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.

본 연구에서는 에너지 소모가 큰 기존 진공 증류 공정의 대안으로 친환경이면서 에너지 효율적인 투과증발 분리 공정을 이용하여 1,2 hexane diol/water (1,2 HDO/water) 혼합물에서 물을 분리하는 데 적용되었다. 사용한 분리막은 glutaraldehyde (GA)로 가교된 PVA를 알루미나 중공사 막(Al-HF) 내부에 코팅하여 사용하였다. 1,2 HDO/water 투과증발 분리공 정에서는 PVA/GA 비율, 경화 온도 및 투과증발 분리공정 운전 조건에 대한 막의 최적화를 연구하였다. 장기 안정성 시험에 서 PVA/GA (몰 비율 = 0.08, 경화 온도 = 80°C) 로 코팅된 Al-HF 막이 공정온도 40°C에서 1.90~2.16 kg/m2h 범위의 투과 도를 보였으며, 투과용액의 수분 함량은 99.5% (separation factor = 68) 이상이었다.

In this study, the effect of osmotic drying conditions of mangoes on hot air drying was investigated. Four different osmotic agents of 60 Brix, such as S60, SM10, HF80, and SG25, were prepared. Mango slabs were osmotically dried with the agents at a ratio of 1:4 (w/w) for up to 8 hours. SG25 showed the lowest weight reduction and moisture loss during the process. As a result of hot-air drying, all samples showed a high correlation with the Page model (0.9761~0.9997), and the required drying time of all samples that were osmotically dried was reduced compared to the non-osmotically dried group. After hot-air drying, the pH value increased according to the drying temperature. The L, a, and b values and the total polyphenol content also decreased. Through this study, the possibility of osmotic drying was confirmed to increase the efficiency of hot air drying of mangoes, which is expected to contribute to the industrial use of domestic mangoes.