The use of aluminum metal in daily life has widely used coloring techniques to enhance the aesthetic value of the metal. Aluminum anodizing process can produce porous on the metal surface. The formed porous can be used to store and hold the coloring agent to make them more durable. The research intends to observe the coloring characteristics on the aluminum surface influenced by several parameters of the anodizing process, including electrolyte concentration and electric current. In this study the current H2SO4 concentration was used as a variable to improve the quality of staining on anodized aluminum surfaces. The anodization process was carried out on H2SO4 electrolyte solution with variations in concentrations of 10% to 20% and the current density used was 3 A to 5 A. The tests were carried out using micro Vickers to observe the hardness value. The hardness was higher at lower concentration of electrolyte solution due to thinner layer of oxide film, scanning electron microscope to observe the structure and visual observations for anodized color quality. From the results given, the tendency of the lower current density the size and density of porous lower. With the same condition, the color was darker than higher current density.

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Macrosegregation occurs in casting the most case is as a result of slow interdendritic flow due to shrinkage geometry, solid deformation or gravity. In some cases could be the result of solid movement in the early stages of solidification[1]. The problem is that the observation of macrosegregation in steel material is not easy because of high temperature condition. This recent work uses low melting temperature material alloy to simulate the actual condition as a model material. Various efforts to prevent macrosegregation are aimed to control liquid flow and movement of solid, one of them is by cooling rate controling. In this experiment the mold is cooled in three types of cooling medias to represent three different cooling conditions in order to observe the influence of cooling rate on macrosegregation during solidification of the alloy. The outer part close to the mold wall and the bottom of casting contains less solute than inner location. This occurs in all cooling conditions but cooling rate can cause the solute in casting distributed differently. At high cooling rate condition, distribution of Bi rich grain is more uniform. It is mean that macrosegregation is reduced. Bi-richer grains accumulate at the bottom of the ingot. It could be caused by those grains settle due to their relative density to surrounding liquid during solidification.

The use of aluminium metal in daily life has widely used colouring techniques to enhance the aesthetic value of the metal. Aluminium anodizing process can produce porous on the metal surface. The formed porous can be used to store and hold the colouring agent to make them more durable. The research intends to observe the colouring characteristics on the aluminium surface influenced by several parameters of the anodizing process, including electrolyte concentration and electric current. In this study the current H2SO4 concentration was used as a variable to improve the quality of staining on anodised aluminium surfaces. The anodization process was carried out on H2SO4 electrolyte solution with variations in concentrations of 10% to 20% and the current density used was 3 A to 5 A. The tests were carried out using micro Vickers to observe the hardness value. The hardness was higher at lower concentration of electrolyte solution due to thinner layer of oxide film, scanning electron microscope to observe the structure and visual observations for anodised colour quality. From the results given, the tendency of the lower current density the size and density of porous lower. With the same condition, the colour was darker than higher current density.