فهرست مطالب f. b. susetyo

Nickel (Ni) is an interesting candidate for corrosion protection of copper (Cu) due to its present passive area. Ni films with larger passive areas have better corrosion protection than those with smaller ones. In the present research, Ni films were produced over Cu. A barreling apparatus was employed to support the produced films in the sulphate solution. Various spinning speeds (0, 50, and 100 rpm) were used on the barrel while it was being processed. Several investigations were conducted, such as deposition rate, current efficiency, surface morphology, phase, film thickness, crystallographic orientation, and electrochemical properties. Increased spinning speed resulted in a decrease in the deposition rate, current efficiency, grain size, thickness, crystallite size, and exchange current density. Compared to a higher spinning speed, the decrease in spinning speed caused an increase in the oxygen content, surface roughness, and micro-strain. The higher speed of the barrel apparatus resulted in a lower corrosion rate Ni film of 0.147 mmpy. Moreover, the lower speed of the barrel apparatus resulted in a higher exchange current density Ni film of 0.997 A/cm².

Nickel (Ni)-rich single-phase nickel-copper (Ni-Cu) alloy coatings were produced on aluminum (Al) substrates by electrodeposition in stabilized citrate baths. Electrodeposition experiments were performed at four different current densities. Increasing the current density resulted in the metal deposition rate increasing faster than the hydrogen evolution rate; thus, the cathodic current efficiency increased. The crystal systems of the Ni-Cu alloys were face center cubic (fcc), with the (111) plane as the preferred crystal plane. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) measurements showed that the Ni content in the coating increased with increasing current density. The Ni-Cu 40 sample had the most Ni content and showed a homogeneous and compact morphology. It was found that the higher the concentration of Ni in the solution, the smaller the grain size. Measurements recorded with a vibrating sample magnetometer (VSM) showed that the Ni-Cu 40 sample provided magnetic saturation, with the highest value being 0.108 emu/g. The microhardness method produced 404 HV on the Ni-Cu 40 sample. In conclusion, higher current densities were associated with a higher Ni composition and increased thickness, which were responsible for the increases in the magnetic properties and hardness.

In this research, polyvinyl alcohol (PVA)-chitosan composite films were produced using nanocellulose from coconut fibers (Cocos nucifera) in an Indonesian plantation in order to enhance mechanical properties and biodegradability. The process began by separating lignin and hemicellulose by delignification, bleaching, and then cellulose hydrolysis to produce nanocellulose. The PVA was mixed with chitosan with specific compositions and added the nanocellulose in 0%, 1%, 3%, and 5% concentrations, respectively. A tensile test was conducted to obtain tensile strength and elongation break. Biodegradability test was also carried out to determine the level of mass losses. Based on SEM observations, addition of nanocellulose appears to increase the reactivity of the formation of PVA-chitosan composite films, which are characterized by a reduction in film thickness. Addition of 5% nanocellulose resulted in a high quality of nano-composite. The tensile strength, fracture elongation and biodegradability of the composite film were 31.50 MPa, 39.9% and 9.04%, respectively.

The hardness and corrosion resistance of nickel (Ni) deposit on a substrate could be reached by controlling electrolyte temperature during deposition. In this research, the electrodeposition of Ni at various temperatures of electrolytes was performed. Electrodeposited Ni films using an optical digital camera, X-ray diffraction (XRD), scanning electron microscope with energy-dispersive x-ray spectroscopy (SEM-EDS), microhardness test, and potentiostat were investigated. The bright deposit occurred at 25 °C; an increase in the temperature to 40 °C leads to a change of color into semi-bright. Shifting to a higher temperature would increase the deposition rate, cathodic current efficiency, grain size, and oxygen content. The X-ray reflections in the planes (111), (200), and (220) correspond to as the Ni phase with a face center cubic (FCC) crystal structure. Decreasing crystallite size and micro-strain promoted to reach high hardness. Increasing the corrosion current density implies decreasing polarization resistance. The sample at the lowest electrolyte temperature has a better hardness, and the sample formed at 25 °C sulfate solution had less corrosion rate.

Enhance the surface hardness of materials usually conducted through a hardfacing technique. Hardfacing is popular, whereby materials with better properties are deposited over cheaper bulk material. This work fabricated hard layers by adding titanium (Ti) wire during the welding process. This research used low-carbon steel as the base material, wire optime Ti grade 1 for Ti addition, and an HV 600 electrode with a diameter of 3.2 mm for filler metal. A single-layer weld was conducted with SMAW (positive polarity and 90 A). The samples were directly quenched in a different solution after welding. The properties of the weld layer were examined phase, structure, microstructure, macrostructure, and hardness using optical emission spectroscopy (OES), x-ray diffraction (XRD), an optical microscope, a digital camera, and a hardness device, respectively. Adding titanium (Ti) to the weld layer and quenching the samples after welding in the solution enhances the hardness. This phenomenon is attributed to different phase compositions, oxides, and microstructures. A fine dispersion of small particles and oxide amount is important in increasing hardness. There is no cracking in the weld and base metal. In conclusion, samples BNTiO and BNTiM are recommended for lathe-cutting tools.