Advanced Materials Research Vol. 789

Abstract: In Indonesia, a lot of wastes of glasses and metals have potency to be one of brake raw materials. For example, little bottles of used food packages are usually directly thrown into environment. The scraps of metal machining wastes are usually collected to be manufactured into other products. In this research, both wastes are used as fillers for brake friction materials, the effects of them on the thermal properties are studied in details. The glass wastes are crushed, grinded and filtered to simplify the mixing process with other raw materials when the fabrication of brake fiction materials done. During fabrication, samples are cured at 190°C for 3 hours. The samples are characterized using x-ray diffractometer and thermogravimetric analysis. Based on these characterizations, the increase of glass powders content plays role in increasing the percentage of crystalllinities. This is suspected the glass used as ingredient of friction material has crystalline structure. The glass waste quantity does not influence significantly on the thermal properties. During heating up to 1200°C, the mass loss occurs due to epoxy, bamboo fiber and styrene butadiene rubber decompose. The optimum composition is found at sample B2, a sample with lowest total mass loss (2 mg).

Abstract: Metal matrix composites (MMCs) are new materials, which are very essential for industry manufacture applications, such as automotive, aerospace and military. So far, an enhancement of the MMCs hardness has been interestingly studied. In this paper, we study the formation of Al-5%Cu-4%Mg matrix with the reinforcement of SiC by thixoforming process. Several important parameters for increasing the MMCs hardness, such as volume fraction of reinforcement, ageing time and temperature, are investigated. It is found from the microstructure analysis that the distribution of SiC particles is homogen for both MMCs with 5 vf.% SiC and 10 vf.% SiC. We also found fine, globular and non-dendritic structures, indicating that an appropriate structure of thixoforming process is obtained. From the hardness measurement, the hardness values are influenced by the reinforcement, thixoprocess and ageing. Our experimental results indicates that such parameters have to be considered in order to obtain the optimum performance of Al-5%Cu-4%Mg matrix.

Abstract: PbSn composites have been prepared by powder metallurgy for Advance Energy Transfer Bullet Application. Sn compositions was variety 5, 10, 15wt%. The compacting pressure performed at 10, 15, and 20 MPa. Temperature and holding time of sintering constantly in 150^OC for 2 hours. The microstructure and mechanical performance of PbSn composites are investigated by Scanning Electron microscope (SEM), and compression tests. The results show that the Pb-15%wtSn Composite which is compacted in 20 MPa has result greatest density which was 10.969 gr/cm³ and the smallest porosity (1.5%). Mechanical performance test of PbSn composite show the greatest hardness, compressive strength and modulus elasticity reach are 11.01 HV, 46.82 MPa and 34.96 GPa

Abstract: Electroless plating is one method to coat Al₂O₃ particles reinforced. This process has been carried out to coat Al₂O₃ with electrolite solution which content of nitride acid (HNO₃), Al and Mg powders. The metal oxide layer of spinel phase (MgAl₂O₄) is formed on the surface of Al₂O₃ which can improve wettability of Al₂O₃. The addition of Mg powder into solution was various from 0.002 to 0.012 mol while Al powder was kept constant i,e. 0.018 mol. The effect of Mg on formation of metal oxide layer on Al₂O₃ particles have been studied. It is found that the addition of 0.004 mol of Mg generated homogeneous thin spinel layer (MgAl₂O₄) on the surface of Al₂O₃ particles. This condition was applied to form spinel layer on Al₂O₃ particles reinforced for making Aluminium Matrix Composites (AMC) with 12.5Vf% of Al₂O₃ particles reinforced. It is found that tensile strength and hardness as well as wear resistance of AMC has been improved compare to unreinforced.

Abstract: Strontium titanate (SrTiO₃) thin film has been deposited on Si (100) substrate using pulsed laser deposition technique. Film deposition was carried out at low temperature (150°C) by maintained the pressure at 10^-4 Torr. Nanometer-thick SrTiO₃ film on Si substrate was characterized using SEM, AFM, XRD, and Raman Spectroscopy. SEM and AFM images show that SrTiO₃ film has growth on Si substrate uniformly. Raman and XRD spectroscopy also support the growth of SrTiO₃ film on Si substrate. Furthermore, to investigate the effect of post-deposition thermal annealing, the samples were annealed up to 900°C. Thermal stability of SrTiO₃/Si structure was studied by mean XRD spectra. The X-Ray Diffraction pattern indicates the crystallinity improvement through atomic arrangements during thermal annealing process.

Abstract: Barium - Strontium Hexaferrite and Barium Strontium Titanate are both well established materials which widely used respectively as permanent magnets and piezoelectric devices. As the properties are a structure sensitive, materials structure as well as crystal structure must be properly designed to meet a specific application. In this paper, we report our recent investigation on material structure analysis of Ba_0.3Sr_0.7Fe₁₂O₁₉ and Ba_0.7Sr_0.3TiO₃ composite system prepared by a mechanical alloying process to promote feroic properties. The average of particle size for composites system was found initially increased to a large size of 9 μm after mechanically milled for 30 hours and then start to decreased to smaller size of ~ 5μm when the milling time was extended to 80 hours and showing trend toward further reduction in mean particle sizes. In the latter case, the XRD trace for milled powders showed broadened diffracted peaks pattern due to deformation during mechanically milling. After sintering at a temperature of 1050 °C much finer crystallites of 7-13 nm size in a dense pellet were observed. Hence, sintering to the milled particles has promoted formation of nanocrystal containing particles. The mean crystallite size for magnetic phase was about more than 350 times smaller than the mean particle size of composite particles. Finer crystallite sizes were found in B₃SF in which the mean was about 700 times smaller than the mean particle size. The magnetic and electric properties of the composite system are also discussed.

Abstract: This article introduces a new technique involving concurrent engineering (CE) strategy and analytical network process (ANP) technique to form a ranking methodology as a part of the conceptual design selection (CS). The proposed method is referred as concurrent network (CN). The objective of this study is to simultaneously consider of all features of product elements by implementing CE strategy. Furthermore, CN enables interdependence and interrelationship analysis between product elements by application of ANP. In this study, CN is utilized for a conceptual design of metal matrix composite (MMC) component. The results show that by using CN, all important product parameters can be considered simultaneously during the CDS and the importance weights of manufacturing process parameters and material parameters which are related to MMC component performance are attained.

Abstract: The formation of barium hexaferrite, BaFe₁₂O₁₉ single phase with nanosize crystalline is very important to get the best performance especially magnetic properties. The samples were prepared by sol gel method in citric acid-metal nitrates system. Hence the mole ratios of Ba²⁺/Fe³⁺ were varied at 1:12 and 1:11.5 with pH of 7 in all cases using ammonia solution. The solution was then heated at 80-90°C for 3 to 4 hours. Then it was kept on a pre-heated oven at 150°C. The samples were then heat treated at 450°C for 24 hours. Sintering process was done at 850°C and 1000°C for 10 hours.Crystallite size was calculated by X-Ray Diffraction (XRD) peaks using scherrer formula. To confirm the formation of a single phase, XRD analyses were done by comparing the sample patterns with standard pattern. The peak shifting of pattern could be seen from XRD pattern using rocking curves at extreme certain 2θ. It was used MPS Magnet Physik EP3 Permagraph L to know magnetic characteristics. This method can produce BaFe₁₂O₁₉ nanosize powder, 22-34 nm for crystallite size and 55.59-78.58 nm for particle size. A little diference in nanosize affects the peak shifting of XRD pattern significantly but shows a little difference in magnetic properties especially for samples at 850°C and 1000°C with mole ratio of 1:12 respectively. The well crystalline powder is formed at mole ratio of 1:11.5 at 850°C since it has the finest particle (55.59 nm) and crystalline (21 nm), the highest remanent magnetization (0.161 T) and the lowest intrinsic coersive (275.8 kA/m). It is also fitting exactly to the standard diffraction pattern with the highest value of best Figure of Merit (FoM), 90%. XRD peak position of this sample is almost same with XRD peak position of another sample with sinter temperature 1000°C at same mole ratio.

Abstract: Quasi-solid state dye-sensitized solar cells (DSSC) having bilayer structure were made by using nanocrystalline anatase-rutile TiO₂ to enhance the photovoltaic performance. The bilayer structures were coated to FTO glass using doctor blade technique with total active area of 0.4 cm². Cyanidin dye extracted from mangosteen pericarp was used as photosensitizer. Bilayer anatase-anatase was formed with surface area of 99.9 m²/g and pore volume of 0.23 cc/g while anatase-rutile structure has surface area of 103.5 m²/g and pore volume of 0.21 cc/g. Overall energy conversion efficiencies under illumination of 10 mW/cm² of 0.461% and 0.1365% were achieved for DSSC employing anatase-anatase and anatase-rutile TiO₂ structure, respectively. Both efficiencies were higher than that of monolayer anatase and rutile TiO₂ structure whose efficiencies in the range of 0.02% to 0.037%. The photocurrent action spectra of bilayer structures performed high efficiency spectrum in the wavelength range of 420 480 nm owing to cyanidin effect of dye.

Abstract: The synthesis and characterization of the magnetic materials of La0.8Ba0.2Mn (1-x)TixO3 system (x = 0 0.7) by mechanical alloying process have been performed. This magnetic material is prepared by oxides, namely La2O3, BaCO3, MnCO3 and TiO2. The mixture was milled for 10 h and then sintered at 1000 ° C for 10 h. The refinement results of x-ray diffraction pattern showed that the doping concentration (x < 0.5) was a single phase, which has a structure monoclinic (I12/a1) with lattice parameters a = 5.5169(5) Å, b = 5.5437(5) Å and c = 7.8553(7) Å, = 90o and 89.75(1) o, V = 240.25(4) Å3 and 6.345 gr.cm-3. The microstructure analysis showed that the particle shapes was polygonal with the varied particle sizes distributed homogeneously on the surface of the samples. We concluded that the maximum number of titanium atoms substituting manganese atom is around x ~ 0.43 without changing the structure of this system.