Materials Science Forum Vol. 840

Abstract: The surface modification of RH filler was carried out using silane coupling agents in order to improve the adhesion between LLDPE and RH. RH was treated using silane coupling agent at four different concentrations (1, 3, 5 and 7 %) at room temperature. In this study, both untreated and treated RH/LLDPE composites were tested under static (0.001 s^-1, 0.01 s^-1 and 0.1 s^-1) and dynamic loading rates (650 s^-1, 900 s^-1 and 1100 s^-1) using universal testing machine and split Hopkinson pressure bar apparatus, respectively. Results show that the 5% treated LLDPE/RH composite shows the higher ultimate compressive strength (UCS) and rigidity as compared to untreated LLDPE/RH composites under various loading rates. Overall, it is proved that the surface treatment of RH gives significant contribution towards the UCS and rigidity of LLDPE/RH composites under both static and dynamic loading rates.

Abstract: The structure and dielectric properties of Barium Zinc Tantalate (BZT) doped by copper oxide (CuO) with a variety of values of mol% doping from 0, 0.1, 0.25, 1.0, 1.5 and 2.5 were prepared using a solid state method. The addition of CuO did not disturb the 1:2 ordering structure of the BZT ceramic. The grain size increased when the addition of doping increased. A small amount of doping elements increased the relative density. The dielectric constant (ɛ_r) value of the BZT significantly improved with the addition of the CuO for the specimens sintered at 1250°C and it could be explained by the increase of the relative density. The tan δ of the CuO doped with BZT ceramics is lower than pure BZT ceramics, and decreases as the CuO content increases. Meanwhile, for the percentage of bandwidth (%BW) it is shown that the best result is produced when it is doped with 0.25 mol% CuO and sintered at 1250°C. The best microwave dielectric properties obtained were ɛ_r=70.28, tan δ = 0.024, %BW = 7.83 which occurred for the 0.25 mol% doped CuO and when sintered at 1250°C/4 h.

Abstract: Titania (TiO₂) is one of a common and favorable material use in the manufacturing industry due to its uniqueness and functional performances to human and environment. The study was focused on the performance of glaze added TiO₂ (anatase phase) in the application of porcelain tiles. Anatase powder in micro size was used (varies at 5 wt%, 10 wt % and 15 wt%) to observe their performance as antibacterial materials. The anatase powders were mix into the glaze composition and apply to the porcelain tile through dip coating. The viscosity of each composition was observed to study their effect. Characterization used to observe the properties of anatase mixed glazed porcelain tile were X-ray diffraction (XRD), Scanning electron microscopy (SEM) and antibacterial test. The results shown that higher composition of anatase powder, viscosity of the mixed glaze is higher and a rougher surface of glazed tiles was formed. XRD result shows that the higher the composition is more the intensity of TiO₂ on the glaze coating surface, supported by SEM results. Antibacterial testing towards E.Coli was observed by counting the colonies of bacterial growth in 0 hr, 2 hrs, 4 hrs and 8hrs. The antibacterial properties increase when the composition of anatase increases.

Abstract: The dip coating procedure led to accumulation of coating particles at the coating solution and substrate interface. After sintered, frit dissolution implied an occurrence of liquid phase sintering. Simultaneous improvement of surface morphology and bulk density was evident. The significant appearance of cracks and roughed surface of plain porcelain was revolved into crack free and smoother exterior following the dip-coating and sintering process. The surface was properly glazed. This led to enhanced body densification, and sealing of apparent micropores. At the same time, the deposited coating reduced the amounts of open cells and surface defects, which caused reduction in porosity and increment of bulk density.

Abstract: Glasses in the system [wt%: (55-x)% SiO₂-(15+x)% B₂O₃-15% P₂O₅-10% Na₂CO₃-5% Fe₂O₃] where 15 ≤ x ≤ 40 % have been prepared with the different amount (35-55 wt%) of boron oxide. The compositions were limited by fixing the P₂O₅ at 15 wt%, Na₂CO₃ at 10 wt% and fixing the Fe₂O₃ at 5 wt%. The objective of this study is to determine the effect of boron oxide on phosphate ion released from borosilicate glass in seawater. The glass has been prepared by melting in the alumina crucible within 2 hours of soaking time at 1300 °C in the furnace and cooled to room temperature. The obtained glass was crashed and sieved with yielding a mean size of 710 μm. The samples were immersed in seawater under dynamic condition by stirring at 310 rpm. The water sample was taken 6 times at every 15 minutes until 75 minutes and analyzed using Discrete Auto Analyzer. The functional group and morphological characterization on the glass surface have been investigated using Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy (SEM). Analysis of the data indicates that the amount of 50 wt% boron was the best and optimum for the phosphate ion release which is 126.53 ppm.

Abstract: Currently, phosphate-based glasses have been extensively studied for their special characteristic of being soluble in aqueous medium and capable of releasing ions. This paper presents the relationship between the solubility properties and ion released of phosphate glasses having a composition of 6Al₂O₃-15K₂O-14Na₂O-(20-x)CaO-xFe₂O₃-45P₂O₅, where x = 2, 4, 6 and 8 wt.%. Clear and free bubbles of dark green glasses were obtained from the used of conventional melting technique at 1300 oC. The ion released and weight loss studies were determined from the immersion of the glass samples in deionised water for about 16 weeks under static condition. IR spectra revealed the formation of phosphate units such as metaphosphate and orthophosphate unit around 1097 cm^-1 and 1107 cm^-1 with the presence of Fe₂O₃ in the glass system. SEM image of the phosphate glass structure before and after immersion seems to be associated with the solubility of these glasses. From the study, the concentration of Na⁺ and K⁺ release decreased when more Fe₂O₃ contents were added to the system. Fe₂O₃ stabilize the network structure via the formation of P-O-Fe bond which more hydration resistant towards water penetrating molecules.

Abstract: Zirconia toughened alumina (ZTA) has good mechanical properties and widely used in cutting insert application. Although the ZTA is well known of its good mechanical properties, its still can be improved in order to produce better properties. It can be done by adding additives as reinforcement such as magnesium oxide (MgO), cerium oxide (CeO), titania (TiO₂) and chromia (Cr₂O₃). The effect of TiO₂-Cr₂O₃ addition on the physical properties of ZTA were investigated in this study. The composition of TiO₂ was varied from 0 wt% to 3.5 wt% while Cr₂O₃ was fixed at 5 wt%. The starting powder materials were mixed by wet mixing for 30 minutes in acetone. Then the powder mixtures were hydraulically pressed at 260 MPa. The green pellets were sintered at 1600°C for 1 hour using an electrical furnace in presureless condition. The results were characterized by XRD, density, and also Vickers hardness. The ZTA-Cr₂O₃-TiO₂ ceramic composite achieved the highest density of 4.1 g/cm³ and Vickers hardness of 1919 HV prior to the addition of 2.0 wt% TiO₂. Therefore, it can be decisively concluded that the addition of Cr₂O₃-TiO₂ does affected the properties of ZTA.

Abstract: An extensive studied has been done with rice husk ash (RHA) as a substitute element for quartz to produce porcelain. Rice husk (RH) was treated with HCL. The treated RH was subjected to calcinations at 700°C for six hours, then subjected to the XRF analysis. The composition of RHA and porcelain powder were mixed using a ball mill for 1.5 hours, then was pressed into pellets at a pressure of 91 MPa. The pellets were sintered at a temperature of 1200°C for 1 hour, 2 hours and 3 hours soaking time, at a heating rate of 5°C per minute. The bulk density and Vickers hardness were measured. At the soaking time of 2 hours, the maximum density and hardness were achieved at 2.45 g/cm³ and 1052 HV respectively. SEM analysis reveals a typical sequence of densification enhancement with the increasing of soaking time.

Abstract: Cordierite glass of non stoichiometric (2.8MgO 1.5Al₂O₃ 5SiO₂) can be used to synthesis the synthetic gems because of it properties. The colorant glaze material; 2% , which from trace element cam give colorant to cordierite glass sample. The XRD analysis give result that α-cordierite formed at temperature 1250°C. The density and porosity of cordierite glass decreased as the sintering temperature increased. The hardness from Vickers Hardness are increased as the sintering temperature incerased.