Effect of Ball Milling Process on the Characteristics of Natural Based- And Synthetic Based-Wollastonite for Biomedical Application

Wollastonite (CaSiO3) is a potential biomaterial, particularly beneficial for biomedical purposes such as tissue bone regeneration. The objective of this study is to evaluate the effect of dry and wet milling conditions on the formation of solid wollastonite bioceramic. In this study, synthetic-type wollastonite was produced from chemically synthetic powder; meanwhile, a combination of seashells and rice husk ash (RHA) was used to form natural-type wollastonite. In sample preparation, CaO and SiO2 powder (1:1 weight ratio) were milled together by planetary ball milling operation under different milling conditions: dry and wet milling. The ball-milled powder mixtures were compacted before sintering at 1200°C for 4 hours. The weight loss and shrinkage of the samples were measured and characterized using XRD, FTIR, and SEM analysis. The results confirmed that the wollastonite phase was formed after the sintering process for both dry and wet ball milled processes with anorthic and monoclinic structure types of calcium silicate phases. The wet-milled processed natural powders relatively formed denser bodies and had a higher weight loss percentage compared to dry-milled processed synthetic powders. In conclusion, wet milling is a more suitable method for producing solid wollastonite via powder sintering. In addition, the natural-based sources from RHA and seashells were able to reach the mineralogical properties comparable to synthetic-based sources for forming wollastonite, which could be promising as an alternative material in biomedical applications.