Lifang Xia

Structural characterization of TiCx films prepared by plasma based ion implantation

Abstract TiC x films with a wide range of C/Ti ratios have been prepared by plasma based ion implantation. The bonding states and structure were investigated as functions of the relative carbon content to titanium. The results of Rutherford backscattering spectroscopy showed that there was more than 20 at.% hydrogen contained in the films. By the deconvolution of X-ray photoelectron core level spectra, the excess carbon was suggested to lead to the formation of interstitial carbon, amorphous hydrogenated carbon (or graphite), polymer-like carbon, and organic compound of titanium. The cross-sectional transmission electron microscopy (XTEM) displayed that the TiC 0.81 films mainly consisted of rod-shaped TiC crystal arranged along the growth direction, while the TiC 1.55 films contained a relatively random microstructure. XTEM also provided evidence for the existence of amorphous carbon in carbon-rich films, not graphite.

Tribological performance of Ti-6Al-4V plasma-based ion implanted with nitrogen

A low-temperature (< 180°C) plasma-based ion implantation (PBII) with nitrogen that did not affect structure and surface morphology of the substrate barely changed the sample dimension. The hardness increasing factor increased with an increase in implantation dose and/or increase in implantation energy, reaching 1.4-1.7 at the lowest plastic penetration of nearly 300 nm. Wear resistance increased greatly after implantation, and increased with decrease in sliding speed. Friction coefficient decreased, and wear resistance increased with an increase in implantation dose and/or energy or when the counterbody AISI 52100 was replaced with Ti-6Al-4V when treated in the same manner as the disc. Both wear of the unimplanted and implanted discs are abrasive-dominated. A tribofilm, mainly made up of wear debris which was transferred from the disc wear-surface formed the wear surface of the counterbody. The observed wear weight increase of the counterbody (Ti-6Al-4V same treated as the disc) with wear cycle could be the result of the transferred wear debris or tribofilm. The formation and transition of tribofilm during the wear process (the morphology, distribution of the wear debris transferred and the adhesion between the tribofilm and the underlying ball wear surface) are important to the tribological properties and wear mechanism of the implanted samples.

Structure and wear behavior of nitrogen‐implanted aluminum alloys*

Aluminum alloys L2, LD2, LF12, LY12, and Al‐4% Cu were implanted at room temperature with nitrogen ions at an energy of 80 keV and dose range of 1×1016–8.3×1017 N+ cm−2. The surface structure and chemical state of the implanted surface layer was investigated by x‐ray photoelectron spectroscopy, transmission electron microscopy and transmission electron diffraction. Hardness measurements were made using a Vickers microhardness tester, and wear tests were carried out using a pin‐on‐disk wear testing machine. The results reveal that implanted nitrogen combines with aluminum to form AlN precipitates at room temperature and nitrogen implantation accelerates the aging process of Al‐4% Cu alloys. The results also reveal that nitrogen implantation increases the hardness and sliding wear resistance of aluminum alloys. The improvements are mainly attributed to the formation of AlN precipitates.

The mechanical properties of an aluminum alloy by plasma-based ion implantation and solution-aging treatment

The age-strengthening 2024 aluminum alloy was modified by a combination of plasma-based ion implantation (PBII) and solution-aging treatments. The depth profiles of the implanted layer were investigated by X-ray photoelectron spectroscopy (XPS). The structure was studied by glancing angle X-ray diffraction (GXRD). The variation of microhardness with the indenting depth was measured by a nanoindenter. The wear test was carried on with a pin-on-disk wear tester. The results revealed that when the aluminum alloys were implanted with nitrogen at the solution temperature, then quenched in the vacuum chamber followed by an artificial aging treatment for an appropriate time, the amount of AlN precipitates by the combined treatment were more than that of the specimen implanted at ambient temperature. Optimum surface mechanical properties were obtained. The surface hardness was increased and the weight loss in a wear test decreased too.

Structure and frictional characteristics of Ti–6Al–4V plasma-based ion implanted with nitrogen then acetylene

Abstract The concentration depth profiles, structure and ball-on-disk frictional characteristics of Ti–6Al–4V plasma-based ion implanted with nitrogen (energy 60 keV) then acetylene (energy 10–30 keV) were investigated. The implanted samples ( R =0.05–2×10 11 Ω cm −1 for the modified layers) included three zones: a top H–DLC zone, a C, N, Ti, O coexisting intermediate zone which had undergone chemical state changes indicating TiN, TiC, and Ti(C,N) second phases were formed, and the bottom zone of the substrate. The samples showed higher hardness especially at low plastic penetrations and higher wear resistance (lower coating brittleness) in the order of 10, 20, 30 and 10, 30, 20 keV implantation, respectively. A tribofilm transferred from disc to ball wear surface was found, lowering friction coefficient and reducing the ball wear, and this result possibly caused the ball weight increase after wear testing. With decreased load and increased speed, the function of the transfer film became more important, and tribological properties were improved (stable friction coefficient 0.15–0.25). When counterbody AISI 52100 was changed to Ti–6Al–4V modified as the disc, initial friction and wear life decreased, and wear was changed from only disc to both disc and ball abrasive dominated. The as-implanted samples demonstrated greatly improved tribological properties compared with unimplanted ones, showing a possible optimal implantation energy.

Metal plasma source ion implantation using a UBM cathode

Abstract A brief description is given of an industrial prototype DLZ-01 PSII implanter which uses a radio frequency source for enhancing plasma production and four unbalanced magnetron (UBM) cathodes for metal particle achievement. The emphasis of this description is put on the structural traits of UBM cathodes and the metal plasma properties. The characteristics of this method are also discussed. For preliminary research, the same UBM deposition and fixed implantation parameters are selected. The characteristics of the UBM cathodes are described using the unbalanced magnetic field distribution. The ionization determined by the detection of the deposition rate and saturation current is very small (

Characterization of interface of c-BN film deposited on silicon(100) substrate

Abstract The interfacial microstructure of cubic boron nitride (c-BN) film deposited on single silicon substrate using magnetically enhanced active reaction evaporation (ME-ARE) has been investigated through thinning methods, in which X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) absorption spectroscopy were used for compositional and microstructure analysis. c-BN film was etched at size 4×4mm 2 by argon ion in XPS equipment to obtain depth concentration profile of the BN film and B1s XPS spectra at different etching depth. FTIR was alternately used to determine the microstructure of the BN film at different etching depth. The results show that a thin layer of hexagonal boron nitride (h-BN) phase exists at the interface between c-BN layer and substrate. In addition, transmission electron microscopy and selected area electron diffraction further confirm above the conclusion.

Tribological behavior of aluminum alloys surface layer implanted with nitrogen ions by plasma immersion ion implantation

Abstract Some 2014 and 2024 aluminum alloys were implanted with nitrogen ions (N+) by Plasma Immersion Ion Implantation (PIII), and dose range was from 2×1017 to 1×1018 N+ cm−2. The microstructure of surface layer was studied by Transmission Electron Microscopy (TEM). The depth profile of the implanted layer was investigated by Auger Electron Spectrometry (AES). The wear test was carried on a pin-on-disk wear tester. The micro-morphology of wear was observed by Scanning Electron Microscopy (SEM). The results reveal that: after implanted with nitrogen ions, the friction coefficient of surface layer decreased, and the relative wear resistance increased with the increase of the nitrogen dose. The tribological mechanism was mainly adhesive, and the adhesive wear tended to become weaker gradually with the increase of nitrogen dose. The upper two effects were mainly attributed to the formation of hard AlN precipitation and supersaturated solid solution of nitrogen in the surface layer.

Tribological behavior of gradient modified layer on 2024 aluminum alloy modified by plasma-based ion implantation

The N-pre-implanted 2024 aluminum alloy was implanted with Ti and N, or implanted with Ti, and then with Ti and N by plasma-based ion implantation (PBII) to form two gradient layers, respectively. The composition depth profiles of the gradient layers were characterized by X-ray photoelectron spectroscopy. A series of ball-on-disk wear experiments have been carried out in ambient air, to investigate the tribological behavior of the gradient layer against steel ball under dry and un-lubricated conditions, employing various applied loads and a constant sliding speed. The results revealed that tribological properties of the gradient layers were improved markedly in contrast with those of the unmodified sample, and strongly dependent on their composition depth profiles. The gradient layer implanted with Ti, and then with Ti and N was much thicker and contains higher N, thus it corresponded to higher hardness which slowly decrease from surface to substrate and the optimal tribological properties including higher load carrying capacity. As load was increasing, the tribological properties decreased, and the adhesive degree increased since the gradient layer became thinner rapidly. Of course, more proper gradient layers will be obtained as the qualified candidates in some particular engineering applications by optimizing PBII parameters.

Structure of titanium films implanted with carbon by plasma-based ion implantation

Abstract By combining plasma-based ion implantation with unbalanced magnetron sputtering deposition, ion implantation mixed films were prepared on steel 45 substrate. X-ray photoelectron spectroscopy analysis shows that the concentrations of carbon and titanium have a periodical distribution in the prepared films. It comes from the periodical deposition and ion implantation process. The binding energy of C1s in the film varies with implantation depth, corresponding to the variation of the carbon distribution. It is found by glancing angle X-ray diffraction that TiC phase exists in the mixed films and the elemental titanium is not in a state of crystalline structure.