Long-term exposure of plasma-sprayed ZrO2 in high temperature reactor helium

Plasma-sprayed coatings will be used in future high temperature reactors (HTRs) to help overcome friction and wear problems. Extensive investigations have shown that an air-plasma-sprayed Ni-Cr-Al-Y/ZrO₂-Y₂O₃ duplex coating offers effective protection against thermal shock, non-self-welding, sliding wear, strain tolerance and short-term exposure to HTR helium. A report is given on the response of a duplex coating prepared by reduced pressure plasma spraying (composition as above) to high temperature wear testing and long-term exposure in HTR helium.