nan Suryanto

Synthesis and Characterization of ZnO Thin Film Memristor

ZnO films were deposited on Cu substrate using electrodeposition and thermal oxidation method. The effect of deposited thin film thickness varied with deposition time was discussed. Synthesized ZnO films were characterized using XRD, FE-SEM and electrical measurement. The results from electrical measurement showed the deposited ZnO exhibits pinched hysteresis IV curves. The synthesized ZnO shows a potential applications and options in production of a non-complex and low cost memristor.

Protein Foaming-Consolidation Method for Fabrication of High Performance Porous Bioceramics

Protein foaming-consolidation method is a facile technique for production of porous materials using egg yolk as pore creating agent. Usage of the yolk in the process offers a number of advantages over other proteins such as egg white and bovine serum albumin (BSA). Various materials were successfully fabricated using this technique. The present paper gives a brief review of the preparation and characterization of the materials through protein foaming-consolidation technique for biomedical application.

Influence of Oxalate Concentration and Temperature on the Microstructure Morphology of Nano Anodized Copper Coating

Nanostructures anodized copper coating was successfully synthesized through electrochemical anodization method. Effects of oxalate concentration and temperature on the morphology and corrosion resistance of the anodized coating were investigated through the observation of the critical polarization current variations. The anodizing parameters were selected in the ranges of anodizing temperature 0-24 °C, oxalate concentration 0.1-0.5 M and applied voltage 7.5-9 V. Phase analysis of the anodized coating was carried out using XRD (X-ray diffraction). Resulted peaks of the X-ray diffraction referred to the formation of a monoclinic crystalline phase of nanostructure cupric oxide CuO. The results of critical polarizing current were analyzed to evaluate the charge transfer through the coating. The lowest critical polarizing current was obtained when the porosity of the coating was in its lowest values. The increasing of oxalate concentration increases solution conductivity leading to form coating of larger grain size with fewer pores. The decreasing of temperature decrease coating porosity. The highest resistance to charge transfer through the anodized coated surface was achieved in the highest oxalate concentration and lowest anodizing temperature.

The Effects of Water Flow Rate on Copper Corrosion

This study investigates the effect of water flowrate on the copper alloy corrosion by using a hydrodynamic corrosion test in operating conditions of water flow rate range between 0.05 and 3.5 m/s, the temperature range between 20 and 45 °C. Dissolved oxygen concentration was in the range between 6.1 and 9.2 mg/l. The effects of water properties density, viscosity, and the tube geometric dimensions also considered. Corrosion rate determined by the weight loss calculation method and the tested samples microstructures characterized using FESEM. The results showed that the copper surface layer more affected by water flow at the beginning of turbulent flow condition, while at fully developed turbulent flow condition the surface covered with a fixed oxide layer. Therefore, corrosion found to be at higher rates during the initial stage of the turbulent flow condition, but it reduced at fully developed turbulent flow conditions at higher water velocity. These results indicate that the overall flow rate conditions, which include physical properties of the fluid, hydrodynamic parameters, and the geometric tube dimensions, have the dominant influence on corrosion rate.

Modelling and Optimization of Copper Electroplating Adhesion Strength

In this paper, Response surface methodology (RSM) was utilized to design the experiments at the settings of CuSO4 and H2SO4 concentrations and current densities. It also used for modelling and optimize the parameters on the adhesion strength of austenitic stainless steel substrate. The adhesion strength was investigated by the Teer ST-30 tester, and the structure of the samples investigated by using scanning electron microscopy (SEM). The modelling approach adopted in the present investigation can be used to predict the adhesion strength of the copper coatings on stainless steel substrate of electroplating parameters in ranges of CuSO4 100 to 200 g / L, H2SO4 100 to 200 g / L and current density 40 to 80 mA / cm2. The results showed that, operating condition should be controlled at 200 g/L CuSO4, 100 g/L H2SO4 and 80 mA/cm2, to obtain the maximum adhesion strength 10N.

Evaluation of the effects of copper electroplating parameters on the adhesion using response surface methodology

In this paper, response surface methodology (RSM) was utilized for the experiment design of CuSO4 and H2SO4 concentrations and current densities. RSM was also used to evaluate the significance of each parameter and its interaction on the adhesion strength of austenitic stainless steel substrate. Adhesion strength was investigated by a Teer ST-30 tester, and the structure of the samples investigated by using scanning electron microscopy (SEM). Results showed that increasing the concentration of CuSO4 and decreasing theat of H2SO4 strengthens adhesion. Conversely, the current density only has a slight effect.

Sol-Gel Synthesis of Zn doped HA Powders and their Conversion to Porous Bodies

The present study was aimed at fabricating porous ceramic scaffolds via polymeric sponge method for biomedical applications using as synthesized Zinc doped Hydroxyapatite (ZnHA) powders. Zn doped HA powders were prepared via sol-gel method using diammonia hydrogen phosphate [(NH4)2HPO4] and calcium nitrate tetrahydrate [Ca (NO3)2.4H2 as starting materials. The obtained powders were then used for the preparation of porous ZnHA scaffolds via polymeric sponge method. The green porous bodies so developed by impregnating cellulosic sponges with HA slurries, were subjected to sintering process at a temperature of 1300 Field-emission scanning electron microscopy (FESEM) was used to observe the surface morphology of the powder and sintered porous sample. The structure and crystallinity of (Zn)HA powder and the sintered porous samples was analyzed using X-ray diffractometer whereas Fourier transform infrared spectroscopy (FTIR) was used to determine the presence of various phases in the powder. FESEM results showed the formation of agglomerates at an increased Zn concentration. The morphology of the porous samples showed high degree of fusion and densification with an increase in Zn concentration. Preliminary mechanical testing results show that maximum compression strength of HA porous bodies was 0.12 MPa.

The Effects of Excess Calcium and Aging Media on the Mechanical Properties of Calcium Phosphate Filling Materials

The effect of excess calcium and aging media on calcium phosphate biomaterials mechanical strength was studied. The variation of excess calcium and sample type has shown different performance when they are being aged in the moist environment (ME) and the simulated body fluid (SBF). The calcium phosphates were synthesized via low temperature hydrothermal method and sampled to two types of powder-water (3:2) mixture and paste for 90 days of the aging time. Two mechanical tests were applied, compression and diametrical tensile test, while XRD to evaluate phases. Scanning electron micrograph showed the paste samples that soaked in SBF was better entanglement of the particles, better compression strength but with degradation and diametrical tensile strength improvement by aging. Calcium hydroxide and ammonium di-hydrogen phosphoric was traced in all the samples along with calcium deficient hydroxyapatite as the main phase.

Thermal stability of nickel molybdenum electrodeposits

Thermal stability of nickel molybdenum electrodeposits was investigated. This investigation is important to show that electrodeposits can be used at elevated temperature and to understand electrodeposit behaviour as a function of temperature. Crack-free electrodeposits with up to 17 at% molybdenum were produced by the square pulse electro-deposition technique from a solution containing nickel sulphamate. The experiment was performed using vacuum furnace. Microstructure of deposits was investigated using microscope SEM, while the phase of deposits was studied using x-ray diffraction. Chemical composition of deposits was observed using energy dispersive x-ray analyzer and hardness of deposits was measured using micro hardness tester. The result shows that nickel molybdenum electrodeposits stable up to 400 oC. For 550 oC, grain growth was observed to start but the hardness of electrodeposits has no significant changed. Hardness analysis shows that hardness of electrodeposits does follow Hall Petch relationship.

Internal Oxidation of Ni-Cr-Al Alloys under Various Oxygen Partial Pressures at 1273 K

Alloys for high temperature application always rely on their ability to form protective, dense Cr2O3 and Al2O3 scales. In case of Ni-Cr binary alloy, a minimum composition of Cr is required for the formation of continuous protective scale. However, addition of small amount of third element such as Al may results in decrease of required Cr composition to form protective scale. This study aims to clarify the effect of ternary element on the formation of protective scale quantitatively. Ni-Cr alloys composed with 2 mass% and 4 mass% of Al were exposed in oxidizing environment under Cr/Cr2O3, Fe/FeO and Ni/NiO oxygen partial pressure. The oxidation of all samples is following parabolic rate’s law. XRD and SEM results show that Al2O3 and Cr2O3 are formed internally. Parabolic rate’s constant of samples oxidized in Ni/NiO oxygen partial pressure is higher by few magnitude orders. Higher Al concentration decreases the parabolic rate’s constant. It is concluded that the formation of protective scale is enhanced by the addition of Al as ternary element in Ni-Cr alloys.