The purpose of this research is to find the effects of cutting speed on the performance of the ZTA ceramic cutting tool. Three types of ZTA tools used in this study which are ZTA-MgO(micro), ZTA-MgO(nano) and ZTA-MgO-CeO2. Each of them were fabricated by wet mixing the materials, then dried at 100°C before crushed into powder. The powder was pressed into rhombic shape and sintered at 1600°C at 4 hours soaking time to yield dense body. To study the effect of the cutting speed on fabricated tool, machining was performed on the stainless steel 316L at 1500 to 2000 rpm cutting speed. Surface roughness of workpiece was measured and the tool wears were analysed by using optical microscope and Matlab programming where two types of wear measured i.e. nose wear and crater wear. Result shows that by increasing the cutting speed, the nose wear and crater wear increased due to high abrasion. However, surface roughness decreased due to temperature rise causing easier chip formation leaving a good quality surface although the tool wear is increased.
Vickers hardness of zirconia toughened alumina added MgO with different composition and particle size has been studied. Five different size of magnesium oxide particle at different composition (0.5 wt % to 0.9 wt %) were used in this experiment. Each batch of composition was mixed, uniaxially pressed into 13 mm pellets and sintered at 1600oC for 4 hours in pressureless conditions. Analysis of Vickers hardness, microstructural observation and EDX analysis has been carried out. Microstructural observation showed that the addition of magnesium oxide greatly affected zirconia toughened alumina microstructure. Smaller Al2O3 grain size is observed with the presence of MgO thus improving its mechanical properties such as hardness and density. Results of Vickers hardness increased linearly with addition of more MgO until a certain composition. Each particle size of MgO addition show different composition is needed to reach the optimum Vickers hardness, depending on the particle size. The increase of hardness of the cutting insert is mainly contributed by small sized Al2O3 grains due to the microstructure pinning effect introduced by MgO. Maximum Vickers hardness achieved in this experiment is 1710 Hv, obtained at 0.7 wt% MgO with 0.15 µm particle size.
The mechanical properties and microstructure of zirconia-toughened-alumina ceramic composite doped with nanoparticle of MgO is investigated. The nanoMgO weight percent was varied from 0.3 wt % to 1.3 wt %. Each batch of composition was mixed using ultrasonic cleaner and mechanical stirrer, uniaxially pressed and sintered at 1600 °C for 4 h in pressureless conditions. Analysis of bulk density, Vickers hardness and microstructural observation has been carried out. Results of Vickers hardness increased linearly with addition of more nanoMgO until a certain composition. Maximum Vickers hardness obtained was 1740HV with 1.1 wt % MgO. Furthermore, microstructural observations show that the Al2O3 grain size depends on the particle size of MgO, and is directly related to its hardness property.
Delamination and crack were considered as significant failures in electronic packaging. For these circumstances, Modified Crack Closure Integral method was tested and applied to determine crack growth rate and for the purpose to understand failures. TQFP package was successfully verified by using the method. A PBGA package was modeled for thermal distribution and moisture concentration in order to calculate vapor pressure acted on crack. The energy release rate was the main concern among fracture parameters, which had been proven fully related with vapor pressure and crack length ratio in popcorn cracking.
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