CaCO_(3)为钙源固相法合成榍石时SiO_(2)和TiO_(2)物相的影响

Effect of SiO_(2) and TiO_(2) with Different Crystalline Phases on Preparation of Sphene by Solid Phase Method with CaCO_(3) as Calcium Source

采用榍石为主要乳浊相物质制备陶瓷釉面具有广阔的前景,而固相法是合成榍石的有效手段。因此,明确原料的物相在固相法合成榍石过程中对其结构和性能的影响至关重要。以CaCO_(3)为钙源,通过CaCO_(3)-SiO_(2)-TiO_(2)体系固相法煅烧合成榍石(CaTiSiO_(5))过程所用不同物相SiO_(2)和TiO_(2)对榍石产物成分、颗粒形貌的影响,对反应机理和榍石产物的主要物理性能进行了分析和测试。结果表明,当SiO_(2)和TiO_(2)均为非晶相物质(白炭黑和偏钛酸)时,将CaCO_(3)-SiO_(2)-TiO_(2)在1200℃煅烧,可得到由单一榍石相组成的产物;而SiO_(2)和TiO_(2)均为晶体(石英和锐钛矿),或其中一种为晶体时,1200℃煅烧产物主要成分为榍石,同时含少量石英和金红石。说明SiO_(2)和TiO_(2)为非晶相物质有利于提高CaCO_(3)-SiO_(2)-TiO_(2)高温时各组分的化合反应程度,抑制各组分形成游离态和发生自身相变。本研究为以CaCO_(3)为钙源,通过固相法合成高品质榍石及消除TiO_(2)高温时游离态和自身相变提供了一条可行途径。

The preparation of ceramic glaze with sphene as the main opacifying substance has a broad prospect.The solid-phase method is an effective method to synthesize sphene.Therefore,it is important to clarify the effects of the phases of raw materials on the structure and properties of sphene in this process.CaCO_(3) was used as calcium source in this experiment.In CaCO_(3)-SiO_(2)-TiO_(2) system,effects of SiO_(2) and TiO_(2) with different crystalline phases on the composition and morphology of sphene(CaTiSiO_(5))in the process of preparing sphene by solid state calcination was investigated.The results showed that when SiO_(2) and TiO_(2) were amorphous materials(silica and metatitanic acid),sphene was obtained after calcinating the CaCO_(3)-SiO_(2)-TiO_(2) at 1200℃.Moreover,there were no other crystalline phases in the product.When both SiO_(2) and TiO_(2) were crystals(quartz and anatase),or one of them was crystal,not only sphene but also quartz and rutile were obtained after calcinating the CaCO_(3)-SiO_(2)-TiO_(2) at 1200℃.It showed that amorphous SiO_(2) and TiO_(2) were conducive to improving chemical reaction of each component in the CaCO_(3)-SiO_(2)-TiO_(2) at high temperature,and inhibiting the formation of free state and self-phase transition of each component.This study provided a feasible way for the preparation of high-quality sphene by solid phase method with CaCO_(3) as calcium source and the elimination of free state and self-phase transition of TiO_(2) at high temperature.