Forming Miniature Ceramic Components Using Micro-forming and a Field Activated Sintering Technique (Micro-FAST)

Abstract

The demand for miniature products has recently significantly increased as has the need for these products to be produced rapidly, flexibly and in a cost efficient manner. The application of electrical sintering shows significant potential to produce these components by using powder materials. However, previous research has shown that there are still challenges that need to be considered in order to achieve increased densification of products and simplification of the processes. The process concept utilised in this study is called Micro-FAST, which comprises the combination of an electrical-field activated sintering technique (FAST) and micro-forming processes. The aim of the work was to develop the process concept for the manufacture of miniature components, and to develop the necessary die sets along with other tooling for experimental work to enable the forming of ceramic micro components from powder materials and to also develop a new tool design for mass production. A comprehensive literature review is given on micro-manufacturing processes, challenges, key issues, micro forming, micro scale size effects, sintering processes and the electrical field activated sintering processes and their application. The concept of the Micro-FAST process was explained, and development of the die sets and materials selection justification for the process is described. The finite element (FE) analysis of the effect of the coupled thermal-electrical characteristics of the die sets during the heating and cooling process was carried out. This was done in order to study the heating flows of the die sets using the material properties chosen for this research, the materials were zirconia, alumina and piezoceramic. The simulation analysis was focused on the heating distribution process resulting from the die set design. An experimental study has also been conducted in this work to validate the results from finite element (FE) analysis. The experiment was conducted using a Gleeble® 3800 testing system, a Scanning Electron Microscope from HITACHI S-3700N, Energy Dispersive Spectroscopy and Nano Test Vantage system (Nano-indentation). The material powders that have been used for this experiment were three different types of zirconia, alumina (Al2O3), and piezoceramics (PZT). The first zirconia powder was yttria partially stabilized zirconia (3Y-ZrO2), the second powder is magnesia partially stabilized zirconia (MSZ) and the third powder was magnesia partially stabilized zirconia with 5 wt% organic additives or organic binders (MSZ(#) ) to improve the forming process. Based on the results, the development of a new tool die-design concept has been introduced which can potentially be used for mass production to produce miniature ceramic components. The new alternative design is going to be validated and examined using the finite element (FE) analysis of the new tool design sets effect on the coupled thermal-electrical characteristics during the heating and cooling process using ABAQUS/CAE software. In conclusion, improvements and promising results have been presented regarding a reduced process time for the manufacture of miniature components with a variety of ceramic powder materials. Recommendations for future work have been suggested and explained at the end of this work in order to make further improvements to the process