powder metallurgy P/M hole sealing processing steps

P/M hole sealing processing steps

In the manufacturing process of die-casting and powder metallurgy parts, due to gas residue, crystal shrinkage and other reasons, the leakage of many micropores, sand lines, cracks and micropores inevitably brings danger to the use of mechanical equipment, so we must seal the holes. So what are the processing steps of powder metallurgy hole sealing? ABCDPrecise Powder Metallurgy Sharing:

1. Passivation liquid filling method

Immerse the powder metallurgy parts in the weight of solution prepared by 2g/L potassium dichromate, 2g/L baking soda and water, and fill the passivation solution into the weight of pores. The temperature of passivation solution is 70-80 ℃. After electroplating, the method of heating the parts at 100-110 ℃ and discharging the passivation solution from the void through evaporation of void water is applicable to galvanizing.

2. Organic silicide sealing method

The powder metallurgy parts are immersed in carbon tetrachloride solution containing 4% organic silicide. After the parts are preheated to 200 ℃, they are suddenly immersed in the above solution. After soaking, dry at 200 ℃. Therefore, organic silicide film can be formed on the surface of powder metallurgy parts to prevent the intrusion of plating solution. The method is satisfactory for nickel and cadmium plating.

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3. Mechanical sealing method

Powder metallurgy parts still have a large amount of finishing allowance, and the clearance on the surface is blocked by finishing. Other mechanical methods can also be used to deform the surface and block the gaps such as sand blasting, polishing and polishing.

4. Fixed material plugging method

Immerse the powder metallurgy parts in molten zinc stearate at 200 ℃, soak the pores and seal the pores. After immersion, remove the surplus zinc stearate on the surface and conduct electroplating. Impregnating resin and high softening point paraffin in vacuum is also a simple method.

5. Steam treatment

Steam treatment can form Fe3O4 oxide film on the surface of P/M parts and block the surface voids. Fe3O4 is a compact semiconductor that does not interfere with electroplating. Steam treated P/M parts need not be cleaned before electroplating.

These are the processing steps of powder metallurgy hole sealing. I hope that we can have a better understanding of the process of powder metallurgy hole sealing. If there is a need for powder metallurgy, please call zhongwei Precision.