Papers by Author: J.Z. Liu

Abstract: Based on the SEM observation on cracks in lined ceramics of the composite pipes, the stress fields in lined ceramics were analyzed. The results indicated that there are the compressive field and heat stress field in lined ceramics, resulting in the existence of radial cracks and net cracks; besides being influenced by wall thickness of ceramic layer, the strength of compressive stress field is also dependent on bonding strength between metal and ceramics, and the strength of heat stress field is dependent on temperature gradient in lined ceramics during cooling of the ceramics.

Abstract: In this paper the surfaces of Al2O3 fine powders with average size of 500nm were modified by heterogeneous azeotropic distillation process. IR spectrums of the powders show that the distillation can effectively dehydrate hydrous Al2O3 powders, and succeed in substituting the hydrate water with butanol molecular. The dispersion of Al2O3 powders in epoxy resin is improved remarkably, which is observed by means of SEM. Experimental results show that abrasion property of the resin filled with modified Al2O3 powders is improved.

Abstract: The effects of two silane coupling agents (KH550, KH570) and three coupling agents of organic titanate (JSC, CT136 and NTC401) on the surface modification of superfine Al2O3 powders were tested and compared. The results showed that three coupling agents of organic titanate succeeded in modify the surface of Al2O3 particle from hydrophilic property to lipophilicity, while two silane coupling agents failed. The group changes of the surface were confirmed by IR spectrum, which also indicated that chemical absorption occurred between NTC401 and the powders surface, but for JSC and CT136 mainly occurred physical absorption. SEM photos of the powders showed that agglomeration-free particles could be obtained when the powders were treaded by NTC401. However, when treated by JSC or CT136 the powders tended to be secondly agglomerated. The proper coupling mechanism was analyzed, and it was thought that space structure of octahedral complex of titanium ion with six ligands could effectively impede agglomeration.