The specific volume of glasses and ceramics depends on the cooling rate applied during the transition from a viscous liquid to a solid glass. A slow cooling rate allows molecules to reorganize from the disordered liquid structure to the partially ordered glassy phase, with a dramatic reduction in the coefficient of thermal expansion and a smaller specific volume.
The bending of green tile is common during glazing process.
Excessive deformation frequently happens during tile glazing, and it is caused by the decorating machine which sometimes imposes such high deformation on the raw tiles to sometimes lead to the breaking of the material.
The study of deformation after firing of glazed ceramic materials detect the state of tension between the ceramic bodies and its decoration (engobe, glaze)
This study takes advatge of both the Optical Dilatometer and the Optical Fleximeter.
Sintering is a densification process occurring during a heat treatment in powders systems, which involves a reduction in porosity and volume (shrinkage).
The sintering tests are run using the Optical Dilatometer.
Fusibility analysis can be carried out thanks to the heating microscope, which allows the direct observation of materials behaviour during a heating cycle. This technique can be applied to direct characterization of glazes, glasses, powders for continuous casting, coal, slag, ashes, etc…
Sintering is a densification process occurring during a heat treatment in powders systems, which involves a reduction in porosity and volume (shrinkage).
Traditional sintered ceramic bodies, like stone-ware or porcelain-ware, achieve densification through mass transfer by means of a mechanism known as glassy phase viscous flow.
Pyroplasticity is the material tendency to deform under its own weight, due to a low viscosity during firing.
The measurement of pyroplasticity is particularly important for ceramic bodies that have to be completely sintered, because during the final stage of firing they develop an abundant vitreous phase with a sufficiently low viscosity to cause rapid deformation of the material.
The thermal expansion analysis measures the dimensional variations of a material subjected to a heat treatment as a function of the temperature.
The thermal expansion of incoherent materials (like sands), plastic materials (like glasses or polymers above their glass transition temperature), extremely thin samples (having thickness of tens microns) or soft materials (like felt or wax) cannot be studied by means of traditional dilatometry.
It is really important to study the behaviour fo glazed tiles during their firing. Indeed, both the engobe and the glaze can affect the sintering process.
This plot shows how the enamel application on the ceramic body changes its own behaviour.