Preparation and Characterization of Polysulfone/Celullose Acetate (PSF/CA) Blend Membrane

Blend polysulfone (PSF)/cellulose acetate (CA) membranes have prepared by phase inversion method. In here, CA was prepared from bacterial cellulose by acetylation reaction. Various temperature of coagulation bath were used as variable to investigated water uptake, water flux, porosity and thermal properties of membranes. As comparison, the CA commercial (CCA) was also investigated with the same parameters. As the result, the functional group analysis by FTIR show that CA has successfully prepared from bacterial cellulose. The parameters include water uptake, water flux and porosity have the similar trend. The parameters increase with increasing of temperature of coagulation bath. The other hand, CCA membrane have similar trend to CA membranes for parameter of water water uptake, water flux and porosity. However, CCA membrane is higher than CA membranes for all parameters. Thermal analysis by Differential Scanning (DSC) showed that all blend membranes with different temperature of coagulation bath have single transition glass temperature (Tg) that indicated that molecular homogeneity. Keywords: blend membrane, phase inversion, coagulation bath, water flux, porosity

Cyclic Oxidation Resistance of MoSi2 Added FeCrAlTiY Coatings on ST41 Steel at 700oC Prepared by a Flame Spraying Technique

Advanced power generation will be operated at higher temperatures and pressure to achieve higher efficiency and reduce CO2 emission. This may significantly impact the use of carbon steel that previously has been used in boiler fabrication. In this study, a flame spraying technique was applied to develop a highly resistant coating of MoSi2 added FeCrAlTiY on ST41 steel to improve its oxidation resistance. Four variations of MoSi2 concentration as 0, 10, 20 and 30 in mass% were prepared to investigate the effect of its addition on the cyclic oxidation resistance of FeCrAlTiY coating at 700oC for 8 cycles. The phase composition and microstructure of the coating before and after the oxidation test were analyzed using XRD and SEM, respectively. While the element distribution along the coating was characterized using an EDX. According to the results, partially and fully melted particles, oxides and pores are present in the coatings. It becomes more porous with the increase of MoSi2 concentration. The oxidation test results indicate that the FeCrAlTiY with 10 mass% MoSi2 addition exhibits the lowest mass gain (0.217 mg/mm2) compared to that of MoSi2-free coating (0.261 mg/mm2) and FeCrAlTiY coating with 20 and 30 mass% MoSi2 (0.297 and 0.308 mg/mm2, respectively). As the MoSi2 concentration increases, its addition leads to the deterioration of FeCrAlTiY coating oxidation resistance. The results suggest that FeCrAlTiY-10 mass% MoSi2 is the most resistant coating to cyclic oxidation at 700oC in air and can be applied as a protective coating in advanced power generation

Fabrication of magnesium-carbonate apatite by conventional sintering and spark plasma sintering for orthopedic implant applications

Magnesium-Carbonate Apatite (Mg-xCA) is one of the potential magnesium composites to be developed as an alternative biodegradable implant material. Several attempts were made to optimize its characteristics. In this study, Mg-xCA (x = 0, 5, 10, and 15% wt) was prepared by powder metallurgy through warm compaction (WC) and further densified by 2 sintering process methods, namely conventional sintering (CS) and spark plasma sintering (SPS). The characterization included density test, XRD test, microstructure test (OM and SEM-EDS-Mapping), microhardness test, and electrochemical test. The SPS process improves the characteristics of Mg-xCA better than the CS process. The SPS process can increase the relative density by about 0.7-2.4%, increase the hardness by about 2-13%, and reduce the corrosion rate by about 32-49% compared to the initial condition before sintering (WC). The SPS structure has a lower oxygen elemental content than the CS structure. The sintered process with SPS is considered effective for the fabrication of Mg-xCA powder-based composites compared to the CS process