A customer inquired that the use of chemical nickel additives in powder metallurgy parts can cause many problems in the surface treatment process due to the unique structure of the workpiece. So, what would be the better pre-treatment process for these powder metallurgy parts?
Based on on-site experience and the characteristics of the product chemical nickel additive Ni-809, Bigley Technology conducted an analysis. Generally, powder metallurgy parts cannot use sand blowing for rust removal. Although the surface after sand blowing will be relatively smooth, the sand powder will penetrate into the pores of the workpiece. During chemical nickel plating, these sand films will escape and adhere to the surface of the workpiece, thereby affecting the quality of the chemical nickel layer. So, the pre-treatment process of the workpiece mainly includes the following five processes:
1. Bake oil. The drying oil temperature should be controlled between 250~300 ℃ until the oil fumes are completely removed. Drying oil is one of the key processes for electroless nickel plating on workpieces, which greatly promotes subsequent oil and rust removal.
2. Chemical degreasing. Chemical degreasing can remove oil stains from the surface of the workpiece. If chemical degreasing powder T-19 is used, the concentration is 60-90g/L, the temperature is 60-80 ℃, and the degreasing time is controlled within 1-6 minutes.
3. Electrolytic degreasing. Electrolytic oil removal can further reduce oil stains that penetrate into the holes and gaps of the workpiece. If electrolytic degreasing powder T-20 is used, the concentration is 60-90g/L, the temperature is 60-80 ℃, the electrolysis current is 3-6A/dm2, and the degreasing time is 0.5-2 minutes.
4. Hot water washing. The temperature of hot water washing should be controlled above 85 ℃, which is higher than the temperature of hot water washing for surface treatment of general materials. It is beneficial for cleaning alkali, soap, and dirt that penetrate into the workpiece hole.
5. Rust removal activation. Use acid salt activator BC-629, with a concentration of 30-240g/L, at room temperature, and the activation time should be controlled within 1-3 minutes. The activation time should not be too long, and the workpiece should be thoroughly cleaned to avoid the phenomenon of coating blooming.
Therefore, when using chemical nickel additives in powder metallurgy parts, in order to ensure the good quality of the workpiece coating, the above five pre-treatment processes can be followed for treatment. If you are interested in chemical nickel additives, please contact Bigley customer service for free samples and detailed technical information!
If you want to learn more about chemical nickel, you can click to view the "Electroplating Encyclopedia".