Amorphous-crystalline transformation control on the microstructural evolution of magnesium phosphate cements

Magnesium phosphate cements are chemically-bonded ceramics exhibiting high strength and good adhesive properties. In-situ investigation of the reaction of Mg-K phosphate cements, indicated that microstructural evolution is controlled by a cement densification process entailing amorphous-to crystalline transformation during hardening. Owing to the replacement of the amorphous fraction with a material of higher density, possessing elongated crystal habit, an increase in porosity with time occurs, at variance with previous models. The beneficial effect provided by the developed interlocked lath shaped microstructure, constituted by crystals embedded in the amorphous matrix, prevails over the detrimental role of the increased porosity, explaining the increase in mechanical strength. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

Magnesium phosphate cements undergo a transformation from amorphous to crystalline during hardening, leading to an increase in porosity. However, the interlocked lath shaped microstructure provides a beneficial effect which outweighs the detrimental role of increased porosity, resulting in an increase in mechanical strength.