利用SiO2中间层提高铝化物涂层的高温防护性能

Improvement of the High-temperature Oxidation Resistance of Aluminide Coating by SiO2 Interlayer

目的提高TiAl合金的抗高温氧化性能。方法采用料浆法和电沉积法在TiAl合金表面制备Al-SiO2复合涂层。通过静态空气氧化测试评价复合涂层对TiAl合金抗高温氧化性能的影响,利用X射线衍射仪分析高温氧化前后涂层物相组成,借助扫描电子显微镜分析试样表面和截面微观组织和形貌。结果1000℃氧化过程中,铝化物涂层具有一定的抗高温氧化性能,氧化100 h后增重为10.44 mg/cm^2。然而其表面仍然出现了淡黄色TiO2氧化层,并且存在裂纹等缺陷,表面涂层物质在热处理过程中与基体组织发生了大量互扩散。Al-SiO2复合涂层经过100 h氧化后,表面形貌基本保持不变,未观察到裂纹等缺陷,随着SiO2中间层沉积时间延长,试样的抗高温氧化性能总体呈现上升趋势。−2 mA/cm^2下电沉积300 s制备的SiO2涂层抗高温氧化性能显著提高,其氧化增重仅为3.03 mg/cm^2。结论Al-SiO2复合涂层能够有效地提高TiAl合金的抗高温氧化性能。

The work aims to improve the high temperature oxidation resistance of TiAl alloy.An Al-SiO2 composite coating was prepared on the surface of TiAl alloy by slurry and electrodeposition.The high temperature oxidation resistance of the coated TiAl alloy was evaluated by static air oxidation test.The phase composition of the coating before and after high temperature oxidation was analyzed by X-ray diffractometer.The surface morphologies and cross-sectional microstructure of the samples were analyzed by scanning electron microscopy.After oxidation at 1000℃,the aluminide coated TiAl alloy exhibited good oxidation resistance and the weight gain for 100 h was 10.44 mg/cm^2.However,a yellowish oxide layer consisting of TiO2 was detected on the surface,and some defects such as cracks were observed.Moreover,serious interdiffusion of elements occurred between the coating and substrate during the heating treatment process.The surface morphology of the Al-SiO2 composite coating almost kept unchanged after oxidation for 100 h,and no obvious defects were observed.The oxidation resistance of the specimens increased with the prolonging of electrodeposition time for SiO2 interlayer.The best resistance was observed when the SiO2 interlayer was electrodeposited at−2 mA/cm^2 for 300 s,and the oxidation weight gain was only 3.03 mg/cm^2.The Al-SiO2 composite coating can effectively improve the high temperature oxidation resistance of TiAl alloy.