粒度对蓝晶石制备莫来石晶体的影响研究

Influence of Kyanite Granularity on Preparing Mullite Crystals

莫来石晶体主要应用于热障涂层,适量莫来石晶体可以降低涂层之间的失配应力,提高涂层的结合强度和抗热震性能。本论文主要研究粒度对蓝晶石高温下生成莫来石晶体的影响,将特定粒度蓝晶石和氧化铝混合样,在催化剂及一定温度制度下进行热处理,采用SEM和XRD对产物进行分析发现:-200～+325目蓝晶石分解温度较高,反应过程中没有形成莫来石晶体;-325～+400目之间的蓝晶石颗粒表面和内部的晶体晶形完整、均匀,反应体系表面晶体分布均匀,长径比为20～30;-400目蓝晶石体系经烧结后在体系表面有晶体分布,但是晶体分布不均匀,晶体长径比也不一致。

Mullite crystals are mainly used in thermal barrier coatings; the right amount can reduce the mismatch strain between the coatings and improve the bonding strength of muUite crystals and thermal shock resistance. This paper mainly studied the influence of kyanite granularity on mullite crystals synthesis at high temperatures, particular granularity kyanite and alumina mixed samples were treated under a certain temperature regime with catalyst, analyzed the product with scanning electron microscope and x-ray diffraction, and found that - 200- ＋ 325 mesh kyanite did not decompose, the reaction process did not generate mullite crystals; -325-＋ 400 mesh kyanite generated uniform mullite crystals on the surface and inside of the particles, crystal form was complete, and there also were uniform distribution crystals on the surface of the whole reaction system, the aspect ratio was 20 to 30; - 400 mesh kyanite after sintering, surface had crystal too, but the distribution of crystal was uneven, and crystal aspect ratio was also inconsistent.