₃is formed. The melting layer is stratified under the action of centrifugal force. Fe is close to the inner wall of the steel tube, while Al₂O₃is far away from the tube wall to form ceramic lining.