| 摘要 |
PURPOSE:To shorten the hardening time of water glass as well as to improve reliability in pressure resistance, by applying acid treatment to a defective portion of die-casting parts upon impregnation with the water glass. CONSTITUTION:Aluminum die-casting parts are filled into a high pressure vessel 10 for impregnation use, and pressure inside the vessel is decompressed down to, for example, 4cm Hg over ten minutes long, then impregnation water glass having, for example, a temperature of 30 deg.C and a specific gravity of 1.38 is injected into the vessel from a tank 11 and pressurized for 15min at the pressure of, for example, 6kg/cm<2> while successively dipping treatment in a 4N- CH3COOH solution, by way of example, for 30min long is carried out for the defective part and finally washed in water. |
