Research On In-situ VC Particle Reinforced Iron Matrix Composite Coating By Plasma Cladding

Wear is one of the main reasons of the failure of mechanical parts,and the forms of wear are complex and diverse.Strong abrasive wear with a certain impact is a very common way of destruction.Ceramic particle reinforced metal matrix composites have high hardness and toughness and are more suitable for this wear condition.In order to save resources for additive manufacturing or recycling for remanufacturing,plasma cladding technology with a high degree of automation is used to prepare in-situ vanadium carbide-iron-based cladding alloy coatings on the surface of parts.The research has high theoretical value and practical significance.The modern industry’s requirements for material performance cannot be met by a single material.By preparing the coating method,the advantages of the coating and the substrate material can be effectively brought into play,while avoiding their respective limitations.Plasma cladding is widely used to improve the surface properties of parts.Plasma cladding can prepare coatings of sufficient thickness and realize the metallurgical bond between the coating and the base material.Compared with the traditional casting method,plasma cladding has a faster cooling rate,the solidification interface is far from the equilibrium state,the coating structure is more refined,and it has typical rapid solidification characteristics.In this paper,an in-situ VC particle-reinforced iron-based alloy powder formula is designed,and a high-vanadium iron-based coating is prepared on Q235 steel plate by using an optimized plasma cladding process.Using metallographic microscope,scanning electron microscope,energy spectrum analyzer,laser confocal microscope,super depth of field microscope,hardness tester,rubber wheel abrasive wear tester and impact abrasive wear tester,the structure and performance of the coating were characterized.The results show that the high-vanadium iron-based cladding and the base metal present a metallurgical bond,the dilution rate is about 15.7%,and the cladding structure is that VC particles are dispersed on the eutectic carbide and solid solution matrix.When C is 3.5% and V is 2～10% in alloy powder,with the increase of vanadium content,the number and size of primary VC particles gradually increase,and the matrix changes from flaky martensite + retained austenite→lath martensite Body + retained austenite→lath martensite + ferrite→ferrite transformation.The wear mechanism of the VC particle-reinforced iron-based alloy coating under the condition of strong abrasive wear is plowing.The hardness of the coating of C3.5% and V6% alloy powder is the highest,and the furrow is uniform,small and discontinuous.The high-vanadium iron-based alloy coating with spherical VC particles+lath martensite structure has the highest relative wear resistance,which is13.4 times that of Q235 base material.The strong lath martensite matrix is its high wear resistance the decisive factor.The wear mechanism of the in-situ VC particle-reinforced iron-based alloy coating under impact abrasive wear depends on the type of matrix.The flake martensite matrix is mainly brittle sloughing,the lath martensite matrix is mainly micro-cutting,and ferrite matrix is dominated by micro-cutting and severe plastic deformation.Dispersed VC particles+lath martensite matrix is more suitable for medium and low impact abrasive wear conditions.Adding niobium in an appropriate amount can effectively increase the nucleation rate of VC particles,refine the grains,and help improve the hardness and wear resistance;but when niobium is excessive,the MC carbide particles will coarsen,and the hardness and wear resistance of the matrix will decrease instead.Plasma cladding VC particles + lath martensite matrix coating is suitable for hard abrasives and has certain impact wear conditions,low cost,and good application prospects.