Ba_(0.75)Sr_(0.25)Al_2Si_2O_8粉体的制备及其抗氧化性能初步评价

Preparation and the Oxidation Resistance of Barium Strontium Aluminum Silicate Powders

采用凝胶固相反应法制备SiC陶瓷基复合材料EBC涂层用Ba0.75Sr0.25Al2Si2O8粉体,并以SiC陶瓷片为基体材料初步评价了BSAS涂层的抗氧化能力。通过DSC/TG确定了凝胶前驱体的热分解情况;利用XRD、SEM、粒度和热膨胀系数的测定对合成粉体进行了表征;对该粉体的抗氧化性能进行了初步评价。结果表明,1200℃下成功制备颗粒中位径3.9μm、分散均匀的BSAS粉体;粉体室温至1200℃的热膨胀系数为5.02×10-6 K-1,与SiC陶瓷有很好的热胀匹配;该涂层可在1300℃、大气环境下保持均匀无开裂,与基体结合紧密,可以基本满足现阶段国内航空用SiC陶瓷基复合材料抗氧化的要求。

In this paper, barium strontium aluminum silicate powders, used for environmental barrier coatings on SiC ceramic matrix composites, are prepared by the gel-solid reaction method. DSC/TG thermodynamics is used to analyze the thermal decomposition of the precursor. The XRD, SEM, the particle size distribution and the thermal expansion of the BSAS powders are investigated, and its oxidation resistance is evaluated primarily. The results show that uniformly dispersed BSAS powders with a diameter of 3.91am can be prepared at the temperature of 1200℃ ; the thermal expansion of the BSAS powders is determined as 5.02× 10.0 K^-1 from room temperature to 1200 ℃ which matches with the thermal expansion of SiC ceramics very well; the coating will maitain uniform and no-cracking till 1300℃ in air, and it combines with the substrate closely. The coating materials meet with the oxidation resistance requirements of the SiC ceramic matrix composites for current domestic aeronautic application.