Abstract: A wear resistant ceramic coated aluminum alloy article. The article is made by a method including the steps of: a) immersing the article in an aqueous electrolyte containing from about 1.5 to about 2.5 grams per liter of alkali metal hydroxide and from about 6.5 to about 9.5 grams per liter of alkali metal silicate. No more than 1 g per liter of alkali metal pyrophosphate is present and no more than about 0.05 percent of hydrogen peroxide is present, and b) applying an alternating current through the electrolyte using the article as one electrode where a second electrode includes at least one of an electrically conductive container or an immersed separate electrode, where applied EMF is selected to provide a current density of from about 15 to about 25 A/dm2, for a sufficient time to obtain a wear resistant ceramic coating having a thickness of from about 125 to about 150 ?m.

Abstract: A wear resistant ceramic coated aluminum alloy article. The alloy preferably contains from about 85 to about 92 percent aluminum with a plurality of other oxidizable metals selected from copper, magnesium, zinc, and chromium. Less that about 2 percent total of other elements is usually present. In accordance with the invention, the alloy preferably contains less than 0.5 percent each of manganese, iron and silicon. An example of such an alloy is 7075 aluminum alloy. The article is made by a method including the steps of: a) immersing the article in an aqueous electrolyte containing from about 1.5 to about 2.5 grams per liter of alkali metal hydroxide and from about 6.5 to about 9.5 grams per liter of alkali metal silicate. In general no more than 1 g per liter of alkali metal pyrophosphate is present and no more than about 0.

Abstract: A method for forming a wear resistant ceramic coating on an aluminum alloy article. The alloy preferably contains from about 85 to about 92 percent aluminum with a plurality of other oxidizable metals selected from copper, magnesium, zinc, and chromium. Less that about 2 percent total of other elements is usually present. In accordance with the invention, the alloy preferably contains less than 0.5 percent each of manganese, iron and silicon. An example of such an alloy is 7075 aluminum alloy. The method includes the steps of: a) immersing the article in an aqueous electrolyte containing from about 1.5 to about 2.5 grams per liter of alkali metal hydroxide and from about 6.5 to about 9.5 grams per liter of alkali metal silicate. In general no more than 1 g per liter of alkali metal pyrophosphate is present and no more than about 0.