The lamellar–equiaxed microstructural transition of 316L coatings by low pressure plasma spraying

The equiaxed microstructure of 316L stainless steel coating was successfully deposited by low pressure plasma spraying (LPPS), which was different from the lamellar microstructure prepared by other thermal spraying technologies. In this article, the coatings were deposited at different substrate temperatures of about 345 °C, 613 °C and 890 °C and at different spray distances of 250 mm, 350 mm and 450 mm to investigate the effect of surface temperature and spray distance on the lamellar–equiaxed microstructural transition. The results indicated that the homogeneous equiaxed grains without lamellar boundaries coatings were observed when the deposition temperature was about 890 °C. Lamellar microstructural coatings with the equiaxed grains between the layers and completely lamellar microstructural coatings were also deposited at the substrate temperature of about 613 °C and 345 °C, respectively. Higher substrate temperature and shorten spraying distance promoted more homogeneous equiaxed microstructures. Hardness of lamellar microstructure was higher than that of equiaxed microstructure.

► The equiaxed microstructure of 316L coatings was successfully deposited by LPPS.
► Higher substrate temperature promoted homogeneous equiaxed microstructures.
► Lower substrate temperature promoted inhomogeneous lamellar microstructures.
► Hardness of lamellar structure is higher than equiaxed structure.