新型多元复合熔剂对瓷质建筑陶瓷低温烧结特性的影响及机理研究

In order to meet the needs of reducing firing temperature and energy-saving emission reduction in ceramic industry, and reduce the firing temperature by the substantial increase of one or two kinds of low temperature flux for the current high-temperature porcelain building ceramics, therefore, the amount of liquid phase increases dramatically, and makes the product soft collapse and deformation. In this project, under the premise of properties requirements and process performance, the project would put forward new multivariate flux system to reduce the sintering temperature. We would detailed comparatively analyze the two and multivariate flux system on the effects and reaction densification behaviors of the porcelain building ceramic, and grasp the ladder-like appearance of the high viscosity liquid at different sintering temperature for the two flux and multivariate composite flux system and its influence factors. The cooling mechanism of the multiple flux system superior to binary flux system would be revealed. The project would build the diagram of the multiple flux kinds, composition and melting characteristic, and the performance diagram between the multiple flux system and sintering characteristics of porcelain building ceramic, and form the semi empirical formula containing liquid quantity factors for the multivariate flux system, which is used to predict the low - temperature sintering properties of multivariate composite flux system on the porcelain building ceramic. The achievement of the project would provide new technology and new method to promote the energy-saving emission reduction technology for the lower sintering temperature of porcelain building ceramic, which has good economic and social benefits.

为了满足陶瓷行业降低烧成温度、节能减排的需要，针对目前瓷质建筑陶瓷经验性地大量引入（K2O、Na2O）二元熔剂数量以降低烧成温度结果导致液相量急剧增加而使产品软塌和变形等问题，本项目提出采用新型多元复合熔剂降低烧成温度，在保证烧成工艺性能和物化性能的要求下，详细分析在低温快烧条件下二元与多元复合熔剂对建筑陶瓷性能的影响作用和反应致密化过程行为。研究二元熔剂与新型多元复合熔剂体系在不同烧成温度区逐步出现粘度较高的液相及影响因素，认识二元与多元复合熔剂与其它组分之间的反应过程及其影响规律的差异，揭示多元复合熔剂优越二元熔剂的降温作用机理。构建复合熔剂的熔融特性图以及在瓷质建筑陶瓷中的烧结特性图，并形成影响多元复合熔剂液相量因素的复合熔剂烧结半经验性公式，用于预测建筑陶瓷的低温烧结。为研究开发更低烧成温度的瓷质建筑陶瓷提升节能减排的技术水平提供新技术路径和新方法，具有良好的经济和社会效益。

为了满足陶瓷行业降低烧成温度、节能减排的需要，针对目前建筑陶瓷经验性地大量引入（K2O、Na2O）二元熔剂数量以降低烧成温度结果导致液相量急剧增加而使产品软塌和变形等问题，本项目在保证烧成工艺性能和物化性能的要求下，研究了引入二元和多元复合熔剂建筑陶瓷性能的影响作用和反应致密化过程行为。采用XRF、TG-DTA、XRD、SEM、EDS、高温显微镜和熔块模拟等测试手段对多元复合熔剂试样低温烧结性能影响进行研究，从科学层次上解析认知引入二元与多元复合熔剂能有效地降低陶瓷坯体烧成温度的机理和作用规律。研究结果表明：相对“K2O-Na2O”二元熔剂材料试样而言，合适的“K2O-Na2O-Li2O”、“K2O-Na2O-Li2O-CaO”、“K2O-Na2O-Li2O-B2O3-CaO”多元复合熔剂体系能在低于它们自身熔融温度条件下提前发生反应形成低共熔物，并阶梯性产生液相不断熔解Al、Si，使液相粘度增加不但降低了烧结温度，而且拓宽了烧成温度范围，并提高了试样的抗折强度。运用相图并结合复合熔剂试样的烧成收缩数据及模拟低共熔点的熔块熔融分结果，反向推出初始三元复合熔剂中难以检测到的Li2O含量。构建了不同多元熔剂体系下的粘度-温度的理论模型。相比于二元、三元、四元熔剂体系，五元熔剂体系在成瓷温度下具有更高粘度。当高温液相粘度>5×106Pa·S时，高温塑性形变指数PI随着粘度降低变化并不明显；当高温液相粘度≤5×106Pa·S时，其PI随着粘度降低而明显增加。为进一步验证多元复合熔剂理论的适用性，选取低品位稀土尾砂为主要原料及合适的配方组成，将原料中与复合熔剂相同的元素视为复合熔剂组成，所制备的瓷质建筑陶瓷的烧结温度、粘度及PI与所构建的理论模型及相关理论相吻合。相关研究成果将有效指导陶瓷材料的生产和节能降耗，提升陶瓷行业的理论水平有重要的意义。