Preparation And Performance Investigation Of Cold Coated Induction Cladding Ni-based Alloy Coating

Wear,corrosion and fatigue are the three main forms of metal material failure,and material failure is the direct cause of mechanical component damage,which has brought huge economic losses to the industry.Studies have shown that wear and corrosion of most components often occur on or from the surface,so surface modification of components is an important technical way to extend their service life and reduce the consumption of related metal materials.Cold-coated induction cladding technology is a new surface modification technology proposed in the past 20 years.Cold-coated induction cladding technology eliminates the steps of powder coating in thermal spraying.Pre-coated layer is prepared by cold-coated method,which will realize the industrial vision of energy-saving and green manufacturing.Investigation and improvement of related technologies will promote the transformation and upgrading of traditional thermal spraying induction cladding technology.The cold-coated induction cladding technology was taken as the research object in this paper.The cladding properties of saturated sodium silicate,PVA hydrolysate and self-made binder at high temperature were investigated.Screening out the optimal proportion of self-made compound auxiliary and determining corresponding induction cladding process,then on the base of these,researching the effect of WC content on slag detachability,cladding and formability for pre-coated layer.The thermal fatigue life,wear and corrosion resistance were analyzed by means of SEM,XRD,XPS and Raman for WC modified Ni-based alloy coatings.The main results of this paper are as follows:?1?The solidification front of soturated sodium silicate solution posesses terrible deformation compatibility in high temperature,which will make pre-coated layer crack and disintrgrate easily during induction cladding precess.The oxsidative discomposition of PVA binder in high temperature will result in totally loss of structure strength pre-coated layer.On the contrary,the excellent structure strength and deformation compatibility of self-made binder in high temperature will ensure pre-coated layer structural integrity when heating to melting temperature.?2?The high density Ni-based alloy coating was prepared when induction coil moving speed is 0.4mm/s,electromagnetic induction heating power is 30Kw,the number of induction cladding is twice,and dosage of self-made binder and self-made compound auxiliary is 8%and 3%of total mass respectively.The slag is silicate glass phase structure,and the slag has excellent slag removal performance.?3?The melt will collapse locally during the cladding process after introducing WC,but it has little effect on the apparent quality of the cladding coating.The slag is mainly composed of silicate glass phase structure,and the slag also has excellent slag removal performance.WC hardly undergo oxidative decomposition and exists in the form of WC crystals as a whole during induction cladding process.?4?The addition of WC can improve the high temperature wear resistance of the coating,but the content of WC should be controlled at 15%.Excessive content of WC can easily aggravate the adhesion wear,which makes the friction coefficient fluctuate sharply and deteriorate the friction quality.The content of WC is not enough to improve the high temperature wear resistance.?5?Adding WC can improve the thermal fatigue performance of the cladding layer.WC can hinder the crack propagation,but the oxidation resistance of WC is poor.Adding too much can promote the formation of brittle phase such as WO₃ during thermal fatigue.The addition of WC should be controlled at approximately 20%.?6?The addition of WC can improve the corrosion resistance of the cladding layer.The introduction of WC can improve the uniformity of the corrosion resistant element Cr in the cladding coating.At the same time,the chemical activity of WC is lower than that of Ni and Fe.When the coating contacts with the corrosive medium,it will form the cathode of the local primary battery together with Cr₂O₃ film and is protected.The surrounding alloy structure constitutes the anode and is preferentially corroded.