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The microstructure and mechanical properties of diamond-like carbon (DLC) films fabricated on an AISI52100 bearing steel substrate surface by plasma immersion ion implantation and deposition (PIIID) were studied. Atomic force microscope (AFM) observation reveals that the DLC film has an extremely smooth surface, and high uniformity and efficiency of space filling over large areas. Raman spectroscopy analysis indicates that DLC films are mainly constituted by amorphous and crystalline phases, with a variable ratio of sp 2 / sp 3 carbon bonds, and sp 3 bond content of more than 10%. The maximum nanohardness and elastic modulus of the DLC film are 40 GPa and 430 GPa, and increase by 263.6% and 95.5%, respectively. The friction and wear results exhibit that the friction coefficient against an AISI52100 steel ball decreases from 0.87 to 0.20. The corrosion polarization curves in a 3.5% saturated NaCl solution shows that the corrosion resistance of DLC/AISI52100 samples is much better than that of bearing steel substrate. Compared with the bare bearing steel, the surface mechanical property of the DLC/AISI52100 sample is improved significantly.

Titanium nitride (TiN) films were fabricated on AISI52100 bearing steel surface employing a hybrid plasma immersion ion implantation and deposition (PIIID) technique. The chemical composition, morphology and microstructure of TiN films were characterized by atomic force microscope (AFM), energy dispersive spectrometer (EDS), scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The residual stress of TiN films under different deposition parameter conditions were measured by means of glazing incidence angle X-ray diffraction (GIXRD) method. The influence of film thickness and X-ray glazing incidence angle on residual stress were investigated. AFM observation reveals that the TiN films have extremely smooth surface, high uniformity and efficiency of space filling over large areas. XRD analysis results indicate that TiN phase exists in the surface modified layer and exhibits a preferred orientation with the (2 0 0) plane. The GIXRD data shows that the residual stress in as-deposited TiN films is compressive stress, and the residual stress value decreases with the film thickness and increases with the glazing incidence angle. The compressive stress reduces from 2.164 GPa to 1.163 GPa, which corresponds to the film thickness from 1.5 μm to 4.5 μm, respectively. Reasonably selecting PIIID process parameters for TiN films fabrication, the residual stress in the film can be controlled effectively.

Dual plasma deposition is a versatile method of thin film fabrication in which both gaseous and metal plasmas are co-deposited, thus having the advantageous feature of being able to form films of a wide range of elemental and compound composition. However, since the density of the metal plasma formed by a vacuum arc plasma source is non-uniform both radially and axially, the uniformity of the deposited film is in general poor. We have developed a two-dimensional particle-in-cell (PIC) model describing the spatial and temporal evolution of the metal plasma particle density and potential distributions throughout the simulation region. The results indicate that the time required for steady state distributions of density and potential to evolve is determined by the plasma streaming velocity and the axial distance of relevance. The uniformity of the deposited film is improved as the distance from source to substrate is increased. Comparison with experimental results indicates that the simulation model provides a valid description of the metal plasma flow.

TiN/ZrO2 multilayers with different modulation periods were synthesized on GCr15 bearing steel using plasma immersion ion implantation and deposition (PIIID). The total thickness of the TiN/ZrO2 multilayers was approximately 2 μm and the modulation period was varied from 8 to 400 nm. The as-deposited films were characterized by scanning electron microscopy (SEM), micro-hardness, friction, scratch and corrosion tests. The SEM result indicates that the structure of the TiN/ZrO2 multilayers has a good periodicity. Micro-hardness testing results show that the hardness enhancement effect takes place at the specific period of 15 nm, 100 nm and 200 nm. In addition, the friction coefficient declined from 0.8 to 0.1–0.3 and the cut-through number was increased greatly. The critical load in the scratch test exceeds 100 N, which shows a high adhesion strength. Moreover, the corrosion resistance of the TiN/ZrO2 multilayers was improved significantly at the modulation period of 100 nm and 200 nm.

The effect of plasma immersion ion implantation and deposition (PIII&D) titanium carbide (TiC) film on the rolling contact fatigue (RCF) life of coated on AISI52100 bearing steel surface is studied experimentally. Testing include plan-view optical microscopy (OM), X-ray diffraction (XRD), friction and wear behaviors, rolling contact fatigue life and nano-indentation measurements. XRD patterns show that titanium carbide phase is formed in the film, and the microhardness of treated samples is higher than that of substrate. Rolling contact fatigue failure tracks were observed using conventional light microscope. Surface wear and adhesive delamination existed. Results indicate that the maximum RCF life of the treated sample prolong by 6.5 times at a Hertzian stress level of 5.1 GPa and 90% confidence level, respectively. Comparison with the substrate, the maximum microhardness of treated specimen is increased by 28.4%. The friction coefficient decreased from 0.95 to 0.15 under identical wear conditions. This remarkable fatigue performance appears to be due to a combination of improved microstructure, adhesion, hardness and surface topography. Therefore, the PIII&D is regarded as one of the promising technologies for improving the RCF life of bearing.

Surface modifications of industrial components, such as the balls, inner and outer rings of bearings, are very difficult to perform for their sophisticated shapes. Plasma immersion ion implantation and deposition (PIIID) offers an effective way for surface treatment of such components. However, implantation doses of these components are not uniform in a conventional PIIID process. To obtain uniform surface modifications, we designed a rotating target holder. Using the target holder and proper process parameters, the PIIID batch treatment of sophisticated-shape components has become easy work. In the PIIID batch treatments of balls, outer and inner surfaces of cylinder-like components, the dose uniformity can be evidently improved by using sample rotation, short width high frequency implantation pulse, and middle-frequency and -voltage glow discharge, respectively. The practical test results reveal that the life of these components can be improved significantly by this novel PIIID batch treatment.

Rolling contact fatigue (RCF) performance and mechanical characteristics of nitrogen plasma immersion ion implantation (PIII) on AISI52100 bearing steel surface has been investigated using a conventional three ball-on-rod rig. Testing investigations include optical microscopy (OM), friction and wear behavior, rolling contact fatigue life, and nano-indentation measurements. Results indicate that the rolling elements failed at the surface or near-surface layer. Moreover, an appreciable amount of surface wear was observed on the surface of the rolling elements after RCF tests. The maximum microhardness of treated samples is nearly twice as that of substrate. The friction coefficient of the treated samples is decreased from 0.90 to 0.15. The L 10 life of the treated specimens increase by 99.6% and L 50 life enhance by 236.3% at a Hertzian stress level of 5.1 GPa and 90% confidence level, respectively. OM morphology results indicate that the surface roughness, processing parameters, and inner defects play an important role in surface and near-surface initiated RCF. This improvement of fatigue and mechanical performance is attributed to form a combination of nitrides phase structure and residual compressive stress during the nitrogen-PIII process.

As a crystallization process, the field-aided lateral crystallization (FALC) technique has some outstanding advantages, such as high crystallization rate and low temperature. In this study, the electrical field was directly applied between source and drain areas of H shape patterns using the Mo–W interconnecting layer. The effects of the current density and electrical field strength on the crystallization behavior were investigated. Results show that the crystallization behaviors at different bias areas are different. The difference is attributed to the coexisting effects of electromigration and potential gradient. In addition, the dependence of the degree of crystallization on the current density was studied by Raman spectra and the microstructure crystallized by FALC was observed by a scanning electron microscope.

TiN films were synthesized on GCr15-bearing steel by plasma immersion ion implantation and deposition (PIIID). During the experiments, the bias voltage was varied from −10 to −30 kV, and the ratio of implantation to deposition was adjusted from 1:10, 1:20, 1:30 to 1:40 by changing the pulse durations of the bias voltage and the vacuum arc discharge. Adhesion strength tests were carried out by scratch test. The results reveal that the adhesion strength between the film and the substrate is influenced by the bias voltage and the ratio of implantation to deposition significantly. In addition, the pretreatment of substrates and the interface layer have some impacts on the final adhesion strength.

Titanium carbide films have been synthesized by plasma immersion ion implantation and deposition (PIIID) on 9Cr18 bearing steel. During the experiments, acetylene (C2H2) and titanium plasmas were generated simultaneously. Acetylene plasma was produced by a radio-frequency plasma source, and titanium plasma was generated by cathodic arc plasma source. Influences of gas pressure and pulse width of the bias voltage on properties of the thin film were investigated. The as-deposited films were characterized by X-ray diffraction (XRD), micro-hardness tester, pin-on-disc tribological facility and electrochemistry corrosion equipment. XRD pattern proves that TiC phase is formed in the film. Compared with uncoated substrates, micro-hardness results reveal that the maximum micro-hardness is increased by 70.8%. In addition, the friction coefficient decreases to about 0.1, and the corrosion resistance of coated substrate surfaces is improved significantly.

We have developed a repetitively pulsed cathodic arc plasma source that can operate at high duty cycle and with long lifetime between downtimes for cathode maintenance. The arc discharge current can be up to 300 A, the arc pulse width can be varied from 0.1 to 4 ms, and the source can operate at a duty cycle of up to 30% for many hours. The cathode can be of a diameter from 20 to 40 mm, and can be easily and quickly changed. A 45° magnetic duct is used for macroparticle filtering, employing a pulsed magnetic field. We have operated the source over a wide parameter range, and we report here on the variation of plasma ion deposition current with arc current, duct magnetic field, and duct bias voltage. A momentary ion deposition current of 0.7 A was obtained with the source running stably for more than 8 h with an arc current of 100 A and duty cycle of 20%.

The effects of the substrate temperature and ion impact energy on the surface roughness and morphology of insulating cerium oxide films fabricated by dual plasma deposition were investigated. Cerium oxide films were synthesized on Si(1 0 0) substrates, and the influence of the substrate temperature and applied voltage on the surface roughness was systematically studied. Our results indicate that the roughness of the deposited films decreased when the substrate temperature was increased, probably because of enhanced surface diffusion of the adatoms. The ion kinetic energy had a similar effect as the substrate temperature, and it is believed that a higher ion kinetic energy also improves the surface diffusion of adatoms. It is found that a direct-current voltage applied to the substrate could lead to a rougher surface, whereas an appropriate alternating-current voltage gave rise to a smoother topography.

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.

2Cr13 martensite steel is often used as a piston material in oil pumps. In the harsh environment of an oil field, the materials and components undergo extensive and accelerated wear and tear. In this study, we employ Ti and N plasma immersion ion implantation and ion beam enhanced deposition (PIII-IBED) to enhance the surface wear resistance of 2Cr13 steel in an effort to prolong its working lifetime. To assess the technique efficacy and surface properties of the 2Cr13 steel samples treated by PIII-IBED using different voltages, the coefficient of friction, wear tracks, microhardness, anode polarization curves, chemical composition and elemental depth profiles were determined. The experimental data show that the wear resistance of the treated 2Cr13 steel samples is improved significantly by the method, and the nitride phases formed in the modified layer play an important role in the enhancement mechanism.

In order to lower the growth temperature and improve the crystalline quality, the temperature effects on the growth of CeO2(1 1 1) layer on Si(1 0 0) using dual plasma deposition are investigated. The as-deposited films are characterized by X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS), and atomic force microscopy (AFM). The XRD results show CeO2(1 1 1) has been successfully deposited on Si(1 0 0) even at 200°C, and the best crystalline quality is found in the film deposited at 500°C. The CeO2(1 1 1) pole figure acquired from the sample deposited at 500°C shows that the film has a strong preferred orientation. The RBS results show that the concentration ratio of Ce and O approaches the normal chemical stoichiometry as the temperature is increased. The surface topography of the films revealed by AFM discloses that as the growth temperature is increased, the surface is less rough and the density of the islands becomes higher. © 2001 Elsevier Science B.V. All rights reserved.

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.

Elevated-temperature plasma immersion ion implantation (PIII) increases the surface hardness and thickness of the modified layer and is traditionally performed at a high energy (typically above 5 keV) and low current density. In this article, we report the benefits of a different approach by high-frequency, low-voltage plasma immersion ion implantation (HLPIII). Experiments and a two-dimensional theoretical simulation are conducted to demonstrate the advantages of the process on a bar-shaped sample in terms of ion dose, dose uniformity, and modified layer thickness. Simulation of the sheath dynamics illustrates that the thinner plasma sheath in HLPIII is geometrically more conformal to the target surface, and the incident ion flux is more uniform along the exposed surface when compared to the traditional high-voltage PIII process. The higher ion dose and thicker modified layer can be attributed to the higher ion current density. HLPIII is thus the preferred technique to enhance the surface properties of l...

In the aerospace industry, 9Cr18 martensitic stainless steel AISI 440 is commonly used as a bearing material. Because of its . ability to rapidly treat irregular industrial components, plasma immersion ion implantation PIII is an effective method to improve the wear resistance of 9Cr18 precision bearings and prolong their working lifetime. Vacuum arc plasma sources provide a good means of introducing metal ions into the bearing steel to create a special surface to enhance its surface properties. In this work, tungsten and titanium PIII was performed on 9Cr18 bearing steel using a vacuum arc plasma source, followed by carbon . PIII using acetylene C H plasma, without breaking the vacuum. The surface properties were evaluated by measuring the 22 microhardness, wear properties and friction coefficient, as well as the elemental depth profiles and chemical composition of the modified layer. It was found that the microhardness of the treated samples was much higher. The tribological characteristics were also significantly improved, as demonstrated by the reduced friction coefficient and wear track width. This improvement can be . attributed to the diamond-like-carbon DLC surface layer, as well as favorable ion mixing caused by the implanted metal ions. Q 2000 Elsevier Science S.A. All rights reserved.

For high-dose metal ion implantation, the use of plasma immersion offers the high-rate advantage, but the simultaneous formation of a surface film along with the sub-surface implanted layer is sometimes a detriment. In this work, we describe a metal . plasma immersion approach in which pure and macro-particle free implantation metal andror gas ions , pure deposition without ion implantation, or dynamic metal ion beam assisted deposition and gaseous plasma immersion ion implantation DIBAD metal . and gas plasma immersion can be obtained. We have demonstrated the technique by carrying out Ti and Ta implantation at .

Fast pulsing, low voltage plasma immersion ion implantation (FLPIII) is an effective surface modification technique for metals. Low voltage PIII features high ion current density and the ability to treat components possessing an irregular shape. In this process, a high temperature can be attained at an average to high ion flux enabling fast diffusion of the implanted species and the formation of a thick modified layer. An experimental investigation of FLPIII into AISI304 and mild steels is described. The resulting surface microhardness is much higher, and the friction coefficient as well as wear rate are dramatically reduced on account of the formation of new phases in the near surface. Our experimental results also demonstrate that FLPIII increases the critical load of the materials. Combining the non-line-of-sight advantage that enables efficient processing of samples with an irregular geometry, this method has large commercial potential.

Plasma-based ion implantation (PBII) is a burgeoning surface treatment technique as it offers the possibility of treating complex-shaped and large samples without target manipulation. However, the technique has not been widely adopted in the metallurgical industry due to the difficulty to achieve a thick modified layer at low temperature. In this paper, we describe a method combining PBII and ion mixing to synthesize titanium nitride (TiN) on 304 stainless steel. Titanium and nitrogen ions are generated by a metal arc plasma source and hot filament glow discharge, respectively. By using three different sets of experimental conditions, we investigate the effects of different implantation and deposition parameters on the surface properties of TiN. Results from Auger electron spectroscopy, glancing X-ray diffraction, pin-on-disk test, and microhardness determination reveal significantly improved tribological properties. The enhancement is a consequence of the synergistic effects of the coexistence of titanium, oxygen, and nitrogen, as well as the ion mixed interface.

Plasma immersion ion implantation (PIII) is a proven surface treatment technique and can be used to prolong the working lifetime of industrial components. However, the lateral implantation dose uniformity may not be very good, particularly for samples with an irregular shape. In this work, we focus on the PIII treatment of the inner and outer races of industrial bearings. The sheath expansion around the inner and outer races is simulated using a time-dependent, two-dimensional fluid model. The angular and spatial distributions of the incident ions along both the exterior and interior groove surfaces are derived. It is found that the ion dose is the highest on the bottom or center of the groove for both the inner and outer races. The minimum ion dose is near the corner of the groove as the ions impinge at a more glancing incident angle as a result of the ion-matrix sheath evolution. Compared with the exterior groove, the interior groove receives a smaller ion dose in the same implantation time. Our results also indicate that the spatial ion dose uniformity can be improved by reducing the implantation pulse width.

A surface layer consisting of titanium, nitrogen, and oxygen is implanted/deposited onto SS304 stainless steel using dynamic mixing and plasma immersion ion implantation. Titanium is introduced into a nitrogen glow discharge plasma from a metal arc plasma source. Dynamic mixing is achieved via the co-implantation of Ti ions with high charge states as well as nitrogen and oxygen ions in the plasma. The resulting surface layer possesses superior tribological properties and corrosion resistance. The observed improvement in the wear resistance is more than a factor of 10. The enhancement in the surface properties is believed to be due to the synergistic effects of the coexistence and dynamic mixing of titanium, nitrogen, and oxygen at the interface.

Employing an improved vacuum arc plasma source, metal plasma immersion ion implantation (PIII) is performed on 9Cr18 bearing steel. Titanium, tantalum, molybdenum and tungsten ions are implanted followed by nitrogen PIII to result in a modified surface layer with superior wear resistance. The surface properties of the 9Cr18 bearing steel samples are evaluated by measuring the microhardness, wear property, coefficient of friction, as well as elemental depth profiles and chemical composition of the modified layer. The results show that the wear resistance of the samples treated by metal plus nitrogen PIII is enhanced to a larger degree than that of the samples undergoing nitrogen PIII alone. The XPS results indicate that some nitride phases have been formed in the implanted layer. In this paper, we will also discuss the improvement on the metal vacuum arc plasma source and experimental protocols. Using metal and gas PIII, the surface properties of 9Cr18 bearing steel are enhanced significantly.

This article reports on the measurement of the ion current in plasma immersion ion implantation. Our simulation results indicate that the total current peaks at the end of rise time of the applied voltage. However, our experimental data acquired using a Rogowski coil and digital oscillator show the highest current at the beginning of the voltage pulse. The discrepancy can be explained by a displacement current attributable to the changing voltage, sheath capacitance, circuit loading effects, as well as secondary electron emission.

Titanium is a promising material for medical implants, replacing bones and teeth. However, at pH values below 2, which occur in the dental environment, the corrosion resistance is compromised. The deposition of niobium layers onto titanium is a possibility to increase the corrosion resistance, as measured in 5 N HCl solution.

Plasma immersion ion implantation (PIII) is an effective technique for the surface modification of industrial components possessing an irregular shape. We have recently used PIII to treat a real industrial ball bearing to enhance the surface properties of the race surface on which the balls roll. The implantation dose uniformity along the groove is assessed using theoretical simulation and experiments. The two sets of results agree very well, showing larger doses near the center. However, the highest dose is not observed at the bottom or center of the groove, but rather offset toward the side close to the sample platen when the bearing is placed horizontally. The minimum dose is observed near the edge or corner of the groove and our model indicates that it is due to the more glancing ion incidence as a result of the evolution of the ion sheath near the corner. The dose nonuniformity along the groove surface is about 40% based on our experimental data.

Metal plasma-immersion ion implantation (PIII) employing an improved vacuum-arc plasma source is performed on 9Cr18 bearing steels. Titanium and tantalum ions are implanted followed by nitrogen plasma-immersion ion implantation to yield a modified surface layer with superior wear resistance. The surface properties of the 9Cr18 bearing steel samples are evaluated by measuring the microhardness, wear properties and coefficient of friction. Elemental depth profiles and the chemical composition of the modified layer are acquired by Auger electron spectroscopy and X-ray photoelectron spectroscopy. The results show that the wear resistance of the samples implanted with (Ti+N) and (Ta+N) is better than that of the samples undergoing nitrogen PIII alone. The XPS results indicate the presence of nitride phases in the implanted layer. In this paper, the new improvements made on the metal-arc source are described. Using the new procedures incorporating both metal-ion and gas PIII, the surface properties of 9Cr18 bearing steel are significantly improved.

Plasma immersion ion implantation (PIII) is an excellent surface modification technique because it is not restricted by the line-of-sight limitation that plagues conventional beamline ion implantation. However, the lack of in situ monitoring has hampered wider acceptance of the technique in industry. It is known that the implantation temperature has a large influence on the surface properties of the treated specimens in addition to the more obvious parameters such as implantation voltage, pulse duration, pulsing frequency, and so on. Direct measurement of the target temperature is complicated by the sample high voltage as well as by interference from the electromagnetic field and plasma. In this article, we present a novel interference-free, in situ temperature measurement technique employing a shielded thermocouple directly attached to the sample stage. Our experiments show that the setup can monitor the target temperature in real time, even under severe arcing conditions. Our results also indicate that ...

The performance and characteristics of a cathodic arc deposition apparatus consisting of a titanium cathode, an anode with and without a tungsten mesh, and a coil producing a focusing magnetic field between the anode and cathode arc investigated. The arc voltage V/sub a/ is measured with a fixed arc current for an anode diameter of 40 mm. The relationship between V/sub a/ and the magnetic field B with and without a mesh is obtained. In addition, the relationship between the arc current I/sub a/ and V/sub c/, the voltage to which the artificial transmission line was charged, is measured with and without the mesh to determine the minimum ignition voltage for the arc when the anode hole diameter is 40 mm. The arc resistance increases with the focusing magnetic strength B and decreases when using the mesh. Our results indicate that the high transparency and large area of the mesh allows a high plasma flux to penetrate the anode from the cathodic arc. The mesh also stabilizes the cathodic arc and gives better performance when used in concert with a focusing magnetic field.

Plasma immersion ion implantation is a burgeoning surface modification technique and not limited by the line-of-sight restriction plaguing conventional beam-line ion implantation. It is therefore an excellent technique to treat interior surfaces as well as components of a complex shape. To enhance the implant uniformity and increase the thickness of the modified layer, we are using a high frequency, low-voltage process to achieve high temperature and dose rate to increase the thickness of the modified layer. The low voltage conditions also lead to a thinner sheath more favorable to conformal implantation. In this article, we will describe our special modulator consisting of a single ended forward converter with a step-up transformer. The modulator is designed to operate from 5 to 35 kHz and the output voltage is adjustable to an upper ceiling of 5000 V that is deliberately chosen to be our voltage limit for the present experiments. We will also present experimental data on SS304 stainless steel materials elucidating the advantages of our modulator and high frequency, low-voltage experimental protocols.

Plasma immersion ion implantation (PIII) is an effective technique to enhance the surface properties of industrial components possessing an irregular shape. However, it is difficult to achieve uniform implantation along the groove surface of a ball bearing. In this work, we focus on the PIII treatment of the arc surface of an industrial ball bearing. Three practical sample placement configurations are investigated: I) direct placement on the sample stage platen, II) placement on a copper extension with the same diameter as the bearing race, III) placement on a copper plate erected on the sample stage by means of a small metal rod. Using theoretical simulation, the implant dose uniformity along the groove surface is determined for the three orientations. Our results reveal that configuration III) yields the largest implant dose along the groove surface and the dose uniformity is worse in configuration I). Hence, in order to improve the lateral dose uniformity along the race surface, the bearing should be elevated from the sample.

The absence of the line-of-sight restriction makes plasma immersion ion implantation an excellent interior surface treatment technique. In our experiments, we implanted both the outside and inside surfaces of a set of hollow cylindrical samples with and without a grounded conductive electrode positioned along the center of the bores to evaluate the impact energy as well as dose uniformity along the specimens. Our experimental results show that the use of the coaxial electrode increases the impact energy by 43% and retained dose by 71%. The nonuniformity is 20% to 30% and is worse with larger bore length.

Plasma immersion ion implantation (PIII) is employed to enhance the tribological properties of titanium. The effectiveness of methane PIII and glow discharge nitrogen PIII, as well as radio-frequency (RF) nitrogen PIII, is compared by measuring the microhardness, mass loss due to wear and the coefficient of friction of samples treated by the three methods. Nitrogen PIII is a hybrid surface treatment technique combining nitrogen-ion implantation, which occurs during the high-voltage pulses, and plasma nitriding, which takes place in between pulses. Our experimental data show that the surface properties of titanium are enhanced by all three treatment processes, but nitrogen PIII yields better results than methane PIII, and RF nitrogen PIII is the best treatment process of the three. On the basis of our Auger depth profiling results, the discrepancy appears to be related to the larger penetration depth (implantation plus radiation-enhanced diffusion) of nitrogen by the RF PIII process. The slight difference between methane PIII and glow discharge nitrogen PIII samples appears to arise from the absolute implanted dose.

Plasma-immersion ion implantation (PIII) can be used to process the interior surfaces of odd-shape specimens such as a cylindrical bore. The temporal evolution of the plasma sheath in a small cylindrical bore in the presence of a grounded coaxial auxiliary electrode is derived for voltage pulses of different rise times by solving Poisson's equation and the equations of ion continuity, and motion numerically using the appropriate boundary conditions. It is found that the maximum ion impact energy and the average impact energy are improved for finite rise-time voltage pulses, and shorter rise times yield better results. Our results allow the selection of a suitable auxiliary electrode radius to improve the average impact energy for a given rise time.

The high voltage and electromagnetic field environment poses a big challenge to a control system for plasma immersion ion implantation(PIII). The automation process must be immune to electric field interference produced by the high voltage power supply, modulator, radio-frequency or microwaveplasma generator, MEVVA plasma sources, and so on. We have recently designed and installed a distributed control system, PIIIDCS, to automate the operation of our PIII facility. Programmable logic controllers are used as the field control stations because of their good anti-interference ability and good real time response. A DH-485 network is used as the communication link between the field controllers and the management station in order to improve the robustness and reliability of the system. The newly developed interface is designed to work in a graphic mode in Microsoft Windows 95. Test runs have shown that the system is reliable, flexible, and easy to operate. The development of this novel control system will expedite the development of commercial PIII instrumentation.

A typical oil pump used in oil wells consists of a piston column, piston sleeve and ball valve. The working environment in an oil field is harsh and unforgiving, and the piston column in the oil pump is very vulnerable to wear and corrosion. Hence, improving the wear and corrosion resistance of the piston which is made of 45# steel is critical to the efficiency and profitability of oil companies. Even though ion implantation is an effective means to enhance the surface properties of the materials, the irregular shape and large dimension of the column make conventional beamline ion implantation very difficult. As the technique of plasma immersion ion implantation circumvents this line-of-sight restriction, it is a suitable technique to improve the wear and corrosion resistance of the components in an oil pump. A treatment process involving RF plasma nitriding and ion beam enhanced deposition (IBED) has been developed. The microhardness, mass loss due to wear, and coefficient of friction of the untreated and treated samples were measured. A salt fog test was also conducted to evaluate the resistance against rusting. The results indicate that the treatment improves the wear and corrosion resistance of the 45# steel samples significantly, and that the combined RF plasma nitriding and IBED process is more effective than a single RF plasma nitriding step.

A model utilizing cold, unmagnetized, and collisionless fluid ions as well as Boltzmann electrons is used to comprehensively investigate the sheath expansion into a translationally invariant large bore in the presence of an auxiliary electrode during plasma immersion ion implantation (PIII) of a cylindrical bore sample. The governing equation of ion continuity, ion motion, and Poisson’s equation are solved by using a numerical finite difference method for different cylindrical bore radii, auxiliary electrode radii, and voltage rise times. The ion density and ion impact energy at the cylindrical inner surface, as well as the ion energy distribution, maximum ion impact energy, and average ion impact energy for the various cases are obtained. Our results show a dramatic improvement in the impact energy when an auxiliary electrode is used and the recommended normalized auxiliary electrode radius is in the range of 0.1–0.3.

45 # carbon steel is commonly used in the industry but vulnerable to wear and corrosion in the field. Replacing it with stainless or alloy steel increases the cost significantly, and a better alternative is to improve its surface properties and lifetime using plasma immersion ion implantation (PIII). We have evaluated a variety of treatment processes including nitrogen PIII, radio-frequency (RF) plasma nitriding together with nitrogen PIII, Ti (Cr) deposition in conjunction with nitrogen PIII (IBED), as well as nitrogen PIII on samples electroplated with a layer of hard Cr. To assess the efficacy of each process, the microhardness, mass loss due to wear, coefficient of friction, and anode polarization curve were measured on both the untreated and treated 45 # samples. Our experimental results show that the surface properties of 45 # steel are enhanced by all of these methods, but to a different extent. The IBED technique produces the best enhancement data. For instance, the microhardness increases by almost a factor of 2, mass loss due to wear is reduced by 31/2 times, and the coefficient of friction diminishes by 21/2 times. The RF plasma nitriding/nitrogen PIII technique produces less dramatic enhancement results but is more desirable for complex-shaped industrial components. The hard Cr-electroplating/nitrogen PIII technique is excellent but appears to be least desirable because of environmental impact.

Nitrogen ion implantation improves the wear resistance of Ti-6A1-4V alloys by forming a hard TiN superficial passivation layer. However, the thickness of the layer formed by traditional ion implantation is typically 100–200 nm and may not be adequate for many industrial applications. We propose to use radio-frequency (RF) plasma nitriding and nitrogen plasma immersion ion implantation (PIII) to increase the layer thickness. By using a newly designed inductively coupled RF plasma source and applying a series of negative high voltage pulses to the Ti-6A1-4V samples, RF plasma nitriding and nitrogen PIII can be achieved. Our process yields a substantially thicker modified layer exhibiting more superior wear resistance characteristics, as demonstrated by data from micro-hardness testing, pin-on-disc wear testing, scanning electron microscopy (SEM), as well as Auger electron spectroscopy (AES). The performance of our newly developed inductively coupled RF plasma source which is responsible for the success of the experiments is also described.

A new generation multipurpose plasma immersion ion implanter (PIII) was custom designed, constructed, and installed in the City University of Hong Kong. The system is designed for general R&D applications in metallurgy, tribology, surface modification, and fabrication of novel materials. Using the new rf ion source in conjunction with the internal antenna system, the plasma density achieves excellent uniformity both laterally and axially. The system also incorporates two metal sources, including four metal arc sources and a sputtering electrode, so that multiple metal deposition and implantation steps can be performed in succession in the same equipment without exposing the samples to air. This capability can be critical to the study of surface properties and corrosion resistance. This article describes the design objectives, the novel features, and the characteristics of this new generation PIII equipment.

Titanium Nitride (TiN) films were prepared on AISI52100 bearing steel surface by plasma immersion ion implantation and deposition (PIII&D) technique. The as-deposited films have been characterized using a series of test methods. X-ray diffraction (XRD) proves that the surface layer is mainly composed of TiN phase with fee structure. The depth profiles and chemical bonds were analyzed with X-ray photoclectron spectroscopy (XPS) combined with Ar ion etching. Atomic force microscope (AFM) reveals that the TiNFilm has extremely smooth surface, very high uniformity and efficiency of space filling over large areas. The maximum nanohardness (H) and elastic modulus (E) of treated samples is 25GPa and 350GPa, increases by 127.3% and 59.1%. The friction and wear behaviors, rolling contact fatigue (RCF) life of all these samples were also investigated by ball-on-disc and three-ball -rod testers. Results show that the friction coefficient decreases from 0.92 to 0.2. Compared with the untreated substrate, the L 10, L 50, L a and mean life L of treated samples increases by 5.5, 2.8, 2.3 and 2.2 times, respectively. It indicates that PIII&D has been successful in depositing high-quality TiN films on bearing steel components, and beneficial in improving the mechanical properties and RCF life.

High energy implantation of metal ions can be carried out using conventional ion implantation with a mass-selected ion beam in scanned-spot mode by employing a broad-beam approach such as with a vacuum arc ion source, or by utilizing plasma immersion ion implantation with a metal plasma. For many high dose applications, the use of plasma immersion techniques offers a high-rate process, but the formation of a surface film along with the subsurface implanted layer is sometimes a severe or even fatal detriment. We describe here an operating mode of the metal plasma immersion approach by which pure implantation can be obtained. We have demonstrated the technique by carrying out Ti and Ta implantations at energies of about 80 and 120 keV for Ti and Ta, respectively, and doses on the order of 1×1017 ions/cm2. Our experiments show that virtually pure implantation without simultaneous surface deposition can be accomplished. Using proper synchronization of the metal arc and sample voltage pulse, the applied dose t...

As a crystallization process, the field-aided lateral crystallization (FALC) technique has some outstanding advantages, such as high crystallization rate and low temperature. In this study, an electric field was directly applied between source and drain areas of H shape patterns using the Mo-W interconnecting layer. The effects of the current density and the electrical field strength on the crystallization behavior were investigated. Such crystallization behaviors are attributed to the coexisting effects of electromigration and potential gradient. In addition, the dependence of the degree of crystallization on the current density was studied and the microstructure crystallized by FALC was compared with the microstructure crystallized by metal induced lateral crystallization (MILC) process.

Summary form only given. During the plasma immersion ion implantation (PIII) process, ions are typically created by an external plasma source, such as electron impact glow discharge using hot filaments, radio frequency, electron cyclotron resonance, metal arc, and so on, There is, however, a less obvious ion formation mechanism by the high voltage itself, especially for a long pulse duration or at high working pressure, as shown by the implantation current not decreasing monotonically as predicted by the Child-Langmuir law. A proof of this secondary phenomenon is that the measured total current sometimes increases dramatically in a low vacuum sustained by RF glow discharge. Another example is that the current can gradually rise after a short delay during long pulse, hot filament glow discharge PIII. These phenomena can be attributed to high voltage ionization during the PIII process and are related to the gas pressure, high voltage pulse duration, target size, target materials, and so on. In this paper, we will present supporting experimental data in addition to a theoretical analysis.

Summary form only given. Plasma immersion ion implantation (PIII) is a promising technique for surface modification of materials. Because of its non line-of-sight process, there is the intriguing possibility of implanting "interior" surfaces. If the radius R of a bore is many Debye lengths, the bore will be plasma-filled and it is possible to implant into the sidewalls of the bore. Sheridan (1993) has found that the important length scale is the ion-matrix overlap, D=(/spl epsiv//sub 0//spl phi//en/sub 0/)/sup 1/2/ where /spl phi/ is the (negative) target potential and n/sub 0/ is the (uniform) plasma density. His recent research results indicate that ion implantation in small bores (R/spl les/D) is not very hopeful because the ion-matrix sheath overlap reduces the impact energy of the ions. We are proposing to use an auxiliary electrode, a conductive cylindrical bore which potential is always zero at the axis of the cylindrical bore, to improve the impact energy. We have calculated the structure of the ion-matrix sheath in an infinitely long cylindrical bore (R/spl les/D) with the auxiliary electrode and analyzed the dependence of its radius on the electric field in the bore. Our results show that the auxiliary electrode improves the distribution of the potential and electric field in the cylindrical bore.

Summary form only given. The high voltage and electromagnetic field environment poses a big challenge to a control system for plasma immersion ion implantation (PIII). The automation process must be immune to electric field interference produced by the high voltage pulse power supply, radio frequency plasma generator, MEVVA plasma sources, and so on. We have recently designed and installed a distributed control system, PIIIDCS, for Pill facility. Programmable logic controllers (PLC) are used as the field control stations because of their good anti-interference ability and good real time response. A DH-485 network is used as the communication link between the field controllers and the management station in order to improve the robustness and reliability of the system. The newly developed interface is designed to work in a graphic mode in Microsoft Windows 95. Test runs have shown that the system is reliable, flexible, and easy to operate. The development of this novel control system will expedite the development of commercial PIII instrumentation.

Summary form only given. Previous work concentrated on the determination of the ion-matrix sheath and the temporal evolution of the plasma sheath in a small cylindrical bore for zero-rise-time voltage pulses during plasma immersion ion implantation (PIII). Because realistic voltage pulses have a finite rise time, this paper addresses the temporal evolution of the plasma sheath in a small cylindrical bore with an auxiliary electrode for different rise times by solving Poisson's equation and the equations of ion continuity and motion numerically using the appropriate boundary conditions. The ion density, flux, dose, energy, energy distribution, and average impact energy on the surface of the target for different rise times are determined and compared to the case when the auxiliary electrode is absent. Our results predict a substantial improvement of the impact energy during PIII of a cylindrical bore when an auxiliary electrode is employed even for finite-rise-time voltage pulses.