Surface contact stress limit over an HVOF coating

[HVoilF]

Hello everybody,our costumer Dresser Rand in Venezuela is dynamically balancing some HVOF repaired compressor shafts and they use to support the shaft(in the coating area) over roller bearings that works on the oscillating supports that reads the unbalances forces. So the problem is that the HVOF sprayed Colmonoy 88 coating (Ni Cr B Si W) works directly in contact with the external roller bearing track,finding a high contact stress over the coating. I guess if this balancing practice is common in the industry or if some alternative solution should be taken in order to avoid the coating spalling damage for the high contact stress found. Maybe a sleeve installed over the coating just for the shaft balancing,to be later rejected? Or a very high tough coating as an HVOF Tungsten Carbide would work without suffering any surface damage? Please some suggestion from somebody with a similar experience on this application is needed and really wellcomed !!! Thanks

[djewell]

I have customers doing similar work with hard stainless steel coatings. They apply their coatings with HVAF because HVOF coatings fail due to the high contact pressure.