Effect of si doping and e-glass fiber addition on physicochemical and mechanical properties of calcium phosphate cement

Abstract

Calcium phosphate cements are hydraulic cements.These are formed by a combination of one or more calcium orthophosphate powders. Calcium orthophosphates have been studied as bone re-pair materials for the last 80 years. CPC self-hardens to form hydroxyapatite, having excellent osteoconductivity and bone-replacement capability. The present study was aimed at preparation of alpha tricalcium phosphate and Si doped alpha tricalcium phosphate and studying the effect of addition of glass fibers into them. The physicochemical and mechanical properties of á-tricalcium phosphate (á-TCP) cement and Si doped á-TCP were studied. á-TCP was prepared by solid state sintering of CaCO3, CaHPO4 and Si doped á-TCP powders were synthesized by reacting mixtures of CaCO3, CaHPO4, and SiO2(TEOS). Setting time, phase composition, hydrolysis conversion rate, microstructure, and diametral tensile strength (DTS) of undoped CPC and Si-doped CPC were studied and compared. Both initial and final setting time of the developed cement was delayed because of Si addition. Crystalline phases of HA (JCPDS 9-432), á-TCP (JCPDS 29-359) and â-TCP (JCPDS 9-169) were detected in the X-ray diffraction (XRD) pattern after setting and immersion in SBF for 0 hours to 10 days. The intensities of the á-TCP peaks at 22.2° (201) and 24.1° (161,-331) decreased when the time of immersion in SBF increased from 0 hours to10 days, due to its transformation into HA. Si doped CPC showed little slower rate of conversion into HA phase as compared to undoped CPC. The SEM image of the microstructure of cement showed better compactness and greater crystal entanglement in undoped CPC as compared to Si-doped CPC. This lower porosity and greater compactness in the microstructure attributes to greater DTS values observed in undoped CPC. Addition of 10 wt % of e-glass fiber into Si-doped á-TCP increased the mechanical strength of CPC as the fibers could make the structure compact and provide reinforcement.