METHOD FOR ETCHING CYLINDER MADE OF ALUMINUM ALLOY

摘要

PURPOSE:To etch uniformly the Al matrix of a cylinder and to improve the wear resistance by etching the inner wall of the cylinder with an aqueous soln. contg. prescribed percentages of NaOH and H2O2 to expose Si particles and by carrying out etching further with an aqueous soln. of HNO3 having a prescribed concn. CONSTITUTION:The inner wall of a cylinder made of an Al alloy contg. Si is polished, and the Al matrix of the inner wall is etched with an aqueous soln. contg. 5-10wt% NaOH and 0.05-0.35wt% H2O2. The etched inner wall is washed with water to expose Si particles, and the surfaces of the exposed Si particles are made smooth by etching with an aqueous soln. contg. 3-7wt% HNO3.