Effects of preheating temperature of NAS battery Al cylinders on the flattening behaviors of high Cr-Fe alloy plasma spray particles and the adhesion strength of internally sprayed coatings

In order to improve the adhesion of 75 mass% Cr-Fe alloy plasma spray coatings, which provide sulfide corrosion resistance for the inner surface of NAS battery high-temperature type Al cylinders, the Al substrate temperature and the flattening behavior of the plasma spray particles were studied. Also, experiments were conducted to study how changes in the preheating temperature of the Al cylinder affected the spray coating's adhesion strength. The splat morphology of the spray particles changed significantly in relation to the preheating temperature of the Al substrate, from splash shaped to disk shaped as the preheating temperature increased. It was especially evident that the splat morphology of the particles changed sharply at over 433K, forming disk shaped splats with excellent adhesion to the substrate. A good correlation was found between the flatness of the spray particles and the adhesion strength of the coating formed by changing the preheating temperature of the Al cylinder. When the preheating temperature was set at over 433K, coating's with good adhesion strength were formed. It was therefore shown that by studying the flattening behavior of the plasma spray particles, an effective method could be found for improving the adhesion strength of the plasma spray coating.