Vacuum Arc Source Research Articles

The effect of MEVVA implanted Cr on the corrosion resistance of CrN coated low alloy steel by cathodic arc plasma deposition

Metal vapor vacuum arc (MEVVA) source implantation is a novel and profitable surface modification process. Cathodic arc plasma deposition of CrN coating has been applied on an industrial scale to improve the corrosion resistance of AISI 4140 steel. The effect of the Cr implanted by MEVVA (Cr/steel) on the corrosion behavior of CrN/steel through the surface modification was investigated. Both AISI 4140 steel and its coated assemblies of Cr/steel, CrN/steel and CrN/Cr/steel were evaluated in aerated 0.1 N HCl solution. The composition and structure of the MEVVA implanted Cr and cathodic arc plasma deposited CrN on steel were studied by X-ray diffraction and secondary ion mass spectrometer. The polarization resistance ( R p) of all samples was measured and compared with d.c. polarization resistance and electrochemical impedance spectroscopy. The microstructure of corroded samples was also examined by scanning electronic microscopy and electron probe X-ray microanalyser. The results indicated that the corrosion resistance of CrN coated steel was significantly enhanced by the MEVVA implanted Cr in CrN/Cr/steel.

Effect of solenoid magnetic current on the beam extraction of filtered vacuum arc source (FVAS)

In this study, a new type of filtered vacuum arc source (FVAS) was designed, which was composed of a torus structure with bending angle of 60°. The radius of torus and plasma duct was 266 mm and 80 mm, respectively, and the total length was 600 mm. The magnet part was composed of one permanent magnet, one magnetic yoke and five solenoid magnets. The cathode evaporation region with a modified magnetic mirror configuration was adapted. The plasma duct was electrically isolated from the ground so that a bias voltage could be applied. The cathode was made of graphite and was 80 mm in diameter. A computer simulation and experiment using the Taguchi method (design of experiment) studied the effects of a solenoid magnet on plasma extraction. The source and extraction magnet affected the arc stabilization. The extraction beam current was maximized with a low value of the source magnet current and a high value for the filtering magnet current. The maximized values of the beam current density of 1.8 mA cm 2 and average deposition rate of 5 Å/s were obtained at the conditions of the arc discharge current, source, extraction and bending magnet were 30 A, 1 A, 3 A and 3 A, respectively.

The modification behaviour for Si implanted PET

Polyethylene terephthalate (PET) has been modified by Si ion implantation with a dose ranging from 1 × 10 16 to 2 × 10 17 ions /cm 2 using a metal vapor vacuum arc（MEVVA）source. The surface morphology was observed by atomic force microscopy (AFM). The change in the microstructure of Si implanted PET was observed with a transmission electron microscope (TEM). It is believed that the change would improve the conductive properties and wear resistance. The electrical properties of PET have been improved via Si ion implantation. The resistivity of implanted PET decreased obviously with an increase in ion dose. When Si ion dose was 2 × 10 17 cm -2 , the resistivity of PET could be less than 7.9 W·m. The surface hardness and modulus increased obviously. The mechanical property of the implanted PET has been modified greatly. The hardness and modulus of Si implanted PET with a dose of 2 × 10 17 /cm 2 are 12.5 and 2.45 times greater than those of pristine PET, respectively. The area of cutting groove for Si implanted PET is narrower and shallower than those of the unimplanted PET. So the wear resistance is greatly raised. In comparison with metal ion implantation, the improvement of mechanical properties is obvious in ion implantation into PET. Si ion beam modification mechanism of PET is discussed.

Influence of lanthanum ion implantation on the aqueous corrosion behavior of zirconium

In order to investigate the effect of lanthanum ion implantation on the aqueous corrosion behavior of zirconium, specimens were implanted with lanthanum ions at a dose ranging from 1×10 16 to 1×10 17 ions/cm 2 at maximum 130 °C, using a metal vapor vacuum arc (MEVVA) source at an extracted voltage of 40 kV. The valence of the surface layer was analyzed by X-ray photoemission spectroscopy (XPS). Three-sweep potentiodynamic polarization measurement was employed to determine the aqueous corrosion resistance of zirconium in a 1 N H 2SO 4 solution. It was found that a significant improvement was achieved in the aqueous corrosion behavior of zirconium implanted with lanthanum ions compared with that of the as-received zirconium. Finally, the mechanism of improvement in the corrosion resistance of the lanthanum-implanted zirconium is discussed.

Fractal Pattern Growth in Ti-Implanted Steel with High Ion Flux

We report on the formation of metal nanometre phase and fractal patterns insteel using metal vapour vacuum arc source ion implantation with high ionflux. The dense nanometre phases are cylindrical and welldispersed in the Ti-implanted layer with an ion flux up to 50 µA/cm2. The collision fractal pattern is formed in Ti-implanted steelwith an ion flux of 25 µA/cm2 and the disconnected fractal pattern isobserved with an ion flux of 50 µA/cm2. The average density ofnanometre phases decreases from 1.2×1011/cm2 to6.5×1010/cm2 as the ion flux increases from 25 µA/cm2 to50 µA/cm2. Fractal pattern growth is in remarkable agreement withSander's diffusion-limited aggregation model. The alloy clusters havediffused and aggregated in chains forming branches to grow a beautiful treeduring Ti implantation with an ion flux ranging from 75 µA/cm2 to85 µA/cm2. We discuss the model of fractal pattern growth during ionimplantation with high ion flux.

The nano-structure and properties of Ag-implanted PET

Polyethylene terephthalate (PET) has been modified by Ag ion implantation with a dose range from 1×10 16 to 2×10 17 ions/cm 2 using a metal vapor vacuum arc source. The surface morphology was observed by atomic force microscopy. The Ag atom precipitation was determined. The change of the nano-structure of Ag-implanted PET was observed using a transmission electron microscope. It is believed that this change causes an improvement of the conductive properties and wear resistance. The electrical properties of PET were also changed after Ag ion implantation. The resistivity of implanted PET decreased with an increase in ion dose. When an Ag ion dose of 2×10 17/cm 2 was selected, the resistivity of PET could be less than 0.02 Ω m. The surface hardness and modulus increased compared to the untreated PET. The hardness and modulus of Ag-implanted PET with a dose of 2×10 17/cm 2 is 2.2 and 7.3 times greater than that of pristine PET, respectively. The area of a cutting groove for Ag-implanted PET is narrow and shallow compared to the unimplanted PET. Thus wear resistance improved greatly. The Ag ion beam modification mechanism of PET will be discussed.

Bias voltage influence on surface morphology of titanium nitride synthesized by dynamic nitrogen and titanium plasma immersion ion implantation and deposition

Titanium nitride films were prepared on silicon wafers employing dual titanium and nitrogen plasmas in an immersion configuration. The vacuum arc source provided the titanium plasma and the nitrogen plasma was sustained by hot filament glow discharge. A 30 μs implantation duration and 270 μs titanium arc duration were used in our plasma immersion ion implantation and deposition (PIII–D) process. The impact of the implantation voltages (8, 16 and 23 kV) on the film surface morphology was investigated using atomic force microscopy (AFM). The 8 kV sample shows a surface featuring small islands. The surface of the 16 kV sample is smoother. The cones are more abundant but they are smaller and uniformly distributed on the surface. On the surface of the 23 kV sample, the islands exhibit a directional ripple structure. The implantation voltage unequivocally alters the fabrication dynamics of the coatings, and the difference is believed to be due to the variation in the energy imparted to the substrate at different depths by the incident ions. Films with the optimal surface morphology thus require a suitable voltage process window in the PIII–D technique.

Microchemical and microstructural changes of Co cemented WC induced by ion implantation

Changes in the microchemistry and microstructure of cobalt cemented tungsten carbide (WC–Co) hard alloy which were implanted with energetic Ta ions, with and without an additional C ion beam, have been investigated. Ion implantation was carried out at room temperature using a metal vapor vacuum arc source ion implanter. The extraction voltage and average current density of the ion beam was 45 kV and 50 μA/cm 2, respectively. The concentration depth profiles and microstructure of implanted the WC–Co alloy were analyzed by Rutherford backscattering spectroscopy, Auger electron spectroscopy, and glancing angle X-ray diffraction, respectively. The results showed that as compared with the control, there were no significant microstructural changes in the tungsten carbide phase of implanted WC–Co alloy substrate; both Ta implantation and Ta+C dual implantation induced a transformation from a metastable cubic form to a stable hcp form of cobalt binder phase.

Modeling of nonstationary vacuum arc plasma jet interaction with a neutral background gas

A plasma beam formed by a stationary vacuum arc source with a copper cathode is considered as a supersonic hydrodynamic jet interacting by collisions with a neutral atmosphere of background gas (argon). The plasma jet propagation in the neutral atmosphere is calculated numerically using a one-dimensional approximation. The values assumed at the entrance cross section of the plasma jet were ion temperature 104 K, electron temperature 3×104 K, ion concentration ni=1019 m−3 plasma jet mass velocity 1.5×104 m/s, and neutral concentration of (0.1,1,2,5)×ni. Two cases were analyzed:(1) isothermal gas motion and (2) gas motion with energy transfer from the ions to the neutrals. It is found for the isothermal case that the plasma front expands with decreasing velocity, but it never decreases down to the speed of sound. A snowplow effect is found with respect to the neutral gas. The neutral gas is accelerated by the plasma jet up to supersonic velocity. With ion–neutral energy transfer the plasma jet deceleration leads to shock discontinuities for all studied neutral densities.

Evolution of Fe-rich precipitates in Fe implanted Ge(1 1 0) surfaces as observed by scanning Auger microscopy

Ge(1 1 0) surfaces were implanted with Fe ions with an acceleration voltage of 40 kV using a metal vapour vacuum arc (MEVVA) source implanter at various doses from 5×10 16 to 5.6×10 17 ions/cm 2 . Scanning Auger micrographs (SAM) show that the lateral distribution of Fe is homogeneous up to a dose of 1×10 17 ions/cm 2 . At the dose of 2×10 17 ions/cm 2 , there is a separation of Fe-rich and Fe-poor regions. With further increase in dose, Fe content and lateral size of the Fe-rich region increases. The depth of the Fe concentration profile is found to increase with increase in dose. This is also consistent with the damage width measured by Rutherford backscattering (RBS) spectrometry and ion channelling.

Influence of nanostructure on electrical and mechanical properties for Cu implanted PET

Polyethylene terephthalate (PET) has been modified by 40 KeV Cu ion using a metal vapor vacuum arc (MEVVA) source to fluence ranging from 1×10 16 to 2×10 17 ions/cm 2. The surface morphology was observed by atomic force microscopy (AFM). The Cu atom precipitation and nano-structure of Cu implanted PET were observed. It is believed that the structure change improves the electrical properties and wear resistance of PET. The electrical properties of PET have been improved extremely after ion implantation. The surface resistance of implanted PET decreased obviously with an increase of ion dose. When metal ion dose was higher than 1×10 17 cm −2, the surface resistivity of PET could be less than 0.1 Ω m. The results show that the conductive behavior of a Cu ion implanted sample is much better than that of non-metal Si- and C-ion implanted one. After Cu implantation, the surface hardness and Young's modulus increase and the cross-section area of cutting groove is narrow and shallow comparing with the unimplanted PET. The modification mechanism of PET was discussed.

Nanometer structure and conductor mechanism of polymer modified by metal ion implantation

Polyethylene terephthalate (PET) has been modified by Ag, Ti, Cu and Si ion implantation with a dose ranging from 1×1016 to 2×1017 ions/cm2 using a metal vapor vacuum arc (MEVVA) source. The electrical properties of PET have been improved by metal ion implantation. The resistivity of implanted PET decreased obviously with an increase in ion dose. The results show that the conductive behavior of a metal ion implanted sample is different from Si-implantation samples. In order to understant the mechanism of electrical conduction, the structures of implanted layer were observed in detail by XRD and TEM. The nano carbon particles were dispersed in implanted PET. The nano metallic particles were built up in metallic ion implanted layers with dose range from 1 × 1016 to 1 × 1017 ions/cm2. The nanometer metal net structure was formed in implanted layer when a dose of 2 × 1017ions/cm2 is reached. Anomalous fractal growths were observed. These surface structure changes revealed conducting mechanism evolution. It is believed that the change would result in an improvement of the conductive properties. The conducting mechanism will be changed with increasing metal ion dose.

Dynamic nitrogen and titanium plasma ion implantation/deposition at different bias voltages

Titanium oxynitride films were prepared on AISI 304 stainless steel samples employing dual titanium and nitrogen plasmas in an immersion configuration. The vacuum arc source provided the titanium plasma and the nitrogen plasma was sustained by hot filament glow discharge. A 30 μs implantation duration and 270 μs titanium arc duration were used in our plasma ion implantation and deposition (PIID) process. The impact of the implantation voltages (8 kV, 16 kV and 23 kV) on the film was investigated. The treated samples were characterized using Auger electron spectroscopy (AES) and atomic force microscopy (AFM). Our results reveal that the thickness of the coating is not changed significantly by the applied voltage. However, the surface morphology varies substantially with the implantation voltage. The 8-kV sample shows the highest titanium content and a smooth island-shaped surface whereas the 23-kV sample features peaks with sharper edges.

Annealing behaviour of foreign atom incorporated Co-silicides formed by MEVVA implantation into SiO 2/Si and Si 3N 4/Si structures

Si 3 N 4/ Si(1 0 0), SiO 2/ Si(1 0 0) and SiO 2/ Si(1 1 1) wafers were implanted by keV Co ions under technical conditions to form thin silicide surface films. A metal vapour vacuum arc (MEVVA) source was employed to produce a high fluence of Co ions that was just sufficient to remove the oxide/nitride overlayer by sputter erosion. This high-fluence implantation under technical vacuum introduces foreign atoms into the implanted layer. The behaviour of these impurities following ∼900°C heat treatment in a N 2 atmosphere has been studied. Elemental redistributions, crystal recovery, phase formation and electric properties were analysed. The results show that the annealing leads to an increase in crystal ordering within the implanted layer and stable phase formation, as indicated by a reduction in the channeling signal and a decrease in electrical resistivity. In the case of nitride-coated samples, the heat treatment leads to a reduction in the residual carbon and nitrogen in the samples, while the oxygen content is largely unchanged. In contrast, a remarkable increase in the carbon and especially the oxygen contents is observed in the case of the samples with oxide overlayers, and the Co shows a tendency to spread to greater depths.

Properties of aluminium nitride coating obtained by vacuum arc discharge method with plasma flow separation

Aluminium nitride coating was obtained with the stationary vacuum arc source with separation (filtration) of aluminium plasma flow and nitrogen leak-in into the vacuum chamber at substrate temperature 313–673 K. The growth rate was 5–7 μm/h. The crystal structure of aluminium nitride films with thickness 10–30 nm deposited on monocrystalline NaCl substrate was studied by electron diffraction method. The aluminium nitride coatings with thickness 1–3 μm were investigated by X-ray examination methods. It was determined that the aluminium nitride coating with the thickness up to 30 nm has amorphous structure through the whole deposition temperature range. At the film thickness exceeding 1 μm the coating structure is crystalline with hexagonal lattice. The microhardness of the aluminium nitride coating was 18–20 GPa and their resistivity was 1–2×10 11 Ω cm. The aluminium nitride coating with thickness 1–3 μm deposited on stainless steel samples preserves them from high temperature oxidation up to 1473 K. It was found out by forcing an indenter and by scribing that the aluminium nitride coating obtained at the mentioned substrate temperatures possesses good adhesion to steel, titanium, silicon, glass, sapphire substrates. Studies of optical characteristics of the aluminium nitride coating showed the possibility of its application as optically sensitive coating.

Sputtering transients for some transition elements during high-fluence MEVVA implantation of Si

The approach to quasi equilibrium sputtering of transition elements Co, Er, V and Ni during high-fluence implantation of Si(1 1 1) using a metal vapour vacuum arc (MEVVA) source has been studied by time of flight-energy elastic recoil detection analysis (ToF-E ERDA) and scanning electron microscopy (SEM). The partial sputter yield of the implanted species was determined from the change in the content of the implanted species with the implanted ion fluence. The partial sputter yield of Co exhibits a step-like rise to ∼0.4 that might be associated with a rapid segregation of Co to the surface followed by a slow exponential-like increase. Er on the other hand follows an exponential approach to the quasi-equilibrium partial sputtering yield which is indicative of no strong buildup of Er within the sputter escape depth. Additional data for Ni and V suggest also an exponential approach to quasi-equilibrium sputtering.

Vacuum-arc source of plasma of an extended construction for synthesis of zirconium carbide on grids of power transmitting valves

Abstract Deposition of the covering film is one of the most popular processing operations. The list of technical problems successfully solved by using this processing is permanently extended. The application of vacuum-plasma technology allows to control the phase composition, structure, physical and chemical properties of surface layers by varying ions composition and energy. Use of the speeded-up ion streams of relatively high density provides adhesion which cannot be achieved by any other existing coating methods. These positive properties of a plasma stream are widely used in the electronic industry for the deposition of coats on transmitting valve electrodes. The application of plasma technique for coating large-sized grids of power transmitting valves required a specialized processing equipment.

Polymer modification by MEVVA source deposited and ion implantation

Polyethylene terephthalate (PET) has been modified by Ti, Ni and W deposition using a metal vapor vacuum arc (MEVVA) source and implantation. The surface resistance of deposited PET could decrease to several hundred ohms. The adhesion of metal coating on polymers is very strong. The thickness of the deposited metal coating could be controlled from tens of nanometers to 1 μm. The hardness for thick Ti and W deposited PET is 3.81 and 2.54 GPa, which are several times greater than that of PET. The elastic modulus of deposited PET increases also. Similar results have been observed for other metal implanted PET. The thickness and atomic distribution of deposited metal coating was analyzed using RBS. The surface structure has varied after deposition and implantation. It is believed that the change would cause the improvement of the conductive properties and wear resistance.

Surface properties of Nb+C ion co-implanted stainless steel

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 Fe 2Nb, Cr 23C 6, Cr 3C 2 and Fe 5C 2. 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.

Electrical properties of polymer modified by metal ion implantation

Polyethylene terephthalate (PET) has been modified by Ag, Cr, Cu and Si ion implantation with a dose range from 1×10 16 to 2×10 17 ions cm −2 using a metal vapor vacuum arc (MEVVA) source. The electrical properties of PET have been changed after metal ion implantation. The resistivity of implanted PET decreased obviously with an increase of ion dose. When metal ion dose of 2×10 17 cm −2 was selected, the resistivity of PET could be less than 10 Ω cm, but when Si ions are implanted, the resistivity of PET would be up to several hundred Ω cm. The results show that the conductive behavior of a metal ion implanted sample is obviously different from Si implantation one. The changes of the structure and composition have been observed with transmission electron microscope (TEM) and X-ray diffraction (XRD). The surface structure is varying after ion implantation and it is believed that the change would cause the improvement of the conductive properties. The mechanism of electrical conduction will be discussed.