基板温度对EB—PVD梯度热障涂层的微观结构和性能的影响

EFFECTS OF THE SUBSTRATE TEMPERATURE ON MICROSTRUCTURE AND PROPERTY OF EB-PVD GRADIENT THERMAL BARRIER COATINGS

采用 ＥＢ—ＰＶＤ方法共蒸发 Ａｌ－Ａｌ２Ｏ３—ＹＳＺ混合源，在高温合金基体上沉积了梯度热障涂层，研究表明，基板温度显著地影响着梯度热障涂层的微观结构和性能；在８５０ ℃时沉积得到的热障涂层实现了涂层的结构由金属粘结层向陶瓷顶层的梯度过渡，而且涂层在 １０５０℃的热循环寿命达到了 ５００ ｈ（１０００次循环）以上 由于“阴影”效应，在涂层中形成了梯度微孔结构，从而导致涂层的微观硬度朝着其表层逐渐增加；随着基板温度上升，涂层孔隙率增大，微观硬度减小．

Gradient thermal barrier coatings have been prepared by co-evaporation and deposition of the mixture sources of Al-Al2O3-YSZ Onto superalloy substrate by means of electron beam physical vapor deposition (EB-PVD). It is found that the microstructures and properties were significantly determined by the temperature of substrate. The gradient coating deposited at 850 degreesC, where a microstructure gradually transfers from metallic bond coat to ceramic topcoat, has a thermal cycling lifetime of more than 500 h (1000 cyc) at 1050 degreesC. Due to shadow effect, a gradient porous microstructure was formed in the coating and led to the micro-hardness in the coating gradually increasing towards the surface of the coating. Simultaneously, the micro-porosity in the coating increased with the rise of the temperature of the substrate, and the micro-hardness of the coating decreased thereby.