| Moulds are extremely important and indispensable special basic processing equipment in industrial production.Once the surface defects appear,it will affect the accuracy and decoration of the parts produced by the mold,and the service life of the mold will become more and more prominent.Mold surface treatment technology directly affects mold manufacturing accuracy,mold strength,mold industry life,mold manufacturing costs,etc.Plasma spraying is a green and economical surface modification technology that enhances the corrosion and wear resistance of mold materials by improving the surface quality.In this paper,combining the good spreadability and fluidity of Ni Cr BSi,and the advantages of high melting point and high wear resistance of AZ50 composite ceramics(Al2O3 and Zr O2 powder mixed in a ratio of 1:1),Ni Cr BSi/AZ50 composite materials are prepared by H13 die steel.Plasma spraying technology uses optical microscope,scanning electron microscope,energy spectrometer and X-ray diffractometer(XRD)to coat the coating and optimize the process parameters to analyze and compare the microstructure of the coating,and through stretching,display Microhardness and friction and wear testing to study coatings.Coating strength,microhardness and friction and wear properties.The main work and results of this paper are as follows:Firstly,using the combination strength of the composite coating and the substrate as an index,the four main factors of spraying distance,power supply,main air flow and powder feeding amount are optimized by orthogonal experiment method,and the test index of each factor is determined by range analysis.The order of influence.The results show that the main parameters affecting the bonding strength of Ni Cr BSi/AZ50 composite coatings are arranged in the order of powder feeding amount>spraying power>main air flow>spraying distance,and the optimal process parameter is A2B1C1D1,that is,the powder feeding amount is 0.8 g/min,power supply power It is 35 k W,the main air flow is 55 psi,and the spraying distance is 85 mm.Secondly,according to the difference of the bonding strength between the composite coating and the substrate,the second group(No.2),the fifth group(No.5)and the optimal parameter sample(No.10)in the orthogonal table are selected for comparison.Study the phase and microstructure of Ni Cr BSi/AZ50 composite coating.The results show that the three groups of composite coatings all contain six phases of?-Al2O3,t-Zr O2,?-Ni,Cr7C3,Ni3B,and Cr B.The spraying parameters do not change the phase composition of the composite coating,only for the composite.The crystallinity of the coating has an influence;observe the cross-sectional morphology of the composite coating,the AZ50 enhanced phase distribution in the cross section of the No.10 sample is more uniform,the spreading is better,and the composite coating is more dense;the composite coating is analyzed by energy spectrum line scanning.Interlayer particles and the bonding method of the coating and the substrate,it is found that the bonding mode of the AZ50 reinforcement phase and the Ni-based particles is mainly mechanical occlusion,and the combination of the composite coating and the H13substrate is also a mechanical bonding,which indicates that the spraying parameters are different.The inherent bonding method of the composite coating is not changed.Finally,the mechanical properties of NiCrBSi/AZ50 composite coatings prepared with different parameters of No.2,No.5 and No.10 were tested and studied.The results show that the hardness of the composite coatings of the three groups of samples No.2,No.5,and No.10has the same changing law.The hardness value of the composite coating near the substrate is the highest,and the hardness value of the composite coating surface is the lowest.The main reason is that the particles on the inner side are compacted and heated by subsequent particles,so that the coating is denser and the internal phase crystallinity is higher.Among them,the coating of No.10 has the highest hardness,reaching 960HV0.5,using the reciprocating friction of the ball and disc.The wear machine tested the wear resistance of No.10 composite coating at different loads(10N and 15N)and different linear speeds(1.25 mm/s and2.1mm/s).It was found that under certain load conditions,the greater the linear speed,The greater the friction coefficient of the composite coating;when the linear velocity is constant,the greater the load,the smaller the average friction coefficient of the composite coating.The adhesive tensile test was carried out on three sets of samples of No.2,No.5 and No.10.Among them,No.10 had the highest tensile strength,48.5MPa,No.5 followed by 29.8MPa,and No.2 The tensile strength is the smallest,only 12.6MPa,indicating that the bonding performance of the coating has been greatly improved after optimizing the parameters;the three groups of samples No.2,No.5,and No.10 were subjected to electrochemical experiments and simulated It is found that No.10 has the best corrosion resistance,No.5 has the second best corrosion resistance,and No.2 has the worst corrosion resistance,which is mainly caused by the different density of the composite coating. |
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