【摘要】 采用喷雾造粒-胶粘包覆的方法制备了一种低烧损核壳结构ZrB₂/SiC复合粉末,研究了胶粘包覆过程中不同清漆含量对粉末包覆效果的影响。结果表明清漆含量不足时细粉包覆不完全,细粉出现单独团聚的现象;清漆含量过多时,造成原始球形颗粒的粘连;当清漆含量为4.5%时,获得包覆效果良好的粉末,外层包覆完整均匀。为了研究等离子喷涂过程中核壳结构粉末SiC发生分解烧损程度,对比了分别采用核壳结构和均匀弥散结构ZrB₂/SiC复合粉末所制备涂层的微观形貌及涂层中元素分布。结果表明核壳结构粉末喷涂涂层成分均匀性良好,高熔点ZrB₂保护内层SiC,可有效减少SiC在等离子焰流中的烧损,实现涂层和粉末成分的一致性。对核壳结构复合粉末制备的涂层进行了20s的氧-乙炔火焰烧蚀试验,涂层质量烧蚀率为1.837×10^-3g/s,对涂层抗烧蚀机理进行了初步探讨。更多还原

【Abstract】 A low-burning and core-shell structure ZrB₂/SiC composite powder with homogeneous dispersed ZrB₂/SiC as core and ZrB₂ as shell was prepared by "spray granulation-adhesive coated" methods. The effect of different varnish content on the powder coated effect during the adhesive coating process was studied. When the varnish content is insufficient, the shell is incomplete and the fine powder appears to be agglomerated separately. Too much content of varnish caused the adhesion of the original spherical particles. When the varnish content is 4.5%, the powder with good coated effect is obtained, and the intact outer layer is wrapped. In order to study the degree of decomposition and burning for SiC in core-shell ZrB₂/SiC powder during plasma spraying, the micro-morphology and elements distribution for the coatings prepared by core-shell structure and homogeneous dispersed composite powder were compared. The coating prepared by core-shell structure powder exhibits better uniformity of composition than that prepared homogeneous dispersed. The high melting point ZrB₂ protects the inner layer of SiC, and it can effectively reduce the burning loss of SiC in the plasma flame flow, which achieves the consistency of the coating composition and the powder composition; The coating prepared by core-shell structure powder was subjected to an oxygen-acetylene flame ablation test for 20s. The quality ablation rate of coating was 1.837×10^-3 g/s. The anti-ablative mechanism of the coating was discussed preliminarily.更多还原