Effect of silica sol on the dispersion-gelation process of concentrated silica suspensions for fibre-reinforced ceramic composites
Effect of silica sol on the dispersion-gelation process of concentrated silica suspensions for fibre-reinforced ceramic composites
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DOI：
10.1016/j.jeurceramsoc.2012.10.020
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发表时间：
2013-04
影响因子：
5.7
通讯作者：
M. Tomas;H. Amaveda;L. Angurel;M. Mora
中科院分区：
文献类型：
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作者：
M. Tomas;H. Amaveda;L. Angurel;M. Mora
采用溶胶-凝胶法将硅粉分散在硅溶胶中，获得了适合于纤维增强陶瓷溶胶渗透技术的悬浮液。重点分析了聚电解质含量、pH值、固体负荷和胶凝剂浓度对二氧化硅悬浮液流动行为的影响。制备复合材料基质最合适的悬浮液是一种弱絮凝悬浮液，在pH≥9.5时可忽略触变行为，该悬浮液由分散在41vol硅溶胶中的二氧化硅微粒组成。%的固体负荷和1.8吨。%的Duramax D3005。通过加入0.08M的NH4Cl，稍微改变稳定性条件，使静电斥力降低，pH值降至8，这种悬浮液很容易转变为凝胶。此外，在900°C烧结后，硅溶胶可使陶瓷致密化高达70%，从而允许复合材料的多孔基体加工。
Sol gel process of silica powders dispersed in silica sol has been used to obtain a suitable suspension for the sol infiltration technique of fibre-reinforced ceramics. Efforts have been focused on analysing the effects of polyelectrolyte content, pH, solid load and concentration of gelling agent on the flow behaviour of silica suspensions. The most adequate suspension to manufacture the matrix of composites is a weak flocculated suspension with negligible thixotropic behaviour at pH≥9.5, which is composed of silica microparticles dispersed in silica sol with 41vol.% of solid load and 1.8wt.% of Duramax D3005. This suspension easily undergoes a transition to a gel by a slight alteration of stability conditions adding 0.08M of NH4Cl, which reduces both the electrostatic repulsion and the pH to 8. Moreover, silica sol promotes the densification of ceramics up to 70% after sintering at 900°C, allowing porous matrix processing of the composites.