Chrome finish for abrasion resistance

Hi Sloppy Joe,

Nice name by the way.

We made a stainless part once that had the sole function to deflect galv metal parts (quite big and heavy) to go down a roller conveyor. We had it hard chromed and gave it no polish at all. I think that the slurry you are talking about will Polish the piece in no time so I would not waste any money on it.

The real issue is to use industrial hard chrome and not your average lustre chrome. When finished it should not look shiny at all as hard chrome tends to look dull ish.

If you decide to polish you would be better of to polish the original piece before chroming as that would have more effect on the final outcome than any polishing can have after wards. The better the starting piece the better the finish.

Thanks for the quick response! We do in fact use industrial hard chrome with a Rockwell between 60-65 at about .020" thickness. I agree that the slurry will polish the parts (and we have seen this). We have asked our part supplier and they assured us they prep the parts for chrome, to include polishing prior to being sent to the chromer.

I think we will experiment and have the parts sent with out being polished. The parts aren't polished to a mirror finish and do have a dull but very smooth finish.

Thanks again! Oh, and the name has a kind of funny story behind it haha....

Perhaps you should look into Conforma-Clad, It is a carbide coating that should wear much better than hard chrome.

As for the Conforma-Clad, carbide coating- I looked into a carbide coating about a year ago and the price went from $2,500 (chromed) to $6,000 (carbide coating). That would be ok if I could get 2.5+ times the life from the part but the manufacturer was skeptical and wouldn't back it up. But I'll check into the Conforma-Clad to see if it's different.

Thanks!

Or, for even better performance than cladding, you coud use HARDIDE (Google for UK or US processing centre). This process has been well proven to increase the life of components working 'down-hole' in oil-drilling slurry many-fold. Agree with earlier post about polishing.

Feel free to contact by email directly if you would like some more help.

I haven't heard of HARDIDE and will look it up to learn more (and may even shoot you an email). Anything that can withstand oil drilling must be pretty hard stuff.

Thanks for the response!

Hay slopppy------We use 5/8" Hardok 450 for wear componats in a rock crushers, you might wont to try it .

5/8" Hardock 450? Is that a type of metal?

We typically stick with 304 S.S. because it is in a wet environment and it won't rust, we chrome it to extend the life but I'm open to new ideas and materials.

Any thought to a ceramic component? Should get much improved life over the stainless/chrome version.

Typical rockwell hardness [GPa for 45N] in the upper 70s to lower 80s for Alumina & Zirconia

Well possibly a ceramic coating but there is always the potential for tramp metal to get into the machine. If this happens it would destroy a ceramic component and potentially cause more problems. Is ceramic that much more abrasion resistant that a chromed piece would be?

Ceramics are typically ideally suited to abrasive slurry situations - very stable and tough. Not knowing much about your application, I don't understand the comment about a tramp metal piece destroying the ceramic component - please provide more details.

Well this machine mixes slurry at 300rpm average at a rate of 75-150 tons per hour that is squeezed out through a 1/4" opening. If anything metal ie. a nut or bolt from a failure upstream gets into the machine it can't get out and can cause internal damage to the machine if it isn't shut down immediately. If there were ceramic pieces installed internally I would imagine that the tramp metal (nut or bolt) would shatter the piece causing more tramp (nuts, bolts and now ceramic chunks). But I am not overly familiar with ceramics being used in this capacity.

Sloppy Joe:

I would suggest taking a look at Kolsterising www.kolsterising.info as a solution. It is offered by Bodycote www.bodycote.com out of thier London, Ohio facility. Kolsterising is a diffusion treatment that creates a hardness to 68-70 HRc from the surface inwards. No dimensional change tot he component and ideal for slurry type applications as there is no chance of peeling, chipping or flaking of the layer.

If your going ceramic coatings take a looks at K-Tech, also offered by Bodycote. very robust chemically bonded ceramic coatings that bond to the substrate. They can beviewed at www.ceramiccoatings.com

I recommend either as a solution.

Thanks Bill, I will look into these and now I have three suggestions for a ceramic coating... so I am definately going to pursue that as well as the other suggestions.

try this:

c3international.com

The company above has developed a number of heat treat/ surface modifications for improvements in wear resistance and lubricity in industries ranging from cutting tools to die-casting with tool life increases up to 8000% in some cases.

Thanks Wily I'll check them out, sounds interesting.

Chrome will work, just make sure its HARD chrome. Remember hard chrome will have cracks in it, so if the base material is not corrosion resistant then the chrome will begin to flake and peel due to the corrosion (rust) underneath. If you decide to use a S.S. part and chrome it, that will work in the event of a corrosion problem, but you would be better served chroming over a hardened tool steel surface since the hardened surface would support the chrome layer better. Conforma-clad is not a coating but rather a mesh that contains a binder, matrix alloy (Ni-Cr-B-Si consider the corrosion thing again) and carbide particles, which is brazed on in a furnace using the self fluxing properties of the alloy. The problem here is that your part has to be able to tolerate the heat treatment without suffering from distortion or metallurgical changes. A thermal sprayed coating of tungsten carbide works very well against wear. I have studies that state it will out last hard chrome most of the time. This is not so when it comes to erosion. The coating and for that matter the conforma-clad product as well, will suffer from matrix erosion. If the abrasive particles and even their shape are equal size or smaller than the carbide particles in the coating, then they will remove the soft matrix allowing the carbides to fall out. I think your best bet would be to apply a plasma sprayed ceramic coating. This does not form a matrix and will offer much better abrasion resistance than chrome. Try chrome oxide .030" thick and use a 450 bond coat and troubles will be solved. What works here, is once the green color of the coating is gone you know then that you are into the base material.

All good stuff from NiCrMoNoMore, and these are some of the reasons why the 'down-hole' industry is more and more specifying HARDIDE - a special Tungsten diffusion process.

WOW that's some good stuff! You sound confident in the plasma sprayed ceramic coating. I'll be looking into the companies that IRDglass and BillM suggested, do you know of a company that you would suggest for the plasma sprayed ceramic coating?

Google Thermal spray job shop. Check ITSA international thermal spray association.