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　alpha-Fe　and　Cr　in　build-up　welding　material　has　fine　property　of　crack　arrest,　and　alpha-Fe　turns　into　gamma-Fe　under　frictional　heat　as　well　as　frictional　austenite　phase　gamma-(Fe,　Ni)　+alpha-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　alpha-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.