等离子体浸没离子注入改善45钢的摩擦学性能

采用灯丝放电和射频(RF)辉光放电等离子体浸没离子注入(PⅢ)工艺对45钢表面进行了氮离子注入强化处理。通过X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、显微硬度、针-盘磨损和电化学腐蚀试验等测试手段，分析比较了经灯丝放电PⅢ和RF辉光放电PⅢ改性后试样表面元素的浓度分布、显微硬度、摩擦磨损性能和耐腐蚀性能。结果表明：不同条件下的氮离子注入均能提高45钢表面的显微硬度、耐磨性和抗腐蚀性能；且RF辉光放电PⅢ处理后试样的显微硬度提高了76．8％，摩擦系数下降到0．3，与灯丝放电PⅢ处理后的试样相比，其表面强化效果更加明显。     

Uniformity enhancement of incident dose on concave surface in plasma immersion ion implantation assisted by beam-line ion source

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.     

Improve retained dose and impact energy of inner surface plasma immersion ion implantation using long pulse duration with deflecting electric field

Not restricted by the line-of-sight process, plasma immersion ion implantation (PIII) has shown great potential for inner surface modification, but the impact energy and retained dose turned to be very low. The process was investigated numerically and experimentally in this paper. The results show that a high percentage of low impact energy ions was the key factor that resulted in low impact energy on the inner surface. This was caused by sheath overlapping and appearance of the dead zone during inner surface PIII. Long pulse duration could alleviate this problem and increase ion impact energy on the inner surface, hence the implant depth, which was key factor for the modifying effect of PIII. Also, long pulse duration was helpful in improving the retained dose on the inner surface.     

TWO-DIMENSIONAL NUMERICAL ANALYSIS OF PLASMA IMMERSION ION IMPLANTATION OF CYLINDRICAL BORES

1.IntroductionPlasmaimmersionionimplantation(Pill)[']unrestrictedbysight--lightprocess,isconsideredapropermethodforinnersurfacestrengthening.Inrecentyears,researchershavepaidalotofattentiononapplyingPillininnersurfacemodification.T.E.Sh.,idan[2,3]hassimulatedtheinnersurfacePillprocessofaboreusingone--dimensionalfluidmodel,andpresentedthelowimpactenergyproblemforthefirsttime.Zengetall4'5]presentedanideatoimprovetheimpactenergyusinganauxiliaryelectrode,basedonsimilaranalysis.Wepresentedametho…     

High frequency and low voltage plasma immersion ion implantation of nitrogen on industrial pure iron at different Rf power

Traditional plasma ion immersion implantation (PIII) can effectively improve material mechanical property and corrosion resistance. But the modified layer by PIII is too thin for many industrial applications. High frequency and low voltage plasma immersion ion implantation (HLPIII) has advantages of PIII and nitriding. Comparing with traditional ion nitriding, HLPIII can obtain higher implantation energy and create a thick modified surface layer. In the present paper nitriding layers were synthesized on industrial pure iron using high frequency and low voltage plasma immersion ion implantation with different RF power (400 W, 600 W, and 800 W). The microstructure of the nitriding layers was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mechanical properties such as microhardness and wear resistance were analyzed using HXD1000 microhardness and CSEM pin-on-disk wear testing machine. The anodic polarization characteristics were measured in a 0.9% NaCl solution at room temperature to examine the corrosion resistance of the nitriding layer. The results reveal that Fe₂N, Fe₃N and Fe₄N coexist in the nitriding layer. The nitriding layer is a corrosion protective coating on industrial pure iron in 0.9% NaCl solution. The hardness, wear resistance and corrosion resistance of the nitrided layers on industrial pure iron increase with RF power.     

An automated system for DC and RF plasma characterization by guard double electric probes

Monitoring basic plasma parameters such as temperature (T), density (n), floating potential (V_f) or Debye length (λ_d) provides vital knowledge during the ion implantation processing of materials immersed in plasmas (PIII or PSII) generated either by DC or (13.56 MHz) RF sources. Thus, a fully automated electromechanical system has been designed and constructed on the basis of guard double electric probes in order to prevent both probe erosion and plasma contamination. The electronic components of the system comprise a ± 150 V triangular and ramp wave form generator capable of supplying ± 50 μA to ± 100 mA currents at 1–2000 Hz frequencies and a DAQ PCI-6023E data acquisition board with a 12 bit resolution compatible with LabVIEW graphic language. A program has been specifically developed for the latter in order to control the probe position within the discharge vessel and to capture, filter, visualize, process and store the respective information. The system has been experimentally applied to DC and RF plasmas of helium, argon, nitrogen, oxygen, and multiple gas mixtures with great success, inside several PIII reactors. Results are presented free from RF interference from the process itself or other surrounding sources.     

Surface modification of a polyester non-woven with a dielectric barrier discharge in air at medium pressure

In this paper, a polyester non-woven is plasma treated with a dielectric barrier discharge (DBD) in air at medium pressure (5.0 kPa) and at different discharge powers. Results show that an increasing power leads to a better plasma treatment of the sample. The barrier discharge is characterized by a voltage and current waveform, by a Lissajous figure and by Lichtenberg figures. The surface properties of the plasma treated samples are examined using X-ray photoelectron microscopy (XPS) and scanning electron microscopy (SEM). XPS analysis reveals that surface oxidation by the formation of oxygen-containing functional groups enhances the surface wettability. SEM analysis shows that the sample is not etched by the used barrier discharge. This is due to the low surface energy density of the DBD used in this paper. Therefore, a DBD in air at medium pressure provides an efficient modification of the chemical surface properties of textiles without destroying the physical structure.     

Duplex diamond-like carbon film fabricated on 2Cr13 martensite stainless steel using inner surface ion implantation and deposition

A duplex plasma immersion ion implantation and deposition (PIIID) process, involving carbon ion implantation and diamond-like carbon (DLC) film deposition, is proposed to treat the inner surface of a tube. Samples of 2Cr13 martensite stainless steel were placed inside the tube to investigate the performance of the films. Carbon ion implantation was finished by biasing the tube with a high voltage, and the DLC film deposition was obtained by biasing the tube with a medium voltage. Raman spectrum, ball-on-disc, indentation and scratch tests were used to investigate the structure, tribological property and adhesion strength of the as-deposited films. The Raman spectrum shows that the sp³ bonding is formed in the as-synthesized film. Tribological and scratch test results reveal that the duplex DLC coating with the implantation time of 1 h has the largest adhesion strength and the best wear resistance.     

Effect of pulse rise time on charging effects in plasma immersion ion implantation with dielectric substrates with planar and cylindrical geometries

Using a one-dimensional self-consistent fluid model, the effect of pulse rise time on charging effects at dielectric surfaces is investigated during plasma immersion ion implantation (PIII) with planar and cylindrical geometries. The numerical results demonstrate that the pulse rise time plays an important role in PIII process with dielectric substrates. It is found that the charge dose accumulated on the dielectric surface is significant as decreasing pulse rise time, and the surface potential decreases at the later stage of the pulse, which results in the lower ion impact energy. On the other hand, the longer pulse rise time would lead to the lower charge dose accumulated on the dielectric surface and higher ion impact energy at the later stage of the pulse, which would elevate the effective implanted dose and introduce the ions to the depth deep enough for surface modification.     

Hybrid elevated-temperature,low/high-voltage plasma immersion ion implantation of AISI304 stainless steel

Elevated-temperature plasma immersion ion implantation (PIII) is an effective non-line-of-sight technique to harden austenitic stainless steel by producing expanded austenitic phases in the near surface region. We report here a hybrid elevated-temperature, low/high voltage approach, which improves the efficiency while retaining the non-line-of-sight advantages of PIII. A low-voltage (4 kV), elevated-temperature (355°C) PIII process is first used to produce the modified layer, but the nitrogen concentration in this layer is typically relatively low and the thickness may not be adequate. This is followed by high-voltage (25 kV) PIII at a lower temperature to increase the nitrogen concentration and to achieve the desirable surface enhancement effects. To assess the efficacy of the technique, the samples are characterized using X-ray diffraction (XRD), nanohardness measurements, and secondary ion mass spectrometry (SIMS) depth profiling. The experimental results show that the nitrogen concentration increases by nearly 75% and the nitrogen penetration depth nearly doubles that of the low-voltage sample. The surface microhardness also improves by 150% and our data suggest that it is due to the formation of expanded austenites.     

Plasma immersion ion implantation induced improvements of mechanical properties, wear resistance, and adhesion of diamond-like carbon films deposited on tool steel

Nitrogen-rich layers are formed on the surface of JIS-SKH51 tool steel substrates using the plasma immersion ion implantation (PIII) technique. An unbalanced magnetron sputtering (UBMS) system is then used to coat the steel substrates with diamond-like carbon (DLC) films of various thicknesses. The adhesive strength and wear resistance of the DLC films are then examined by performing nanoscratch and nanowear tests. Finally, the microstructures of the DLC films are analyzed using TEM and Raman spectroscopy. The nanoindentation test results show that the PIII treatment yields an effective improvement in both the hardness and the Young's modulus of the SKH51 substrates. Moreover, cross-sectional observations show that the implantation depth and microstructure of the nitrogen-rich surface layer are dependent on the nitrogen/hydrogen flow ratio used in the PIII process. The nanoscratch test results show that the PIII treatment improves the adhesion of the DLC film to the steel substrate. Furthermore, the Raman spectroscopy results indicate that the use of hydrogen in the PIII process limits the increase in the I(D)/I(G) ratio by increasing the DLC film thickness. Finally, the nanowear test results show that the deposition of a DLC coating with a sufficient thickness yields a significant improvement in the wear resistance of the steel substrate.     

不同电场环境对镀料脱靶方式及TiN镀层微观结构的影响

当前主流的镀层沉积技术中,电弧离子镀因镀料熔融喷溅脱靶致镀料中夹杂微米尺度高温颗粒,易使镀层表面粗糙和基体高温损伤;直流磁控溅射因镀料碰撞溅射脱靶致离化率低,易使镀层厚度不均和组织疏松。为解决以上技术缺点,依据气体放电等离子体物理学知识,采用新型阶梯式双级脉冲电场诱发阴极靶材与阳极腔体间气体微弧放电,依靠微弧放电后产生的高密度等离子体,增强Ar+对靶面的轰击动能和靶面产生的焦耳热,实现镀料由碰撞溅射脱靶向热发射脱靶的转变,并以此提高镀料的离化率,达到改善镀层结构的目的。实验结果表明：双级脉冲电场诱发的气体微弧放电呈现出耀眼白光,而靶面形貌则表现出高低起伏的凹坑和水流波纹,其靶面形貌不同于镀料碰撞溅射脱靶后的多边形凹坑,说明靶面局部区域的镀料以热发射方式脱靶。同时,在双级脉冲电场下制备的TiN镀层具有较为致密的组织结构,沉积速率可达51nm/min。     

等离子体浸没离子注入(PⅢ)在材料表面改性中的应用及发展

等离子体浸没离子注入(PⅢ)是一种用于材料表面改性的新的离子注入技术.系统地分析和讨论了等离子体浸没离子注入技术的原理和特点:该技术直接将待处理材料浸没在等离子体中进行注入,保留了常规束线离子注入(CBⅡ)技术的主要特点,消除了常规束线离子注入所固有的视线限制,克服了保持剂量问题,使注入装置变得简单和价廉.综述了等离子体浸没离子注入技术在金属材料、半导体材料和高分子材料改性方面的应用.展示了等离子体浸没离子注入技术应用的发展前景.     

In vitro corrosion behavior of TiN layer produced on orthopedic nickel-titanium shape memory alloy by nitrogen plasma immersion ion implantation using different frequencies

In the present work, the NiTi surface was modified by nitrogen plasma immersion ion implantation (PIII) in an effort to improve the corrosion resistance and mitigate nickel release from the materials. The implanted nitrogen depths and thicknesses of the surface TiN barrier layers were varied by changing the pulsing frequencies during PIII. In order to determine the optimal parameters including the pulsing frequencies, electrochemical tests including open circuit potential (OCP) measurements and potentiodynamic polarization tests were conducted on the untreated and N-implanted NiTi in simulated body fluids (SBF). Our results reveal that the nitride layer produced using a frequency of 50 Hz has the best stability under the OCP conditions and the TiN layer produced using 200 Hz has the highest potentiodynamic stability after immersion in SBF for a long time. The observation can be correlated to the temperature during PIII and the thickness of TiN layer. The TiN layer on the NiTi surface favors deposition of Ca-P composites thereby compensating for the instability of the TiN layer produced at a higher frequency.     

Plasma characterization and technological application of a hollow cathode plasma source with an axial magnetic field

An efficient plasma source has been established by arranging a hot hollow cathode electron emitter in a strong axial magnetic field, allowing for a reduction of working gas flow by one order of magnitude without loss of discharge stability. Moreover, with the reduction of gas flow not only an increase of the discharge impedance was observed, but also a multiplication of ion current density together with a highly expanded volume of the plasma plume.By means of spatially resolved Langmuir probe measurements, combined with the usage of an energy-resolved mass-spectrometer, plasma density profiles and energy distribution functions of electrons and ions have been measured. Generally, with an increase of the magnetic field and with the reduction of the working gas flow ion energy distribution functions shift from mean values of a few eV to 10 eV and more, while charge carrier densities increase from 10⁹ cm^− 3 to more than 10¹² cm^− 3. A strongly increased ability to dissociate and ionize reactive gases was observed.Two promising applications related to the coating of tools and components are discussed: the sputter etching with argon ions and the reactive pulse magnetron sputter deposition of wear-resistant chromium nitride layers. Whereas the first mentioned process provides pre-heating and etching rates higher than all actually used in tool coating industry, the second one offers advantages for film growth kinetics leading to significant improvements in composition, structure, surface morphology, and hardness of the deposited layers.     

Influence of the Iron Anisothermal Sintering on the Characteristic of the Hollow Cathode Discharge

SINTERING of steels and ceramics is conventionallycarried out in a furnace in a controlled atmosphere.Several alternative techniques have been developedsince 1966, as mentioned by Johnson et al. [1], toobtain components with improved properties, resultingin new applications for powder technology. Plasmasgenerated in microwave cavities, in hollow cathodedevices and microwave or RF-inductively coupleddischarges have all been used for sintering ceramics[2-5]. In the above mentioned papers it …     

ION HEATING PROCESS DURING PLASMA IMMERSION ION IMPLANTATION

1.IntroductionIonbombardmelltusingplasmaimmersionmethodhasprovenaneffectivesurfacemodificationtechnique[2,3].Plasmaimmersionionimplantation(Pill)cansignificantlyimprovethesurfacepropertiesofthecomponents,suchashardness,friction,wear--resistanceandcorrosion--resistanceofthematerials.Meanwhileitsbiggestadvantageistheabilitytotreatirregularlyshapedobjectswithoutthenecessityoftargetmanipulation.Pillprocesscanbeconductedbyeitheratalowtemperature(<100'C)orelevatedtemperatureconditions(usually300'C…     

细长管内表面镀Cu过程中的空心阴极辉光电

为了在细长管内壁获得质地均匀的Cu膜层,采用射频耦合直流空心阴极放电的方法,研究在长度200 mm、内径6～12mm的细长管内沉积Cu薄膜时的放电情况。通过探究改变耦合直流电压、射频电压、中频电压以及管内径和测量管内轴向不同位置带来的放电影响情况,获得最佳的放电参数。研究发现,耦合直流电压越高、射频功率越高,则放电过程中的Ar~*、Ar⁺、Cu⁺活性粒子数量越多;增大中频电压,Ar~*和Cu⁺光谱峰值强度呈现“V”字形,即先降低后升高,Ar⁺光谱峰值强度在0～40 V时处于稳定的状态,在40 V开始上升,并且在60 V之后快速上升;管内径10 mm时放电效果最佳,在内径为6 mm到10 mm的管内Ar~*、Ar⁺、Cu⁺粒子数目增多,当内径到达12 mm,三种活性粒子迅速减少。通过对200 mm长、10 mm内径管内不同轴向位置的测量,发现细长管中部(100 mm)放电强度高于管口(10 mm)和管尾(190 mm)。     

Shunting arc-produced hybrid plasma and its magnetic drive for PBII&D

Hybrid plasmas produced by shunting arc discharge are described in this article. The shunting arc was generated in various ambient atmospheres. When a carbon-shunting arc was generated in a nitrogen atmosphere, the carbon ion species were produced at the arc stage, the electrons of which accelerated toward the wall, colliding with the gas species in the chamber to produce nitrogen ions. When the arc was generated in a methane atmosphere, the hydrogen content in the deposited carbon film changed with the gas pressure. When the arc was generated in gaseous RF plasma, an enhancement in the plasma density was confirmed with ion current measurement. Another method of the shunting arc application is the usage of the Lorentz force, which accelerates the entire plasma body toward the target. This results in a fast deposition of the plasma species such as carbon.