The effects of different spray angles (90°, 85°, 80°) on the microstructure and mechanical properties of a Y2O3 coating layer prepared using the atmospheric plasma spray (APS) process were studied. The powders employed in this study had a spherical shape and included a cubic Y2O3 phase. The APS coating layer exhibited the same phase as the powders. Thickness values of the coating layers were 90°: 203.7 ± 8.5 μm, 85°: 196.4 ± 9.6 μm, and 80°: 208.8 ± 10.2 μm, and it was confirmed that the effect of the spray angle on the thickness was insignificant. The porosities were measured as 90°: 3.9 ± 0.85%, 85°: 11.4 ± 2.3%, and 80°: 12.7 ± 0.5%, and the surface roughness values were 90°: 5.9 ± 0.3 μm, 85°: 8.5 ± 1.1 μm, and 80°: 8.5 ± 0.4 μm. As the spray angle decreased, the porosity increased, but the surface roughness did not show a significant difference. Vickers hardness measurements revealed values of 90°: 369.2 ± 22.3, 85°: 315.8 ± 31.4, and 80°: 267.1 ± 45.1 HV. It was found that under the condition of a 90° angle with the lowest porosity exhibited the best hardness value. Based on the aforementioned results, an improved method for the APS Y2O3 coating layer was also discussed.

Abstract
1. 서 론
2. 실험 방법
3. 결과 및 고찰
4. 결 론
References

• 황유진(인하대학교 신소재공학과) | Yu-Jin Hwang (Department of Materials Science and Engineering, Inha University)
• 김경욱(인하대학교 신소재공학과) | Kyoung-Wook Kim (Department of Materials Science and Engineering, Inha University)
• 이호영((주)이에스티) | Ho-Young Lee (EST Inc.)
• 권식철(베델원(주) 표면처리센터) | Sik-Chol Kwon (Bedell Surface Technologies)
• 이기안(인하대학교 신소재공학과) | Kee Ahn Lee (Department of Materials Science and Engineering, Inha University) Corresponding Author