Dynamic thermoanalytical test method for qualifying brake lining materials

A thermoanalytical test method is described for qualifying brake lining materials, based upon the recording of coefficient of friction f versus temperature T diagrams. Tests are performed at a low sliding speed, thus avoiding substantial increase in temperature due to dissipation of frictional energy. During testing, the temperature in the friction interface of a brake lining-metal ring friction couple is increased linearly with time by means of time-controlled inductive heating of the metal ring. It is shown that the method yields a ‘fingerprint’ of the brake lining material, which is characteristic for its friction-temperature behaviour as related to composition and structure and which can thus be used for identification purposes and in acceptance testing. Repeated runs in the range T o– T max, performed at T dot = 0.07° C/s , yield information on the f− T behaviour of lining materials which, in previous runs, have been exposed to a maximum contact temperature T max. The method is illustrated with results obtained with a resin/asbestos and a cermet/graphite material.