不同表面改質對Ti-15V-3Al-3Sn-3Cr合金在700~900℃之高溫氧化研究

Effect of Surface Modifications on Hightemperature Oxidation of Ti-15V-3Al-3Sn-3Cr Alloy at 700 ~ 900 ℃

本研究主要探討2種不同的表面改質包括熱浸鋁矽後電鍍Ni改質（Ti-15-3（HN））及表面電鍍Ni加滲Al後再重覆鍍Ni滲Al改質（Ti-15-3（NANA））對Ti-15V-3Al-3Sn-3Cr（Ti-15-3）合金在700 ~ 900℃空氣條件下之高溫氧化行為的影響。由研究結果得知，Ti-15-3（HN）在700 ~ 900℃下之氧化動力學遵守拋物線律，而Ti-15-3 （NANA）在700 ~ 900℃下遵守拋物線律；但在900℃約3小時後之氧化動力學有加速增重的趨勢。Ti-15-3（HN）在700 ~ 900℃時表面生成的氧化物為NiO，但在基材與鍍層之間有裂縫，以至於產生TiO2氧化物，促使了氧化速率增快，反之Ti-15-3（NANA）在700 ~ 800℃時生成具有保護性之α-Al2O3；但在900℃時，卻生成TiO2及少量的α-Al2O3和NiAl2O4。

The effects of two different surface modifications, hot dipping in Al-Si followed by electroplating of Ni (Ti-15-3(HN)) and double pre-Ni plating followed by aluminizing coating (Ti- 15-3(NANA)) on the high temperature oxidation behavior of Ti-15V-3Al-3Sn-3Cr(Ti-15-3) alloys were studied over the temperature range of 700 ~ 900 ℃ in air. The results showed that the oxidation kinetics of Ti-15-3(HN) followed the parabolic-rate law at 700 ~ 900 ℃. The oxidation kinetics of Ti-15-3(NANA) also followed the parabolic-rate law at 700 ~ 900 ℃, but a significant increase in mass gain was observed after oxidation at 900 ℃ for 3h. The scales having formed on the surface of Ti-15-3(HN) primarily consisted of NiO, but TiO2 formed between the substrate and the coating and enhanced the oxidation rate. On the other hand, the scales having formed on the Ti-15-3(NANA) were protective α-Al2O3 at 700 ~ 800 ℃, but TiO2, α-Al2O3 and NiAl2O4 formed instead at 900 ℃.