Investigation on microstructure and wear resistance of La-doped micro-arc oxidation coating on TC4 alloy surface
Aiming at the problem of poor wear resistance of TC4 titanium alloy during service,La-doped ceramic coatings were prepared on the surface of TC4 titanium alloy by micro-arc oxidation process in calcium acetate-sodium hexametaphosphate electrolyte system in this paper,the effect of La(NO3)3 doping in electrolyte on the wear resistance of TC4 titanium alloy micro-arc oxidation coating(MAO)was investigated.The phase composition,microstructure,thickness,microhardness,friction coefficient and adhesion of micro-arc oxidation coatings with different La(NO3)3 doping amounts were characterized by XRD,SEM,microhardness tester,friction and wear tester,coating adhesion scratch tester and other instruments.The results showed that with the increase of La(NO3)3 doping amount,the MAO coating was composed of HAp,A-TiO2,R-TiO2 and La2O3 phases.Although the La-doped coating thickness was slightly reduced,the compactness was improved.The microhardness of the coating increased first and then decreased,at the same time,the friction coefficient decreased first and then increased.When the doping amount of La(NO3)3 was 6 g/L,the microhardness of the coating in-creased by 31.18%,the adhesion between the coating and the substrate increased by 30.59%.The friction coefficient of the MAO coating was the smal-lest,which was about 0.55.