Date on Master's Thesis/Doctoral Dissertation

12-2021

Document Type

Master's Thesis

Degree Name

M.S.

Department

Mechanical Engineering

Degree Program

Mechanical Engineering, MS

Committee Chair

Kate, Kunal

Committee Member

Atre, Sundar

Committee Member

Satyavolu, Jaggannadh

Author's Keywords

3D printing; bio-ceramics; medical implants; design for additive manufacturing; hydroxyapatite; sintering

Abstract

Ceramic fused filament fabrication (CF3) enables the fabrication of highly customizable ceramic parts at relatively lower costs compared to other AM technologies. Advanced ceramics, having specific or niche applications, call for a high level of accuracy to meet the performance requirements. For achieving the desired level of accuracy in any manufacturing process, it is important to know the effect of involved parameters at different stages of fabrication. CF3 has been around for a while but there has been a severe lack of literature dealing with understanding the effect of process parameters on the final part properties. In this study, Hydroxyapatite (HAp) components with 75 wt.% solids loading filaments were prepared. A DOE was conducted to analyze and establish the relationship between process parameters and the final printed part properties. Extrusion multiplier, % infill, and print speed were taken as input parameters and the effect of their effect on final part dimensions, layer thickness, bead width, and surface roughness were analyzed. Additionally, the experimental data was analyzed using regression analysis, analysis of variance (ANOVA), % contribution, and main effects using Minitab software. ` vi Furthermore, to establish the capability of HAp CF3 in biomedical applications, HAp and its composite parts with 10 wt.% Si3N4 (HAp10SN) were fabricated. Homogeneous feedstock with 63 wt.% ceramic powder was prepared and used to extrude filaments for further printing using a desktop printer. Our results showed that the addition of Si3N4 to HAp increases the feedstock viscosity. However, the filaments and CF3 parts made using HAp and HAp10SN feedstocks exhibited comparable densities without gross defects. We have obtained relatively smoother CF3 parts with HAp10SN than pure HAp, which is attributed to their high feedstock viscosity and formation of the liquid phase during sintering. Sintering at 1250 °C for 4 h in air, after thermal debinding, resulted in a relative density of ~85% with HAp and tricalcium phosphate (TCP) as major constituents. Sintered HAp10SN samples also revealed an almost 70% reduction in the grain size and 147% increase in the hardness compared to pure HAp. Our results indicate that the CF3 processed HAp10SN samples containing ~15% porosity, Si3N4 particles, and Si-substituted HAp/TCP have strong potential as bone replacements.

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