The effect of air atmosphere casting and oxidation on the properties, crystallinity and biodegradability of novel Zn-3cu-0.3bi

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Jaraba, Khulud
Mahapatro, Anil

The terms biodegradable, bioresorbable, and bio-absorbable, are used interchangeably in literature to describe the ability of a material to degrade in the biological environment. Nonetheless, the definitions of these three terms differ. Biodegradable materials have a natural capability to gradually and safely degrade when in direct contact with a biological organism whereas bioresorbable and bio-absorbable materials are materials that organically decompose and get absorbed by surrounding tissue [1]. In recent years and with the aging of the population, the need for biodegradable implants increase since they eliminate the complications associated with the prolonged presence of inert metallic implants and the need for an implant removal operation [2]. However, there have been many concerns associated with the use of biodegradable metals in the applications of stents and fixation devices, such as unsuitable degradation rate, loss of mechanical integrity, and increased metal ion concentrations. The performance of biomaterials in-vivo is highly correlated to the fabrication environment and technique which is an overlooked area of research Therefore, the objective of this thesis is to investigate the impact of alloy casting atmosphere and methods on the properties, crystallinity, and biodegradability of Zn-3Cu-0.3Bi. To achieve that, different casting methods were examined. The effect of metal melt oxidation and borax flux usage was investigated to help evaluate the efficiency of flux assisted air casting technique. The results suggest that the use of borax flux minimizes metals’ oxidation, increases materials’ crystallinity, reduces crystallite size, and produces more homogenous alloys. Furthermore, the ternary zinc alloy system fabricated showed superior hardness than pure zinc and achieved a uniform degradation with a corrosion rate within the design requirement for cardiovascular and fixation implants.

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Thesis (M.S.)-- Wichita State University, College of Engineering, Dept. of Biomedical Engineering