TY - THES

T1 - Selective Laser Melting of a Zr-based Bulk Metallic Glass for Medical Applications

AU - Spuller, Mirjam

N1 - no embargo

PY - 2021

Y1 - 2021

N2 - Selective laser melting (SLM) is a promising additive manufacturing technique to fabricate biocompatible bulk metallic glass (BMG) components for medical applications such as personalized implants or scaffolds. The aim of this thesis was to find appropriate process parameters in order to produce fully dense and glassy samples from a Zr-based metallic glass powder (trade name VIT105). Besides, mechanical properties, biocompatibility, and influences of a post processing were investigated to examine the BMG’s suitability for its use in the medical field. To achieve this goal, a SLM parameter study was conducted as a first step. Then, those fabricated samples were investigated regarding their relative density, microstructure, and thermodynamic behaviour. In addition, (micro )hardness measurements were carried out. Afterwards, further samples were fabricated with a satisfying process parameter combination and subjected to different heat and surface treatments. 4-point bending test and cytotoxicity tests were carried out using these samples. Within the cytotoxicity tests, cell adhesion and cell growth on the samples surfaces were examined as well.The SLM parameter study showed that a minimum volume energy density is needed for the production of dense samples. However, not only the volume energy density is decisive for the relative density but also the specific combination of the process parameters. Especially the scanning velocity of the laser plays a crucial role in the production of the BMG. It was found that it has a considerable impact on the resulting microstructure and determines the structural relaxation, glass transition temperature and indentation elastic modulus of the sample. 4-point bending tests showed that the as-built samples exhibit adequate flexural strengths and elasticity. Nonetheless, the investigations also showed that the BMG’s properties strongly depend on the building direction and orientation of the testing. Furthermore, it was discovered that a blasting treatment with glass microbeads or corundum is beneficial to achieve higher flexural strengths. However, only samples blasted with glass microbeads are undoubtedly biocompatible. Samples treated with corundum are cytotoxic. Even if a heat treatment below the glass transition temperature improves the cell viability, it impairs the mechanical performance of the BMG. Moreover, the investigations pointed out that samples which are crystallised are unsuitable with respect to their manufacturability and usability.

AB - Selective laser melting (SLM) is a promising additive manufacturing technique to fabricate biocompatible bulk metallic glass (BMG) components for medical applications such as personalized implants or scaffolds. The aim of this thesis was to find appropriate process parameters in order to produce fully dense and glassy samples from a Zr-based metallic glass powder (trade name VIT105). Besides, mechanical properties, biocompatibility, and influences of a post processing were investigated to examine the BMG’s suitability for its use in the medical field. To achieve this goal, a SLM parameter study was conducted as a first step. Then, those fabricated samples were investigated regarding their relative density, microstructure, and thermodynamic behaviour. In addition, (micro )hardness measurements were carried out. Afterwards, further samples were fabricated with a satisfying process parameter combination and subjected to different heat and surface treatments. 4-point bending test and cytotoxicity tests were carried out using these samples. Within the cytotoxicity tests, cell adhesion and cell growth on the samples surfaces were examined as well.The SLM parameter study showed that a minimum volume energy density is needed for the production of dense samples. However, not only the volume energy density is decisive for the relative density but also the specific combination of the process parameters. Especially the scanning velocity of the laser plays a crucial role in the production of the BMG. It was found that it has a considerable impact on the resulting microstructure and determines the structural relaxation, glass transition temperature and indentation elastic modulus of the sample. 4-point bending tests showed that the as-built samples exhibit adequate flexural strengths and elasticity. Nonetheless, the investigations also showed that the BMG’s properties strongly depend on the building direction and orientation of the testing. Furthermore, it was discovered that a blasting treatment with glass microbeads or corundum is beneficial to achieve higher flexural strengths. However, only samples blasted with glass microbeads are undoubtedly biocompatible. Samples treated with corundum are cytotoxic. Even if a heat treatment below the glass transition temperature improves the cell viability, it impairs the mechanical performance of the BMG. Moreover, the investigations pointed out that samples which are crystallised are unsuitable with respect to their manufacturability and usability.

KW - Additive Fertigung

KW - Laser-Pulverbettverfahren

KW - Selektives Laserschmelzen

KW - massives metallisches Glas

KW - Prozessparameter

KW - Porosit�t

KW - mechanische Eigenschaften

KW - Additive Manufacturing

KW - Laser Powder Bed Fusion

KW - Selective Laser Melting

KW - Bulk Metallic Glasses

KW - Process Parameter

KW - Porosity

KW - Mechanical Properties

M3 - Master's Thesis

ER -