Design and Processing of Hollow Ceramic Microspheres and Hybrid Ceramic/Polymer Microparticles

本文对空心陶瓷微球和陶瓷/聚合物杂化微球的设计和制备进行了如下尝试.机械力熔融法制备陶瓷微球以几种球形聚合物为核材料，以Al_2O_3粉末或Al_2O_3与SiO_2的混合粉末为壳材料，采用机械力熔融法制备了核/壳结构陶瓷微球。在1600 ℃烧结3h后，可以得到大部分反映核聚合物形貌和粒径分布的中空氧化铝微球。99%的PMMA微球作为核聚合物，采用高于500 ℃的突然焙烧来去除PMMA微球。采用类似的方法制备了二氧化钛微球.利用杂化体系制备氧化铝/聚甲基丙烯酸甲酯杂化微球 ...更多信息 以PMMA微粒和Al_2O_3粉末为原料，通过对PMMA微粒和Al_2O_3粉末的复合改性，制备了一种新型的PMMA/Al_2O_3纳米复合材料。但在1600 ℃煅烧后，由于Al_2O_3粉末不能均匀包覆在PMMA微球周围，几乎不能得到空心微球.超声波喷雾热分解法制备陶瓷微球以0.5M Al（NO_3）_3水溶液为原料，经超声喷雾、瞬时热分解和1300 ℃煅烧，成功地制备了氧化铝微球。微球的晶相为δ-Al_2O_3，经1300 ℃煅烧2h后，微球的晶相转变为α-Al_2O_3。此外，通过后煅烧，部分微球由实心结构转变为空心结构。在此条件下制备的空心微球的平均粒径为0.7 μ m，空心微球的含量小于30%。然而，通过向前体溶液中添加少量表面活性剂，可以将分数增加至80%。铝/空心氧化铝微球复合材料的制备采用液态模锻工艺，将机械熔融法制备的空心氧化铝微球与ADC-12（Al> 84.4%）铝锭复合，制备了铝/空心氧化铝微球复合材料。与工业氧化铝泡沫、粉煤灰和塞拉斯球制备的复合材料相比，该复合材料具有最高的弯曲强度。少

Design and processing of hollow ceramic microspheres and hybrid ceramic/polymer microparticles were attempted as below.1. Preparation of ceramic microspheres by utilizing a mechanofusion system Core/shell structure was prepared by a mechanofusion system by employing several kinds of spherical polymers as a core material and Al_2O_3 powder or a mixture of Al_2O_3 and SiO_2 powder as a shell material. A large fraction of hollow alumina microspheres reflecting the shape and the particle size distribution of the core polymer could be fabricated after sintering at 1600℃ for 3h, when highly cross-linked PMMA microspheres with a gel fraction of ca. 99% were used as a core polymer and abrupt firing at temperatures higher than 500℃ was adopted to remove the PMMA microspheres. Titania microspheres were also prepared by employing the similar technique.2. Preparation of ceramic microspheres by utilizing a hybridization system Hybrid alumina/PMMA microparticles were prepared by utilizing a hybridiz … More ation system by employing PMMA microparticles and Al_2O_3 powder as a raw material. However, hollow microspheres were scarcely obtained even after calcination at 1600℃, because the Al_2O_3 powder could not be coated around the PMMA microparticles sufficiently.3. Preparation of ceramic microspheres by ultra-spray pyrolysis Alumina microsphreres were successfully fabricated by ultrasonic spraying of 0.5 M Al(NO_3)_3 aqueous solution, followed by instantaneous thermal decomposition and calcination at 1300℃. The crystal phase of as-prepared microspheres was δ-Al_2O_3, but turned into α-Al_2O_3 after post-calcination at 1300℃ for 2h. In addition, some microspheres were changed from solid to hollow structure by the post-calcination. The fraction of hollow microspheres in the resultant products was less than 30% and the mean diameter of these microspheres was 0.7 μm under these preparation conditions. However, the fraction could be increased up to 80% by the addition of a small amount of a surfactant to the precursor solution.4. Fabrication of aluminum/hollow alumina microspheres composites Aluminum/hollow alumina microspheres composites were fabricated by a liquid forging technique by employing aluminum ingot (ADC-12 ; Al>84.4%) and hollow alumina microspheres prepared by a mechanofusion system. The composites showed the highest flexural strength, compared with those prepared from commercially produced alumina bubbles, fly ash and silas balloons. Less