Fabrication and property of nano-SiC whisker/ZrO_2 composite thermal barrier coatings

SiC whisker(SiC_w)/ZrO₂ composite thermal barrier coatings(CTBCs) were sprayed by micro-plasma on stainless steel substrates.Both nano-ZrO₂ and micro-ZrO₂ were used in the CTBCs.The zirconia powders were 7 wt% Y₂O₃ partially stabilized ZrO₂(YPSZ).Microstructure of the coatings was analyzed by scanning electron microscopy(SEM).The chemical composition of the top coating was measured by energy dispersive X-ray(EDX).Phase content of the coatings investigated by X-ray diffraction(XRD).In the spraying process, a large quantity of SiC_w in the powder has been decomposed at high temperature, which produces pores in the top coating, and little SiC_w embedded in the top coating decreases the thermal stress, nailing and bridging the coating.With SiC_w content increasing, the porosity of composite TBCs was increased, and the thermal shock life was improved firstly and weakened later.The highest thermal shock resistance was achieved at 20% volume ratio of SiC_w to nano-ZrO₂, was better than that of the single ZrO₂ coatings.