Metal-polymer friction zone

It should be emphasized that use of inhibited plastics in metal-polymer friction joints assists in a number of cases in solving the problem of fighting mechanochemical wear through the suppression of corrosion processes in the friction zone by Cl liberated by the polymer counterbody. Yet inhibited plastics are not the only means of corrosion inhibition in metal-polymer joints. 

Analogous cycles are observed in the polyacetal-steel and polyolefin-steel friction pairs. Physical-chemical processes can exert a favorable effect on the metal-polymer friction pair as well. For instance, metal-containing compounds of copper stearate and oleate types are formed in the contact zone as a result of tribochemical reactions when CFD copolymer rubs against copper. These compounds retard thermally destruction processes in CFD, serving as wear inhibitors (WI) for this system. 

The analysis of corrosion factors during polymer-metal pair wear has proved that the main path is electrochemical protection of the metal counterbody neutralization of corrosion agents formed in the friction zone and suppression of corrosion processes in the polymer-metal contact. These directions are realized by the means illustrated in Fig. 4.6 [37]. They are subdivided into two groups according to the use of special substances or physical fields and power effects. 

In its true sense, any component of a tribosystem promoting suppression of unfavorable tribochemical processes in the friction zone, irrespective of whether it was impregnated or formed internally, can be related to WI [34]. WI can be formed both as a result of physical-chemical interactions of polymers and metals, or physical fields and energy effects on a part or friction joint. This can be, e.g. thermochemical or radiation-thermal treatment, ion implantation, superposition of electrical and magnetic fields, shifts of electrode potentials, passage of electrical current, etc. 

As has been indicated previously (see Sect. 4.2), polymer parts in friction joints add specific features to electrochemical processes in the friction zone. The polymer components acquire the properties of surfactants during rubbing against metals, which change the electrochemical activity of the metals. In this connection, the effect of the liberation of Cl from inhibited plastics on electrochemical processes in the friction zone has been studied [128]. 

Friction of solid polymer particle or pellet against metal surfaces (termed external friction). This influences feed zone conveying rate as well as hopper flow. 

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