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This paper presents a study on the synthesis of Niobium Carbide (NbC) and Vanadium Carbide (VC) in Copper (Cu) matrix by mechanical alloying (MA) technique. The elemental powders of Cu, Niobium (Nb), Vanadium (V) and synthetic graphite powder were mechanically alloyed for 30 hours at 400 rpm in a planetary ball mill Fritcsh “Pulverisette 6” according to the stoichiometric ratio of Cu-(10-x) vol%NbC-(0+x) vol%VC (x=1,3,5,7,9). The milling was performed under Argon atmosphere. The as-milled powder were compacted at 400 MPa and sintered using a microwave sintering furnace at 900°C with 1 hour soaking time. The phase identification was performed by using the X-ray Diffraction (XRD) analysis on the as-milled powders and sintered pellets. From the result, the NbC and VC phases were successfully formed after milling, and were precipitated after sintering. The average crystallite size and lattice strain of Cu, before and after sintering were 42.302 nm, 0.013%, and 71.294 nm, 0.004%, respectively.

This paper presents a study on the characterization of physical and electrical properties of Niobium Carbide (NbC) and Vanadium Carbide (VC) in Copper (Cu) matrix by mechanical alloying (MA) technique. The elemental powders of Cu, Niobium (Nb), Vanadium (V) and synthetic graphite powder were mechanically alloyed for 30 hours at 400 rpm in a planetary ball mill according to the stoichiometric ratio of Cu-(10-x) vol%NbC-(0+x) vol%VC (x=0,1,3,5,7,9) under Argon atmosphere. The as-milled powder were compacted at 400 MPa and sintered using microwave sintering furnace at 900°C with 1 hour soaking time. The phase identification was made by using the X-ray Diffraction (XRD) analysis. The microhardness, relative density and apparent porosity of sintered pellets were measured using Vickers microhardness and Archimedes principle, respectively. Electrical conductivity was measured using 2 point probe technique. Density of composite increase with increasing NbC content, while electrical conductivity also increase when NbC was added. Microhardness showed that single phase carbide has higher hardness value then multicarbide.

Statistical quality improvement techniques such as design of experiments (DOE) and Taguchi methods form an essential part of the search for improved product performance. This paper applies both the Taguchi and full factorial design techniques to highlight the application and to compare the effectiveness of the Taguchi and full factorial design processes as applied on surface roughness. Besides that, to determine the optimal parameter setting for each factor in surface roughness. For this study, we used two different probes of Mahr Surf XR20 which was MFW 250 tracing arm 6851804 (25μm) and tracing arm 6851806 (50μm). The main effect and interaction plot had been analyzed by using MINITAB (software). The experiment result showed that full factorial design performs better than Taguchi method.

Joining sialon to as-received and nitrided AISI 420 martensitic stainless steels using diffusion bonding is reported in this paper. The samples were joined at 1200°C for one hour under uniaxial pressure of 17 MPa in a vacuum (1x10-5 Torr). After joining process, the microstructure, interdiffusion of elements, and hardness of the joint were studied. The interdiffusion and reactivity of the elements created the reaction layer. It consisted of interface layer on the sialon side whereas thicker diffusion layer was formed on the steel side. Thinner reaction layers were observed in joining sialon to nitrided steels compared to joining sialon to as-received steel due to less reactivity between the joined materials. However, more precipitates such as carbides were formed in the parent steel with longer nitriding time. Gaps were formed between the diffusion layer and the parent steel but the interfacial bonds were strong since no cracking occurred on the samples. Since the reaction layer had intermediate hardness, it contributed to the joint’s ductility that reduced the effect of thermal expansion mismatch between the joined materials by acting as a shock absorbing zone.

Material characterization is a crucial step to ensure the characteristics and properties of the samples are comparable to the standard adsorbent and suitable for CO2 adsorption. The objective of this work is to characterize natural calcium based materials for CO2 adsorption which are obtained from waste cockle shells. Characterization analyses are conducted by using XRD, BET and FESEM. Material characterization indicates that raw cockle shell is made up of aragonite and needle-like structure. It is also shown that CaCO3 can be decomposed to CaO through high temperature calcination process. Through physisorption analysis, the samples are classified as mesoporous materials and it is shown that calcined cockle shell is better than raw cockle shell in term of surface area and pore volume. The results proved that calcium based materials could be successfully employed as sorbent for CO2 separation.

Microwave processing of metal alloy powders have gained considerable potential in the field of material synthesis. This paper aims to present the effect of powder particle size of Tin Based Alloy sintered using different type of heat source. Tin (Sn) based alloy containing two different sizes, 10 μm and 150 μm of Sn powder were successfully sintered using hybrid microwave and conventional sintering. The overall processing time was reduced by about 93% through microwave sintering. The comparative analysis is based on densification parameter, microhardness, microstructures and XRD detected phases of the specimens. All specimen with 10 μm sintered in microwave exhibited 90% of theoretical density while exhibited 86% lower porosity and possessed 30% higher in microhardness value.

The influence in optimization of processing, calcinations and sintering parameter on the physical properties and characteristic of CaCu3Mn4O12 were investigated. The stoichiometric CaCu3Mn4O12 powders were successfully prepared by the citric gel method. Dried gel with three dimension network consisted of molar ratio of [citrates/metallic ion]; 1:2 was formed. The precursor gel formed was calcined and sintered at range 400 °C to 800 °C. A single-phase CaCu3Mn4O12 fairly well densified at relative low temperature under atmospheric sintering condition. FESEM results turned out that CaCu3Mn4O12 powder particle is submicron in size and highly agglomerates due to high calcinations temperature. The smaller particle size with higher grain boundary and less of porosity were found for the sample sintered at 700 °C to 800 °C. The samples show the ‘superparamagnetism’ behavior where the M-H curves are linear with the field and have a smaller value of coercivity at room temperature. Sintering at 800 °C produced the sample with lowest Hc value due to the phenomenon of over grown magnetocrystallites, grain size and grain boundaries.

Due to the disadvantageous of solid state in CaCu3Mn4O12 ceramic processing, the sol gel synthesis has been extensively studied to produce fine size of powder and better homogeneity at low processing temperature. This paper provides a summary to prove that the single phase of CaCu3Mn4O12 ceramic with high purity and characteristic is actually can be produced via sol gel synthesis at relative low temperature under pressureless sintering process. The stoichiometric CaCu3Mn4O12 powders were successfully prepared by the citric gel method with molar ratio of [citrates/metallic io; 1:2. The precursor gel formed was calcined and sintered at range 400 °C to 800 °C. A single-phase CaCu3Mn4O12 fairly well densified at relative low temperature under atmospheric sintering condition. Analysis has been done under XRD and FESEM. Result shown formation of CaCu3Mn4O12 started at 500 °C and was formed completely at 700 °C for 18h. FESEM results turned out that CaCu3Mn4O12 powder particle is submicron in size and highly agglomerates due to high calcinations temperature. Varying in sintering parameter is actually exhibit differences in phase formation, grain size and magnetic behavior.

This paper presents an investigation on the accuracy of average roughness (Ra) in three surface areas of specimen. For this study, we used two different probes of Mahr Surf XR20 which was MFW 250 tracing arm 6851804 (4.5mm) and tracing arm 6851806 (9.0mm). Full factorial design was used in the experiment plan. The normal probability graph, main effect and interaction plot had been analyzed by using MINITAB (software). The experiment result showed that the tracing arm 6851804 (4.5mm) consisted of small errors compared to the tracing arm 6851806 (9.0mm) based on the main effect plot and interaction plot analysis.