thermal spray coating for Galvalume tank

[horsecheng]

Dear All :
I am currently having a problem in find the suitable thermal spray coating for the hot-dip Galvalume ( 55%Al-Zn) tank. Since the erosion of the aluminum on the cobalt in the sprayed WC-12% Co, which resulted in rather short life span of the coating. Any suggestions on the viable coating material and spraying method will be highly appreciated.
Horsecheng, Taiwan

[Gordon]

Hi Horsecheng

to the Surface Engineering Forum.

Plasma sprayed aluminium oxide ceramic coatings. Most metallic coatings will suffer attack from molten aluminium.

[horsecheng]

Dear Mr. Gordon :
Thank you very much for your reply. Would the aluminum oxide be too brittle due to differences in thermal expansion between the coating and substrate material ( stainless steel ) ? Best regards. Horsecheng

[Gordon]

Hi Horsecheng

Yes, oxide ceramic coatings will by nature be more brittle and less mechanically durable than metallic based coatings. I think it is something you will have test for your specific application.

[djewell]

My company has had excellent preliminary success using a molybdenum boride coating applied via AC-HVAF on galvalume sink rolls. So far, the rolls have outlasted the WC-Co coatings, but the tests are not complete yet. The molybdenum boride is not attacked by the liquid metal, and dross does not stick to it. You can contact me off-line for more information.

[Gordon]

Hi djewell

Molybdenum boride coating sound interesting. Can you keep us updated on progress of your tests?

[horsecheng]

(09-08-2009 07:13 PM)djewell Wrote:  My company has had excellent preliminary success using a molybdenum boride coating applied via AC-HVAF on galvalume sink rolls. So far, the rolls have outlasted the WC-Co coatings, but the tests are not complete yet. The molybdenum boride is not attacked by the liquid metal, and dross does not stick to it. You can contact me off-line for more information.

Dear Djewell :
Thank you very much for the suggestion, I will try it and let all the interested parties to know the results. Best regards. Horsecheng

[ramkiyengar]

Please read the article in the August 2010 issue of Iron and Steel Technology on "A Novel Thermal Spray Coating for Galvanizing Rolls". You can contact the authors for more information.

[loriolo]

Hi Horsecheng
First the sinc-rolls were copper coated and after this they applied a chrome plating coating, sometimes they used a molybdenum coating, but, lately application is a chrome carbide coating with a special anti sticking sealing, and on the bearing is applied a hard fused coating