Cathodic Plasma Electrolytic Deposition And Properties Study Of Alumina-based Coatings On TC4 Fabricated

Surface engineering techniques are widely used to improve the surface wear resistance and biocompatibility of TC4. In this dissertation, Al2O3/MOS2 composite coating that aimed at improving the wear resistance and corrosion resistance of TC4 substrate and Al2O3/HA composite coating that aimed at improving the corrosion resistance and biocompatibility of TC4 were produced by cathodic plasma electrolytic deposition process (CPED). The surface structure and their corresponding elemental composition of the coating were obtained by SEM, which was equipped with EDS. Coating phases were analyzed via XRD. The friction property and corrosion behavior were detected by specific machines. The degradation behavior of the coated samples were characterized by electrochemical tests in the simulated body fluid (SBF).The marked feature of coating preparative via cathodic plasma electrolytic deposition is porous. Deposition voltage was the main parameter with significant effects of the coating micro structure, the diameter of the hole was get bigger when the deposition voltage got higher. The voltage duty cycle and deposition time were with no great influence to the coating structure. The thickness of coating was significantly affected by the concentration of Al(NO3)3-C2H6O solution and deposition time.Al2O3/MOS2 coating was prepared in the condition of pulse voltage at 300 V. The results show that the porous coating is mainly composted of a-Al2C3、γ-Al2O3 and MoS2, with the thickness of about 100μm. The friction coefficient of the coating derived from the friction test is deduced by 1/3 to that of Ti6A14V substrate. Much higher corrosion resistance of the coating is also proved by the corrosion behavior analyzer with higher potential value and lower current density value.Two kinds of solutions were used to prepare Al2O3/HA coating. One solution is Al(NO3)3-C2H6O solution with HA granules added, the coating acquired is composted of a-Al2O3, y-Al2O3 and Ca10(P04)6(OH)2. Polarization curves show that corrosion resistance of the coating is better than substrate, and the caoting show significant biocompatibility under the SBF environment. The other solution is the mixture of Al(NO3)3-C2H6O solution and Ca(NO3)2-Na3PO4-H2O solution, but the coating prepared in it performed poor cover ability.