DEGRADATIONS IN A HIGH-SPEED SLIDING CONTACT IN TRANSIENT REGIME

The improvement of a weapon system needs to be balanced between the po wer of the powder and the lifetime of the gun barrels. When a projecti le is fired, different phenomena bring a large amount of heat into the tube. These physico-chemical, thermal and mechanical phenomena are co nnected, hence their study is very complex. In order to study thermal effects induced by mechanical friction, a test device called a 'tribom eter great velocity' has been designed. The surface thermal conditions are derived from thermocouples data and calculated by an inverse heat conduction algorithm. The tribological and thermal behaviour of diffe rent materials were studied on this device. Tested materials have thei r own particular features showing the influence of physical parameters . The mean contact temperature, the heat flux coming into the pin, the heat distribution coefficients and the thermal gradient in the pin we re also investigated on steel. Hard chromium was also studied: it give s good tribological and thermal protection.