after pplication of a thin layer of aluminum, appropriate areas <br/> are etched away using an etchant consisting of a mixture of acids, <br/> which is primarily phosphoric acid, at orerating temperatures form <br/> 20-65 C. A typical aluminum etchant contains 85 parts of concentrated <br/> phosphoric acid, 12 parts of concentrated acetic acid, and 3 parts of <br/> concentrated nitric acid. <br/> "FC-93" added to a commercial aluminum etchant at 100 ppm active <br/> aolids reduced the surface tension form 63.5 dynes/cm to 21.0 dynes/c, <br/> at 65 C.
walnut hulls were found to be the best abrasive for cleanjing <br/> aluminum surfaces prior to painting. samples vlasted with walnut hulls <br/> showed no compressive stress of the surface.samples blasted with <br/> abrasives such as silicon carbide, silica sand, or garnet showed <br/> average compressive stresses of 23.6-33.1 ksi walnut-hull blasting <br/> resulted in the amount of warepage and gave the smoothest surface. <br/> the puality of the repainted surfaces was very similar to a first-time <br/> painted surface. when purchased in quantity, walnut hulls were the <br/> least expensive abrasive.
polishesare generally used to restore the original luster and <br/> finish of a smooth surface. they are also expected to clean the <br/> sudrface and to prevent corrosion or deterioration. there is no one <br/> polish which will give good reeults on all surdfaces. <br/> most polishes contain oil or wax for their lusteruing or polishing <br/> properties. oil polishes are easy to apply, but the surfaces on which <br/> they are used attracy dust and show finger marks. wax polishes are <br/> more eiffictlt to apply, but are more lasting. <br/> oil or wax polishes are of two types: waterless and aqueous. the <br/> former are clear or translucent, the latter are milky in appearance. <br/> for uae on metals, abrasives of various kinds, such as tripoli, silica <br/> dust, ors infusiruak earth, are incorporated to grind away oxide films <br/> or corrosion products.
地址：山东省烟台市开发区南昌大街48号
