Research On Electrospark Deposition Of Amorphous Coating On Aluminium Alloy Surface

Amorphous alloys have promising application prospects for their interesting properties,which include high hardness and strength,superior corrosion and wear resistance.Surface amorphization has become one of the research hotspot in the field of amorphous alloy,which it not only enhance the wear resistance and corrosion resistance properties of the substrate surface,but also extents the applications of amorphous alloys.Electrospark deposition technique is an effective way to obtain good metallurgy bonding and amorphous structure coatings on metallic substrate,this is because the rapid heating and cooling processes inhibit long-range diffusion and prevent crystallization of the impulse discharge treatment.In this paper,Zr₅₅Al₁₀Ni₅Cu₃₀?at.%?and WC-10Co hard alloy deposited coatings were prepared by electrospark deposition technique on ZL101A aluminium alloy surfaces.The microstructure and properties of the deposited coatings were analyzed by optical microscope?OM?,X-ray diffraction?XRD?,microhardness tester,friction and wear tester and eletrochemical measurement system.The influence of the deposition process parameters on the coating thickness,roughness and defects were also studied to optimize process parameters.The process of material removal and the formation mechanism of amorphous structure during deposition processing were also studies by simulate the temperature field using ANSYS software.The results show that capacitance,voltage and frequence of the deposition processing have highly effects on the thickness,roughness and flew of deposition coatings.The optimized deposition processing parameters are using 30?F capacitance,100V voltage and 360Hz frequence to deposite and then using 30?F capacitance,50V voltage and 2000Hz frequence to refine the deposited coating.The Zr-based deposition coating is mainly consists of amorphous,Al?Si?,ZrO₂ and Cu₈Zr₃phases.The amorphous structure distributes among crystal phases as block-like or strip-like.The surface morphologies of the deposition coatings are like orange peel and formed by deposition points superimposed to each other.The deposition coating is about 38?m thickness and has a metallurgy bonding to the substrate.The WC-10Co deposition coating is about 35?m and composed of amorphous,WC and W₂C phases.The average microhardness of Zr-based deposited coating is about 1555HV_0.01,the coefficient friction is 0.096 and the E_corr and i_corr are-724mV and 1.01?A/cm²,respectively.The microhardness of WC-10Co deposition coating is1033 HV_0.01,the coefficient friction is 0.18 and the E_corr and i_corr are-745m V and 1.62?A/cm²,respectively.The heat distribution of ZL101A aluminium substrate and Zr-based amorphous electrode temperature field are highly concentrated.The temperature field of Zr-based amorphous electrode has higher temperature and more fusion quantity than the substrate.In the whole pulse cycle,the average cooling rate is about 10⁶?/s,which can form the amorphous structure.