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Friction factor 0.1 – 0.2
It is the very last bath developped by STA and it offers, in comparison with other competing formulations, the advantage of englobing into the matrix of nickel a very high percentage of PTFE, as in the figure below where the segment up right corresponds to 1 micron. It is moreover possible to have thicknesses till 70-100 micron.
In these conditions the friction coefficient is 0.1 tending to 0.04 of PTFE as the spheres of PTFE are transferred to the other piece.
The process consists in wasting into the electroless nickel bath a big quantity (7-12g/liter) of spheres of PTFE, inferior to 1 micron, after having them stabilized with proper surfactants in order to make them lose the idophoby typical of PTFE
The particles are attracted by the metal surfaces present in the bath and deposit together with nickel. The secret is to deposit a big quantity of PTFE and make nickel act as matrix of the bearing: it is not sufficient to englobe some spheres here and there in order to reduce the coefficient of friction.
The temperature of the bath must be lower as usual and the filtration must be continuous. In these conditions the deposit speed is very low: 7-10 microns per hour.
Properties
chemical stability
autolubrificant
low friction factor
stable till 300°C
Applications
dies
petrol industry
earth movement
mechanical – textile
electronics
