Zirconia-strengthened yttria ceramics for plasma chamber applications

Yttria (Y2O3) is the most popular lining material for the inner walls of plasma chambers, owing to its well-known resistance against corrosion by reactive fluorinated plasma. Yttria has a relatively lower toughness and strength compared to alumina (Al2O3) and zirconia (ZrO2). The present work aims to explore the strengthening and toughening of yttria by doping with zirconia, while retaining its good corrosion resistance. Ceramics with zirconia to yttria molar ratios of 2:8 and 5:5 (named 20ZY and 50ZY, respectively) were fabricated by pressure sintering in Ar atmosphere. The corrosion of the prepared ceramics in reactive fluorinated plasma (C4F8/CHF3/Ar) was investigated and compared with that of yttria as a control. The results indicated that 20ZY exhibited excellent corrosion resistance, comparable to that of yttria, while the fracture toughness and flexural strength showed increases of 87% and 44%, respectively. 50ZY exhibited a further improvement in fracture toughness and flexural strength, but at the price of a much lower resistance against plasma corrosion. A percolation model was proposed to interpret the observed plasma corrosion behaviors.