The Research Of The Preparation And Strengthening Mechanism Of High Hardness Fe Based Ceramic Composite Coating

Low carbon steel has excellent toughness and plasticity,but surface hardness and wear resistance are poor.Using laser surface cladding technology to prepare high-performance coatings is a feasible way to strengthen low-carbon steel materials.In order to make the surface of the laser cladding layer has good bonding properties and surface properties,in the design of cladding metal powder,kinds of ceramic reinforced phase are often added in the alloy,in under the action of laser,to achieve uniform distribution of reinforcements,thus preparing composite coating with special use of energy.But the addition of single ceramic material can only improve the performance of one certain aspect of the coating,which has great limitations.This text based on Fe-based powder and preparation of composite coating materials by adding multi ceramic phase and multi-element ceramic phase,apply the Laser cladding technology to prepare high hardness and high wear resistant coating on the surface of 20#steel.The strengthening mechanism of the coating is also studied.The specific research contents are as follows:According to the design principle of the cladding material,the laser cladding coating material is designed according to the requirements of the matrix material and the surface performance of the coating.Based on TZ625 alloy powder,three kinds of ceramic materials,such as TiC,WC and SiC,Ni and other auxiliary elements were rationally added,and three kinds of different ratios Fe-based multiphase ceramic powder materials,A,B and C are prepared.In order to prepare high quality coatings with good hardness and wear resistance,this text design a complete orthogonal experimental scheme,the parameters and cladding materials of laser cladding were optimized.Through orthogonal experiments of various processing technology and material combinations,combined with the test results of hardness and wear resistance of coating,the influence of process parameters on coating performance is analyzed,and a better laser cladding process and material combination is given.The microstructure of the cladding layer and the fine grain strengthening mechanism of the coating were studied by using different process parameters to prepare the specimen of laser cladding.The microstructure of the cladding coatings was observed by optical microscopy and scanning electron microscopy.The influence of various factors on the fine-grained strengthening degree of the coating was analyzed from the angle of process parameters and coating materials.According to the law of thermodynamics and Gibbs free energy theory,the surface temperature field of cladding layer under the process parameters is analyzed,and the free energy transformation of each ceramic phase in the temperature field is calculated,and the dissolution mechanism of ceramic phase in cladding layer is explored.By means of XRD diffraction test on the surface of the coating on the decomposition of each substance in the coating and the combined form are analyzed,and spectrum analysis experiment analyzed the special triangle area contained in the coating part of the elemental composition of the EDS,the experimental results are consistent with the results of thermodynamic analysis.