The purpose of this work is to reveal the surface roughness and topography of AISI 316L stainless steel due to electropolishing processes. In this paper, AISI 316L was electropolished in various times of immersion and various voltage of the processes. The mechanism of electropolishing is eroding the surface of the substrate by controlling the electron excitation process. The electropolishing processes were carried out at 4, 5, and 6 minutes also in three different voltage 4, 6, and 8 volts. The results show that the surface roughness decrease as the treatment time and also as an increase in voltage.
The aim of this study is to investigate the characteristics of gas-non-Newtonian liquids flow patterns in square microchannels. The microchannels that used in this study was made by acrylic material with horizontal orientation and the side length of 8x10-4 m. Water, Air, Carboxymethyl Cellulose 0.2%wt (CMC 0.2%wt) aquoeus solution, and Xanthan Gum 0.2%wt (XG 0.2%wt) aquoeus solution were used in this study as the liquid test. Moreover, nitrogen gas was used as gas test. The liquid superficial velocity was varied of 0.1-1 m/s. Then, the gas superficial velocity variation of 0.26-7.8 m/s. The differential pressure transducer was used in this study to measure the pressure drop, which is occurs in square microchannels. Whereas, The flow patterns were recorded by using the high-speed camera. Furthermore the flow pattern video was analyzed by using image processing method to obtain the flow pattern charcteristics. The two-phase flow pressure drop of all gas-Newtonian/non-Newtonian liquids two-phase flows in this study increase by increasing JL in the same JG. The flow patterns that occur in this study are bubbly, slug, slug-annular and churn. The viscosity and rheological parameter of liquids test influenced the characteristic of flow patterns. The flow patterns in this study were plotted in the flow patterns map and suitable with the flow patterns transisiton lines based on the previous study. Likewise, the experimental pressure drop shows the good agreement with the pressure drop prediction correlation by Kawahara et al. (2011).
This study aimed to discover the effect of pressure and spraying angle to surface roughness and flatness of stainless steel SUS304 after the sandblasting process. In this study, the variation of the compressor pressure were 4, 5, and 6 bar, while spraying angles were 45°, 60° dan 90°. Silica sand was used as the abrasive particles, which is sprayed onto the specimen surface. The size of silica sand was 200-300 µm. While, the sprayer feedrate was 5 cm min−1 and the distance between nozzle and specimen surface was 15 cm. There were two of spraying methods, i.e., one side spraying and two sides spraying with the same pressure and spraying angle in both sides. Both spraying methods were conducted by using the support of DIY CNC equipment. The roughness test only conducted on the specimen with one side spraying. It gives the result of a higher spraying pressure increased the roughness value due to a bigger sand collision force and more sand mass that collide the surface. The sandblasting process was resulted the presence of compressive residual stress and surface elongation that caused the material become warp and producing a deflection angle. The deflection angle indicates the surface flatness quality of a material, where a smaller deflection angle means better quality of surface flatness and vice versa. Too big of a deflection angle requires a further process. This study analyzed the comparison of one side spraying and two sides spraying with the same spraying variables on both sides. It is discovered that two sides spraying produced a better surface flatness.
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