Research on Worn Mechanism of Disc-Brake Pair Materials for Drilling Rig

Abstract

A new build-up welding material for brake-disc and a new type of asbestos-free frictional material are developed, of which the tribological behaviours and wear mechanisms of build-up welding materials are discovered. XRD pattern shows that iron-base solid solution of ?-Fe and Cr in build-up welding material has fine property of crack arrest, and ?-Fe turns into ?-Fe under frictional heat as well as frictional austenite phase ?-(Fe, Ni) +?-Fe + carbide forms, which improves plastic deformation ability of material in wear surface and anti-thermal fatigue property of brake-disc, in addition, carbide Fe3C, Fe5C2, SiC and intermetallics NbNi, NbNi5 disperse in solid solution of ?-Fe and Cr make frictional surface hardness of brake disc become higher to improve wear-resisting property of brake-disc. SEM and EDAX patterns show that the wear process of brake block and brake disc is a dynamic process of surface film generating, growing, cracking, stripping and regenerating. When frictional temperature is lower, the wear of brake block is mainly abrasive wear and that of brake disc is oxidized and abrasive wear, and their surface film breaks off mostly by fatigue flaking. When frictional temperature is higher, the wear of brake block is mainly adhesive wear and that of brake disc is adhesive and oxidized wear, and their surface film is scaled mainly by adhesive tearing.