Zirconia ceramic has been identified as one of the advanced ceramic material with great mechanical properties which is used as engineering and implant materials. However, the great potential of the ceramic is hindered by low temperature degradation (LTD) where the ceramic experiencing t-m phase transformation that weakens the properties of 3Y-TZP in the presence of moisture. Two-step sintering was found to be effective in producing fully resistance 3Y-TZY but very long holding time is required. Manganese Oxide (MnO2) is reported as good densification aid at low sintering temperature for 3Y-TZP but the LTD issue is not fully resolved. In this study, the effects of different sintering profiles and dwell time on 3Y-TZP added with 0.5 wt.% of MnO2 were studied in order to improve the resistance towards LTD without affecting the intrinsic properties of the ceramic. The effects of adding 0.5 wt.% of manganese oxide (MnO2) into 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) were studied using different sintering profiles and dwell time. The samples were sintered at 1400°C and 1250°C with varying dwell time of 1 min and 2 hours for single step sintering and a combination of 1 min and 30 min, 2 hours and 25 hours for two step sintering. The optimal sintering profile was Profile C2 where doped 3Y-TZP undergone two step sintering with dwell time of 1 minute at 1400°C and 1250°C for 30 minutes. At this optimal sintering conditions, the doped 3Y-TZP samples exhibited 98.5% relative density, with Young’s Modulus of 206.66 GPa and Vicker’s Hardness of 14.35 GPa.

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Malaysian palm biodiesel is one of the attractive biofuels for petroleum diesel due to its zero-sulphur content (i.e., non-toxic), renewable capability, and similar physicochemical properties. Recent studies have reported significant improvement in the performance and emission characteristics of diesel engines by leveraging the blending composition between palm biodiesel and diesel. However, the fundamental aspects of combustion performance due to the blending effects of Malaysian palm biodiesel remain unexplored. This study aims to investigate the isolated droplet combustion behaviour of palm biodiesel-diesel blends at various blending compositions through a time-based image capturing method. Experimental results show that palm biodiesel-diesel blend with 60% palm biodiesel content (B60) and above produce a more prominent blue flame, which indicates cleaner and more complete combustion. The ignition delay (ID) increased when the palm biodiesel content is increased. Similarly, the burn rate constant for palm biodiesel-diesel blends increased with increasing palm biodiesel content. The combustion duration of palm biodiesel-diesel blends increased slightly when the palm biodiesel content is raised to 40% (B40) but decreased significantly when the palm biodiesel content is at 60% and above. Overall results suggest B60 is the optimum blend, which could potentially improve the performance and emissions of diesel-powered vehicles.

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3mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) ceramic is widely used as engineering material owing to its great strength. Recently, 3Y-TZP ceramic is receiving great response in dental restoration due to its bio-compatible properties and aesthetic appearance. To achieve high bulk density, high sintering temperature (> 1500 °C), low firing rate (10 °C/min) coupled with long dwelling period (2 hours) are required in conventional sintering (CS) to fabricate 3Y-TZP ceramic which resulted in high energy consumption. Therefore, non-conventional sintering technique with low energy consumption such as microwave (MW) sintering is worth to explore as almost 100 % of electromagnetic energy is converted into heat largely within the sample itself. The commercial available 3Y-TZP powder was MW fired from 1200 °C to 1400 °C. The 3Y-TZP ceramics fabricated via MW sintering was compared with those CS samples by assessing the densification and mechanical properties of the ceramics. It was revealed that the total sintering time was reduced by 75 % for microwave-sintered 3Y-TZP ceramics to achieve relative density of ∼ 98 %, Young’s modulus of ∼ 205 GPa, and Vicker’s hardness of 14.15 GPa at low sintering temperature (1200 °C) as compared to CS ceramic that required temperature above 1250 °C. However, the properties of both MW and CS-sintered ceramics are comparable when the sintering temperature exceeds 1250 °C.