Tungsten Carbide HVOF Removal

[PrecisionCarbide]

I have been trying to find additional information on the removal of an HVOF tungsten carbide coating on steel using a salt solution. I have read that it must have 6V DC and 4-8 amps per sq in. Our parts are fairly large, over 5m, and have a diameter of about 15cm. Based on the information that has been posted, that would require a lot of amps and might result in the part getting quite hot. Does this sound right? Has anyone seen etching on the steel base material when using this type of stripping for HVOF?

[remistudio]

Development of Pulse Water Strip of Tungsten Carbide HVOF Coatings and Chrome…

[PrecisionCarbide]

Development of Pulse Water Strip of Tungsten Carbide HVOF Coatings and Chrome…

I like the idea of the water pulse, but I am trying to get our current setup to work. If we run into heat issues with the parts due to the high amps, water pulse might be the only option.
I hope to hear something on the salt solution from the members here.

[djewell]

Heat is generated by the electrical current, but that is helpful. The etching works best at a temperature above 120F. Some people even put heaters into their etching tanks to keep the temperature high.

[remistudio]

What we have done to remove the HVOF is just grind it off with the same grinding stones as used to grind the HVOF layer initially to it's roughness requirements.

[J.L.]

I have been trying to find additional information on the removal of an HVOF tungsten carbide coating on steel using a salt solution. I have read that it must have 6V DC and 4-8 amps per sq in. Our parts are fairly large, over 5m, and have a diameter of about 15cm. Based on the information that has been posted, that would require a lot of amps and might result in the part getting quite hot. Does this sound right? Has anyone seen etching on the steel base material when using this type of stripping for HVOF?

Hello! I am new in this forum.

I am working in a method of stripping to HVOF toungsten carbide coating on steel too. We are using Rochelle salt and Sodium Carbonate solution. Our pieces are not so bigs, but we need a lot of amps too.And if you do not masking well the areas that haven´t got tungsten carbide the salt solution etch the surface.

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To remove HVOF Tungsten Carbide coating we use Rochelle Salt solution. We operate at 140ºF and we have 200L of these solution in a tank.After we have removed the coating and we turn off the machine. Can we stop heating the solution?
I think that Rochelle salt may precipitate, Is it possible?

[djewell]

You can turn off the heaters. It is not likely that the rochelle salts will precipitate. If they do, as soon as you stir the solution, they will re-dissolve.

[J.L.]

You can turn off the heaters. It is not likely that the rochelle salts will precipitate. If they do, as soon as you stir the solution, they will re-dissolve.

Thank you Djewell for your answer, it is very useful

[J.L.]

Good moorning

To measure the concentration of a Rochelle Salt-Sodium Carbonate solution we send our samples to a laboratory.
Do someone know an easy method to titrate the rochelle salt concentration? Or how can we control the composition of the solution in our factory?

Thanks
J.L.

[Packiaraj Mutharasu]

I made similar test with phosphoric acid 85% and applied 6V current in reverse polarity (Job as Anode and SS strip as cathode). With this one i got a positive results on TC coated test coupons.