Multi material structures for biomedical applications

Abstract

In this study Direct Metal laser Sintering (DMLS) multi material structures are investigated. The study is developed in two main sections, firstly the conceptualization, validation and optimization of a DMLS multi material DMLS powder deposition system. An ―ideal‖ multiple powder deposition system deposits a homogeneous powder layer with interlocking interface between the different powders. The system need to be time efficient yet deposit powder accurately. In the study a multiple hopper powder deposition system is conceptualized. An experimental was manufactured to establish optimal design specifications with parametric data for powder flow through hoppers. A prototype hopper is developed to validate the hopper system. Ti6Al4V and copper (Cu) powder is deposited side by side and following one another to determine the quality and accuracy of the deposited powder layer. Secondly, DMLS Ti6Al4V and Cu multi material structures are validated as an antibacterial implant interface that reduces the risk of bacterial infection. Ti6Al4V is a commonly used biomaterial because of its suitable mechanical and biocompatible properties. Cu is a proven antibacterial agent and at low percentages is not toxic to the human body. In the study optimal single track process parameters for pure Cu on a Ti6Al4V substrate are determined. Ti6Al4V-1%Cu structures are manufactured in two proposed processes. Firstly by in-situ alloying Ti6Al4V-1%Cu. Secondly, producing pure Cu areas on a Ti6Al4V substrate so that the surface contains 1% Cu by means of surface area. The produced DMLS samples are exposed to Escherichia coli and Staphylococcus aureus. Recommendations are made on the development of more effective antibacterial Ti6Al4V-Cu structures. The work in this study aims to lay a foundation for advanced implant development at the Centre of Rapid Prototyping and Manufacturing (CRPM), Central University of Technology (CUT). By producing medical implants with property specific regions in a single manufacturing cycle will greatly improve the efficiency and functionality of medical implants.