LIQUID MN PENETRATION AND REACTION TREATMENT OF PLASMA-SPRAYED AL2O3 COATING

The penetration phenomena of liquid Mn to porous Al2O3 coating plasma- sprayed on SS400 steel substrate was studied by heating at 1 573 K in vacuum atmosphere. Moreover, the possibility of improving the Al2O3 co ating properties was examined. The formation of MnAl2O4 was clearly re cognized in the connected porosity of Al2O3 coating penetrated with li quid Mn. It was revealed that the hardness and the fracture stress of the composite coating consisted of Al2O3 and MnAl2O4 without porositie s after heat-treatment with Mn increased greatly compared with as-spra yed Al2O3 coating.