摘要
以β-sialon、活性氧化铝微粉和纯铝酸钙水泥为原料,研究了焦炭保护情况下,在1 500～1 650℃温度范围内,sialon/Al2O3/CaO体系材料的烧结性能和物相变化,借助SEM和XRD等手段对材料的显微结构和反应过程进行了观察和分析。结果表明:该体系材料烧结性能与试样组成和烧成温度有关。温度升高,试样体积密度增加,显气孔率降低,当温度升高至1 650℃,试样烧结性能反而下降。试样在烧成过程中存在质量变化,1 500℃下烧成试样均表现为质量增加,而1 600℃以上试样表现为质量损失。从热力学分析推测烧成过程中试样内部存在复杂化学反应,在温度低于1 500℃时sialon与CO反应使碳析出,导致试样质量增加;而温度进一步升高,sialon和Al2O3将被还原形成AIl7O9N(s)和SiC(s),导致试样质量损失。X射线衍射分析显示:烧成材料中除含有刚玉、sialon相外,随烧成温度增加还出现物相变化:1 500℃形成钙黄长石相;1 600℃时钙黄长石相消失,出现了Ca-α-sialon和SiC;温度升至1 650℃,出现γ AlON。
β-sialon/Al2O3/CaO composites were fired in coke powder bed at 1500-1650°C and their sintering properties and microstructure were investigated by SEM, EDX and XRD. Results show that the sintered properties of the composites are associated with their compositions and the sintering temperatures. The bulk densities of composites increase with the increase of temperatures and whereas the apparent porosities decrease. When the temperature increases to 1650°C, the sintered properties become worse. Meanwhile, the mass changes will occur in the whole sintering process. The mass of sintered samples increases when the temperatures are below 1500°C, while the mass of samples loses at the temperatures higher than 1600°C. From the point of thermodynamic analysis, there is a complex chemical reaction in samples during sintering process. The extraction of carbon by the reaction of sialon with CO at the temperatures lower than 1500°C is responsible for the mass gains of composites, and the reduction of sialon and Al2O3 leads to the mass loss at higher temperatures than. 1500°C. Additionally XRD analysis shows that there are phase changes with the increase of temperatures. Except corundum and sialon phases, anorthite phase appear at 1500°C of the sintering temperature, and it disappears at 1600°C, while Ca-α-sialon and SiC are formed and γ-A1ON is found at 1650°C.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2004年第2期156-161,共6页
Journal of The Chinese Ceramic Society
基金
教育部科学技术研究重点资助项目
关键词
SIALON
氧化铝
铝酸钙水泥
烧结
Alumina
Composite materials
Composition
Microstructure
Phase transitions
Porosity
Sintering
