共查询到20条相似文献,搜索用时 15 毫秒
1.
《Journal of the European Ceramic Society》2014,34(15):3619-3626
cBN–TiN–TiB2 composites were fabricated by spark plasma sintering at 1773–1973 K using cubic boron nitride (cBN) and SiO2-coated cBN (cBN(SiO2)) powders. The effect of SiO2 coating, cBN content and sintering temperature on the phase composition, densification and mechanical properties of the composites was investigated. SiO2 coating on cBN powder retarded the phase transformation of cBN in the composites up to 1873 K and facilitated viscous sintering that promoted the densification of the composites. Sintering at 1873 K, without the SiO2 coating, caused the relative density and Vickers hardness of the composite to linearly decrease from 96.2% to 79.8% and from 25.3 to 4.4 GPa, respectively, whereas the cBN(SiO2)–TiN–TiB2 composites maintained high relative density (91.0–96.2%) and Vickers hardness (17.9–21.0 GPa) up to 50 vol% cBN. The cBN(SiO2)–TiN–TiB2 composites had high thermal conductivity (60 W m−1 K−1 at room temperature) comparable to the TiN–TiB2 binary composite. 相似文献
2.
通过熔融共混法把改性过的超细SiO2加入到聚丙烯(PP)中,制备PP/SiO2复合材料母粒,通过化学发泡注塑工艺制备PP/SiO2微发泡复合材料.用扫描电镜观察了发泡样品的泡孔结构,借助电子探针和转矩流变仪研究了超细SiO2粒子在PP复合材料微孔发泡中的作用.结果表明,SiO2粒子之所以能够改善PP微孔发泡材料的微孔结构,一方面是SiO2粒子的成核作用,另一方面是SiO2的加入提高了PP熔体黏度. 相似文献
3.
4.
5.
将稻壳用10%的盐酸处理后在600 ℃焚烧得到无定形、纯度大于99%的稻壳SiO2,通过红外光谱(FT-IR)、扫描电镜(SEM)以及马尔文粒度仪对稻壳SiO:的结构、形貌和粒径进行了分析,并与气相SiO2进行了对比.将两种SiO2分别与壳聚糖复合,对比了两种复合膜的机械性能和热分解性能.结果表明:稻壳SiO2的FTIR谱图与气相SiO2相同,但吸水值和吸油值均低于气相SiO2,二者的粒度分布均在2~100μm区间;两种SiO2壳聚糖复合膜的拉伸模量、强度和断裂伸长率的最大值相差不大;当SiO2质量分数为5%时,气相SiO2/壳聚糖复合膜热稳定性能略高于稻壳SiO2/壳聚糖复合膜. 相似文献
6.
7.
8.
多孔状纳米SiO2微粉的制备是以水玻璃的盐酸为原料,添加适定的稳定剂(非离了表面活性剂)在适宜的pH值和温度下沉淀合成,要得到性能优良的SiO2纳米微粉,最佳工艺的研究尤其重要,用BDL-B型电位仪,ET,EPMA-电子探针及DTA-TGA等手段对其性能进行表征,结果表明,制得的SiO2超细微粉,颗粒呈多孔状,具有巨大的比表面积,高达1000m2/g以上,孔径为25A左右,粒度分布均匀,粒度可达纳米级,这种粉末具有特殊的性能。 相似文献
9.
10.
11.
《Journal of the European Ceramic Society》2014,34(2):533-539
Equilibrium phase relations in the system CaO·SiO2Na2O·SiO2Na2O·Al2O3·6SiO2 at 40–80 wt% Na2O·Al2O3·6SiO2 composition range have been experimentally studied at temperatures between 800 °C and 1200 °C. The liquidus temperature was determined with differential scanning calorimetry. The equilibrated samples were quenched with pressurized nitrogen, and examined with electron probe X-ray microanalysis and X-ray diffraction for identification of microstructure and phase relations. Five primary phase fields, CaO·SiO2, Na2O·SiO2, Na2O·2CaO·3SiO2, 2Na2O·CaO·3SiO2 and Na2O·Al2O3·6SiO2 were established. The ternary eutectic point of CaO·SiO2, Na2O·2CaO·3SiO2 and Na2O·Al2O3·6SiO2 was determined to be at 1030 °C with the composition of 29.0 wt% CaO·SiO2, 12.0 wt% Na2O·SiO2 and 59.0 wt% Na2O·Al2O3·6SiO2. Peritectic reaction of Na2O·2CaO·3SiO2, 2Na2O·CaO·3SiO2 and Na2O·Al2O3·6SiO2 occurred at 930 °C with the composition of 13.0 wt% CaO·SiO2, 29.0 wt% Na2O·SiO2 and 58.0 wt% Na2O·Al2O3·6SiO2. The liquidus surface projection of the ternary system has been constructed in the composition region important for the bottom ash application. 相似文献
12.
13.
14.
15.
16.
17.
18.
新型SiO2-TiO2-BaO-CaO耐碱涂层 总被引:1,自引:0,他引:1
采用Sol-gel方法制备出新型SiO2-TiO2-BaO-CaO耐碱涂层.合成了适合于浸涂工艺的稳定溶胶涂液.红外光谱表明:醋酸与钛离子形成稳定的配位体,从而延长了凝胶时间;500℃处理后,凝胶中已形成氧化物网络.通过测定侵蚀后涂膜玻璃的失重量和原子吸收光谱,分析组成和热处理温度对涂层耐碱性的影响.XRD图谱和SEM照片表明:涂膜玻片经NaOH侵蚀后,表面形成富钛保护层,提高耐碱性,而侵蚀后生成的复杂晶体使侵蚀加剧. 相似文献
19.