Improving microstructure and properties by multi-function micro-plasma spraying

Al2O3-13wt%TiO2(AT13) coatings were deposited by multi-functional micro-plasma spray and Metco 9M plasma spray, respectively. The microstructures and the performances of the AT13 coatings were examined by scanning electronic microscope (SEM) and X-ray diffraction (XRD). The effects of the different axial feeding manners on the performances of AT13 coating were investigated. The research results show that the powder particles in AT13 coating were fully melted upon adopting multi-functional micro-plasma spray which used axial internal injection feeding. The coating is dense and uniform, composed of the phases such as α-Al2O3, γ-Al2O3, Al2TiO5 ZrO2 and CeO2 etc, its hardness is 975-1441 MPa, the average bonding strength is 42.7 MPa. While the powder particles in AT13 coating were partially melted upon adopting Metco 9M plasma spray which used external injection feeding, the coating is composed of α-Al2O3, γ-Al2O3, Al2TiO5, TiO2, ZrO2 and CeO2 etc, its hardness is 655-946 MPa, the average bonding strength is 19.7 MPa, It is revealed that the performance of the coating by multi-functional micro-plasma is better than that by Metco 9M plasma spray.