University of Malaya, Faculty of Engineering, Kuala Lumpur, Malaysia
Advanced Ceramics, Bioceramics, Failure Analysis, Welding Technology
Brief introduction of your research experience:
Professor Ramesh is a Senior Professor of Mechanical and Materials Engineering. He received his PhD in Advanced Materials (1997) and Bachelor of Mechanical Engineering (Hons) – First Class (1994), both from the University of Sunderland, UK. He has received many accolades as a distinguished professor and have a strong track record in administration, teaching and research. He has served for two terms as an Associate Director for the Engineering Accreditation Department, Board of Engineers Malaysia and is serving in numerous capacities as a consultant, external examiner, expert advisor, reviewer, editorial board members and visiting professor. Ramesh has made over 350 scientific publication, including nearly 240 peer-reviewed research papers and has completed the supervision of more than 75 postgraduate students. He has received research funding of more than USD$ 4 million and more than 85 research awards as well as recognition for his work including the prestigious Young Engineer Award from the Institution of Engineers Malaysia and the Malaysia Toray Science Foundation (MTSF)-Science & Technology Award in recognition for his outstanding research achievement. He is a Fellow of the Academy of Sciences Malaysia which is the highest accolade bestowed on distinguished scientist in the country, Fellow of the Institution of Engineers Malaysia, Fellow of the Institution of Mechanical Engineers UK and Fellow of the Institution of Engineers Australia. He is a Chartered Engineer (UK), Chartered Professional Engineer (Australia) and a Professional Engineer (Malaysia). Ramesh’s research interest includes development of specialty ceramics and composites for mechanical and biomedical applications, laser welding of metal alloys, powder metallurgy, mechanical behavior of materials, materials characterization, failure analysis, corrosion and degradation of engineering materials, and engineering education.
Effectiveness of Manganese Oxide in Supressing the Low-Temperature Degradation (LTD) of Tetragonal Zirconia
Numerous researchers have focused on ways to suppress the LTD or hydrothermal ageing phenomenon in zirconia, but have often been hampered by an unacceptable loss in toughness. Furthermore, in some cases, the processes that are used to synthesise and consolidate the zirconia powder can be labour intensive and the need for specialty equipment which can be uneconomical. Thus, there is global interest in resolving this problem economically since the LTD phenomenon represents a major barrier to the widespread use of Y-TZP ceramics as a structural material and biomaterial. In this research, the effect of sintering additive, in particular manganese oxide (MnO2), on the sintering behaviour and mechanical properties of Yttria-Tetragonal Zirconia Polycrystals (Y-TZP) has been investigated. In addition, the effectiveness of MnO2 in retarding the low temperature degradation (LTD) of the zirconia when exposed to superheated steam condition was evaluated. The study found that the additions of small amounts (up to 1 wt%) MnO2 as sintering additive were beneficial in enhancing densification and mechanical properties of Y-TZP. The MnO2-doped Y-TZPs retained high bulk density (> 95% of theoretical density) and high Young’s modulus (> 180 GPa) when sintered at relatively low temperatures of 1150ºC and 1250ºC without sacrificing tetragonal phase stability and inducing grain growth. The optimum level of MnO2 was found to be in the region of 0.5 wt% for sintering between 1250ºC and 1500ºC using short holding time cycle, with sintered body exhibiting excellent combination of properties when compared to the undoped ceramics. Microstructural investigation indicated that for the same temperature, the tetragonal grain size was not affected by the dopant.