Steps of pretreatment process for nickel phosphorus plating
Today's small series for you to introduceNickelPhosphorus plating pretreatment process steps, want to know the friends together to follow the small series to see it.
1, mechanical oil removal and rust removal
Pre-use grinder to grind six sides, so that not only rust, but also can make the surface of the specimen flat, conducive to the specimen plating after the comparative analysis.
2, chemical oil removal
Chemical oil removal is the use of alkaline solution saponification and surfactant to non-saponification oil emulsification, remove all kinds of oil on the surface of the specimen. The temperature of chemical oil removal is usually taken between 60~80℃, the effect of oil removal of the specimen is generally visual, that is, the surface of the specimen can be completely wet by water is the complete removal of oil signs. The general oil removal liquid is composed of sodium hydroxide, sodium carbonate, phosphate, water glass, emulsifier and so on.
Although sodium silicate can play emulsification and dispersion, to help skim, but the specimen after skimming must be cleaned very thoroughly, otherwise after pickling will be due to residual sodium silicate and acid reaction to form insoluble silica gel, so that the coating produces speckle, affecting the bonding force. Therefore, the selection of surfactants with equal effect, but no side effects on the plating solution to replace sodium silicate. Surfactants to choose alkali-resistant, that is, in alkaline solution can be stable existence, you can choose non-ionic and anionic type or their combination. The surfactants applicable in alkaline solution are: NET lotion 6501, 6503, 664 and 12 sodium alkyl benzene sulfonate, etc.
If the oil removal is not thorough at one time, should be rinsed with water and then immersed in the oil removal solution, so repeated operation until the oil is removed. The standard of oil removal is the substrate surface to achieve a complete wetting state, can form a uniform water film, no hanging beads.
3. Pickling
Pickling solution formula: 1:1 Hydrochloric acid (volumetric ratio)
Process conditions: temperature: room temperature; time: 15-30 seconds
4. Activation
Activation is a surface that enables parts to be fully activated, and this acid etching is different for the acid used in parts of different materials. The activation of general steel parts can be carried out by 10% sulfuric acid or 1:1 hydrochloric acid, and the activation standard is generally to stop activation when small and uniform bubbles appear on the surface of the specimen.
Activation Solution formula: 10% sulfuric acid (volumetric ratio): ρ=1.84g/cm3
Process conditions: room temperature; time 10-20 seconds.
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Keyword:Nickel