鋁化改質效應對MoSi_2基合金抗高溫氧化之研究

Effects of Aluminizing Treatments on Hightemperature Oxidation of MoSi_2-based Alloys

10.6376/JCCE.201409_28(3).0001

周鈺峰(Y. F. Chou)；何昱瑾(Y. C. Ho)；開物(W. Kai)

鋁化改質 ； MoSi_2合金 ； 高溫氧化 ； 氧化動力學 ； 反應機制 ； Aluminizing Treatments ； MoSi_2 alloys ； High-temperature oxidation ； Oxidation kinetics ； Reaction mechanism

防蝕工程

28卷3期（2014 / 09 / 01）

105 - 110

繁體中文

本研究探討Mo-Si基三元合金經熔煉(MoSi_2)_(90)Al_(10) (MSA_(10))及其在經固體滲鋁改質之試片(MS-A)，於700 ~ 1100 °C之空氣下的氧化行為。研究結果顯示，MSA_(10)合金在700 ~ 800°C呈現加速氧化現象，但在900 °C以上具有良好的抗氧化性質；另一方面，MS-A合金在800 °C之氧化動力學是加速反應，而900 °C則遵守拋物線律，且氧化速率隨溫度增加而趨緩，但在1000 °C 以上則呈現嚴重的氧化失重現象。由顯微結構分析得知，MSA_(10)在800°C氧化所形成的Al_2O_3氧化層較為鬆散，保護性較差；在900°C以上氧化後，其表面會形成較緻密的α-Al_2O_3保護層，能有效地提升MoSi_2的抗氧化能力；而MS-A，經氧化後亦會生成具保護層的α-Al_2O_3，但會有較多且不連續裂縫，其保護效果較差。關鍵詞：鋁化改質；MoSi_2合金；高溫氧化；氧化動力學；反應機制。

The effects of adding 10 at.% Al to form (MoSi_2)_(90)Al_(10) and surface aluminizing (MS-A) on the isothermal oxidation of MoSi_2-based alloys were investigated over the temperature range of 700 ~ 1100 °C in dry air. The breakaway kinetics of the MSA_(10) alloy was observed at T ≤ 800 °C, however, the parabolic kinetics with better oxidation resistance was noted at T ≥ 900 °C. On the other hand, the mass-loss kinetics was observed at T ≥ 1000 °C for the MS-A alloy. The Al_2O_3 layer formed on the MSA_(10) at 800 °C that provided poor oxidation resistance. However, the scales formed on MSA_(10) was composed of α-Al_2O_3 at T ≥ 900 °C, whose formation is responsible for the better oxidation resistance. On contrast, the α-Al_2O_3 layer formed on the MS-A alloy containing numerous crackes, which provided poor oxidation resistance.