Build-up resistance of HVOF thermal sprayed NiCrAlY-Y_2O_3 cermet coatings

摘要

Agglomerate sintered and blended NiCrAlY-Y_2O_3 cermets were prepared from NiCrAlY and Y_2O_3 powders by two process routes. The particle morphologies and powder characteristics of both cermets feedstock using for thermal spraying were investigated. Both types of NiCrAlY-Y_2O_3 cermets and one commercial CoCrAlY-Y_2O_3 cermets were HVOF thermal sprayed onto the stainless steel substrate to obtain coatings having a thickness about 100 microns. Porosity and thermal shock resistance of coatings were examined. Four thermal sprayed coatings were comparatively evaluated build-up resistance by contacting reaction with MnO, Fe_3O_4 powders and manganese bearing carbon steel statically at high temperatures. The agglomerate sintered NiCrAlY-Y_2O_3 coatings have good resistance to manganese oxide build-up but bad resistance to iron oxide build-up. The agglomerate sintered cermets coating has better build-up resistance than blended cermets coating.