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EB-PVD热障涂层热循环过程中粘结层的氧化和相结构
OXIDATION AND PHASE STRUCTURE OF THE BOND COAT IN EB-PVD THERMAL BARRIER COATINGS DURING THERMAL CYCLING
【摘要】 采用磁控溅射方法在镍基单晶高温合金基体卜沉积 Ni30Cr-12Al-0.31Y(质量分数、%)粘结层,采用电子束物理气相沉积方法(EB-PVD)沉积 7%Y2O3(质董分数)-ZrO2陶瓷顶层 结果表明.在热循环过程中.非平衡相 t’-ZrO2中的 Y2O3含量逐渐减少,t’-ZrO2相逐渐分解成平衡相 t-ZrO2(冷却时会转变成单斜相)和立方相 ZrO21050C循环 200次,粘结层氧化物(Al2O3)厚度约为3um,表明NiCr-Al-Y适宜作粘结层 继续热循环,陶瓷层中出现单斜相,粘结层中Al贫化,氧化层中出现NiO 及尖晶石等,引起应力集中.导致涂层失效.
【Abstract】 After depositing Ni-30Cr-12Al-0.3Y(mass fraction, %) bond coat on a Ni base single crystal superalloy by magnetron sputtering, a ceramic top coat(7%Y2O3-ZrO2) was deposited by electron beam-physical vapor deposition(EB-PVD). During thermal cycles, the Y2O3 content in non- equilibrium phases t’-ZrO2 decreased gradually and the t’-ZrO2 decomposed gradually to equilibrium t-ZrO2(transforming to monoclinic phase after cooling) and cubic ZrO2 phase. After 200 thermal cycles, the thermally grown oxides(TGO) layer with 3 um thickness consists of Al2O2 exclusively, indicating that the sputtered Ni-Cr-Al-Y coating is suitable as bond coat for EB-PVD thermal barrier coatings. With increasing thermal cycles, a small amount of monoclinic m-ZrO2 formed from t-ZrO2. Al was depleted, and NiO and Ni(Al, Cr)2O4 formed near the interface between TGO and bond coat. Stress concentration due to oxide growth and phase transformation between t-m ZrO2 would weaken the combination between top and bond coats, and then cause thermal barrier coating to spall from the substrate.
【Key words】 thermal barrier coating; bond coat oxidation; phase transformation; thermal cyclic;
- 【文献出处】 金属学报 ,Acta Metallrugica Sinica , 编辑部邮箱 ,2002年01期
- 【分类号】TG174.4
- 【被引频次】32
- 【下载频次】423