Brass bar hard coating

[HilaryE]

Hi,

I have the brass component (overall size 50mmx50mm1000mm). Brass is CZ121.
This brass component has hundreds of through holes of diameter 0.3mm each and 2.4mm deep.

I need to cover this brass component with hard and low-abrasive protective coating (thickness approx. 10microns) that has to be evenly distributed also inside those deep (2.4mm) and tiny (0.3mm diam.) holes (blockage of the hole with coating material is not acceptable).
The working temperature of this brass component is approx. 230degC.

The best technique that I have identified so far is the electroless nickel plating. It can provide relatively thin, hard, low-abrasive, 4-6um thick coating.
CZ121 has 100-160HV whereas electroless nickel plating hardness starts from 600HV.

Would there be any another technology?

Thank you.
Regards

 

[btrueblood]

HilaryE, I think you have found the best choice. Other coatings I can think of are either electro-platings (e.g. hard chrome) or spray-applied (HVOF or plasma) ceramics; neither type will reliably coat those i.d.'s

 

[HilaryE]

@btrueblood, Thank you for your response.

 

[tbuelna]

HilaryE,

If cost is not a big concern there are proprietary DLC coatings that are very hard (>1500 HV), corrosion resistant, can be applied to a thickness around 10 micron, and can coat inside holes with an L/D up to 15. The particular process linked is also fairly low temperature (<200degC), so would be suitable for your base material.

Hope that helps.

 

[HilaryE]

@tbuelna - thank you for this info. I will read about this technology. It looks very promising.