DZ-40M钴基合金低压气相沉积铝化物涂层的高温氧化行为

HIGH TEMPERATURE OXIDATION BEHMIOR OF LOW PRESSURE GAS PHASE DEPOSITED ALUMINIDE COATINGS ON Co－BASE SUPERALLOY DZ4OM

以新型定向凝固钻基合金DZ40M为基体，对其低压化学气相沉积铝化物涂层的高温氧化行为作初步探讨．结果表明，该涂层在900～1100℃的静态空气氧化过程中有一个平稳期，沉积渗剂中加入Ti及提高氧化温度均可加速涂层的氧化和退化，使平稳期提前结束．由于生成了θ－Al2O3，使得900℃时的氧化增重大于1000℃时的氧化增重，而1000℃时的氧化增重又大于1050℃时的氧化增重．

High temperature oxidation behavior of aluminide coatings obtained by low pressure gas phase des position under 0－0.014 MPa at 1080℃ for 4 hours on Co－base superalloy DZ40M has been primarily investigated. The results indicated that isothermal oxidation process of the costings in air at 900－1100℃ showed three stages， including the initial， the stable and the accelerative. During the initial stage the coating oxidation controlled by interface reaction developed rapidly. The stable stage was controlled by decision within oxide film and proceeded very slowly. Because the degeneration of the coatings obstructed the formation of the protective oxide scale， the samples were oxidized strongly during the accelerative stage. The addition of Ti during deposition and increase in temperature accelerated the oxidation and degeneration of the coating， and transfered the stable okidation stage into the accelerative. Due to the formation of θ－Al2O3 the oxidation weight gains of the coatings at lower temperature were more than that at higher temperature， thus decreased in the order: at 900℃， 1000℃ and 1050'C. At 1050℃， only α－Al2O3 appeared.