The condition is both the mating parts are hardened steel and the requirement is to increase dry static coefficient of friction, as the hardened steel to steel contact coefficient of friction is not sufficient. Could you suggest the suitable process with material to increase the coefficient of friction by the coating process?
Dear Prabhakar - it depends quite some on the type of interaction that the parts are designed to experience.
Can you provide a bit more of a description for the complete interaction.
Regards
-Jack
Hi,
I would guess that SiC PVD coating could do a good job.
Best wishes
Sten
@ Sten
Dear Sten, I wasn't aware you could increase coefficient of friction with SiC PVD coating; is the increased mu due to an increase in surface roughness?
How does it perform vs deformation and rolling/sliding contact?
I'm super interested, because I've been looking for a way to increase mu for a friction drive, without sacrificing wear and ultimate load capacity.
Any good papers on the topic?
Dear Dr Jack Schorsc,
The problem I am working on is a type of frictional clamp, When the pneumatic force is applied the clamp has to but against the steel plate in stationary part and hold the part in a fixture.The advantage is the position will be reached and then only commend is given to cylinder for clamping therefore negligible heat will be generated
Fa ( axial force) is generated by pneumatic pressure which is considered as 5 bar in constant area (therefore force cannot be varied) is one limitation
i (number of friction surface is 1) is another limitation one surface is of hardened steel and another is of steel
Td ( Transmit torque) expected to be maximum as possible
rm (mean radius) can be varied by varying the contact area (b)
Kindly provide your valuable input, image of similar problem attached, suggest the suitable process with material to increase the coefficient of friction by the coating process
Regards
Prabhakar Purushothaman
Dear Prabhakar,
How high are you looking for a friction coefficient?
Generally, you can increase the frcition by increasing the roughness of the material. It can be done by coating or also by a abrasive process.
In case of coating I would suggest a coanting doped with diamond crystal. The diamond crystals around 500 nm particles. They will increase the roughness of the surface, as well as, the friction.
Regards,
Romina
Dear Dr. Romina Costa
My expectation is above 0.5 can you suggest any process for diamond crystal coating? should it be coated on single surface or both?
Regards
Dear Mr. Prabhakar,
In principle is difficult to say if both parts should be coated or not. So anyway 2 experiments would be necessary. Basically I talk about a carbon coating doped with diamond nanoparticles by PECVD Technology. Currently the friction coefficient is around 0.2 when the coating is doped with 500 nm diamond particles. However i believe that the friction can be increased in case bigger particles are used.
I am not responsible for such coating. More details you can have with Dr. Fernanda Roberta Marciano. I am sure she can help you.
Regards,
Romina Costa
Article Influence of crystalline diamond nanoparticles on diamond-li...
Dear Prabhakar,
There are going to be several mechanisms you can get better friction with;
You have the option of increasing surface roughness, as suggested by Romina, but simple surface roughing will wear quickly if you have large loads and slip during loading.
Alternatively, you can go the other direction, and go to extreme surface finish, and rely on a thin film & molecular adhesion process. This will be much fussier in terms of production and tuning, but potentially can give really nice results.
Most of the surface treatments increase friction via mechanical means; and for this there are pretty wide range of options. the right choice is going to be a combination of increased friction vs wear properties.
A sintered steel coating gives a reasonable increase in friction, and is very long wearing, it's also pretty straightforwards to manufacture.
Aramid or PAN composite bonded to the surface gives a very good increase in frictive properties, but comes at a fairly high wear rate.
I don't know, off the top of my head, what the wear characteristics of diamond doping or SiC PVD treatment looks like.
Dear Dr. Romina Costa & Mr. Jack Schorsch
Thanks for sharing your knowledge
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