ã€China Aluminum Network】 1. Process Gasoline or Trichloroethylene Degreasing → Drying → Drying → Cooling → Upper Fixture → Weak Alkali Corrosion → Warm Water Washing → Washing in Running Water → Nitric Acid Immersion → Washing in Clean Water → Cleaning in Running Water → Zinc immersion → Zinc plating → Washing with running water → Washing with water → Chrome plating → Washing in the recovery tank → Washing → Lower jig → Washing → Washing with hot water → Drying → Cooling → Self test. 2. Main recipes and processing conditions of pretreatment (1) Weak alkali corrosion trisodium phosphate (Na3PO4) 25~30g/L Sodium carbonate (Na2CO3) 25~30g/L Additive 2~4g/L OP-10 emulsifier 0.5~1ml/L T75~85°C T40~60s (2) Acid etching solution nitric acid (HNO3) 400~500ml/L Water balance T room temperature t30~60s 3. Zinc dipping solution formula and process conditions Zinc oxide (ZnO) 55~60g/L Sodium hydroxide (NaOH) 300~325g/L Ferric chloride (FeCl3·6H2O) 1.0~1.2g/L Potassium sodium tartrate (KNaC4H4O6·4H2O) 40~50g/L Sodium nitrate 0.5~1g/L T30~37°C T40~60s Note: After the aluminum parts are immersed in zinc, electroplating is performed in the solution with 0.8~1.2A/dm2 current. The time is 1~2min and the effect is good. 4. Hard chromium plating solution formula and process conditions CrO3 250~260g/L Sulfuric acid (H2SO4:d=1.84)2.5~2.6g/L Trivalent chromium (Cr2O3) 2~4g/L CrO3: SO42-100: 0.9~1.05 T52°C DK25~35A/dm2 V6~8V t depending on the thickness needs