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In this paper, a platinum coating was deposited on titanium alloy substrate by a double glow plasma. Phase and microstructure of platinum coating were examined by X-ray diffraction and scanning electron microscopy, respectively. The microhardness of the coating was estimated by nanoindentation instrument. The adhesive force between the coating and the substrate was performed with scratch tester. The electrochemical behavior of the platinum coating in 3.5 wt % sodium chloride solution was investigated by potentiodynamic polarization. The results indicated that an adherent platinum coating could be successfully obtained on titanium alloy substrates. Compared with the titanium alloy substrate, the platinum coating had a relative low corrosion current density and high corrosion potential. It indicated that the platinum coating had a better corrosion resistance than the titanium alloy substrate. [ABSTRACT FROM AUTHOR]

Abstract: Ir–Zr co-deposition coatings with 71at% Zr were deposited on graphite by double glow plasma at 1073–1123K. The structure and composition of the coatings were confirmed by FE-SEM, XRD, XPS and EDS. The hardness and the elastic modulus of the coatings were estimated by nanoindentation instrument. The adhesion strength between the coating and the substrate was evaluated by a scratch tester. The results showed that the coating was composed of nanocrystalline grains with a size of 80–90nm compared with 0.5μm for the pure Ir coating. The fine grains of the coatings might be attributed to the additional Zr element. New phases IrZr and ZrC were formed due to the high content of Zr and high deposition temperature. The hardness and elastic modulus of the coatings were about 7.5GPa and 388GPa, respectively. The adhesive force between the coating and the substrate was about 10N. [Copyright &y& Elsevier]

Abstract: Ir–Zr gradient coating was obtained on the Mo substrate by double glow plasma. The structure and composition of the coatings were confirmed by SEM, AFM, XRD and EDS, respectively. The adhesion strength between the coating and the substrate was evaluated by a scratch tester. Compared with preferential growth orientation of (220) crystal plane of Ir coating, the Ir–Zr coating had a random orientation structure. The RMS roughness value of the Ir–Zr coating is 19.3nm, which was lower than the roughness value of 45nm for Ir coating. The Ir–Zr coating with the thickness of 5.0μm was composed of two distinct layers. The proportion of Ir decreased gradually from the surface of the coating to the coating/substrate interface. The Zr distribution decreased slightly in the coating. The adhesive force of the Ir–Zr coating was 15N. [Copyright &y& Elsevier]

Abstract: Iridium coating was produced on various substrates using a double glow plasma. The effects of bias voltage and gas pressure on orientation and microstructure of the coating were studied. The orientation, microstructure and composition of the coating were evaluated by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The results showed that iridium coatings on various substrates all exhibited the preferred (220) orientation under the same deposition conditions. The microstructure of the coating was affected by bias voltage, gas pressure and substrate effects. The bias voltages had a significant impact on the crystal orientation of the coating. The increase of bias voltage resulted in high substrate temperature and large deposition rate. An increase in the coating thickness can affect the microstructure and orientation of the coating. [Copyright &y& Elsevier]