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AssigneeDaimler-Benz Aktiengesellschaft
InventorsWilfried Rauchle, Walter Preisendanz, Leonhard Scholtissek
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A process for exposing silicon crystals on the surface of an aluminum alloy of high silicon content and with undissolved silicon particles, wherein the aluminum alloy is connected as the cathode in an electrolyte containing an aqueous alkali nitrate solution which is at least 0.01 molar with respect to the nitrate ions and is subjected to electrolysis with a minimum current density of 0.5 A/dm.sup.2 to remove aluminum from the alloy surface without removing silicon crystals. The electrolyte can also contain at least 0.005 mol/l fluoride ions and 0.05 mol/l-14 mol/l nitrite ions to suppress generation of hydrogen at the cathode and oxygen at the anode, respectively.
Process for exposing the silicon crystals on the surface of a component of an aluminum alloy containing 6-20% by weight of silicon and with undissolved silicon particles, by removing aluminum on the alloy surface with the use of electric current, characterized in that the surface is connected as the cathode and is subjected to an electrolysis with a minimum current density of 0.5 A/dm.sup.2 in an electrolyte containing an aqueous alkali nitrate solution which is at least 0.01-molar with respect to the nitrate ions.
Dependencies are inferred from the claim text.