TUNGSTEN CARBIDE COATING 1

[pumpguykc]

I have been doing some research on coating tungsten carbide. I have some applications that we will be supplying equipment into. If I coat the equipment I have a choice of Stainless Steel or High Carbon Steel. I have been doing some research on which would be better. Can anyone tell me if there is an advantage of coating TC onto CS vs SST?

Thank you

 

[TerryR1]

Fwiw, we use chrome plated stainless steel, due to the porosity of the chrome plating. Carbon steel base would rust in our applications. I have not used TC before, but apparently porosity is a factor.

http://www.carbidetechnologies.com/questions.php

 

[KENAT]

Um, how about some vague idea of what applications or what the requirements are or something.

Plus can I confirm you are looking to coat mystery Carbon Steel or Stainless Steel parts with Tungsten Carbide - in your post you talk about doing the opposite as well.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[pumpguykc]

The application is for a screw auger transferring a sludge off of an industrial application. The manufacturer has what they are calling a High Carbon Steel (trying to gather more data on it) and a stainless auger. The application has abrasives in it. We work a lot with tungsten carbide in many pieces of equipment but not as a coating. What I am hoping to understand is will the tungsten have better adherence to carbon steel or stainless steel.

 

[MikeHalloran]

I am confused. That is not unusual.

AFAIK, Tungsten Carbide is actually a fine powder, mixed and sintered into a solid in a metallic matrix like cobalt, if memory serves.

I am aware that it can also be flame-sprayed onto steel or stainless, producing a rough, abrasive, and abrasion resistant coating whose thickness is typically much more than a few mils and whose thickness is difficult to control. (I am told that a friend of a friend had his cloth-covered 3-ring binder flame sprayed with WC, and it wore through three pairs of jeans before he realized what was going on.)

There is a more common coating for ferrous metals, TiN, which does not stand for the element tin, but for the compound titanium nitride. It is commonly applied to cutting tools for abrasion resistance, and commonly arrives in a shiny golden color. Perhaps you were thinking of TiN. ... or perhaps you should.



Mike Halloran
Pembroke Pines, FL, USA

 

[pumpguykc]

Mike thank you for the feedback. Yes this is not unusual for coatings. The augers are available manufactured in Stainless Steel or Carbon Steel the coating they have available to apply to these augers is Tungsten Carbide. What I am hoping to understand is which is better to have TC applied to. I wondering if there would be issues with the TC flaking off of the SS vs CS.

 

[MintJulep]

In general, stainless steel is difficult to get anything to stick to it really well because of the passive film that spontaneously forms on the surface.

To get things to stick really well requires that the surface be activated. Typically this requires etching the surface by submerging it or flooding it in a witch's brew of acids. Then washing in distilled water. Then you have a relatively short time to apply your coating before the passive film starts to develop again.

What that often means is that a small flat coupon sample prepared in a laboratory performs brilliantly. Passing all imaginable tests.

Then production parts fail miserably.

Carbon steel is much more forgiving, although not immune too production screw ups.

So what this really means is that you have to do your homework. Understand your application. Your loads. Your stresses. Your parts.

Test real parts, make to real production quality levels, under real conditions.

 

[tomwalz]

Can you talk to the auger supplier and maybe even some of their customers?

Coating with WC (Tungsten Carbide) as a flame sprayed material leaves WC grains in some sort of a matrix, maybe a Stellite(c) or similar. This is very common on dirt moving equipment (The crude lines and /or cross hatching you see on some buckets and blades is one example.)

Lots and lots of variables all the way through.



Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[tbuelna]

If the sludge mixture will cause corrosion of a carbon steel substrate, then stainless steel might be a better choice. If the WC coating wears thru or chips, then the substrate material will be exposed to whatever the slurry is composed of.

With a component like a screw auger that has complex surface geometry, it can also be difficult to get good adhesion and uniform coating thickness over the entire part surface with flame spray or D-gun.