Effects of laser surface modification on microstructures and properties of copper based PM friction plates

Abstract

The copper based powder metallurgy friction plates were treated by a broad beam laser. The microstructures were characterised by SEM, TEM, electron probe microanalysis and XRD. The hardness and density also have been tested. The properties of the friction plates were tested by the clutch and friction element dynamic properties tester. The test results show that, after the laser surface modification the α-Cu aggregates generate edge solid phase dissolution and the large agglomerate aggregates of α-Cu dismember to small strips. The nanocrystal is discovered in the α-Cu aggregate. The density and apparent hardness of friction material is increased by 6 and 12·7% respectively. The microhardness of α-Cu is increased by 14%. The static and kinetic friction coefficient of friction plate is increased by 7·4 and 9·2% respectively. The wear loss and wear rate is reduced by 33 and 49·6% respectively. The allowable heat load value is increased by 40%.