Microstructure And Properties Of In-situ Synthesizing WC Particles Reinforced Fe-based Alloys By Vacuum Arc Smelting

By the method of TIG to prepare WC particles reinforced iron-based compositecoating, there is a problem that the alloying elements burn seriously and especially itis difficult to generate WC particles in the preparation of the coating process usingWO3.In this study, the creative use of vacuum arc reactor technology is used in situsynthesis methods, choosing WO3and W as tungsten source powder when preparingWC particles reinforced iron-based composite materials deposited.This paper analysis was based on the reaction principle, tissue morphology of thedeposited layers,WC particle size controlling and wear resistance of the compositecladding.The morphology of deposited sample and phase composition were studied usingoptical microscopy, scanning electron microscopy, X-ray diffraction, and the effects ofhardness and wear mechanism deposited composites also were investigated.The results showed that:1) Compared with the TIG welding under open environment, vacuum arcreactor technology can reduce the vaporization burning of WO3, accelerate thereduction process of WO3, improve the W, C diffusion rate, successfully generate theWC particles. WC grain microstructure is with the characteristics of edge aggregationand η phase morphology change, hardness gradient distribution and edge hardness to1968.9HV0.1.2)The effects of WO3and graphite content on the microstructure and propertiesof welding, also the effects of boron iron on the refinement of the WC particles wereinvestigated when choosing WO3as tungsten source.The particles can be in-situ synthesis of WC with small grain size and optimumhardness and wear resistance when the WO3content was60%. WC grain size tendedto increase with the increasing of WO3contentThe WC particle size is moderate when graphite content is12%. However, whenthe graphite content exceeds12%, WC particle size increases with the graphitecontent increasing and graphite tissue appeared.The boron iron had obvious refinement on WC particles. When boron ironcontent was6%, the size was about20um and hardness and wear resistance was best. 3)The effects of C,V and B content on the microstructure and properties ofwelding, also the effects of V, B content on the refinement of the WC particles wereinvestigated when choosing W powder as tungsten source.Under closed vacuum environment, the C content significantly affect the size ofthe WC particles. WC grain size increased and hardness increased with the increasingof C content.Adding vanadium iron can significantly inhibit the WC particles growth, becausethe organization generated VC to reduce WC dissolved in the liquid phaseprecipitation, while the solution to the VC form W (W, V) C blocked WC particlesgrowth, to get around10um size of WC particles.When the iron content is greater than12%, WC reduced while (W, V) C phaseincreased, the hardness and abrasion resistance is lowered.Boron iron alloy powder can refine WC particles because boron boride gatheredat the grain boundaries and matrix WC to inhibit the WC particles to grow. Whenboron iron content is5%, the inhibitory effect is better, the hardness of the hard phaseand the matrix structure are improved with excellent wear resistance.