Research On Microstructure And Properties Of Adding Wolfram And Tantalum About Nickel-based Self-fluxing Alloys Coating Of Plasma Surfacing Coating

In this thesis, as the background a large number of surface failure about wearing and corrosion of mud pump plunger shaft of mining process and other corresponding engineering parts, researching to further improve the technical process parts surface wearable and corrodible properties, using plasma powder prepared NiCrWTa nickel-based alloy layer coating on45#steel surface. Comparing with Ni60A alloy cladding layer that prepared under the same process, comprehensive analysis of the chemical composition of the alloy cladding layer NiCrWTa, organizational structure, surface hardness, acid resistance, abrasion resistance and other physical properties.By scanning electron microscopy (SEM), EDS (EDS), X-ray diffraction analysis (XRD) analysis methods such as analysis of the surfacing layer morphology structure and composition of the experimental results showed that:NiCrWTa two alloys with Ni60A surfacing with the same nickel substrate and a hard phase composition, the difference that NiCrWTa alloy cladding layer NiCrWTa precipitated a new phase WC, NiO.9Ta0.1, Nb0.1Ni.09etc.,precipitates more evenly distributed within the organization, and its dense.By hardness test and wear test analysis showed that:NiCrWTa alloy surfacing layer Rockwell and Vickers hardness were62.9and613.6, Ni60A alloy cladding layer hardness60.8and520.0, respectively, compared to the both hardness that the former is higher; wear rate of both are0.495and1.025, respectively, the later is2.05times of the former, the former has significantly better wear resistance.Determination of the anodic polarization curve measured and by the gravimetric method to measure the corrosion rate, results showed:in HCL solution (1mol/L), the corrosion rate of alloy cladding layer of NiCrWTa alloy and Ni60A alloy were4.6and58.212, rate of the alloy cladding layer Ni60A corrosion is almost13times to NiCrWTa, which shows the performance of NiCrWTa salt corrosion is much higher than the former;In H2SO4solution (lmol/L), the both corrosion rate were3.196and64.364, which the former is about20times as many as the later, and the former acid corrosion much better than the latter; their respectively corrosion potential in H2SO4solution (lmol/L) is (?)corr (V)-0.332and (?)corr (V)-0.288; The density of Corrosion current are Jcorr (A/cm2)1.886e-4and3.937e-5. The corrosion potential in HCL solution (1mol/L) of the two layers are (?) corr (V)-0.292and (?) corr (V)-0.188; The Corrosion current density are Jcorr (A/cm2)1.569e-4and Jcorr (A/cm2)2.423e-5. NiCrWTa alloy cladding layer than Ni60A alloy surfacing layer exhibits better resistance to acid corrosion. The results also showed that the nickel-based alloys in an acidic solution containing Cl-ions, owing the presence of pitting, the corrosion rate is higher than other acidic solution.By adding the right amount of alloying elements Cu, Mo, Nb, Ta, W, and a trace amounts of rare earth elements Ce can significantly improve its original structure, strengthen nickel texture, refine grain, and purge the grain boundaries. Making using of powder plasma reactor to get surfacing welding layer that is with better wearable and corrodible performance and excellent value for money. Repairing parts and preparing wearable and corrodible properties of the coating in advance of the application components surface has a very good market prospects in the field, and has a great promotional value.