Microstructure And Properties Of Plasma Sprayed Fecocrmocby Amorphous Alloy Coatings

In this paper,FeCoCrMoCBY amorphous alloy powder was prepared by gas atomization method.FeCoCrMoCBY amorphous alloy coating was prepared by plasma spraying technology.Then the coating was treated by different cryogenic treatment methods.The effect of different content of Zr-based alloy powder on FeCoCrMoCBY amorphous alloy coating was studied.The phase structure of the coating was analyzed by X-ray diffractometer,and the microstructure and morphology of the powder and coating were observed by scanning electron microscopy(SEM).The microhardness,friction and wear and electrochemical corrosion properties of the coating were analyzed by microhardness tester,wear tester and electrochemical workstation.The microstructure and prop,erties of the coatings were studied.The results are as follows.The XRD pattern show that the amorphous phase of FeCoCrMoCBY amorphous alloy powder exhibits diffuse scattering peaks between 30 and 60 degrees without sharp diffraction peaks,indicating that the Fe-based alloy powder prepared by gas atomization is amorphous;the amorphous phase of ZrCuNiAl powder exhibits diffuse scattering peaks between 30 and 50 degrees,but also contains sharp diffraction peaks,amorphous content is about 67 vol%.The results show that the amorphous content of Zr-based alloy powder prepared by gas atomization is higher.Scanning electron microscopy showed that the amorphous powder of FeCoCrMoCBY was spherical,a few were ellipsoidal or rod-shaped,and the surface was smooth.ZrCuNiAl powder was spherical,a few were elliptical,and had good fluidity.Small particles were adhered to the surface of large particles.The particle size and shape basically met the requirements of plasma spraying.The effect of nine spraying parameters on the porosity of coatings was studied by measuring the porosity of coatings.The suitable process parameters were obtained:spraying power was 22.5 kW(arc voltage was 50 V,arc current was 450 A),spraying distance was 120 mm.The porosity of FeCoCrMoCBY amorphous alloy coating prepared under this parameter is 4.32%.The coating has uniform structure and smooth surface.The coating has a wide diffuse diffraction peak and its amorphous content is about 90 vol%.By observing the SEM cross section of the coating and the substrate,it can be seen that the thickness of the coating is about 250 microns.The bonding strength test between N80 carbon steel substrate and FeCoCrMoCBY amorphous alloy coating sbows that the bonding mechanism between coating and matrix is simple mechanical bonding.The average bonding strength of coating reaches 31.96 MPa,which is higher than that of common ceramic coating(25 MPa).It can meet the requirements of the general working environment of the coating and the requirements of the project.The wear resistance tests of N80 carbon steel substrates and FeCoCrMoCBY amorphous alloy coatings show that the main wear mechanisms of substrates are micro-cutting and adhesion wear.The wear forms of FeCoCrMoCBY amorphous alloy coatings are mainly abrasive wear and fatigue wear.The friction coefficient of substrates fluctuates around 1.0.The friction coefficient of coatings is lower than that of substrates and fluctuates around 0.8.FeCoCrMoCBY amorphous alloy coatings treated by different cryogenic treatment processes show that the amorphous properties of Fe-based amorphous alloy coatings can still be obtained under different cryogenic treatment time.Proper cryogenic treatment of the coatings can effectively reduce the porosity and increase the hardness of the coatings.When cryogenic treatment lasts 48 hours,the porosity reaches 2.54%and the microhardness reaches 720 HV.Long,on the one hand,the friction coefficient of the coating decreases gradually,reaching 0.6 at 48 h of cryogenic treatment,and the wear loss decreases gradually,reaching 0.5 mg at 48 h of cryogenic treatment,that is,the wear resistance increases gradually;on the other hand,the corrosion potential of the coating increases gradually,and when the corrosion potential reaches-0.39285 V at 48 h of cryogenic treatment,the corrosion tendency decreases gradually,the corrosion current density decreases gradually,and the corrosion current density decreases gradually at 48 h of cryogenic treatment.The corrosion rate of the coating decreases to 2.0111×10-6 A/cm2,which means that cryogenic treatment improves the corrosion resistance of the coating.By adding different content of Zr-based alloy powder into FeCoCrMoCBY amorphous alloy powder,it is shown that the amorphous phase partially crystallized during spraying process after adding different content of Zr-based alloy powder into FeCoCrMoCBY amorphous alloy powder.The composite coating contains Cu4Y,Y3.45(B12)13B42.08 and YNiBC,but the main phase of the coating is still amorphous phase;with the content of Zr-based alloy powder,the amorphous phase of the coating is still amorphous.The surface roughness,water contact angle,microhardness,wear resistance and corrosion resistance of the composite coatings decrease with the increase of surface roughness,water contact angle and microhardness.