| 摘要 |
PURPOSE:To improve the durability of a diaphragm, for speaker, by forming a film due to chemical conversion treatment on tne surface of a substrate of Mg or its alloy and ensuring an anticorrosive effect by said film. CONSTITUTION:A diaphragm obtained by the press-working of Mg-Al alloy is dipped into an aqueous solution of 30g/l NaOH for instance to remove the fat and oil on the surface of the diaphragm. The diaphragm is washed by the water and then dipped into the 2% nitric acid solution for 1-2sec to active the surface. After this, the diaphragm is dipped while being swung, into aqueous mixed solution containing 11cc/l HNO3, 72.5g/l NaH2PO4 and 15g/l H2SeO3 respectively; swung in the static water and then washed by the flowing water. Then the diaphragm is dried at 70 deg.C and about 20min. Thus the oxidation of the diaphragm is prevented by the chemical conversion-treated film to increase the durability. |
