純Ti及Ti-Al合金在H2/H2S/H2O混合氣氛下之高溫腐蝕

The High-Temperature Corrosion of pure Ti and Ti-Al alloys in a H2/H2S/H2O Gas Mixture

本研究探討純Ti、Ti3Al及Ti3AI+TiAl合金於H2/H2S/H2O混合氣氛下，溫度範圍800~1000℃間的高溫腐蝕行為。研究結果顯示，純Ti，Ti3Al及Ti3Al+TIAl合金的腐蝕動力學皆遵守抛物線型定律，且腐蝕速率隨著溫度的增加而加快，但隨著鋁含量的增加而降低。純Ti 在800~1000℃的腐蝕生成物皆是TiO2，而Ti3Al和Ti3Al+TiAl則形成兩層易剝落的腐蝕物，包括外層的TiO2，及內層多量TiO2和少量的Al2O3和微量的Ti1-xS，其中，Al2O3的生成是造成Ti3Al和Ti3Al+TiAl合金腐蝕速率較純Ti為低的主因。

The corrosion behavior of pure Ti, Ti3Al, and Ti3Al+TiAl was studied over the temperature range of 800~1000℃ in a H2/H2S/H2O gas mixture. The corrosion kinetics of pure Ti and both alloys followed the parabolic rate law at all temperatures. The corrosion rate constants increased with increasing temperature, but decreased with increasing Al content. The scale formed on pure Ti is exclusively TiO2 regardless of temperature, while the scales formed on Ti3Al and Ti3Al+TiAl were duplex and always spalled after cooling, consisting of the outer-layer of most TiO2 and the inner-layer of most TiO2, Al2O3, and minor Ti1-xS. The formation of Al2O3 is responsible for the reduction in the corrosion rates of Ti-Al alloys as compared to those of pure Ti.