yyh020635 Posted September 3, 2014 Posted September 3, 2014 Teflon(polytetrafluoroethene) is an organic material for non-sticky pan coating. As we know, Teflon is a material with very low coefficient of friction. So during the production, how do producers coat such a low-friction material on metal? Why does Teflon have so low coefficient of friction in terms of its structure? Please help! Thank you so much!
Endy0816 Posted September 3, 2014 Posted September 3, 2014 High temperature ovens are used. Not sure what the answer is to your question about friction for a polymer. http://www2.dupont.com/Teflon/en_US/products/safety/how_its_made.html
fiveworlds Posted September 3, 2014 Posted September 3, 2014 (edited) Why does Teflon have so low coefficient of friction in terms of its structure? PTFE is a self-lubricating material http://en.wikipedia.org/wiki/Lubricant The coefficient of friction of plastics is usually measured against polished steel The coefficient of friction (COF), often symbolized by the Greek letter µ, is a dimensionless scalar value which describes the ratio of the force of friction between two bodies and the force pressing them together. Or effectively how much force does it take to pull a weight http://www.engineeringtoolbox.com/friction-coefficients-d_778.html PTFE's resistance to van der Waals forces means that it is the only known surface to which a gecko cannot stick Edited September 3, 2014 by fiveworlds
Enthalpy Posted September 4, 2014 Posted September 4, 2014 From what I read (not absolutely direct information) the metal, say aluminium, is first attacked by an acid to corrugate it deeply. Then the Ptfe is produced or deposited in situ and holds mechanically at the metals' cavities. I suppose that some alloys are better, for their heterogenous composition: grains and joints, eutectic precipitates... lets the acid dissolve them at uneven speed. I also believe that the coating isn't pure Ptfe, which would be far too weak against scratches. It's much loaded with a ceramic powder. ---------- The friction coefficient is complicated, poorly understood, and relates little with the surface tension nor with simple chemical properties. Proof of that: already at moderate heat (60°C?), Ptfe's coefficient jumps to values like 0.3, absolutely banal for a polymer. One of the many drawbacks that make it unusable pure as a bearing.
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