High-Performance Ceramic Coatings Sprayed via Novel Supersonic Plasma Spraying System

Abstract

A novel supersonic plasma spraying system was developed with a maximum power of 80 kW and a maximum working gas flow of 6 m3/h, at which gas and particle velocities of 2400 and 600 m/s can be achieved respectively. This paper deals with novel supersonic plasma spraying system design, the structure of novel supersonic plasma gun includes a special Laval nozzle as the single anode and inner powder supply, and the mechanisms of supersonic plasma jet as well as the effects on the sprayed particles. The spraying process parameters of several ceramic powders such as Al2O3, Cr2O3, ZrO2, Cr3C2 and Co-WC were optimized. The properties and microstructure of the sprayed ceramic coatings were investigated. Nano Al2O3-TiO2 ceramic coating sprayed by using novel supersonic plasma spraying was also studied. Novel supersonic plasma spraying improves greatly ceramic coatings quality compared with conventional air plasma spraying (Metco 9M), as well as it has lower energy and gas exhaustion compared with high power supersonic plasma spraying (Plazjet), which can spray high-performance ceramic coatings at low cost.