Plasma Resistant Highly Densified Yttria Ceramics Prepared via Dehydration Treatment of Raw Powders

Abstract

This study identifies the crystalline defects commonly observed in conventional yttria ceramics, and proposes a processing route to produce highly densified yttria without the use of sintering aids. The primary objective is to obtain a dense yttria monolith with optimized microstructure and enhanced functional properties. The sintering behavior, mechanical performance, and plasma etching resistance of the yttria specimens were systematically analyzed as a function of the initial powder characteristics. A three-step sintering protocol was employed to suppress abnormal grain growth, yielding fully densified ceramics with uniform and controlled grain size distribution. Calcination of the yttria powder at 1,250 °C for 48 h effectively eliminated oxygen deficiencies and minimized hydration effects. The duration and temperature of each sintering stage significantly influenced grain evolution, which was reflected in the variations in Vickers hardness, Young’s modulus, and fracture toughness (KIC). The resulting yttria ceramics exhibited superior plasma resistance compared with Al2O3, ZrO2, quartz, and Si wafer, demonstrating markedly reduced weight loss during plasma etching. These findings highlight the critical role of proper initial powder treatment and precisely controlled sintering kinetics for achieving yttria monoliths with enhanced densification, mechanical integrity, and plasma erosion resistance. This work provides a practical route for high performance yttria ceramics, offering enhanced densification, structural stability, and the reliability necessary for integration into advanced systems exposed to harsh plasma environments.