tungsten carbide vs high chromium

[Gem1]

Hi All,

I'm looking into options for arc spray coating materials on a grey cast iron component. Currently a Ni-5Al coating layer is applied, followed by a high chromium alloy coating. The component is exposed to dry coal and possibly some direct metal to metal contact.

I'm wondering if a tungsten carbide coating layer would give better wear protection than the high chrome alloy (which is prorpietary, but I'm assuming is a strain transformation stainless alloy)

Consumable suppliers have told me that the particulate exposure can remove tungsten carbide particles from the matrix, but is this really a concern with coal?

Thanks

 

[gr2vessels]

The coal is soft, but the sand content is hard. If exposed to dry coal means high velocity pulverised coal transport, that is highly erosive. If the exposure is static contact in a storage or conveyor / chute environment, then you can expect some erosion, but not significant. However, a continuous exposure in a feeding chute will produce some higher erosion than the static one. The carbides are brittle and can be removed by sand bombardment, say during the pneumatic transport of the dry pulverised coal from the mill to the burner. The rate can reach a staggering 25 mm/year, but that's rare, more like 5-10 mm/year. For static applications, 1 mm/year is a high rate, more like 0.5 mm/year in normal applications.
Cheers,
gr2vessels

 

[Gem1]

Thanks for your help gr2vessels.