HVOF or Wire Arc

[Noviandy]

Dear All,

I wish your help. I have a backwash pump which operate in seawater. I would like to repair shaft of the pump. But i have no idea which one is the best solution, HVOF or Wire Arc. For your information, material of the shaft is SUS316. How about result hardness for this case? It shall be same with base material (SUS 316) or harder? Thanks!

Regards,

Andy

[Gordon]

Hi Andy

to the Surface Engineering Forum.

Your question is not that easy to answer with the information given. Basically, I assume firstly you need to restore shafts dimensions and finish. How much coating thickness is required? How is it to be finish, turning or grinding?

What coating material or materials? Now it is natural to think rebuild shaft back to its original state say using 316 stainless steel, which could be a good option, but it must be understood that a 316 s/s coating is not the same as a bulk wrought 316 s/s, physical, metallurgical and chemical properties can be very different due to the thermal spray process. Fortunately, thermal spray can be used to apply a vast range of different materials, so this is not a limiting factor. In fact, it may well be possible with good coating selection, to rebuilt the shaft so that it will perform/live better than the original.

Hardness of the coating really should be dictated by what it is running against, rather than the original surface or substrate, which may not have been optimal anyway.

HVOF coatings will generally be technically superior to arc spray, but not necessarily better or the best in your case. Are you limited to HVOF and arc? as other thermal spray processes could also be considered.

As you can probably tell my knowledge of coatings may be good, but my knowledge on backwash pump shafts is not so I hope some of our other members may be able to help with more specific experience.

[Intel55]

I vote for twin wire arc cheaper and good.