本研究使用Tnconel738(Tn-738)鎳基超合金於硫分壓la' Pa之氣氛，鈞。°C-lOO°C之高低 溫進行熱循環腐蝕，並另以表面噴塗質量比3: I之Na2SO.，及VQ '於750�鈞。°C相同硫分壓進行混合鹽之柄溫熱腐蝕試驗，藉此探討合金之熱腐蝕行為。研究結果顯示合金股熱循環高溫硫化動力學遵守拋物線型定律，且其腐蝕速率隨循環次數的增加而降低。合金;於混合鹽之恆溫熱腐蝕動力學亦呈拋物線型定律，隨溫度之上升，其腐蝕反應速率呈緩慢增加之趨勢。合金經第一次熱循環腐蝕後，表面生成之腐蝕物為塊狀的N�S2及微量的Co，S，及Cr，S/Cr、試，內層腐白血物主要為Ni、民、微量的AI，S，與CoCr，氓，經過多次熱循環腐蝕後，表面則生成球狀的Ni，S，及少許的c。可S，及Cr2S/Cr，試，其內居亦為Ni，S，、微量的人12S1WCoCr，S，0合金經混合鹽恆溫熱 腐蝕後，腐蝕牛成物主要搞Ni哎，Cr，S.，及氧化物(含NiO、Cr，O月及Al，O)。由缺氧化物的形 成，f�吏合金熱腐蝕之速率低於單純的高溫硫化。

The purpose of the research is to study the thermal-cycling corrosion behavior of In-738 superalloy at Ps2=104 Pa (The cycling period is at 850 for 1 hr and at 100 for 1 hr), and the hot corrosion behavior of the alloy over the temperature range of 750~850 at Ps2=104 Pa with mixed coating of Na2SO4/V2O5 (at the weight ratio of 3 1). The thermal-cycling corrosion kinetics followed the parabolic rate law, and the corrosion rates decreased with increasing cycling times. The hot corrosion kinetics also followed the parabolic rate law, and the corrosion rates slowly increased with increasing temperature. The scale formed on topograph of the first thermalcycling specimens is main feather-shaped Ni3S2 and minor amounts of Co3S4 and Cr2S3 /Cr3S4, while the inner layer was a heterophasic mixture of Ni3S2, Al2S3, and CoCr2S4. however, the bignodule-
shaped Ni3S2 is observed after several cycling-times. In addition, the scales formed on the hot corrosion of In-738 consisted of mostly Ni3S2, Cr2S3 and some oxides of NiO, Cr2O3, and Al2O3.