高強度鈦合金高溫氧化與硫氧化腐蝕行為

High Temperature Oxidation and Simultaneous Sulfidation and Oxidation Behaviors of High- Strength Titanium Alloys

本研究主要探討兩種高強度鈦合金（Ti-6Al-4V及SP-700）在700 ~ 1000℃的空氣氧化及H2/H2S/H2O混合氣硫氧化之腐蝕行為。結果顯示，兩種合金的氧化及硫氧化動力學皆遵守抛物線型定律，腐蝕速率隨溫度之上升而加快；在同溫度，兩種合金的硫氧化速率皆比氧化速率快。Ti-6Al-4V及SP-700之氧化生成物為TiO2及α-Al2O3；在硫氧化氣氛下的腐蝕生成物則為TiO2，並有硫化鈦在靠近基材的腐蝕層生成。生成α-Al2O3為合金氧化速率較硫氧化速率慢的主因。

The oxidation and the simultaneous oxidation and sulfidation of Ti-6Al-4V and SP-700 were studied in air and in H2/H2O/H2S gas mixture over the temperature range 700 ~ 1000 ℃. The results indicated that the oxidation and the simultaneous corrosion kinetics followed the parabolic rate law at all temperatures. In general, the corrosion rates of both alloys are faster than their oxidation rates. The scales formed on Ti-6Al-4V and SP-700 after oxidation were composed of TiO2 and α-Al2O3, while the scales formed in H2/H2O/H2S gas mixture consisted of mostly TiO2 and minor Ti1-xS. The formation of Al2O3 is responsible for the reduction in oxidation rates for the two alloys as compared to their corrosion rates.