Study On Surface Modification Of C61900Copper Alloy By Depositing Titanium And Nitriding

In order to improve the surface hardness and wear resistance of C61900copperalloy, a composite modified layer with good mechanical properties was successfullyproduced on the surface of C61900copper alloy by two procedures. First, thecopper alloy substrate was deposited wite Ti film by closed field unbalancedmagnetron sputtering. After that, the Ti coated copper alloy was plasmanitrocarburized. The phase structure, surface and cross-sectional morphology andelements distribution in composite modified layer were characterized by SEM, XRDand EDS. Additionally, the microhardness and wear resistance of the modified layerwere also measured.The results show that the surface of as-obtained Ti film is smooth and mainlyconsists of α-Ti with hexagonal structure, and it has a preferred orientation (002).The modified layer mainly consists of Titanium-nitrogen compound in the surfacelayer and AlCu2Ti in the sub-surface layer, also a few of Fe4N and Al2Ti are in it.Alonging with the increasing of time and temperature, the phase of Titanium-nitrogen compound in the modified layer changed as follows: TiN0.3�'Ti2N�'TiN,moreover, the boundary between Titanium-nitrogen compound layer and AlCu2Tilayer became straight and clear. Increasing the thickness of Ti film deposited on thesubstrate could lead to the decreasing quantity of Ti2N but increasing quantity ofTiN0.3and AlCu2Ti. The microhardness test results show that surface hardness ofC61900alloy has been improved markably, and it decreased smoothly from surfacetowards the substrate. Ti-coated specimen nitrided at650℃for6h exhibited ahardness of881HV0.025, which is6times hard of the untreated one. The wearmechanis m of the untreated specimen is adhesive wear with severe plasticdeformation and ploughing, while the modified specimens perform good wearresistance with low wear rate. The specimen with6.3μm Ti film treated at650℃for4h exhibited the best wear resistance that the wear rate was just0.14×10-7g／rN,which decreased about90%comparing with the untreated one.