| A layer of gradient distributed titanium carbide hard enhanced phase was producedby in-situ synthesized process in the surface of gray cast iron matrix through short hightemperature casting and heat treatment under eutectic temperature reaction technology,and the TiC/Fe surface gradient composite was prepared by this method succefully. Inthis process, we tried to get the ductile cast iron base composite materials reinforced bythe titanium carbide particulates beam. The phase composition of the composite wasanalyzed by XRD, EDS, the macrostructure and microstructure was observed by SEM,HDX-1000and other detection methods. The wear test of surface gradient compositewas performed by two-body abrasion tester, and researcher the wear property andmechanism of the composite materials under different volume fraction, differentabrasive, different load and multi-granularity. And the microhardness of the surfacegradient composite was tested by the sclerometer. Finally, the high performance TiC/Fesurface gradient composite materials were obtained.(1) Under this process, the surface gradient composite materials were made bythree different reaction times (6h,8h,10h). The researches showed that TiC/Fe surfacegradient composite material was obtained successfully by8hours heat preservation. Thegradient layer was divided three areas, and TiC particles present different forms indifferent layers. These are spherical particles area, long strip particles or irregular largeparticles area, block and high density ceramics hard phase separately. The totalthickness of composite gradient layer is about266.7?m, and the thickness of threedifferent reaction layers are80.0?m (Area A),76.7?m (Area B),110.0?m (Area C)respectively. The tissue of the gradient layer is made of TiC, ?-Fe and graphite, theboundary combined well between between TiC particles and the gray cast iron matrix. And the grain diameter of the particles is average of2?m. The small particulates of TiCexpressed sphericity was inseted between the pearlite matrixs.(2) Under the same load, the same size abrasive (Al2O3) and different volumefraction of TiC particles abrasion experiment, the outermost TiC layer (Block of TiCdensify ceramic layer) have the highest relative abrasion resistance. The maximumvalue of relative abrasion resistance is approximately37times than gray cast ironstandard sample.(3) Under the same load, the same granularity and the different hardness of theabrasive, the wear performance between large blocks of TiC ceramic layer and granulateTiC results showed that the weight loss of the sample increased gradually as theabrasive hardness increased. The loss of weight of big block ceramic area is inferior togranulate TiC area.(4) Under the same abrasive, the same granularity and the different load(5N,10N,15N,20N), the wear performance of large blocks of TiC ceramic layer results showedthat weight loss of the ceramic layer increased, as the loss increased. The relative wearresistance increased slightly under each load. The relative wear resistance of thecomposite sample ceramic layer is about42times than gray cast iron standard sampleunder the load of20N.(5) Under the same load, the same abrasive and different granularity (180mesh,240mesh,320mesh,360mesh), the wear performance of small TiC particulate layerresults showed that weight loss of small TiC particulate decreases, as the abrasivegranularity decreased. The relative wear resistance increased under each abrasivegranularity. And the relative wear resistance of the composite sample particulate layer isabout17.58times than gray cast iron standard sample under the abrasive of360mesh.(6) In the TiC/Fe surface gradient composites, the highest microhardness area isbig block ceramic layer, and the biggest hardness value is about3231HV0.05, and themicrohardness of big block ceramic layer is about21.83times than gray cast iron. |
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