Studies On The Performance Of Mild Steel-Alumina Joining Fabricated Via Friction Welding [TA470. Z21 2008 f rb].

Joining of metal-ceramic can be done by different techniques such as brazing, diffusion bonding and friction welding. The joint strength of metal and ceramic has been studied extensively due to the differences in their mechanical and chemical properties. Sambungan seramik-keluli boleh dilakukan dengan menggunakan pelbagai teknik seperti pateri keras, ikatan resapan dan kimpalan geseran. Kajian tentang kekuatan sambungan keluli dan seramik telah banyak dilakukan kerana perbezaan sifat mekanikal dan kimianya

Observation of charge ordering signal in monovalent doped Nd0.75Na0.25-xKxMn1O3 (0 ≤ x ≤ 0.10) manganites

K doping in the compound of Nd0.75Na0.25-xKxMn1O3 (x = 0, 0.05 and 0.10) manganites have been investigated to study its effect on crystalline phase and surface morphology as well as electrical transport and magnetic properties. The structure properties of the Nd0.75Na0.25- xKxMnO3 manganite have been characterized using X-ray diffraction measurement and it proved that the crystalline phase of samples were essentially single phased and indexed as orthorhombic structure with space group of Pnma. The morphological study from scanning electron microscope showed there was an improvement on the grains boundaries and sizes as well as the compactness with K doping suggestively due to the difference of ionic radius. On the other hand, DC electrical resistivity measurement showed all samples exhibit insulating behavior. However, analysis of dlnρ/dT-1 vs. T revealed the clearly peaks could be observed at temperature 210K for x = 0 and the peaks were shifted to the lower temperature around 190 K and 165 K for x = 0.05 and x = 0.1 respectively, indicate the existence of charge ordering (CO) state in the compound. Meanwhile, the investigation on magnetic behavior showed all samples exhibit transition from paramagnetic phase to anti-ferromagnetic phase with decreasing temperature and the TN was observed to shift to lower temperature suggestively due to weakening of CO stat

Effect of operating temperature on direct recycling aluminium chips (AA6061) in hot press forging process

A method of solid-state recycling aluminum alloy using hot press forging process was studied as well as the possibility of the recycled chip to be used as secondary resources. This paper presents the results of recycled AA6061 aluminium alloy chip using different operating temperature for hot press forging process. Mechanical properties and microstructure of the recycled specimens and as-received (reference) specimen were investigated. The recycled specimens exhibit a good potential in the strength properties. The result for yield strength (YS) and ultimate tensile strength (UTS) at the minimum temperature 430˚C is 25.8 MPa and 27.13 MPa. For the maximum operating temperature 520˚C YS and UTS are 107.0MPa and 117.53 MPa. Analysis for different operating temperatures shows that the higher temperatures giving better result on mechanical properties and finer microstructure. The strength of recycled specimen increases due to the grain refinement strengthening whereas particle dispersion strengthening has minor effects. In this study, the recycled AA6061 chip shows the good potential in strengthening as the comparison of using only 17.5% of suggested pressure (70.0/400.0) MPa, the UTS exhibit 35.8% (117.58/327.69) MPa. This shows a remarkable potential of direct recycling by using hot press forging process

Crystalline phase, surface morphology and electrical properties of monovalent-doped Nd0.75Na0.25Mn1-yCoyO3 manganites

Perovskite-type manganites Nd0.75Na0.25Mn1-yCoyO3 (y = 0 – 0.05) have been investigated to clarify the influence of Co-doped on crystal phase and morphological study as well as electrical transport properties. The Nd0.75Na0.25Mn1-yCoyO3 samples are prepared via solid state synthesis method. X-ray diffraction analysis revealed all the samples are essentially single phased and the peaks are indexed to an orthorhombic structure with Pnma space. The morphological study from scanning electron microscope shows the improvement of the grains boundaries and sizes as well as the compaction of particles can be seen as cobalt doping increased. On the other hand, the temperature dependence of electrical resistivity measurements using four-point-probe technique indicates all samples maintained an insulator like behaviour down to low temperature. Analysis of the resistivity change with respect to temperature, dlnρ/dT-1 versus T reveals a slope changes of resistivity has been observed and a boarder peak exist for y = 0 sample and the peaks become significantly obvious for y = 0.02 and 0.05 samples. The peaks are observed in the range of charge ordering (CO) transition indicate the existence of CO in the system

Crystalline Phase, Surface Morphology and Electrical Properties of Monovalent-doped Nd0.75Na0.25Mn1-yCoyO3 Manganites

Perovskite-type manganites Nd0.75­Na­0.25­Mn­1-yCo­y­O­3­ (y = 0 – 0.05) have been investigated to clarify the influence of Co-doped on crystal phase and morphological study as well as electrical transport properties. The Nd­0.75­Na­0.25­Mn­1-yCo­y­O­3­ samples are prepared via solid state synthesis method. X-ray diffraction analysis revealed all the samples are essentially single phased and the peaks are indexed to an orthorhombic structure with Pnma space. The morphological study from scanning electron microscope shows the improvement of the grains boundaries and sizes as well as the compaction of particles can be seen as cobalt doping increased. On the other hand, the temperature dependence of electrical resistivity measurements using four-point-probe technique indicates all samples maintained an insulator like behaviour down to low temperature. Analysis of the resistivity change with respect to temperature, dlnÏ/dT-1 versus T reveals a slope changes of resistivity has been observed and a boarder peak exist for y = 0 sample and the peaks become significantly obvious for y = 0.02 and 0.05 samples. The peaks are observed in the range of charge ordering (CO) transition indicate the existence of CO in the system

Rice husk ash (RHA) and palm oil fuel ash (POFA) and soaking times: analysis of compressive strength of porcelain ceramics

Rice husk ash (RHA) and palm oil fuel ash (POFA) is a by-product from agricultural waste produced thousand tonnes every year. This paper presents the use of RHA and POFA as a substitute material for quartz in fabricating an improved porcelain ceramic. The RH was thoroughly washed with distilled water in order to remove adhering soil and dust. After that it was dried in an oven at 100 ºC for 24 hours. Then the dried husk was subjected to the chemical treatment; 2M HCL, 5% solid at 25 ºC before calcinations to increase silica content. Untreated POFA was dried in an oven at 100 ºC for 24 h. It was ground in a ball mill for 1.5 h with the revolution rate of 200 rev/min to reduce the particle size. Untreated POFA was sieved to remove the particles coarser than 50 μm. The POFA was treated by heating it at a temperature of 600 ºC for 1.5 h. The mixed powder was then pressed into pellets at mould pressure (MP) 91 MPa. All the pellets were sintered at the temperature of 1100 ºC for 1 h hour, 2 h hour s and 3 h hours soaking times. It was found that the highest compressive strength occurred at 20 wt% RHA and POFA and a soaking time of 2 h. The increment in the strength could be attributed to the changes in the increase in mullite and critobalite

Physical and Mechanical Properties of Porcelain Formed by Substituting Quartz with HCl Treated Palm Oil Fuel Ash

Palm Oil Fuel Ash (POFA), is a waste material from palm oil industries that has potential of recycling in the porcelain production due to its high content of silica. POFA is produced by burning palm oil shells, empty fruit branches and fibers as a fuel to heat up the boiler for electricity generation in the industries. This research is aimed at producing porcelain with the substitution of treated POFA with quartz at 20 wt%. Treated POFA was dried in an oven for 24 hours at 110°C and ground using ball mill machine for 12 hours to get particle size ˂50µm. 20 wt% of POFA powder was substituted for quartz and mixed with the composition of porcelain for 12 hours and then pressed into pellets at a mold pressure of 91 MPa. The pellets were sintered at a temperature of 1200°C for 2 hours soaking time at a heating rate of 5°C per minute. It was revealed that the maximum density was achieved at 2.38g/cm3 as the molarity of HCl is increased to 3 mole with the counterpart hardness of 7826 MPa. This improvement may be attributed to the increased in the silica content as a result of treatment of POFA with HCl acid

Effect of soaking time to the bending strength of porcelain with palm oil fuel ash

Silica from a treated palm oil fuel ash (POFA) was used as a substitute material in producing an improved porcelain ceramics. POFA was grounded in a ball mill until the median particle size was reduced to about 50 μm. It was heated at 600 ºC for 1.5 hours in an electric furnace. Then it was substituted quartz in porcelain composition from 5 wt.% up to 25 wt.%. The mixed powder was pressed into pellets at pressure of 91 MPa. All the pellets were sintered at 1100 ºC for the soaking times of 1 hour, 2 hours and 3 hours, respectively. It clearly indicated that the bending strength of the samples increases with the increase in POFA substitution and the increase in soaking time. With a value of 45 MPa bending strength of the samples containing 15 wt.% of POFA and sintered at a soaking time of 2 hours is the highest. This could be attributed from the increase in mullite and sharp microstructural changes. Porcelain containing POFA has about 7% weight reduction compared to the standard porcelain

UCE program and 3D students development

The purpose of this study is to evaluate the impact of the application of University Community Engagement (UCE) on the development of 3D students of Universiti Tun Hussein Onn Malaysia. A total of 10 students from various fields of study who are in the background of engineering flow have joined UCE. This review is more emphasis on the consistency of the elements contained in the UCE curriculum with the holistic development of students from the cognitive, affective and psychomotor perspectives. The impact of this UCE implementation can also be expressed in students. UCE is a program that emphasizes the concept of development and empowerment to produce future generations as true leaders. The program that has been collaborating with UGM has given the students the opportunity to directly participate in the project implementation on selected communities. Because of the observations found, based on the activities performed by the students have gone through each level for each specified domain. This has a positive impact on student development. Hence the concept of UCE can be used as a foundation in the development of the 3D Student Development Model concept framework

Effect of Mmolarity of HCl on production of Silica (SiO2) from Palm Oil Fuel Ash (POFA)

Palm oil fuels ash (POFA) is a by-product from palm oil industries that constitutes of different compounds such as silica (SiO2), alumina (Al2O3) and many others, its abundances and improper disposal in waterways and as a landfill cause environmental pollution and hence need for its modification and usage. This paper presents an alternative way of producing silica from POFA. Untreated POFA was dried in an oven for 24 hours at a temperature of 110 °C and ground in a ball mill machine for 12 hours at a speed of 250 rev/s. After sieving, the powder was dispersed in 1 mole, 2 mole and 3 mole of HCl. An increase in the composition of SiO2 was observed using X-ray Fluorescence (XRF) analysis due to the increase in the molarity of acid, X-ray Diffraction analysis (XRD) and Scanning Electron Microscopy (SEM) shows that POFA has a crystalline and porous cellular structure. This shows that acidic wash treatment is good and an improved method for the production of silica from POF