Study On Ionic Liquid-assisted Modification Of Particle Coating Based On ZTA_p@Me/Fe Composite Interface Optimization

Compared with traditional metal wear resistant materials,ZTA _p/iron matrix composites have attracted much attention due to their high hardness,high wear resistance of ceramics and good fracture toughness of metals.However,there are problems such as poor wettability,difficulty in casting infiltration composite,and low interfacial bonding strength between ZTA ceramics and iron matrix,which seriously affect the service life of composite materials.By depositing a uniform and controllable metal coating layer on the surface of ZTA particles（ZTA_p@Me）.It can effectively improve the wettability of molten iron on ZTA _p preforms and enhance the interfacial bon ding strength.In this paper,ZTA_p@Me is prepared by electroless deposition,mechanical agitation and electrodeposition using ionic liquid ChCl-EG as additive.The nucleation mode and growth mechanism of the ZTA_p@Me preparation process,the formation of the ZTA_p@Me/iron-based composite interface transition zone,element distribution,phase co mposition,and interface bonding strength are mainly studied.The research work provides new ideas and methods for optimizing the design of ZTA honeycomb ceramic-reinforced iron-based composite interface,solving the problem of non-wetting ceramic/metal-based composite interface,and improving the performance of composite materials.The main research results are as follows:（1）Based on the electroless deposition method,two new methods for the preparation of ZTA_p@Me using ionic liquid ChCl-EG as additive are proposed:electroless deposition-electrodeposition method and mechanical agitation-electroless deposition method.The process of electroless deposition-electrodeposition:The non-conducting ZTA_p is converted into electrically conductive ZTA_p@Ni by electroless nickel deposition,ZTA_p@Ni W is electrodeposited in nickel salt and tungsten salt deposition solution;ZTA_p@Ni-Ti B₂,ZTA_p@Ni-B₄C and ZTA_p@Ni-Ti O₂ are electrodeposited in nickel salt and powder suspension.The process of mechanical agitation-electroless deposition method:Ti and adhesive are mixed and coated on the surface of ZTA_p,and then ZTA_p@Ti-CuNi is prepared by electroless deposition on the surface of ZTA_p@Ti.Compared with ZTA_p@CuNi prepared by electroless deposition,considering the coating types,plating cost,preparation time and equipment requirements.The products of ZTA_p@CuNi and ZTA_p@Ti-CuNi prepared in large quantities at low temperature and within a short time are screened to meet the needs of industrial production of iron matrix composites.ZTA_p@CuNi and ZTA_p@Ti-CuNi prepared in large quantities at low temperature and in a short time are screened out to meet the needs of industrial production of iron-based composites.（2）ZTA_p@CuNi is prepared by electroless deposition,and the effects of ionic liquid concentration,reaction temperature and ZTA_p loading on the reaction process and coating are investigated.Finally,the optimal plating conditions have obtained:C_CHCl-EG=35 g·L^-1,T=65℃,C_ZTAp=30～50 g·L^-1.The nucleation and growth process of CuNi coating on ZTA_p surface are analyzed:Ni²⁺is reduced by the reducing agent Na H₂PO₂ to Ni particles and grows on the active site;Cu²⁺is reduced by the replacement reaction of Ni atoms first formed on the ZTA _psurface.Because ionic liquids are easy to adsorb on protruding metal particles,it hinders the continuous nucleation and growth of grains in this area and slows down the depositi on rate.Therefore,ZTA_p@Me with uniform,dense and flat metal coating is finally obtained by changing the preferential adsorption sites of ionic liquids and the nucleation and precipitation rate of grains.When the ZTA_p loading is 50 g·L^-1,the CuNi coating layer metallized the composite matrix,in which the content of Ni is about 0.45 wt.%and that of Cuis about 1.58wt.%;When the ZTA_p content is 30 g·L^-1,the Cu-rich phase will be formed in the composite.（3）ZTA_p@Ti-CuNi is prepared by mechanical agitation-electroless deposition,and the effects of the ratio of Ti powder to binder and the ratio of Ti powder to ZTA _p on the quality and thickness of Ti coating were investigated.When the mass fraction of binder is 50%of that of Ti powder,ZTA_p@Ti with neither residual Ti powder nor agglomeration can be obtained.When the mass fraction of Ti powder is 4%of ZTA_p,the coating thickness is 35.81μm;8%,the thickness is 56.08μm;When the content is 12%,the thickness is 96.51μm,which has already met the thickness required by ZTA_p@Me in iron-based composites.When ZTA_p@Ti is activated,PVA is used to protect it,so as to avoid the influence of binder failure on the uniformity of Ti powder coating during activation.When the mass fraction of Ti powder is 8%of ZTA_p,the as-cast ZTA_p@Ti-CuNi/HCCI interface consists of Ti O,Na₄Si O₄,undissolved Ti,carbides formed by HCCI and Si and Ti,and copper-rich and nickel-rich phases.After quenching at 1030℃and tempering at 530℃,Cuand Ni diffuse,the copper-rich phase and nickel-rich phase disappear,and carbides are further formed.The microhardness and modulus of the interface are 11.51 GPa and 225.00 GPa,both of which are between HCCI matrix and ZTAp,playing a good transition role.（4）The wetting angle of molten HCCI on ZTA plate is 127.3°.After surface modification,the wetting angle of molten HCCI on ZTA@CuNi plate is 103.6°,while that on ZTA@Ti-CuNi plate is 110.5°.As-cast S2′（ZTA_p@CuNi/HCCI）has the optimal wear resistance,and the volume loss after 6 hours is 392.27 mm³,which is 17.19%lower than that of as-cast S1′（ZTA_p/HCCI）;S5′（ZTA_p@Ti-CuNi/HCCI）after heat treatment has the optimal wear resistance,and the volume loss after 6 hours is 325.54 mm³,which is 16.78%lower than that of S1′after heat treatment.