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将6H-SiC和α-Al2O3按质量比为7:3混合,添加0～10%的[BaO+TiO2]作为烧结助剂,球磨后的均匀粉体压制成生坯,在1 200℃预氧化1 h后在氢气气氛下常压烧结1h制备SiC-莫来石复相材料。研究了烧成温度和BaO–TiO2含量对该复相材料烧结性能和相组成的影响。结果表明:1500℃下,随着烧结助剂含量的增加,烧结致密性明显提高,当含量(质量分数)达到8%时,获得显气孔率为0.17%的致密复相材料。预氧化时,烧结助剂中的BaO与α-Al2O3及SiC氧化生成的方石英反应,生成钡长石BaAl2Si2O8,烧成过程中,钡长石转化成玻璃相,促进莫来石的生成,同时促进烧结。复相材料主晶相为6H-SiC和莫来石,次相为玻璃相和Al2SiO5。
The mass ratio of 6H-SiC and α-Al2O3 is 7: 3, and 0-10% [BaO + TiO2] is added as a sintering aid. The ball mill uniform powder is pressed into a green body and pre-oxidized at 1200 ℃ 1 h after atmospheric pressure sintering in hydrogen atmosphere 1h prepared SiC-mullite composite material. The effects of sintering temperature and BaO-TiO2 content on the sintering properties and phase composition of the composite were investigated. The results show that the sintering densification is obviously improved with the increase of sintering aid content at 1500 ℃. When the content (mass fraction) reaches 8%, the dense phase material with apparent porosity of 0.17% is obtained. During pre-oxidation, BaO in the sintering aid reacts with c-quartz formed by α-Al2O3 and SiC oxidation to form barium feldspar BaAl2Si2O8. During the sintering process, the barium feldspar is transformed into the glass phase to promote the formation of mullite, meanwhile, Promote sintering. The main phase of the composite material is 6H-SiC and mullite, the secondary phase is the glass phase and Al2SiO5.