This study aimed to address the limitations of traditional plasma nitriding methods by implementing a short-term plasma oxy-nitriding treatment on the surface of AISI 420 martensitic stainless steel. This treatment involved the sequential formation of nitride and oxide layers, to enhance surface hardness and corrosion resistance, respectively. The process resulted in the formation of a 20 μm-thick nitride layer and a 3 μm-thick oxide layer on the steel surface. Initially, the hardness increased by 2.2 times after nitriding, followed by a subsequent decrease of approximately 31 % after oxidation. While the nitriding process reduced corrosion resistance, the subsequent oxidation process led to the formation of a passive oxide film, effectively resolving this issue. The pitting corrosion of the oxide passive film started at 82.6 mVssc, providing better corrosion resistance characteristics than the nitride layer. Consequently, the trade-off between surface hardness and corrosion resistance in plasma oxy-nitrided AISI 420 martensitic stainless steel is anticipated to be recognized as an innovative and comprehensive surface treatment process for biomedical components.

To increase the mechanical property of zirconia, we have investigated the phase change and the resulting hardness of zirconia ceramics by hydroxyapatite (HA) powder bed sintering. It was observed using X-ray diffraction that the cubic zirconia phase, which has a higher hardness value than that of the tetragonal phase, was obtained at the surface of 3 mol% Y2O3 doped tetragonal zirconia polycrystal (3Y-TZP) ceramics during the sintering process; in our experimental conditions, the phase change at the surface increased as the sintering time increased. We believe that the observed crystalline phase change originated from the decomposition of HA and the diffusion of CaO, as follows. CaO, which was derived from the decomposition of HA at high temperature (1400˚C), diffused into the surface of 3Y-TZP and acted as a stabilizer. As a result, the Vickers hardness value of the treated specimens was higher than that of the non-treated specimen due to the formation of the cubic phase on the surface of 3Y-TZP.

본 연구에서는 고경질 도막재로 PET 필름을 접합하는 시공방법에 있어서 PET 필름의 표면처리 조건 및 겹침이음 길이에 따른 접합특성 및 내구특성을 검토하였는데, 그 결과 무처리 보다 코로나 방전 처리에 의해 접촉각, 접합 인장강도, 벗김저항성이 개선되었다. 특히 시험체 E (코로나 방전+프라이머+강접접착제+폴리에스터 부직포)에서 가장 높은 것으로 나타났으며, 특히 겹침 이음길이 15mm 이상일 때 16주간 장기간 열화처리에도 안정적인 접합성능을 확보하는 것으로 나타나 방수재료로서 수밀성을 확보할 것으로 판단된다.