Juxian ZHANG
,
Jinjun FENG
,
Longqiao GAO
材料科学技术（英）
The sintering additives such as Al2O3 and/or Y2O3 were coated on the surfaces of Si3N4 particles via heterogeneous nucleation processing using a buffered pH solution as the precipitation reagent. They nucleated and grew only on the surfaces of Si3N4 and did not form sol particles in solution by TEM observation. The isoelectric point (IEP) of coated Si3N4 was different from that of as-received Si3N4. The IEP of Al(OH)3-coated Si3N4 occurred at pH8.4, which is close to that of alumina. When Al(OH)3-coated Si3N4 particles were coated with Y(OH)3, the IEP of coated Si3N4 powder shifted from pH8.4 to pH9.2, similar to that of yttria. In addition, the rheological data showed that Al2O3 and/or Y2O3 coated Si3N4 suspension is nearly Newtonian and that added Si3N4 suspension shows a shear rate thinning behavior.
关键词:
Si3N4 powder
,
null
,
null
,
null
陈桂才
,
刘晓明
,
范锦鹏
宇航材料工艺
研究了以聚丙烯酸铵为分散剂的Si3N4悬浮体的分散特性,以及酸洗和热氧化两种表面改性方法对Si3N4悬浮体的分散性和流变特性的影响.结果表明:分散剂聚丙烯酸铵的最佳酸碱环境为pH=9,最佳使用含量为0.2wt％,酸洗可有效去除粉料中的金属杂质,使Si3N4粉体在悬浮体中粒径分布更集中且粒径主峰值向小粒径移动,同时可使悬浮体的黏度降低.热氧化处理可大幅度降低Si3N4悬浮体的黏度,提高其流变特性.
关键词:
Si3N4粉体
,
分散性
,
流变特性
,
酸洗
,
热氧化
王琴
,
王健
,
吕春祥
,
崔鑫有
,
李时雨
,
王皙
新型炭材料
doi:10.1016/S1872-5805(16)60033-1
采用流变仪和激光共聚焦显微镜对不同氧化石墨烯( GO)掺量的新拌水泥浆体的流变参数以及浆体微观形态进行了定量化研究,并采用Modified-Bingham ( M-B)模型和Herschel-Bulkley ( H-B)模型对所测数据进行了拟合处理,提出了GO影响新拌水泥浆体的作用机理。结果表明,GO的掺入可以使新拌浆体中在减水剂作用下分散的水泥颗粒发生再次凝聚,形成重组絮凝结构,且随着GO掺量的增加,重组絮凝结构的数量越多,从而使得浆体流变性发生显著变化。一方面,新拌浆体的塑性粘度、屈服应力以及触变性随GO掺量的提高而显著增加。另一方面,GO的掺入提高了新拌浆体的临界剪切速率,使其在较大剪切速率下的流变行为仍然表现为剪切变稀；降低了浆体的剪切增稠程度,提高了浆体的稳定性。
关键词:
氧化石墨烯
,
水泥浆体
,
流变性能
,
絮凝结构
