粘结层成分对单晶合金热障涂层寿命影响研究

采用电子束物理气相沉积工艺(EB-PVD)制备了针对第二代单晶高温合金的热障涂层,用SEM观察分析了不同成分粘结层的热障涂层热循环试验后的结构和晶体形貌,在N2条件下对比了不同成分粘结层材料与第二代单晶高温合金的热膨胀系数,分析了热循环试验后粘结层与热生长氧化(TGO)层成分、厚度及完整性情况。结果表明:NiCoCrAlYHf与第二代单晶高温合金热膨胀系数更为接近,匹配性更好;采用EB-PVD工艺制备的热障涂层在热循环试验过程中会产生大量垂直裂纹使涂层具有良好的应变容限;粘结层中Al元素含量的提高以及Hf等元素的加入,使得热循环试验后涂层TGO层的Al2O3纯度较高、生长缓慢无块状物生成,并且极大地改善了粘结层和合金基体的内氧化,涂层1 100℃循环氧化寿命达到1 200 h以上。

Influence of Bond Coating Composition on Thermal Barrier Coating Life for Single Crystal Superalloy

Thermal barrier coating was deposited on bond coat for the second generation single-crystal superalloy by EB-PVD. Thermal barrier coating structure and crystal morphology with different composition bond coats were observed and analyzed by SEM after thermal cycle test. In N2 condition, the thermal expansion coefficients of different composition bond coat materials and the second generation single crystal superalloy were compared. The composition, thickness and integrity situation of bond coats and TGO layers were analyzed after thermal cycle test at 1 100 ~C. The results show that the thermal expansion coefficients of single crystal superalloy and NiCoCrA1YHf are closer to each other and the matching is better. Thermal barrier coatings by EB-PVD produced a large number of vertical cracks in thermal cycling test process, making coating have good strain tolerance. Bond coats with A1 improvement and Hf joining makes A1203 in TGO layer more pure, grow slowly and no massive matter form, which greatly improves the internal oxidation performance of the bonding layer and matrix. The thermal cycle life of TBCs can mount up to 1 200 h at 1 100 ℃.