埋碳烧结法制备碳/铝酸钙复合粉体及其微观表征

Preparation of Carbon/Calcium Aluminate Composite Powder by Carbon-bed Sintering and Its Microstructure Characterization

以有机酸钙(草酸钙、柠檬酸钙、硬脂酸钙)和氧化铝为原料,采用埋碳烧结法制备碳/铝酸钙复合粉体。借助X射线衍射仪(XRD)、拉曼光谱(Raman)和扫描电子显微镜(SEM),研究了烧结温度和有机酸钙种类对产物物相组成及显微结构的影响,通过粒度分析仪、热重分析仪对其性能进行检测。结果表明,烧结温度由1 200℃升至1 400℃,产物中C_(12)A_7逐渐转变为CA和CA_2,与以碳酸钙为钙源的试样相比,有机酸钙1 400℃烧结试样的CA_2含量较高;各试样拉曼光谱图中在1 350cm^(-1)和1 580cm^(-1)附近均出现了自由碳的D峰和G峰,表明各试样中均含有自由碳;SEM分析表明以柠檬酸钙为钙源和碳源的试样(1400-Cit)经1 400℃埋碳烧结后产物中自由碳弥散分布于铝酸钙中并被其包裹,形成球形复合粉体。利用氧化失重法测得1400-Cit试样的碳含量最高,其质量分数达5.98%。

Carbon/calcium aluminate composite powder was synthesized by carbon-bed sintering, taking organic calcium （oxa- late, calcium citrate, calcium stearate） and aluminium oxide as raw materials. The impact of sintering temperature and the species of organic calcium on the phase and microstructure of the obtained composite powder were analyzed by XRD, Raman spectroscopy and SEM. And the properties of the composite powder were characterized by particle size analyzer and thermogravimetric analyzer. The results indicated that C 12 A 7 in the product gradually convert into CA and CA 2 as the sintering temperature raised from 1 200 ℃ to 1 400 ℃. Compared to specimen with calcium carbonate as calcium source, the specimen that take organic calcium as calcium source and sinter at 1 400 ℃ present higher CA 2 content in the Raman spectra of all the samples, D and G peaks corresponding to free carbon appear at about 1 350 cm^ -1 and 1 580 cm^ -1 , respectively, which indicate that all the products contain free carbon. As can be seen in the SEM results, the free carbon of the specimen （1400-Cit） sintered at 1 400 ℃ with the calcium citrate as calcium and carbon sources is dispersively distributed in calcium aluminate and wrapped by it, forming a nearly spherical composite. The 1400-Cit contains the highest carbon content of 5.98wt% which is obtained by oxidation weightlessness method.