Effect Of Re-melting Process Parameters On Interface Characteristics And Impact Wear Properties Mechanism Of WCp/Steel Matrix Surface Composite

In recent years,researchers have successfully optimized ceramic reinforced metal matrix co mposites by element addition and controlling sintering process,which improved the organizat ion and performance of the interface structure and pushed interface control theory forward further.The interface control aims at adjust ing organizat ion and performance o f the int erface structure then transfer load,cushio n impact energy and thermo-physical properties.This paper is based on the premise o f controllable interface,adjust ing the structure,width o f the int erface by interface re-melt,and aiming to controlling interfacial properties.In this paper,the co mposites w ere prepared by three la yer transit io n structure design,powder-sintering and interface re-melt ing.Lots of test instrument were used to characterize the effect law of re-melt parameter to Interface characterist ics and impact wear properties of co mposites,lying the foundat ion for interface adjust ment mechanism and composites'industrial application.The fo llowing conclusio ns are drawn from the analysis:t he co mbinat io n o f composites'tungsten carbide particles and matrix belongs to simply mechanical state without re-melt process and have a low property.The composites wit h re-melt process there exists a interface react io n laye r between tungsten carbide part icles and matrix.Wit h the development of re-melt temperature,interface layer widt h,state and bond strength have been significant ly improved.When the re-melt temperature increased to 1280-1320?,interface layer has a proper width and state.At this time,the performance of interface structure reaches its peak.On this basis,increasing the re-melt ing temperature will cause excessive second phase precipitat io n in the matrix region,leading the change of matrix to hard and brittle and finally the decrease of material properties.Wit h the development of re-melt time,the width o f the interface react ion layer increases and the inner and outer surfaces beco me smoother.When the re-melt time increased to 80-120min,the interface width is appropriate and the interface bonding reached a high state.When the re-melt t ime exceeds 140min,the edge of tungsten carbide part icles start continuous melt ing and the hardness o f the particles decreases gradually.The interfacial la yer also grows into the interior of the particle in the form o f spike,which split s the part icles and causes the stress concentration.Impact wear test results show that the impact wear resistance o f WC _P/steel matrix surface co mposite has bee n significant ly improved after re-melt treat ment.Wit h the increase of re-melt temperature,the impact wear resistance o f the material increases first and then decreases,reaching the best wear performance at the re-melt time of 80-120min.The main wear mechanism o f WC_P/steel matrix surface composites under different impact loads is summarized by characterizing t he wear surface of materials aft er impact wear test.When the impact energy is a small load of about 1J,the surface o f the material is dominated by the shedding mechanism.Wit h the cont inuous wear of the matrix,the tungsten carbide particles gradually protrude on the surface of the material and remain int act under the impact load,and the interface react ion layer is less damaged.After the particles protrude more than halfway,the co mbinat ion o f the particles with the matrix gradually beco mes smaller and fina lly falls o ff under the act ion o f cyc lic stress lo ad.When the impact energy is a medium load about 2J,the material surface is do minated by t he semi-fracture mechanism.At this t ime,the surface damage degree of protruding tungsten carbide particles increases.The interfacial la yer absorbs a higher load and produces a large area of shedding,which protects the integrity o f part icles to a certai n extent.There is no obvious crack on the surface of tungsten carbide particle but it is cut off by the waist under transverse shear stress after protruding over half,which decrease material properties.When the impact energy is a high load about 3J,the material surface is do minated by the crushing mechanism.At this time,the buffering effect of the interface react ion layer on the impact load reaches its limit.Large lo ngitudina l cracks appear under the impact load towards the center of the particle an d part icles beco me broken and peeling unt il particles are all peeling o ff.