Huixing Zhang

Behaviour of MEVVA metal ion implantation for surface modification of materials

Abstract MEVVA ion implantation of Mo, Mo + C and Ti + C in H13 steel at high ion flux was studied. The results show that dispersive hardening phases grow with increasing ion flux. The growth of the phases is accelerated by annealing. The resistance to wear and corrosion for Mo-implanted steel is improved relative to unimplanted steel. After corrosion, the dispersive hardening phases which inhibit corrosion can be observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A dense network of phases for Mo + C-implanted steel is observed by SEM and TEM. The corrosion resistance of Mo + C-implanted H13 steel is much better than that of Mo-implanted H13 steel. The corrosion current density for Ti + C-implanted H13 steel is very small (0.1 mA cm −2 ); after annealing, the current density is near zero. SEM observation shows that, after corrosion for 50 voltage loops, no corrosion trace can be observed.

Formation of complex carbon films on implanted carbon layers by pulsed V=C and Ti+C dual implantation into steel

Abstract Thin carbon films and implanted C complex layers are formed using pulsed V + C and Ti + C dual implantation into H13 steel. The thickness of the C films on the implanted layers were observed by Auger analysis to be 20–50 nm. The C film can reduce the surface friction factor and induce surface lubrication. The surface hardening properties of pulsed Ti + C and V + C were studied. Solid solution hardening was obtained for implanted atom concentrations of 20–45 at.%. Fine grains and dense dislocations were observed by transmission electron microscopy, so fine grain hardening and dislocation hardening are expected. The dispersion hardening phases were distinguished by X-ray diffraction and electron spectroscopy to be Fe 2 Ti, FeV, TiC and VC.

Metal vapour vacuum arc source ion implantation as a surface treatment technique for industrial tool bits

Abstract Multicharged, pure, high current, divergent and pulsed ion beams of titanium and carbon species have been extracted from a metal vapour vacuum arc (MEVVA) source, manufactured at the Beijing Normal University, and then implanted directly into steels and other metals for surface modifications in both research and industrial trials. The preliminary results of the tribological influence of ion species, the dependence of wear performance on titanium dose, the uniformity and reproducibility of MEVVA source ion implantation and Auger electron spectroscopy concentration profile analyses were used as a guide for tooling applications. Selected examples of successful improvements in the wear lifetime of industrial tools are presented to evaluate MEVVA source ion implantation as an innovative ion beam process for industrial applications, especially for high value, low dimensional tolerance, critical and precise tools and components.

Measurement of some parameter on MEVVA ion source

The charge density and the charge state distribution of ions extracted from metal vapor vacuum arc ion source have been measured by single, double probe, and time of flight systems, and the ion beam density distributions near the extracting electrode have been measured with and without a cusped magnetic field in order to improve the performance of ion beams. The charge state distributions as a function for many operational cathode materials were investigated.

Mevva ion source for the application of material surface modification

Several versions of Mevva ion sources have been developed in our institute since 1988. It operates in a pulsed mode with a pulse length of 1.2 ms and a repetition rate of up to 50 pps. A time‐averaged beam current of 10 or 50 mA has been extracted at 30–80 kV from Mevva IIA‐H and Mevva IIB, respectively. In order to develop surface modification of materials by ion implantation we have constructed three kinds of Mevva ion source implantation systems. High dose (3–5×1017 cm−2) implantation with Ti, Ce, Y, and Ti+C, etc. has been carried out for improving the lifetime of metal cutting tools, relay contacts, dies, and some sophisticated components.

Surface structure and corrosion properties of binary Ti-C and Mo-C coatings co-deposited by filtered vacuum arc plasma deposition system

Abstract Thin (Ti,C) and (Mo,C) binary coatings were respectively formed on the surface of H13 steel by Ti + +C + and Mo + +C + dual beams deposition using filtered vacuum arc plasma deposition (FVAPD) system with three MEVVA sources. Using the three-electrode potential-kinetic polarization technique, the corrosion properties of these coatings in acetic acid and sodium acetate solutions or sodium chloride solutions were measured. The results indicate that the binary coatings fabricated by this technique have good compactness and corrosion resistance. A comparison between (Ti,C), (Mo,C) coatings and H13 steel with pure Ti coating in terms of the corrosion resistance was given. Electron diffraction and XRD results show that the structure of the binary coatings presents a mixed polycrystalline and amorphous state.

Structure and corrosion behavior of (Ti, Fe, C) films co-deposited by three metal vapor vacuum arc beams

Abstract Thin (Ti, Fe, C) ternary films were formed on the surface of H13 steel by Ti + , Fe + , C + three-beam co-deposition using a filtered vacuum arc plasma deposition (FVAPD) system with three metal vapor vacuum arc (MEVVA) ion sources. Using the three-electrode potential–kinetic polarization technique, the corrosion resistance of these coatings in acetic acid and sodium acetate solutions or sodium chloride solutions was measured. The results indicate that the films formed by this technique have good compactness and high corrosion resistance. A comparison between the (Ti, Fe, C) films and pure Ti films or (Ti, Fe, C) layers formed by C + +Ti + dual implantation into H13 steel as regards the corrosion resistance is given. Reflective high-energy electron diffraction (RHEED), X-ray diffraction (XRD) and scanning electron microcopy (SEM) results show that the structure of the films present a mixed polycrystalline and amorphous state, which results in excellent corrosion resistance of the films.

Property improvement of multilayer TiN/Ti films with C+ implantation

Using the MEVVA ion source, carbon ions have been implanted in TiN coatings deposited by multiarc ion plating. The Vickers microhardness of the C+-implanted TiN films increased with the increase in the ion flux and dose. X-ray diffraction (XRD) analysis showed that the TiC phases had been formed in the films. In addition, the films had the preferred growth orientations of TiN and TiC, both of which were (111) orientation after annealing at 500°C for 30 min. Auger electron spectra analysis indicated that C+-implanted profile was in typical Gaussian-like distribution in single films. The distribution with multipeaks of C atoms was obtained in multi-layer TiN/Ti. The possibility of the multilayer films (Ti(C,N)/TiN/Ti(C,N)/TiN and Ti(C,N)/TiC/Ti(C,N)/TiC) forming using the C-implanted TiN/Ti films is presented for the first time.