The purpose of this paper is to evaluate the characteristics of corrosion protection of stainless steel substrates coated with silica by electrophoresis with pulsed direct current (PDC) and constant direct current (CDC) with anodization. Electrophoresis was carried out using silica sol from sodium silicate solution as an electrolyte solution. Stainless steel functioned as an anode and carbon as a cathode with a constant electrode distance of 2 cm. The amplitude, duty cycle, and anodization effect on stainless steel corrosion protection characteristics were evaluated. The samples were characterized by linear polarization and electrochemical impedance spectroscopy (EIS) to see the characteristics of metal corrosion protection and scanning electron microscopy (SEM) analysis to see the morphology of the coating. This study showed that PDC electrophoresis and CDC accompanied by anodization could obtain silica film with good corrosion protection characteristics (high pore resistance and low admittance). Linear polarization results showed that metal corrosion protection behavior was increased by anodization. Similar results were obtained by EIS analysis which showed that pore resistance increased by anodization. The highest pore resistance obtained by the constant current with anodization is 543 ohms, and the lowest admittance is 0.0217. Corrosion protection characteristics are also influenced by the amplitude and duty cycle during electrophoresis. Silica film with a high pore resistance and a low admittance were obtained at a frequency, amplitude, and duty cycle of 80 Hz, 0.5 volts, and 60%, respectively. The silica film produced by pulsed electrophoresis resulted in better coating characteristics than by constant current with anodization, which is seen from the pore resistance value and its admittance.

The composite restorations in posterior teeth have recently received an increasing interest due to the improvement of their physical and mechanical properties. However, compositing by the most common polymerization procedure tends to deform the tooth structure that may cause some damage in the marginal seal due to the imperfect interfacial attachment. Several techniques have been used to overcome this problem, one of them is using a flowable composites on the bottom of the cavity as the first layer. The purpose of this study is to develop fiber-reinforced composite (FRC) material made of coir fiber (Cocos nucifera) with matrix (Bis-GMA, TEGDMA, DGEBA, and camphorquinone). Cellulose fiber was formed by an anti-solvent method from an aqueous NaOH-urea cellulose solution dropped into ethanol-water mixture. The resulting cellulose fibers were then mixed with the matrix using a magnetic stirrer. The composition of nanocellulose in the matrix was varied 10:90 and their characteristics were compared with the commercial nanofiller composite (Z 350 and 3M) as control. The sample was tested for cross-linked using a scanning electron microscope (SEM) and Fourier transform infrared (FTIR). The morphology of nanocellulose look like a fiber as cross-linked with matrix. Therefore, the formation of a crosslink bond between cellulose and matrix C-O-C with a new wavenumber in 890 cm-1. The nanocellulose composite also form fibers that binds the matrix, while flowable composites from manufacturers from fibers and particulates. From this experimental method it can be suggested coconut fiber has high potential as raw material to be filler in a dental flowable composite.

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Boehmite (g-AlOOH) has demonstrated to have superior performance as coating material for battery separator, especially lithium-ion battery, due to its excellent wetting ability and thermal stability. The products of Bayer process from bauxite are typically in the form of aluminum trihydrate (ATH). Observing the phase diagram of Al2O3-H2O, it was assumed that the ATH might be converted into boehmite by controlling the pressure and temperature under hydrothermal condition. Therefore, the purpose of this work is to investigate the effect of operating conditions on the conversion of ATH to boehmite in a hydrothermal reactor. The experiments were carried out in a 100-mL hydrothermal reactor with a liquid filling volume of 30% and 50%. The reaction time was varied from 2 to 8 h. The hydrothermally treated ATH particles were characterized by an X-ray diffraction (XRD) and a scanning electron microscopy (SEM). The XRD patterns exhibited that the ATH has not been converted yet into boehmite at a reaction time of 2 h for all conditions. When the reaction time was prolonged to 4 h, ATH was transformed into boehmite at filling volume of 30% and 50%. It appears that liquid filling volume influences the transformation of ATH into boehmite. As observed by the SEM images, the morphology of particles also changed by the change of the crystalline phase. The particles changed from nearly spherical-shaped to cube and the particle size was typically larger

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