Effect of sintering temperature on microstructural properties of bioceramic bone scaffolds

Bioactive calcium phosphate (CaP) scaffolds have emerged as synthetic alternatives to bone grafts, acting to target serious fracture healing and bone disease such as osteoporosis. Previous research has shown that these bioceramic materials due to their osteoinductive and biocompatible properties can potentially induce bone formation from the surrounding native tissue. Sintering temperature of CaP scaffolds has been shown to influence the microstructure and properties; however, a comprehensive study to determine the influence of sintering temperature on CaP scaffolds has yet to be performed. Thus, the objective of this work was to determine the microstructural properties of an injection molded CaP scaffold based on the crystallographic phases and grain arrangement for different sintering temperatures. The CaP scaffolds were fabricated using tricalcium phosphate and sintered at three different target temperatures. The microstructural and mechanical properties were characterized by different techniques such as: X-ray diffraction, scanning electron microscopy with associated energy dispersive X-ray spectroscopy, and micro-hardness. It was found that grain size, degree of density, crystallite size, and microhardness increased with increasing sintering temperature; whereas, the crystallographic and the Ca/P atomic ratio did not vary for a sintering temperature range of 950-1150°C. These results support the design and fabrication of bioceramic scaffolds with controlled microstructural properties to provide structural integrity and encourage bone ingrowth.