Author(s)

Mustapha Hidouri^1,2*, Faycal Ben Tahar¹, Khaled Bouzouita²

¹Higher Institute of Applied Sciences, Gabes University, Gabes, Tunisia.
²RU Catalysis and Materials for Environment and Process, Engineering School, Gabes University, Gabes, Tunisia.

A study was performed to investigate the effect of some selected sintering additives on the densification and microstructure of fluorapatite (FAp, Ca₁₀(PO₄)₆F₂). The sintering aids, used for improving the material densification at lower than 1080℃ temperature, were classified according to their cations as alkaline such as Li₂CO₃, NaF, Na₂CO₃, Na₃PO₄, KCl, K₂CO₃, and alkaline-earth such as CaF₂, CaCl₂ and MgCl₂. Amounts of 0.1; 1 and 3 wt% were vigorously homogenized with FAp powders then the solid mixture was pressurelessly sintered under argon flow with 10℃ . min^-1 heating and cooling speed. The density of each sintered material was determined by calculation of the pellet dimension and weight, the crystalline phases were identified using X-ray diffraction (XRD) and the phase morphology was examined by scanning electron microscopy (SEM). The dependence of densification and microstructure on sintering temperature range 900℃ - 1000℃ and amount of sintering aids was studied. It was found that all sintering additives were able to ameliorate the sintrability of the material at temperatures 900℃ and 1000℃. Maximums of about 96% were reached with adequate amounts and sintering temperatures. An exception was found with KCl which had no effect on the density. The microstructures of sintered specimens strictly follow the densification ratios and the sintering mechanism depended on the melting point of the additive.

Fluorapatite, Sintering Additive, Densification, Microstructure

Hidouri, M. , Tahar, F. and Bouzouita, K. (2018) Densification and Microstructure of Fluorapatite Sintered with Alkaline and Alkaline-Earth Additives. Journal of Materials Science and Chemical Engineering, 6, 52-67. doi: 10.4236/msce.2018.61007.