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Mo ions extracted from a metal vapor vacuum arc ion source were implanted into H13 steel with a high implantation dose of 5 × 1017 cm−2 and a pulsed ion beam flux of about 300 μA cm−2. An optical interference microscopy and pin on disc apparatus investigated the wear and friction characteristics of the steel. The Mo concentration depth profile was measured by using Rutherford backscattering spectroscopy. It was observed by X-ray photoelectron spectroscopy and grazing angle X-ray diffraction that carbide of Mo appeared in the doped region. The concentration depth profile and microstructure analysis could serve to illuminate the wear resistance improvement mechanisms of the Mo implanted steel.

Ultra-thin (5 nm) Fe catalyst films were deposited by a metal vapor vacuum arc (MEVVA) ion deposition system. The surface morphologies of the films were controlled by varying the angular relation of the substrate surface with respect to the incoming vapor direction. The Fe films grown with the incident flux at an angle of 30° with respect to the surface were shown to be smooth and after thermal treatment in NH3 the particles with a narrow size distribution and high N/Fe atom ratio were followed. When they were used to synthesize carbon nanotube arrays, pure and well-aligned multi-walled carbon nanotubes were obtained.

Metal Vapor Vacuum Arc (MEVVA) ion source and ion implanter developed in Beijing Normal University (BNU) is introduced. The application in surface modification of materials with MEVVA ion implanter is reviewed.

H13 steel samples were implanted with tungsten using a metal vapor vacuum arc (MEVVA) ion source, with an implantation dose of 1×1017 cm -2, an extraction acceleration of 30 kV and pulsed ion beam fluxes of between 0.3 mA·cm -2 and 6 mA·cm -2. The surface mechanical properties and microstructure for the W-implanted samples was characterized by the Rutherford backscattering spectroscope (RBS) and a high voltage electron microscope (HVEM). Experimental results of wear and hardness indicated that the hardness and wear of H13 steel increased when the voids were produced by tungsten ion implantation with a high pulsed current density. Forming causes for voids and their influence on the tungsten concentration depth profile in the implanted H13 steel and the surface mechanical properties were discussed in terms of spike theory.

Tetrahedral amorphous carbon films have been widely recognized as being wear-resistant coatings with a low friction coefficient, but their tribological behavior strongly depends on the tribotesting conditions and the nature of the coating, which depends on the technique used for film deposition. In this paper the structure, mechanical properties and wear resistance of the tetrahedral amorphous carbon films deposited on silicon, W18Cr4V high-speed steel and Cr18Ni9 stainless steel substrates by pulsed filtered catholic vacuum arc system have been investigated. The wear test results show: the tetrahedral amorphous carbon films have wear coefficient of 0.14–0.20 and wear rate of 5.833×10 −9 mm 3 /N m for an applied load of 5 N and 6000 cycles against sapphire ball. The effects of substrate, applied load, frequency and film thickness on coefficient of friction have been studied.

In this work, high concentration erbium doping in silicon-rich SiO2 thin films is demonstrated. Si plus Er dual-implanted thermal SiO2 thin films on Si substrates have been fabricated by using a new method, the metal vapor vacuum arc ion source implantation with relatively low ion energy, strong flux and very high dose. X-Ray photoelectron spectroscopy measurement shows that very high Er concentrations on the surfaces of the samples, corresponding to ∼10 at.% or the doping level of ∼1021 atoms cm−3, are achieved. This value is much higher than that obtained by using other fabrication methods such as the high-energy ion implantation and molecular beam epitaxy. Reflective high-energy electron diffraction, atomic force microscopy and cross-section high-resolution transmission electron microscopy observations show that the excess Si atoms in SiO2 matrix accumulate to form Si clusters and then crystallize gradually into Si nanoparticles embedded in SiO2 films during dual-ion implantation followed by rapid thermal annealing. Er segregation and precipitates are not formed. Photoluminescence at the wavelength of 1.54 μm exhibits very weak temperature dependence due to the introduction of Si nanocrystals into the SiO2 matrix. The 1.54-μm light emission signals from annealed samples decrease by less than a factor of 2 when the measuring temperature increases from 77 K to room temperature.

Microarc oxidation is an advanced coating process to deposit thick, hard ceramic oxide coatings on metal surfaces. In this paper, a ceramic oxide coating of 30μm was prepared on TA2 pure titanium by alternating-current microarc oxidation in aluminate solution. Its morphology, composition and structure were characterized by scanning electron microscopy, X-ray diffractometry, Raman spectroscopy. The Al, Ti, O concentration profiles across the coating were determined by energy dispersive spectroscope. The outer layer of the coating is composed of a large amount of TAl 2 O 5 and a little rutile type TiO 2 compounds. But the rutile content in the inner layer is much higher than in the outer layer while the TiAl 2 O 5 content decreases obviously in the inner layer. All of these oxides derive from a rapid solidification of the melt in microarc discharge zone. The Al atoms from the aqueous solution have diffused to the coating/titanium substrate interface, but are enriched in the outer layer. However, the oxygen and aluminum atoms have not diffused into the unoxidized titanium substrate, even near the coating/substrate interface. This facilitates maintaining mechanical properties of pure titanium substrate after microarc oxidation treatment on titanium surface.

A dense ceramic coating up to 130μm thick was deposited on high silicon cast aluminum alloy by microarc discharge in silicate electrolyte. Its microstructure and composition were analyzed by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and phase identification was performed by X-ray diffraction (XRD). In addition, the distributions of hardness, H, and elastic modulus, E, across the ceramic coating were determined by nanoindentation method. The coating has a three-layer structure. The profiles of H and E in the coating are similar. From the surface to the inner layer of the coating, H and E gradually increase. The inner layer is dense and hard, in which the H and E can reach about 15 GPa and 250 GPa, respectively. This coating consists of mullite, γ-Al 2 O 3 , γ-Al 2 O 3 and amorphous SiO 2 phases. The surface layer enriched in Si element has a high fraction of amorphous SiO 2 , where the Si element comes mainly from the electrolyte rather than the alloy substrate. However, the Si element from Al-Si substrate enhances the formation of mullite phase in the coating.

A dense ceramic oxide coating, about 50 µm thick, was prepared on a Ti–6Al–4V alloy by alternating current microarc oxidation in an aluminate solution. Its microstructure and phase composition were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The oxide coating contains two layers: an outer layer and a dense internal layer. The coating is mainly composed of TiO2 rutile and TiAl2O5 spinel phases. In the outer layer coating, the TiAl2O5 fraction is much higher than the rutile fraction. However, in the internal layer, rutile becomes the main phase while the TiAl2O5 fraction decreases significantly. During microarc oxidation, local melt–solidification processes take place in the coating, however, the microstructure of the Ti–6Al–4V substrate near the coating/metal interface is not changed. Aluminium from the solution is enriched in the outer layer coating, although it has also diffused into the interior of the coating.

Growth regularity of ceramic coatings formed on Al–Cu–Mg alloy by microarc oxidation was investigated, and the formation mechanism of coatings was discussed. After oxidation of several hours with linear growth, the growth rate of coatings decreases gradually. During the early stage, the sample geometrical dimension increases with oxidation. However, when the ceramic oxide coating reaches a certain thickness, the sample geometrical dimension will no longer increase although the total coating thickness keeps increasing. The oxide coatings contain a loose layer and a compact layer. The loose layer is formed first. After several hours, the compact layer begins to grow towards the Al substrate while the thickness of the loose layer changes little. The thickness of the compact layer can finally reach over 75% of the total coating thickness. After the surface loose layer is ground off, the sample dimension is approximately the same size as the sample before the treatment.

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.

In this paper, Ni–Cr–Mo–Nb multi-element surface alloying has been investigated on a substrate of three kinds of industrial steels (industrial pure iron, low carbon steel and 304 stainless steel) by means of the double glow plasma surface alloying technique. The results showed that highly alloyed nickel-based surface alloying layers were formed on the surface of the three kinds of steels. The alloying layer was uniform, continuous and compact. The alloying layers consisted of a γ phase or γ matrix with several precipitates (P or Laves phase, and NbC carbide, etc.). A method of eliminating these precipitates has also been discussed. The corrosion resistance of the nickel-based surface alloying layer was investigated by an electrochemical method in a 3.5% NaCl and 5% HCl solution, and 200-h exposure tests in a 20% H2SO4 and 20% HCl solution. The corrosion resistance of surface alloying layer formed on stainless steel substrate was better than that of the nickel-based alloy Inconel 625 and 304 stainless steel. The experimental results indicated that this is an effective way to obtain a high quality corrosion resisting surface alloying layer on the surfaces of steels using the double glow plasma surface alloying technique.

The surface properties of Nb+C co-implanted stainless steel have been studied. The co-implantation of Nb+C ions was carried out using a modified cathode of a metal vapor vacuum arc (MEVVA) source ion implanter. The results of the experiment showed that the properties of wear resistance and the hardness in the co-implanted surface layer were improved. The dislocation network and tangle were observed by TEM. The dispersion hardening phases were determined by XRD and TEM to be Fe2Nb, Cr23C6, Cr3C2 and Fe5C2. Therefore, dispersion hardening and dislocation hardening were expected. The results were also compared with those of Nb+C ion dual implantation. This showed that there were some unique advantages to co-implantation.

The microstructure near the interface between a 2024 Al alloy substrate and a ceramic coating formed by microarc oxidation has been studied using scanning electron microscopy and energy dispersive spectrometry. Hardness and elastic modulus on the two sides of the interface were investigated using nanoindentation and Vickers microhardness measurement. The results showed that the microstructure of the substrate was not changed by application of the coating, and a hardened zone was not observed. During microarc oxidation, no remelting of the substrate occurred, but remelting of the alumina ceramic coating on the other side of the interface did take place. The mechanical properties on the two sides of the interface had obvious differences: in a certain range of coating thickness there was a gradual increase of hardness and elastic modulus from the interface to the interior of the coating, but hardness remained almost constant in the substrate.

The electrochemical behavior of H13 steels implanted with titanium and carbon ions using MEVVA ion implantation was investigated. Anodic polarization measurement in acetic acid and sodium acetate solution was used to evaluate the corrosion resistance of steels before and after implantation. Lower corrosion current density and wider passive region were obtained on the implanted specimens. The saturated corrosion current density for implanted specimens decreased by 60–88% of that of unimplanted specimens in multi-polarization tests, indicating that the corrosion rate of the implanted surface was much lower. Scanning electron microscopy indicated that the pit density was lower on the surface of implanted specimens. The corrosion resistance was clearly improved after implantation.

Strong ultra-violet and visible frequency up-conversion fluorescence spectroscopy in neodymium-ion implantation single crystalline silicon at the excitation wavelengths of 625, 650, 675 and 700 nm, was experimentally investigated. The PL intensity increased with the increase in the excitation wavelength and ion fluence. The photoluminescence excitation (PLE) spectrum in the wavelength range of 500–770 nm was also studied. For 700-nm pumping, a mechanism of two-photon absorption and radiation transition process was proposed.

The cathode in a metal vapor vacuum arc (MEVVA) source was modified and co-implantation of V + C was carried out with the modified cathode. The result of the experiment shows that the properties of wear resistance on the co-implanted surface layer have been improved. The surface hardness has increased by 16 ∼ 82%, and the wear resistance is 1.4 ∼ 2.2 times that of unimplanting surface. By means of X-ray diffraction (XRD) and transmission electron microscopy (TEM), intermetallic compounds, such as FeV, Cr 2 VC 2 , Cr 23 C 6 , VC and Fe 5 C 2 , were observed. These new phases contributed to the improvement of the surface properties for implanted layer. The results were also compared with that of V + C dual implantation. It is shown that co-implantation method is more effective than dual-implantation for surface modification.

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.

High-current metal-ion sources for the surface modification of materials have been under development at Beijing Normal University since 1988. The present paper discusses both a large-scale metal source ion implanter installed at this Institute at the end of 1995 for research and industrial applications, and a metal plasma deposition/implantation system with three filtered vacuum-arc plasma sources. The metal source implanter is equipped with three ion sources and hence can provide three beams of metal ions into a large target chamber of 80 cm diameter and 125 cm length. It allows processing of critical components with various shapes and tooling inserts. Cutting tools — such as inserts, drills, disc cutters and dies — and sophisticated components — such as rotors and stators of off-gas pumps for returnable artificial satellites — have been implanted with many different metal species to improve properties like hardness, wear resistance, coefficient of friction, fatigue strength, corrosion resistance, adhesion and to prolong lifetimes. Some good results are presented.

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.

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.

The formation of intermetallic compounds on titanium implantation into H13 steel at different target temperature (-196, 150 and 400 °C) is studied. The steel strengthening mechanism of titanium implantation with different doses and target temperatures was discussed. The titanium ions are implanted in the energy range from 100 to 300 keV and dose range from 1 × 10 17 to 5.5 × 10 17 cm -2 . The observations of phase change, microstructure and intermetallic compounds were carried out by high voltage (1 MV) electron microscopy and X-ray diffraction analysis. The hardness of the implanted layer increases one to 2.5 times for low temperature (-196 and 150 °C) implantation, two to three times for moderate temperature (MT) (400 °C) implantation. The wear rate decreases two to 2.6 times for low temperature implantation and ten times for MT implantation. The influence of target temperature and dose on metallic strengthening is discussed.