Plasma electrolytic oxidation（PEO） coatings were prepared on AZ31 magnesium alloy using alkaline phosphate as base electrolyte system, and with the addition of sodium silicate（Na2SiO3）, sodium aluminate（NaAlO2） ...Plasma electrolytic oxidation（PEO） coatings were prepared on AZ31 magnesium alloy using alkaline phosphate as base electrolyte system, and with the addition of sodium silicate（Na2SiO3）, sodium aluminate（NaAlO2） and potassium fluorozirconate（K2ZrF6） as additives. The microstructure, phase composition and element composition as well as surface profile of the PEO coatings were analyzed by means of scanning electron microscopy（SEM）, X-ray diffraction（XRD）, energy dispersive X-ray spectroscopy（EDS）, and threedimensional（3 D） optical profilometry. The corrosion and wear properties were evaluated by electrochemical potentiodynamic polarization in 3.5 wt% Na Cl solution and ball-on-disc wear tests, respectively. The results showed that the anions of the additives effectively participated in the coating formation influencing its microstructural features, chemical composition, corrosion resistance and tribological behaviour. It was observed that the sample treated by PEO in the electrolyte solution containing K2ZrF6 as an additive showed better corrosion and abrasive resistance.展开更多
La2Zr2O7 thermal barrier coatings（TBCs） with dispersed Pt particles were prepared by cathode plasma electrolytic deposition（CPED） with ceramic balls added to the cathode region. Compared with the conventional CPED...La2Zr2O7 thermal barrier coatings（TBCs） with dispersed Pt particles were prepared by cathode plasma electrolytic deposition（CPED） with ceramic balls added to the cathode region. Compared with the conventional CPED, when ceramic balls are used in the cathode region, the plasma discharge ignition current density decreases approximately 62-fold and the stable plasma discharges occur at the whole cathode surface. Such TBCs with a thickness of 100 μm exhibit a crack-free surface and are composed of pyrochlore-structured La2Zr2O7. Cyclic oxidation, scratching, and thermal insulation capability tests show that such TBCs not only exhibit high resistance to oxidation and spallation but also provide good thermal insulation. These beneficial effects are attributed to the excellent properties of TBCs, such as good thermal insulation because of low thermal conductivity, high-temperature oxidation resistance because of low-oxygen diffusion rate, and good mechanical properties because of the toughening effect of Pt particles.展开更多
基金Funded by National Natural Science Foundation of China(No.51371039)Zhejiang Provincial Natural Science Foundation of China(No.LGG18E020004)+1 种基金Open Foundation of Zhejiang Provincial Top Key Discipline of Mechanical EngineeringScience and Technology Project of Zhejiang Province(No.2015C37037)
文摘Plasma electrolytic oxidation（PEO） coatings were prepared on AZ31 magnesium alloy using alkaline phosphate as base electrolyte system, and with the addition of sodium silicate（Na2SiO3）, sodium aluminate（NaAlO2） and potassium fluorozirconate（K2ZrF6） as additives. The microstructure, phase composition and element composition as well as surface profile of the PEO coatings were analyzed by means of scanning electron microscopy（SEM）, X-ray diffraction（XRD）, energy dispersive X-ray spectroscopy（EDS）, and threedimensional（3 D） optical profilometry. The corrosion and wear properties were evaluated by electrochemical potentiodynamic polarization in 3.5 wt% Na Cl solution and ball-on-disc wear tests, respectively. The results showed that the anions of the additives effectively participated in the coating formation influencing its microstructural features, chemical composition, corrosion resistance and tribological behaviour. It was observed that the sample treated by PEO in the electrolyte solution containing K2ZrF6 as an additive showed better corrosion and abrasive resistance.
基金financially supported by the National Natural Science Foundation of China (No. 51271030)
文摘La2Zr2O7 thermal barrier coatings（TBCs） with dispersed Pt particles were prepared by cathode plasma electrolytic deposition（CPED） with ceramic balls added to the cathode region. Compared with the conventional CPED, when ceramic balls are used in the cathode region, the plasma discharge ignition current density decreases approximately 62-fold and the stable plasma discharges occur at the whole cathode surface. Such TBCs with a thickness of 100 μm exhibit a crack-free surface and are composed of pyrochlore-structured La2Zr2O7. Cyclic oxidation, scratching, and thermal insulation capability tests show that such TBCs not only exhibit high resistance to oxidation and spallation but also provide good thermal insulation. These beneficial effects are attributed to the excellent properties of TBCs, such as good thermal insulation because of low thermal conductivity, high-temperature oxidation resistance because of low-oxygen diffusion rate, and good mechanical properties because of the toughening effect of Pt particles.
