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Study On Electroless Ni-P-diamond Composite Coatings On Copper Substrate Surface In Magnetic Field

Posted on:2019-06-18Degree:MasterType:Thesis
Country:ChinaCandidate:X L LiuFull Text:PDF
GTID:2321330566465910Subject:Materials Processing Engineering
Abstract/Summary:PDF Full Text Request
Chemical composite plating is a process to prepare a coating with special properties by adding inert particles with special properties to the plating bath and co deposition withthe matrix metal.The electroless plating has a uniform plating layer,a deep plating ability,a dense plating layer,and a simple plating process,which is convenient for application on various newmaterials;By adding different kinds of particles,composite coatings with different properties can be obtained,such as high hardness,wear resistance,self-lubricating,electrical contact,and corrosion-resistant plating.The application of chemical composite coatings under conditions of high speed,low wear,low coefficient of friction,and high temperature oxidation resistance indicates that their performance is much better than that of pure electroless plating.Due to its advantages of high hardness,high wear resistance,high temperature resistance,low friction coefficient,etc.,diamond powder has gradually become a research hotspot.In this project,a Ni-P-diamond composite coating was prepared on the surface of a copper substrate by a electroless composite plating method.By changing the magnetic field strength,magnetic field mode,diamond particle concentration,stirring speed,particle pre-treatment and other methods to study its effect on the coating performance,and then characterization of the coating performance.The surface morphology,wear resistance,adhesion and hardness of the coating were tested and analyzed by optical microscope,friction and wear tester,automatic scratch tester and microhardness tester,and the mechanism of electroless composite plating and the influence of various factors on the properties of the coating were explored.The results show that the appropriate static magnetic field strength is beneficial to improve the deposition rate,the diamond particle content and thickness of the composite coating,the maximum deposition rate is 9.56?m/h at 10.60mT in the experiment,and the diamond content in the coating reaches 24%at 10.60mT,4g/L,thickness reaches 17?m.In the case that the amount of diamond particles is determined,the wear resistance and binding force of the composite coating increase as the magnetic field increases.In the alternating magnetic field,the situation is different.The large alternating magnetic field is good for wear resistance and hardness.When 24V voltage is applied,the friction coefficient is stable,and the hardness shows an upward trend,but it is unfavorable for the thickness,and the large alternating magnetic field will make the thickness decrease.There is no obvious effect on the binding force.Different diamond particle treatment methods also affect the coating.Concentrated hydrochloric acid,concentrated nitric acid,aqua regia,sodium dodecylbenzenesulfonate,cetyltrimethylammonium bromide,and OP-10are used to treat diamond particles.The results show that the thickness and hardness of the coating obtained after the aerobic treatment of particles deposited are greatly improved,reaching 19?m and 778HV100g respectively,and the binding force is excellent,reaching 63N.Hydrochloric acid facilitates the improvement of friction and wear properties.In addition,the coating friction coefficient after heat treatment at 400C.for 1h is significantly more stable than without heat treatment.Increasing the stirring speed will make the coating thickness decrease and also increase the diamond content in the coating.The maximum thickness is 33?m at 300r/min,and the maximum hardness is1322HV100g at 500r/min.The wear resistance is affected by the thickness and hardness.The wear resistance of the coating obtained at 600 r/min is optimal,and the stirring speed has no significant influence on the binding force.
Keywords/Search Tags:external magnetic field, electroless composite plating, diamond, copper based material, hardness
PDF Full Text Request
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