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No adhesion of phosphatizing to ground surface

17 mm dia steel(EN8M) component after heat treatment we do OD grinding and the surface has mirror finish.(.2 Ra). When we subject this to phosphating process there is no adhesion on the smooth surface.Could you suggest a solution?On areas where the surface is rough there is good adhesion.

Ganesh.J
auto components manufacturing - Chennai, Tamil Nadu, India
2004

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No adhesion of what? What type of phosphate treatment are you using? Possibly what you are seeing is a lack of anodic sites forming during the phosphate process, leading to less formation of coating. There is most likely some coating there, but obviously not enough. Depending on the final use of these parts this may be OK. If you need more coating in these areas you'll have to change something. More time in the phosphate, Lower pH in the phosphate, acid pickle step ahead of phosphate, and less smoothness in the area are all things that would improve coating weight. Be careful though, everything you do to this area will also happen to the rest of the part, higher coating weights may not be good for overall quality.

Jeff Watson
- Pearland, Texas
2004