卫生陶瓷模具石膏劣化机理研究

Research on the Deterioration Mechanisms of Sanitary Ceramics Gypsum Model

摘要:

采用MIP，XRD，XRF，SEM测试分析了陶瓷石膏模具使用前及报废时的微观结构变化，对其劣化机理进行深入研究.结果表明：新陶瓷石膏模具孔隙在010～1000μm分布均匀，至报废时其孔隙显著细化，约67%的孔隙集中分布在001～010μm，010～500μm的孔隙大幅减少，500～1000μm的大孔隙数量基本不变，总孔隙率略有下降；报废陶瓷石膏模具中长径比大、搭接紧密的针状和棒状二水石膏晶体(呈网状结构)已转化为结晶度低且晶粒粗大的板状、片状及短柱状二水石膏晶体(呈疏松结构)，同时该模具表面有Na2SO4晶体析出；010～500μm的孔隙为陶瓷石膏模具吸浆有利孔隙，001～010μm的孔隙为其吸浆不利孔隙，陶瓷浆体的吸附堵塞造成孔隙细化是其吸浆能力下降的主要原因；二水石膏晶体的溶解和再结晶会使其晶型发生不利转化；陶瓷浆体的电解质可与石膏反应生成Na2SO4，其结晶膨胀导致陶瓷石膏模具结构破坏，工作及力学性能大幅下降.

Abstract:

In order to investigate deterioration mechanisms of gypsum models, MIP, XRD, XRF and SEM techniques were applied to analyze the differences of the microstructure of new models and the waste. The results show that pores distributed homogeneously in the range of 0101000μm for new models. However, pores are thinned significantly and centered in 001010μm at the ratio of 67% at the waste stage. Pores between 010μm and 500μm are markedly reduced while the 5001000μm pores are unchanged. The porosity is slightly decreased. Crystal structure of waste models is loosed as dihydrate gypsum translated from needle and clavuligerus to tabular, plate like and short columnar. Moreover, sodium sulfate crystals are detected on surfaces. Mechanisms investigation indicates that pores of 010500μm and 001010μm are separately favorable to destruct for slurry absorbing property. The decrease of water absorbing capacity is due to the pore fining by ceramic slurry. Meanwhile, the decline of mechanical and working performances is due to the crystal transformation of dihydrate gypsum and the crystalline expansion of sodium sulfate generates by the chemical reaction of gypsum and slurry electrolytes.