The study of ceramic materials behaviour during firing


Traditional sintered ceramic bodies, like stoneware or porcelain-ware, undergo a viscous flow sintering process, where the driving force is mainly given by the surface tension of the liquid glassy phase, and the speed of the process is controlled by the viscosity of the glassy phase [1]. Fast firing is now the dominating technology and the time available to reach a optimal stabilisation of the body is reduced to few minutes. Firing the ceramic body up to maximum densification means reducing to the minimum its porosity, which has a detrimental influence on mechanical strength. Thus, minimizing porosity allows to reduce the product thickness, to save in cost and transportation. One of the major concerns in the design of fast sintering bodies is the determination of the best top firing temperature, which is the temperature at which the given body composition is able to achieve full densification, with no bloating in the minimum time [1]. Firing above this temperature results in a drastic fall of the mechanical properties and arising of deformations, due to bloating caused by bubbles growth inside the body. Optimizing the firing process and predicting sintering behaviour are not recent challenges, as a matter of fact they have been fundamental objectives of sintering studies for many decades.

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