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Pulse-enhanced vacuum arc evaporation (PEVAE) which combines pulsed and direct current operation of the arc source is a new approach in cathodic arc evaporation technology. One potential advantage is to deflect the arc along new paths over the target and prevent it from moving in only preferred areas. In this work, the cathode group spots (GSs) are photographed using a high-speed digital camera with exposure time of 100 μs and 25 ms and the influence of the pulse current and nitrogen pressure on the motion of the GSs including velocity and distribution are investigated. The experimental results reveal two types of GSs. With respect to the traditional DC arc current of 100 A, the GSs consist of a few fragments close to each other and for the PEVAE, and the GSs tend to organize in a roughly circular expanding ring. Quasi-quantitative analysis of the experimental results shows that a self-generated transverse magnetic field by the high pulsed arc current may bend and extend the GSs motion trajectory. It may also be related to the enhancement effect of the high pulse current on electron emission which can also contribute to the higher expansion speed of the GSs.

Hydrophobic/superhydrophobic materials with intrinsic water repellence are highly desirable in engineering fields including anti-icing in aerocrafts, antidrag and anticorrosion in ships, and antifog and self-cleaning in optical lenses, screen, mirrors, and windows. However, superhydrophobic material should have small surface energy (SE) and a micro/nanosurface structure which can reduce solid-liquid contact significantly. The low SE is generally found in organic materials with inferior mechanical properties that is undesirable in engineering. Intriguingly, previous theoretical calculations have predicted a negative SE for θ -alumina ( θ -Al 2 O 3 ), which inspires us to use it as a superhydrophobic material. Here, we report the experimental evidence of the small/negative SE of θ -Al 2 O 3 and a θ -Al 2 O 3 -based superhydrophobic coating prepared by one-step scalable plasma arcing oxidation. The superhydrophobic coating has complete ceramic and desired micro/nanostructure and therefore exhibits excellent aging resistance, wear resistance, corrosion resistance, high-temperature tolerance, and burning resistance. Owing to the rarity of the small/negative SE in inorganic materials, the concept to reduce SE by θ -Al 2 O 3 may foster a blowout to develop robust superhydrophobicity by complete inorganic materials.

Target poisoning is prevalent in reactive magnetron sputtering and causes deleterious effects, especially in deposition using metal targets. Both the deposition rate and the stoichiometry ratio of the coatings will be compromised because of the quicker coverage of the poisoning materials on the target relative to removal by sputtering. Continuous high-power magnetron sputtering (C-HPMS) possesses merits such as more rapid sputtering than high-power impulse magnetron sputtering and better target poisoning resistance. In this work, the discharge and plasma characteristics of C-HPMS for an Al metal target in reactive O2/Ar atmospheres are investigated by modeling and alumina deposition. At a constant oxygen partial pressure, larger discharge power increases target etching significantly compared to surface combination with O2, leading to reduced surface poisoning. Besides, a higher temperature is produced near the target to produce more intense rarefaction effects and decrease the risk of target poisoning. In Al discharge, the stable deposition window in the O2/Ar ratio under 120 W/cm2 is 5 times of that under 20 W/cm2. Moreover, a large deposition rate of 112 nm/min is achieved at the poisoning-saturated point and a target/substrate distance can be increased to larger than 40 cm, thus providing more flexibility in the design of deposition parameters and hardware requirement. Our results show that high discharge intensity improves plasma density and ionization rates of reactive particles boding well for the deposition of under-stoichiometric and higher-quality amorphous Al2O3 films. The reactive C-HPMS technique has large potential in the commercial production of functional coatings and thin films.

T-shape structure can make inorganic materials superhydrophobic, but conventional preparation methods based on etching is usually costly and unscalable. In this work, a facile and scalable technique utilizing plasma electrolytic oxidation (PEO) is employed to prepare superhydrophobic inorganic alumina coatings. By optimizing the gradient electric field, the etching behavior of OH– is tunable so that a T-shape micro/nano structured alumina coating can be prepared in one step. Without any organic modification, the coating shows a water contact angle (CA) of 150°±3° and water rolling angle (RA) of 8°±2°. The prepared inorganic ceramic coating remains superhydrophobicity under a harsh environment including 360 days of sunlight, and they have excellent corrosion resistance and can bear long-time flame burning. The preparation technique is simple and economical thereby boding well for great potentials in applications of solar cells, electronic devices, etc.

Although aluminum alloys are widely used in the aerospace industry, their relatively poor wear and corrosion resistance have hampered some applications and reduce the lifetime of the components. In this work, by using a zinc-containing phosphate electrolyte, the corrosion resistance, surface hardness, and wear resistance of the coatings produced by plasma electrolytic oxidation (PEO) are simultaneously improved. The micro-arc discharge is optimized by changing the phosphate concentration instead of introducing hard phase cations to improve the crystallinity of the zinc-doped alumina coating. Our results reveal that by using a concentration of (NaPO3)6 of 50 g/L, the hard phase of crystralline alumina and corrosive-resistant phase of Zn3(PO4)2 are produced in concert. In the salt spraying test, the lifetime of the PEO coating is over 5000 h and the electrochemical corrosion current density is reduced by about 2 orders of magnitude confirming the improved corrosion resistance and durability. Moreover, the surface hardness increases from 400 HV for the coating prepared using the conventional phosphate electrolyte to 711.8 HV and the wear rate also drops from 8.5 × 10−4 mm3·(N·m)−1 to 2.0 × 10−5 mm3·(N·m)−1. This strategy can guarantee the aluminum alloy PEO coating with simultaneous excellent wear and corrosion resistance to cope with the complex service environment.

Lead-free solder is increasingly used in the wave soldering but corrosion of the stainless steel holders frequently occurs and produces deleterious effects. To enhance the service life, a Ti/TiC coating is deposited by filtered cathodic vacuum arc (FCVA) on the stainless steel holders. The morphology, structure, composition, microhardness, wear resistance, electron chemical corrosion, and wetting properties against solder are investigated. The results show that not only good frictional properties and corrosion resistance are achieved by the Ti/TiC coatings, but also good tin repelling and hydrophobic characteristics are observed. The Ti/TiC coating provides excellent protection against corrosion of lead-free solder in wave soldering.

This article presents the principle of operation, design, and performance data of a hollow cathode vacuum arc plasma electron source. The required electric strength of the accelerating gap can be ensured by generating a longitudinal magnetic field in the electron extraction region. This method is used to generate a high current DC electron beam. The effect of the magnetic field on the discharge and the emission characteristics of the plasma electron source are observed. With extraction voltages up to 700 V, and a magnetic field as high as 100 mT, we demonstrate a DC emission current of roughly 9 A. The hollow cathode vacuum arc plasma electron source exhibits emission characteristics characterized by three different stages: a rapid increase stage in which high-energy electrons are extracted; a slow increase stage in which a small number of high-energy electrons and a large amount of low-energy electrons are extracted together; and a stable stage.

An unstable stage is observed from the discharge current during the transition from gas-dominant discharge to the self-sputtering dominant regime in high-power impulse magnetron sputtering (HiPIMS). The phenomenon and the formation mechanism are time dependent and there is a dynamic transition between the two stable stages. The threshold of the high stable discharge is investigated at different pressure and hybrid DC discharge. According to the derivation of the discharge current, the temperature in the discharge is found to play a major role in the dynamic transition at moderate voltage.

High power impulse magnetron sputtering (HIPIMS) is an emerging technique that improves the ionization rate of magnetron-sputtered materials. However, HIPIMS often demands further improvement in the ionization rate in some applications. In this study, we applied an unbalanced magnetic field to enhance the HIPIMS discharge, using a conventional magnetron and a coaxial electro-solenoid coil. Vanadium target discharge currents and substrate ion currents were recorded using a digitizing oscilloscope at different coil currents. The elemental composition and temporal and spatial distributions of argon and vanadium atoms and ions in the high vacuum plasma were measured by optical emission spectroscopy. The results showed that the substrate ion current increased gradually with the coil current over the range 0–6 A, and that a high-density plasma beam was formed between the substrate and target. We explained this effect as the confinement of energetic electrons by the external magnetic field. Total ion production was also increased. Finally, we observed that the line intensities of Ar 0 , Ar 1+ , V 0 , and V 1+ increased gradually to varying degrees under the external magnetic field.

Meshed Plasma Immersion Ion Deposition (MPIID) using cage-like hollow cathode discharge is a modified process of conventional PIID, but it allows the deposition of thick diamond-like carbon (DLC) films (up to 50 μm) at a high deposition rate (up to 6.5 μm/h). To further improve the DLC film properties, a new approach to the MPIID process is proposed, in which the energy of ions incident to the sample surface can be independently controlled by an additional voltage applied between the samples and the metal meshed cage. In this study, the meshed cage was biased with a pulsed DC power supply at −1350 V peak voltage for the plasma generation, while the samples inside the cage were biased with a DC voltage from 0 V to −500 V with respect to the cage to study its effect. Si-DLC films were synthesized with a mixture of Ar, C 2 H 2 and tetramethylsilane (TMS). After the depositions, scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectrons spectroscopy (XPS), Raman spectroscopy and nanoindentation were used to study the morphology, surface roughness, chemical bonding and structure, and the surface hardness as well as the modulus of elasticity of the Si-DLC films. It was observed that the intense ion bombardment significantly densified the films, reduced the surface roughness, reduced the H and Si contents, and increased the nanohardness ( H ) and modulus of elasticity ( E ), whereas the deposition rate decreased slightly. Using the H and E data, high values of H 3 / E 2 and H / E were obtained on the biased films, indicating the potential excellent mechanical and tribological properties of the films. In this paper, the effects of the sample bias voltage on the film properties are discussed in detail and the optimal bias voltage is presented.

The nose cones of plane engines adjust the airflow direction and guarantee steady operation but they are vulnerable to icing at high altitude leading to potential hazards and accidents. Superhydrophobicity is effective against icing but most organic superhydrophobic materials are not suitable for engineering applications. Herein, a mechanically robust superhydrophobic coating is prepared on stainless steel by incorporating laser-textured micro/nano structures into the plasma-coated multilayered structure of Cr/CrC/DLC/F-DLC. The multilayered coating shows a stable surface contact angle of >150° in addition of robust mechanical properties even in harsh environments such as prolonged ultraviolet light irradiation, wear, and corrosion. Tests conducted under simulated working conditions reveal significantly reduced ice accumulation on the coating because of easy roll-off of droplets consequently giving rise to excellent anti-icing properties.

Pulse-enhanced vacuum arc evaporation (PEVAE), an advanced version of conventional DC vacuum arc evaporation, generates a high flux of electrons to ionize more gaseous and metallic atoms in the deposition system to facilitate coating deposition. Compared to the conventional DC mode, the highly ionized plasma improves the structure and properties of the coatings deposited by the PEVAE mode. To obtain a better understanding and evaluate the advantages and limitations of this technique, we conduct a comparative study on TiSiCN coatings deposited by the traditional DC mode and PEVAE mode for different target-to-substrate distances (Dt-s) in the reactive environment of HMDSN. The substrate current is determined by an oscilloscope and optical emission is monitored by a miniature fiber-optics spectrometer. The microstructure and properties of the coatings are characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, indentation test, nanoindentation, electrochemical measurement, and ball-on-disk wear test. The results demonstrate that the average substrate current increases by 53.8% as Dt-s increases from 200 mm to 300 mm. The pulsed current discharge in the HMDSN atmosphere increases the deposition rates by up to 36.4% and Ebi increases by 29% reflecting a denser microstructure. The PEVAE mode improves the microstructure of the TiSiCN coatings as well as resistance to corrosion and wear. Furthermore, it has good processing adaptability for different target-to-substrate distances.

TiAlN coatings are widely used in high-speed cutting, machining, and other high-temperature applications. However, owing to the high cathode temperature, large amounts of metal droplets are produced during fabrication in arc ion plating (AIP) and the shadowing effect introduces particles and voids in the coatings. Continuous high-power magnetron sputtering (C-HPMS) can produce high ionization rates similar to high-power impulse magnetron sputtering (HiPIMS) and high deposition rates similar to AIP. In this work, the morphology, adhesion strength, tribological properties, corrosion resistance, and oxidation resistance of Al-rich TiAlN coatings prepared by C-HPMS are studied systematically. Higher Al and Ti ionization rates and deposition rates are achieved by increasing the power density. The largest deposition rate is 0.45 μm/min and coating hardness is 34.4 GPa. More importantly, no particles are produced as manifested by small surface roughness of 17.8 nm.

Superhydrophobic surfaces with large contact angles (CAs) and small sliding angles (SAs) are used in many applications such as wings of airplanes or engine front cones to reduce air crashing caused by icing. Most anti-icing studies have mainly focused on the icing behavior on surfaces with specific hydrophobic properties but there have been fewer investigations on the dynamic change of hydrophobicity of the materials during the icing process. In this work, micro/nano structures are prepared on stainless steel by laser etching and modified with a fluorine-doped diamond-like carbon (F-DLC) coating to produce a superhydrophobic surface. The dynamic behavior of the wetting state and icing of water droplets on the F-DLC surface during cooling are studied. As the temperature drops, the hydrophobicity of the surface decreases significantly before freezing and the rate of decrease is related to the temperature and environmental humidity. Water vapor condenses to droplets on the micro/nano structured surface consequently weakening the function of the rough structure and deteriorating the coating hydrophobicity. The results provide a deeper understanding of the dynamic changes of superhydrophobicity during the icing process.

Li(NixMnyCoz)O2 cathode materials (NMC) have advantages such as the good Li ion diffusivity, stable reversible capacity, and environmental compatibility in spite of a low actual capacity. Although a double-layer lithium structure can be generated by pre-lithiation, the thickness is very small and the capacity improvement is limited. In this work, a series of Li([Formula: see text][Formula: see text][Formula: see text])O2 nanoparticles are prepared by the sol–gel method and centrifugation and the pre-lithiation process are monitored by transmission electron microscope (TEM). A double lithium structure of about 10 nanometers thick is produced on the NMC materials with different sizes. With decreasing NMC particle size, the proportion of the double-layer lithium structure increases and reaches 48% for a particle diameter of 100[Formula: see text]nm. The results reveal a viable means to improve the capacity of NMC materials in charging and discharging.

Vacuum brazing of Titanium–Zirconium–Molybdenum (Abbreviated as TZM) alloy using Ti–28Ni (wt%) eutectic brazing alloy was successfully achieved in this study. Reliable TZM brazed joints were obtained at the temperatures ranging from 1000 °C to 1160 °C for 600 s. The interfacial microstructure of TZM joints was characterized by employing SEM, EDS and XRD. The effects of brazing temperature on interfacial microstructure and joining properties were investigated in details. TZM brazed joints mainly consisted of δ-Ti2Ni phase and Ti-based solid solution (Ti(s,s)). The interfacial microstructure of TZM joints was influenced obviously by brazing temperature. Both the thickness of brazing seam and the amount of δ-Ti2Ni phase was reduced with the increasing brazing temperature, while the Ti(s,s) layer did not change significantly. The maximum average shear strength of TZM joints reached 107 MPa when brazed at 1080 °C. The presence of δ-Ti2Ni intermetallic phase and crack-like structure in joints deteriorated the joining properties, which resulted in the formation of brittle fracture after shear test. In addition, fracture locations were related to the brazing temperature. When the brazing temperature was relatively low, cracks initiated and propagated in the continuous δ-Ti2Ni layer. However, the fracture locations preferred to locating at the interface between TZM substrate and brazing seam when brazing temperature exceeded 1080 °C.

In the low voltage apparatus manufacturing industry, the welding quality of electrical contact directly determines the switching capacity, lifespan and reliability of electrical equipment. Currently, only a little research on online monitoring of large-size electrical contact high frequency induction brazing has been carried out. In this research, CJ400 electrical contact was used as samples to be welded in the way of pulse induction brazing. And the electrical parameters during the whole welding process were collected and integrated with the dual 32-bit ARM (Advanced RISC Machines) controller. The relationship between welding quality and integral value of electrical parameter was analyzed. The results showed that the deviation between the ideal integral value of electrical parameters and the actual integral value of electrical parameters could be identified an indication for welding quality.

To obtain both high ionization and high deposition rate, a modified global model for a continuous high-power DC magnetron sputtering (C-HPMS) is established by considering the continuous generation of the hot electrons and the high temperature caused by continuous high-power discharge. The results show that the plasma density is on the order of 1019 m−3 for power densities of only 183 W cm−2 (Al) and 117 W cm−2 (Cu). The ionization rate exceeds 90% of high-power impulse magnetron sputtering (HiPIMS) (peak power density of 564 W cm−2) for a DC power density of 180 W cm−2, and the total diffusion fluxes of the two targets are 26 (Al) and 30 (Cu) times that of conventional HiPIMS, leading to very high deposition rates. The work provides a theoretical basis for the realization of C-HPMS and gives an enlightenment to the development of deposition equipment for continuous high-power discharges.

Aluminum alloys are widely used in many industrial applications. However, they are susceptible to corrosion especially in aggressive media such as high salinity which can expedite the corrosion reactions. In this work, zinc phosphate modified plasma electrolytic oxidation (PEO) coatings are fabricated and demonstrated to have excellent corrosion resistance for a much longer duration (>11,000 h) than conventional PEO coatings (

Systematic analysis of discharge processes is needed for a good understanding of the physical mechanism that enables optimal coating deposition, especially pulsed discharges sustained by high voltages and large currents. Owing to the temporal and complex characteristics of the discharge process and relatively simplistic analytical methods, the discharge process and particle evolution in high-power impulse magnetron sputtering (HiPIMS) are still not well understood. In this work, a cylindrical cathode is introduced to restrict the discharge and delay plasma loss, and a global model is established to simulate the discharge on a Cr target in N2/Ar. Particles with different reaction energies appearing successively produce an asynchronous discharge phenomenon, and a series of inflection points corresponding to different physical processes including excitation, sputtering, ionization, and diffusion are observed from the particle density evolution curves. High-precision and time-resolved spectrometry (400 ns) is utilized to monitor the evolution of particles with time, and inflection points predicted by the model are observed experimentally to verify the particle behavior in the HiPIMS discharge.Systematic analysis of discharge processes is needed for a good understanding of the physical mechanism that enables optimal coating deposition, especially pulsed discharges sustained by high voltages and large currents. Owing to the temporal and complex characteristics of the discharge process and relatively simplistic analytical methods, the discharge process and particle evolution in high-power impulse magnetron sputtering (HiPIMS) are still not well understood. In this work, a cylindrical cathode is introduced to restrict the discharge and delay plasma loss, and a global model is established to simulate the discharge on a Cr target in N2/Ar. Particles with different reaction energies appearing successively produce an asynchronous discharge phenomenon, and a series of inflection points corresponding to different physical processes including excitation, sputtering, ionization, and diffusion are observed from the particle density evolution curves. High-precision and time-resolved spectrometry (400 ns) is...

Good oxidation and corrosion resistance are required for cutting tools and other industrial components used in high temperature applications. The highest operational temperature of CrN is normally about

The ta-C films were fabricated using direct-current cathodic arc evaporation (DC-CAE) and pulse-enhanced cathodic arc evaporation (PE-CAE). The effect of peak currents (Ip) on arc discharge, microstructure and mechanical properties of the films was focused on. The enhanced discharge process, microstructure and mechanical properties of the ta-C films were investigated by means of optical emission spectra (OES), Raman spectroscopy, Nano-indentation, etc. With the same average current, the Ip of 300 A of PE-CAE produced the substrate current of 1.14 A, but a markedly low current (0.82A) was observed for the DC-CAE. The plasma emission intensity of Ar II, C I and C II also increased by about 86%, 66% and 630% at pulse mode. This evidently indicated an enhanced arc discharge by PE-CAE. The highest ratio of CII/ArII (2.98) and electron excitation temperature (1.38 eV) was observed. DC-CAE led to a lower concentration of sp3 bonding (47.3%, ID/IG = 0.39) of ta-C films with a thickness of 171 nm. In contrast, the ta-C films fabricated by PE-CAE (Ip = 300 A) possessed the smallest ID/IG (0.22) as well as the highest concentration of sp3 bonding (65.1%). The thickness increased by about 30% in comparison with that by DC-CAE. The largest thickness (330 nm) was obtained at the peak current of 200A, mainly relating to the increased evaporation of carbon atom/ions. The hardness evaluated from the ta-C films fabricated by DC-CAE was about 29 GPa. However, the hardness increased significantly to 57 GPa by PE-CAE (Ip = 300 A), and the preferable toughness (H/E* of 0.11 and H3/E*2 of 0.68) was simultaneously achieved.

article i nfo A nanostructured interfacial layer with a graded structure is produced by hybrid high-power pulsed magnetron sputtering-plasma immersion ion implantation and deposition (HPPMS-PIII&D) to improve adhesion of multi- functional coatings. As a demonstration, a ceramic CrN film is prepared on stainless steel together with a Cr interlayer. High-resolution transmission electron microscopy (HR-TEM) reveals the presence of a 40 nm thick nanostructured interfacial layer between the Cr interlayer and substrate with gradually changing compositions, and this layer which possesses a dense and pore/void free structure is responsible for the strong film adhesion. The hybrid technology combines the benefits of both the HPPMS and PIII&D enabling fabrication of functional films with the desired properties. The technique and fabrication strategy have many potential applications in photovoltaics, energy storage, tribology, lubrication, aeronautics, and astronautics. © 2013 Published by Elsevier B.V.

In order to achieve excellent adhesion between coatings and substrates, PBII&D technique was proposed and used more and more widely to produce hard coatings. Among the metal plasma source, one based on HPPMS technique (HPPMS-PIID) proposed recently seems to have great prospects. The present study aims to develop the difference of CrN films deposited on Si (100) and SU201 stainless steel substrates with PBII&D technique using different metal plasma sources of HPPMS, FCA and DCMS. In contrast to the other two samples, the sample based on HPPMS appears to have dense knitting-like surface and discontinuous columnar structure. The highest intensity of CrN(200) preferential orientation, best adhesion and hardness is obtained by HPPMS plasma source for the highly energetic ion implantation and bombardment, but the C fraction is a little higher since the sputtering of highly energetic ions.

Inorganic silica/alumina multilayer films with excellent mechanical and anti-atomic-oxygen erosion properties were fabricated on polyimide by the hybrid implanting and depositing processes. X-ray photoelectron spectroscopy demonstrated that the silica/alumina graded structures consisted of Si O and Al O bonds, as well as Al O Si and Al O C bonds in the transition layers. The results revealed that bonding between the alumina coating and the polymer occurred primarily via Al O C bonds, and Si O Al bonds were formed in the interface between silica and alumina coatings. The multilayer films presented good adhesion property, demonstrating that balanced internal stresses and alternating bonding structures were crucial for enhancing anti-crack performance. The multilayer inorganic films exhibited good anti-atomic-oxygen erosion properties were well matched with the behavior of adhesion property.

Plasma immersion ion implantation (PIII) is a potentially excellent interior surface treatment technique due to no line-of-sight restriction. However, some problems have been encountered due to the low ion energy and ion fluence non-uniformity especially for treatment of the interior wall of a thin tube. In this paper, a new method for inner surface PIII using internal inductively-coupled radio-frequency (RF) discharge is described. A cylindrical inductive coil inserted inside the tube serves as both the plasma source and grounded electrode to avoid overlapping of the plasma sheath fronts propagating from opposite sides. The effects of the gas species, gas pressure, RF power, and number of coil turns are investigated. Our results demonstrate the feasibility of this novel inner surface treatment method and the number of turns in the coil has a critical influence on the discharge behavior. If the number of turns is little, the plasma density is low and non-uniform inside the tube due to the relatively intense capacitively-coupled RF discharge at the two ends. In contrast, the plasma density and uniformity are evidently improved by using more turns in the coil.

a b s t r a c t Multilayer inorganic silica/alumina films with excellent mechanical, optical and anti-atomic-oxygen ero- sion characteristics were fabricated by the hybrid implanting and depositing processes of Al/Si plasmas on polyimide. The multilayer films exhibited an excellent mechanical stability, demonstrating that balanced internal stresses and alternating bonding structures were crucial for enhancing mechanical stability. The multilayer inorganic films exhibited higher optical transmittance. The slight change surface morphology and high mechanical stability of polyimide covered with multilayer silica/alumina films suggest that the techgnique used is an effective method to protect polymer materials which are applied to thermal control system of spacecrafts in low Earth orbit.

Plasma immersion ion implantation employing hybrid radio-frequency (RF) and high-voltage (HV) pulses via a single feedthrough is an effective surface modification method. In this technique, the sample holder is connected to both the RF generator and the HV modulator in order to generate a high-density plasma in the vicinity of the sample. HV pulses are applied to the sample in between the RF pulses to conduct ion implantation. Polyethylene terephthalate (PET) samples were modified using an C2H2 plasma generated by this technique, and diamond-like-carbon films were successfully deposited. In this process, the pulsed HV changed from 2.5 to 10 kV with an RF power ranging from 0 to 150 W and an RF of 13.56 MHz. The C2H2 gas pressure was maintained at 1.0 Pa with a processing time of 15 min. Cleaning effects were observed without arcing damage with increasing sample bias from 2.5 to 10 kV. The negative bias and RF were observed to influence the water contact angles of treated PET samples. The plasma-implanted surface became more hydrophilic with increasing sample bias and RF power, respectively.

Proton irradiation of Kapton-H films was physically simulated in plasma immersion configuration with hydrogen plasmas. Hydrogen ion was implanted into the samples biased to a negative pulse of 20 kV. Optical transmittance of the sample in the wavelength region of 200–2500 nm was determined by a UV–vis–NIR scanning spectrophotometer, and the functional group evolution was examined by X-ray photoelectron spectroscopy (XPS). Atomic force microscopy (AFM) was utilized to determine the roughness and morphology of the samples, and the bulk modification was analyzed by FTIR. The experimental results showed the optical transmittance of the treated sample in the wavelength of 500–2000 nm weakened after proton irradiation, and decreased with the increase of irradiation time. Finger-like bulges emerged on the surface of the sample irradiated by ion irradiation for 30 min, and became bigger and denser with the increase of the irradiation time. The content of C element of the sample increased after proton irradiation, while that of N and O elements decreased because of the bonds breakage of C O, C O C and C N during irradiation process.

A two-dimensional particle-in-cell (PIC) model considering secondary electron emission (SEE) as a function of ion instantaneous incident energy is developed for describing ion trajectories and shadow effects in mesh-assisted plasma immersion ion implantation (PIII) of insulator. The simulation results indicate that mesh-assisted PIII can improve the equivalent surface potential, suppress the emission of secondary electrons and provide better implantation dynamics for ions implantation on insulator. On 5 mm thick polymer substrate, an aluminum plasma implanted coating is achieved with excellent adhesion strength by mesh-assisted PIII with 10 mm mesh height. Consistent results are obtained from experiments and numerical simulation disclosing that shallow effects can be eliminated, and ions incident energy is enhanced.

Plasma immersion ion implantation (PIII) is a promising surface treatment technique for the irregular-shaped components. However, it is difficult to achieve uniform implantation along the surface of a concave sample due to the propagation and overlapping effect of plasma sheath. In this paper, a new ion implantation process is presented for improving the dose uniformity, especially for enhancing the lateral dose of the samples with concavities. In PIII enhanced by beam-line ions process, a beam-line ion source with certain energy is introduced from an external source into the concavity to suppress the sheath propagation and consequently to improve the dose uniformity. The time-dependent evolution of the potential, electrical field and the particle movement surrounding the surface of concave sample is studied by a particle-in-cell/Monte Carlo collision (PIC/MCC) simulation during a single bias high voltage (HV) pulse. The simulation results show that the plasma sheath propagation surrounding the concave sample is suppressed effectively by beam-line ions, and can be quasi-steady state during a single HV pulse. The influence of the energy of induced beam-line ions on the incident ion dose and energy distribution is discussed. Compared with the traditional PIII process, the dose uniformity of the sample surface is improved obviously due to the increase of the ions implanted into the lateral surface.

A newly proposed technique has been utilized to improve surface properties of gas barriering DLC films deposited on PET bottle. The discharge in the bottle is induced by radio-frequency discharge and an external DC system is coupled to the RF power supply to control the potential of discharge electrode. In contrast to conventional discharge configuration, this leads to the capability to optimize the ion bombardment energy and surface properties of deposited films. The effect of negative DC voltage on the adhesion strength, optical transmittance, surface profile, roughness, and permeability of DLC coated PET samples has been investigated using immersion test, UV-visible spectroscopy, optical profilometry, and gas permeability tester, respectively. The results have demonstrated that the DLC coated PET samples with external bias show slight damage during beer immersion tests. Lower light transmittance is induced for the films deposited at high negative bias due to larger ion bombardment effect. There exists a proper bias to give rise to a small surface roughness. The gas permeability of DLC coated PET samples deposited with external bias has been substantially decreased compared to that of untreated one.

Plasma immersion ion implantation into inner surfaces of tubes has practical importance, but intrinsic drawbacks such as poor dose uniformity and small equivalent ion flux have limited wider applications. In this paper, a new technique utilizing a moving auxiliary electrode inside the tube to improve the dose uniformity and ion implantation efficiency is described. The effects of the moving auxiliary electrode are investigated by 2-D particle-in-cell simulation. The results show that, when the grounded auxiliary electrode is withdrawn along the axis of the tube, external ions are continuously attracted into the tube and implanted into the interior wall. It is verified by the incident dose peak when the auxiliary electrode is kept at a certain location inside the tube. Uniform ion implantation into a cylindrical bore can be accomplished by physical translation of the electrode, and this technique is suitable for implantation of long tubes without an internal plasma source.

a b s t r a c t CrN films with strong adhesion with the substrate have been fabricated on Ti6Al4V alloy using novel plasma immersion ion implantation and deposition (PIII&D) based on high power pulsed magnetron sputtering (HPPMS). A macro-particle free chromium plasma is generated by HPPMS while the samples are subjected to high voltage pulses to conduct PIII&D. The CrN coatings have a dense columnar structure and low surface roughness. The grains in the films have the face-center cubic (fcc) structure with the (2 0 0) preferred orientation. An excellent adhesion is achieved with a critical load up to 74.7 N. An implantation voltage of 18 kV yields a hardness of 18 GPa and better wear resistance and a low friction coefficient of 0.48 are achieved.

a b s t r a c t Multilayer silica/alumina films were created by plasma immersion implantation and deposition to protect against atomic oxygen (AO) in low earth orbit environment. The AO erosion mechanism of polyimide under multilayer silica/alumina films has been investigated using a ground-based AO simulator and Monte Carlo model. The results demonstrate that protective films are detached and plumped due to AO undercutting, and the exterior silica film is partly detached proven by chemical composition depth profile and erosion patterns. The undercutting model involving collision, diffusion, reaction, gas releasing, and retroaction on films is proposed. Based on the model, scattered impingement has serious erosion, although AO does not directly attack interior polymer. AO erosion predictions at two neighborhood cracks are first studied by Monte Carlo model for various incidence angles of AO. The protective film between cracks hinders the escape of AO, and accelerates the erosion.

TiN/TiAlN multilayer coatings were prepared by arc ion plating with separate targets. In order to decrease the unfavorable macroparticles, a straight magnetized filter was used for the low melting aluminium target. The results show that the output plasmas of titanium target without filter and aluminium target with filter reach the substrate with the same order of magnitude. Meanwhile, the number of macroparticles in TiN/TiAlN multilayer coatings deposited with separate targets is only 1/10–1/3 of that deposited with alloy target reported in literature. Al atom addition may lead to the decrease of peak at (200) lattice plane and strengthening of peak at (111) and (220) lattice planes. The measured hardness of TiN/TiAlN multilayer coatings accords with the mixture principle and the maximum hardness is HV2495. The adhesion strength reaches 75 N.

To enhance the properties of hard alloy, rare-earth metal yttrium (Y) was implanted into its surface by using Metal Vapor Vacuum Arc (MEVVA) source implantor. The experiments were finished under different vacuum conditions with/without aerating nitrogen in the chamber. The metallograph and phase formation of sample were characterized and analyzed with metallurgical microscope and X-ray diffraction. The results show that there exist new phases of C, YC2, Y2O3, and WN in the sample surface. Moreover, it can be found that the performances of sample surface (such as microhardness, friction coefficient and corrosion resistance) are evidently improved, and that nitrogen atmosphere plays a very important role in farther promoting these performances. The surface modification of hard alloy is not only affected by the implantation itself, but also related to the microstructure transformation, which can be partly induced by the atmosphere.

High-power impulse magnetron sputtering boasts high ionization, large coating density, and good film adhesion but suffers from drawbacks such as low deposition rates, unstable discharge, and different ionization rates for different materials. Herein, a cylindrical cathode in which the special cathode shape introduces the hollow cathode effect to enhance the discharge is described. To study the discharge performance of the cylindrical cathode, a hollow cathode effect modified time-dependent global model is established to fit the discharge current pulses. The simulation results indicate that the cylindrical cathode has relatively large Hall parameters of 24 (700 V) to 26 (1000 V). Compared to the planar cathode, the cylindrical cathode has a larger plasma density as a result of the hollow cathode effect. In addition, the ionization rate and ion return probability increase by about 3.0% and 4.3%, respectively. Particle transport derived from the plasma diffusion model shows that the magnetic field enables further diffusion of ions than atoms, resulting in nearly pure ion deposition on the substrate. The deposition rate and ion current measured experimentally support the simulation model and results, and this model provides a universal platform to simulate plasma systems with similar structures.

A novel high-voltage pulse power system based on a programmable logic controller (PLC) is developed for plasma immersion ion implantation (PIII). The PLC unit with strong anti-interference ability is utilized to optimize both electrical parameters and ion-implantation processes with manual or/and procedure modes. Specially designed periphery circuits are developed to realize the arbitrary adjustment of pulsing frequency and width which is impossible for conventional PLC systems. The electrical protection can also work rapidly in the case of a sudden short circuit. In the main power circuit, a tetrode hard tube is employed to switch the dc high voltage. In order to reduce the rise time of the pulse as much as possible, the potentials on the tetrode grids are optimized. A closed-loop system is also designed to ensure implantation voltage not to depend on the plasma load during the PIII processes. With the help of numerical calculation or simulation, the expected ion energy-number spectrum can be easily obtained.

article i nfo Plasma immersion ion implantation and deposition into the inner wall of a small diameter tube has gained more interest. A custom-designed plasma source based on hollow cathode discharge excited by radio- frequency (RF) is utilized to deposit a DLC film inside the slender tube. The internal cathode nozzle (shielded by an external grounded electrode) is made of stainless steel 6 mm in inner diameter and, 10 mm in outer diameter whereas the inner diameter of the tube to be treated ranges from 20 to 40 mm. The discharge is ignited and sustained in tubes with inner diameter of 20 mm and lengths of 140 mm and 500 mm. The DLC films with similar Id/Ig value and G-band position can be fabricated on the inner wall of the entire tube. The film thickness increases from the bottom to the upper parts and the tube diameter also has a critical influence on the deposition rate and film thickness uniformity. This can be attributed to the special discharge behavior in the hybrid hardware system composed of the internal hollow cathode and tube itself. Better film thickness uniformity can be readily achieved by moving the tube. The custom-designed hollow cathode discharge system is demonstrated to be an effective tool to treat the inner wall of small diameter tubes. © 2010 Published by Elsevier B.V.

Plasma immersion ion implantation (PIII) employing high-voltage glow discharge is an effective tool to achieve better material properties without external plasma sources. The efficacy of high-voltage glow discharge can be enhanced by the use of a magnetic field. Our experimental results disclose that the addition of permanent magnets effectively increases the plasma density and decreases the delay time to ignite the glow discharge. The discharge can also be ignited at a lower pressure in the presence of a magnetic field. This helps to improve the implantation energy due to reduced particle collisions. In addition, the process is more flexible since plasma generation depends less on the gas pressure and target bias compared to conventional high-voltage glow discharge PIII. To demonstrate the advantages of this simple, flexible and efficient technique, polyethylene terephthalate (PET) foils are treated by glow discharge PIII to improve the surface properties and smaller water contact angles are observed from the implanted samples.

Magnesium alloys are potential materials in biodegradable hard tissue implants. However, their fast degradation rates in a physiological environment constitute the main limitation for their applications. In this work, a ZrN/Zr bilayered coating is deposited on AZ91 magnesium alloy using a filtered cathodic arc deposition system. The ZrN/Zr bilayered structure buffers the serious mismatch between the substrate and ZrN coating thus improving film adhesion. The composition of the coating is evaluated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical behavior of the coated alloy is systematically studied by means of potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). Our results disclose that the corrosion resistance of the coated alloy is significantly improved.

Ionized magnetron sputtering (MS) has gained more interest due to the flexible process control and better surface properties. A new apparatus utilizing capacitively-coupled radio-frequency (RF) discharge is described here. The sample holder is connected to the RF power and pulse bias systems. The influence of the continuous or pulsed RF discharge on the operation voltage of MS system is investigated. The operation voltage is observed to decrease when the RF discharge is ignited. It is attributed to the enhanced plasma density in front of the sputter target. The variation in the operation voltage depends on the MS current. At a low MS current, the operation voltage decreases with increasing RF discharge power. In contrast, the operation voltage increases at higher RF discharge power together with a higher MS current. A larger RF pulse width does not increase the operation voltage although the average RF power increases. The TiN films fabricated using this apparatus possess better corrosion resistance and wear resistance despite a large friction coefficient. It is believed to be due to the synergistic effects of the higher plasma density and self-biasing at higher RF power. Our results demonstrate that this special magnetron sputtering process that couples the sample holder to the RF discharge and negative bias is an effective approach to achieve better surface properties.

The influence of radio-frequency (RF) power on the structure and gas permeation through amorphous hydrogenated carbon films deposited on cylindrical polyethylene terephthalate (PET) samples is investigated. The results show that a higher radio-frequency power leads to a smaller sp3/sp2 value but produces fewer defects with smaller size. The permeability of PET samples decreases significantly after a-C:H deposition and the RF only exerts a small influence. However, the coating uniformity, color, and wettability of the surface are affected by the RF power. A higher RF power results in to better uniformity and it may be attributed to the combination of the high-density plasma and sample heating.

Diamondlike carbon (DLC) films are deposited on AISI 304 stainless-steel substrates using hollow-cathode chemical vapor deposition. The effects of the substrate bias on the structural and mechanical properties of the films are studied. X-ray photoelectron spectroscopy reveals the existence of CC (sp2) and C–C (sp3) functional groups in the films, and Raman spectra show that the ratio of the G (graphite) peak to the D (disorder) peak depends on the sample bias. The DLC film deposited at −50V bias has the highest sp3 content, and this is consistent with the G-band position and D-band full width at half maximum as a result of substrate biasing. The sample bias also has a critical influence on the thickness and hardness of the deposited films. The largest thickness (1700nm) and highest hardness (HV1099) are achieved at a bias voltage of −50V. All the films show low friction coefficients, and the sample treated at −200V gives rise to the lowest friction coefficient.

Under atmosphere and vacuum cycle condition, characteristics of a disc-type traveling wave ultrasonic motor (TWUSM) are tested, variations of rotation speed with time and load are also obtained. Two vacuum conditions used are low vacuum of 2 Pa and high vacuum of 5 × 10−3 Pa. The lower the environment pressure is, the smaller the rotation speed of TWUSM. And load characteristics of TWUSM in vacuum are poorer than that in atmosphere. Then, using polyfluortetraethylene (PTFE) composite and p-hydroxybenzoic acid polymer (Ekonol) composite as friction materials, load characteristics of TWUSM are compared. As a result, the load characteristics of Ekonol composite are better than the former one, which can hold bigger torque with higher speed. Both principle of ultrasonic motor and knowledge of tribology are applied to analyze the reason that stall torque of TWUSM in vacuum is smaller than in atmosphere.

Amorphous hydrogenated carbon (a-C:H) films have been deposited on polyethylene terephthalate by plasma immersion ion implantation and deposition. The influence of deposition parameters such as gas pressure, bias voltage, and nitrogen incorporation on the mechanical properties of the a-C:H films are investigated. X-ray photoelectron spectroscopy reveals that the ratio of sp3 to sp2 is 0.24 indicating that the film is mainly composed of graphitelike carbon. Nanoindentation tests disclose enhanced surface hardness of ∼6GPa. The friction coefficient of the film deposited at higher gas pressure, for instance, 2.0Pa, is lower than that of the film deposited at a lower pressure such as 0.5Pa. The films deposited using a low bias voltage tend to fail easily in the friction tests and nitrogen incorporation into the a-C:H films decreases the friction coefficient. Mechanical folding tests show that deformation failure is worse on a thinner a-C:H film.