This study was evaluated by changing the mass loss ratio and the strength maintenance ratios of the fibers after treatment. The fibers were treated with sodium hydroxide and hydrochloric acid solutions for different amount of times. The environmental resistance was analyzed by changing the time of treatment in NaOH and HCl solutions. The fibers’ surface corrosion morphologies were analyzed using the optical microscope. The acid resistance was much better than the alkali resistance for the basalt and slag fibers. Nevertheless, the situation for the glass fibers was different: the acid resistance was almost the same as the alkali resistance. Between the two types of aqueous environments evaluated, the alkali solution is the most aggressive to the fibers’ surface.
:This study intends to study about the blade performance loss occurred due to the variation in the shape of airfoil from the attachment/non-attachment of blade erosion shield for hovercraft. This study model has used NACA 4412, has designed NACA 4412 by using Auto CAD and designed the shape that has attached an erosion shield to this model according to the thickness and length. By using these models, we have generated a grid by using GAMBIT and calculated the lift coefficient (Cl) and drag coefficient (Cd) by using the FLUENT code for flow analysis. Through this, we have calculated and compared the lift-to-drag ratio that is an indicator of airfoil performance according to the shape and attachment/non-attachment of erosion shield.
In this study, supercritical nano plating was performed to observe its effect on materials. Using supercritical carbon dioxide as a solvent, we observed how different pressures and temperatures of the supercritical fluid affected the process and its outcome. The plating current increases as pressure increases from 8 MPa to 16 MPa, but it decreases after that. Similarly, the plating current increases as temperature is increased from 35 ℃ to 45 ℃, but the current decreases after that. Also, the thickness of the wet electrolyte plating is about 35~50 ㎛, while the thickness of the plating done using supercritical fluid is about 20~25 ㎛. At the results, It to it is considered that supercritical nano plating enable to form more thin and stable plating than wet electroplating methods. Also both of the electroplating methods could be affected plating quality by surface condition, and the supercritical nano plating has been confirmed to product more uniform plating surface than wet electroplating.
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