Mo Ion Implantation Research Articles

Influence of dual Mo and Ru ion implantation on the characteristics of commercial TiN-TiAlN-coated WC-10wt%Co-0.5wt%Cr3C2 face milling inserts

The influence of simultaneous dual Mo + Ru ion implantation into commercial TiN and TiAlN hard metal coated WC-10wt%Co-0.5wt%Cr3C2 face milling inserts were investigated at dosages from 5 × 1015 to 1 × 1017 ions/cm2 at 100 keV acceleration voltage. Various characterisation techniques such as field emission scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy, glancing incident X-ray diffraction, and X-ray photoelectron spectroscopy were used to characterise the microstructure and topography of the as-received and ion implanted samples. The micro-hardness and residual stresses were also determined. Face milling tests were conducted to determine the effect of ion implantation on the wear rate. It has been observed that the dual Mo + Ru ion implantation with a biased Mo content extended 1000 nm into the dual TiN/TiAlN layer with significantly improved microhardness and increased anisotropy between the σ11 and σ22 stress components of the substrate, indicative of related effects in the coatings. The strengthening effect of Ru was observed at all ion implantation dosages even though wt% of Ru was significantly lower than the wt% of Mo. There were no visible changes to the microstructure of the substrate, but the presence of Mo and MoO2 chemical phase contents were observed through XPS. All the ion implantation dosages improved machining performance as the wear rate of the ion implanted face milling inserts was lower than that of as-received TiN and TiAlN coated WC-10wt%Co-0.5wt%Cr3C2 face milling inserts.

Role of Oxygen Vacancy Ordering and Channel Formation in Tuning Intercalation Pseudocapacitance in Mo Single-Ion-Implanted CeO2-x Nanoflakes.

Metal oxide pseudocapacitors are limited by low electrical and ionic conductivities. The present work integrates defect engineering and architectural design to exhibit, for the first time, intercalation pseudocapacitance in CeO2-x. An engineered chronoamperometric electrochemical deposition is used to synthesize 2D CeO2-x nanoflakes as thin as ∼12 nm. Through simultaneous regulation of intrinsic and extrinsic defect concentrations, charge transfer and charge-discharge kinetics with redox and intercalation capacitances together are optimized, where reduction increases the gravimetric capacitance by 77% to 583 F g-1, exceeding the theoretical capacitance (562 F g-1). Mo ion implantation and reduction processes increase the specific capacitance by 133%, while the capacitance retention increases from 89 to 95%. The role of ion-implanted Mo6+ is critical through its interstitial solid solubility, which is not to alter the energy band diagram but to facilitate the generation of electrons and to establish the midgap states for color centers, which facilitate electron transfer across the band gap, thus enhancing n-type semiconductivity. Critically, density functional theory simulations reveal, for the first time, that the reduction causes the formation of ordered oxygen vacancies that provide an atomic channel for ion intercalation. These channels enable intercalation pseudocapacitance but also increase electrical and ionic conductivities. In addition, the associated increased active site density enhances the redox such that the 10% of the Ce3+ available for redox (surface only) increases to 35% by oxygen vacancy channels. These findings are critical for any oxide system used for energy storage systems, as they offer both architectural design and structural engineering of materials to maximize the capacitance performance by achieving accumulative surface redox and intercalation-based redox reactions during the charge/discharge process.

Surface characterization of Mo-implanted 6H–SiC by high temperature non-reactive wetting tests with the Ni–56Si alloy

The effects of Mo ion implantation into SiC monocrystalline substrates and succeeding annealing treatments on the interfacial characteristics of 6H–SiC were investigated by means of wettability tests. Ni (reactive) and the Ni–56Si alloy (non-reactive) have been used as liquid phases as a means to evidence the influence of surface and interfacial tensions on solid–liquid interactions. The variations of contact angle as a function of Mo implantation and of temperature are analyzed and discussed. The results indicated that a significant improvement of wettability was mainly related to the increase of surface energy (σSV) of SiC substrate and to the presence of Mo, rather than to the surface roughness of the ceramic substrate. With increasing annealing temperature, the contact angle of the Ni–56Si/SiC system increased as a result of the crystallization of the SiC amorphous surface and the loss of Mo at the substrate surface due to oxidation and diffusion/vaporization. The influence of these phenomena on technological processes such as metal–ceramic brazing is also taken into consideration.

High temperature wettability of ion implanted multicomponent CrAlSiN films by molten glass

The phenomenon of glass-to-mold sticking is a major problem for industrial glass forming processes. Recently, multicomponent CrAlSiN films attracted considerable industrial interest because of their excellent tribological performance and high oxidation resistance at high temperatures exceeding 800°C. Metal plasma ion implantation has being successfully developed for further improving wear, corrosion and physical properties of engineering materials. In this study, Mo and carbon ions were implanted into the multicomponent CrAlSiN film by using a metal-plasma ion implantation apparatus. The accelerating voltage of metal ions was set at 40kV with implantation doses of 1×1017ions/cm2 for Mo and 2×1017ions/cm2 for carbon. After Mo and carbon ion implantation, molybdenum carbides were found in the implanted layer of CrAlSiN. The wettability of the ion implanted CrAlSiN films by molten glass at 500°C in controlled air under 1.7Pa was measured by using a sessile drop method. Mo and carbon ion implanted CrAlSiN films showed the lowest wettability of all tested samples, which is attributed to a reduced adhesion of molten glass at high temperature. The ion implanted CrAlSiN films showed an anti-sticking characteristic superior to the as-deposited CrAlSiN films. Results of this study demonstrate the potential of metal plasma ion implantation in improving the anti-sticking behavior of the CrAlSiN films by molten glass.

Photocatalytic Activities of Mo Ions Implanted TiO<sub>2</sub> Thin Films

Transparent TiO2 thin films were deposited onto microscope glass slides by means of d.c. magnetron sputtering method. In order to enhance the photocatalytic activity of TiO2 thin films, Mo ions with different nominal doses were implanted into the TiO2 thin films. The samples were characterized by different technologies including X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS) and UV-VIS-NIR spectrophotometer. The photodegradation results of methylene blue dye solution indicated that optimal dose of 2×1012ions/cm2 Mo ion-implantation resulted in a higher photocatalytic activity in the implanted TiO2 thin films.

Mo and Ag ion implantation in austenitic, ferritic and duplex stainless steels: A comparative study

An austenitic (316LVM), a ferritic (430) and an austenitic–ferritic (duplex) stainless steels were implanted with molybdenum ions at 150 keV and silver ions at 170 keV with fluences between 1 × 10 16 and 3 × 10 16 ions cm − 2 . The crystallographic structure of implanted layers was investigated by Grazing Incidence X-ray Diffraction (GIXRD). Experimental data lead to the conclusion that ion implantations induced for low fluences (1 × 10 16 ions cm − 2 ) a shift of diffraction peaks of all the initial lattice(s) toward lower angles in the implanted layer. For higher fluences (from1.5 × 10 16 ions cm − 2 ) ferrite was formed for 316LVM and higher amount of ferrite is observed for duplex steels. The topography and the magnetic response of the surface were investigated by Atomic and Magnetic Force Microscopy (AFM/MFM). For high fluences (from 1.5 × 10 16 ions cm − 2 ), ferrite formation for implanted 316LVM was put in evidence by MFM.

COMPARISON OF WEAR RESISTANCE MECHANISMS OF DIE STEEL IMPLANTED WITHCANDMoIONS

Mo and C ions extracted from a metal vapor vacuum arc ion source were implanted into the surface of die steel (H13) to compare the wear resistance mechanisms of the implanted samples, respectively. The concentration depth profiles of implanted ions were measured using Rutherford backscattering spectroscopy and calculated by a code called TRIDYN. The structures of the implanted steel were observed by X-ray photoelectron spectroscopy and grazing-angle X-ray diffraction, respectively. It was found that the conventional heat-treated H13 steel could not be further hardened by the subsequent implanted C ions, and the thickness of the implanted layer was not an important factor for the Mo and C ion implantation to improve the wear resistance of the H13 steel. Mo ion implantation could obviously improve the wear resistance of the steel at an extraction voltage of 48 kV and a dose of 5 × 1017cm-2due to formation of a modification layer of little oxidation with Mo2C in the implanted surface.

Corrosion Resistance of TC4 Alloy Implanted by La<sup>+</sup>, Mo<sup>+</sup>

The surface treatment for TC4 alloy was conducted by MEVVA ion implantation method. The corrosion resistance of TC4 alloy implanted by La+, Mo+ were measured. It were found that Mo ion implantation improved corrosion resistance of TC4 alloy in acidic chloride solution, but La ion implantation gave the opposite result because they have different chemical activity. The more implanted dose of Mo+, the more improvement of corrosion resistance.

Prediction of intermetallics formation during metal ion implantation into Al at elevated temperature

The model of effective heat of formation in metal-Al binary system proposed by Pretorius et al. was developed based on characteristics of the solid-state reaction at interface to predict the formation of intermetallics during metal ion implantation into Al substrate at elevated temperature. For the Fe, Hf, Mo, Nb, Ni, Ta and Zr ion implantation with the ion energy of 50–140keV under the ion current density of 10–60μA/cm2 into Al substrate to the implantation dose of 1017–1018 ions/cm2 at the elevated temperature ranging from 300°C to 600°C, the model of effective heat of formation predicted the formation of intermetallics Al13Fe4, HfAl3, MoAl12, NbAl3, NiAl3, TaAl3 and ZrAl3, which were consistent with the experimental results. Taking the kinetic factors and the limitation of thermodynamic data into account, the model of effective heat of formation explained the formation of metastable intermetallics Cr14Al86 at the lower temperature of 400°C and of the stable intermetallics Cr2Al13 at the higher temperature of 510°C, and the formation of simple intermetallics VAl3 relative to complex intermetallics V4Al23, VAl7, and VAl10, for the Cr and V ion implantation into Al substrate, respectively, at the elevated temperature up to 510°C.

Modelling of grazing incidence X-ray diffraction spectra from Mo-implanted stainless steel: Comparison with experimental data

Mo ion implantation at 150 keV in an austenitic stainless steel leads to a pseudo-Gaussian concentration depth profile as predicted by calculation using TRIM code and confirmed by RBS analyses. The structural modification of the implanted layer was investigated using grazing incidence X-ray diffraction (GIXD) for different incidence angles. The X-ray austenite peak depends strongly on fluence and incidence angle, and presents one or two peaks as a function of incidence angle. Using the concentration depth profile of implanted element, the information depth profile of diffracted intensity, and a linear relationship between Mo concentration and lattice parameter, we predicted the γ diffracted X-ray peaks. The experimental X-ray diffraction peaks are comparable to the predicted ones. Mo implantation induces a continuous expansion of austenite lattice, which follows the depth profile concentration in the implanted layer even if the signature of this expansion is the apparition of a new austenite peak.

The annealing behavior of H13 steel implanted with molybdenum ions

H13 steel was implanted with molybdenum to a dose of 5 × 10 17 ions cm −2 to investigate the annealing effect on the wear resistance of the implanted steel. The molybdenum ion implantation was done using a metal vapor vacuum arc (MEVVA) ion source. The annealing effect was examined by Rutherford backscattering spectroscopy (RBS), high voltage electron microscopy (HVEM) and grazing-angle X-ray diffraction (XRD). The experimental results have showed that the wear resistance of the implanted steel was not changed significantly by thermal anneal though annealing has made the amorphous layer, which was induced by Mo ion implantation, re-crystallize. The phenomena observed in the experiment are interpreted and the annealing effect on the wear resistance of Mo-implanted surface is discussed by collision theory.

Modification of surface mechanical properties of aluminum by high current Mo ion implantation using a MEVVA ion source

The surface modification of Al by high current Mo ion implantation using a metal vapor vacuum arc (MEVVA) ion source has been studied. A high aluminum content intermetallic compound Al 12 Mo was formed using Mo ion implantation into Al with a current density of 64 μA/cm 2 (the temperature of the sample rises to ∼410 °C ) to a dose of 3×10 17 ions/cm 2 The hardening aluminide layer with a thickness of about 1600 nm was obtained and the hardness of the Al surface increased with increasing the Mo ion dose up to six times larger than that of the unimplanted one. Also, the elastic modulus of the Al surface was increased by the aluminides.

Formation of MoSi 2 and associated fractal growth on Si surface upon high current pulsed Mo-ion implantation

Using a metal vapor vacuum arc ion source, continuous and stable MoSi 2 films were directly obtained by high current Mo-ion implantation into Si wafers with neither external heating nor post-annealing. Interestingly, under some specific conditions, the formed MoSi 2 grains organized themselves in fractal patterns featuring unique self-similarity. The mechanism responsible for the MoSi 2 formation as well as the growth of the fractal pattern is discussed in terms of the dynamic launching of the energetic Mo ions into Si, ion beam heating effect, and the effect of ion dose during high current Mo-ion implantation of far from equilibrium.

Soft X-ray absorption spectroscopy study of the effects of Si, Ce, and Mo ion implantation on the passive layer of AISI 304 stainless steel

The chemical modifications introduced in the passive layer of AISI 304 stainless steel after Si, Ce, and Mo ion implantation were investigated and compared with non-implanted steel by soft X-ray absorption spectroscopy. The influence of ion implantation on the passive properties was evaluated by measuring soft X-ray absorption spectra at the Cr, Fe, Ni, Mn and Si 2p in addition to oxygen 1s thresholds. All ion implanted samples show a relative Cr-enrichment at the surface as compared with non-implanted samples. Fe 2p as well as O 1s spectral changes reveal chemical differences in the passive layer as a function of the element ion-implanted.

The pitting behavior of Al-3103 implanted with molybdenum

The pitting corrosion of Al-3103 (Al–Mn alloy) implanted with molybdenum was investigated in solutions containing 0.1 M NaCl using potentiodynamic polarization tests. The Mo ion implantation in Al-3103 was performed with ion energies from 50 to 100 keV at doses ranging from 5×10 16 to 2×10 17 ions/cm 2. The Mo depth profiles were measured by Rutherford backscattering spectrometry. Polarization tests were performed in the presence and absence of a bicarbonate (HCO 3 −)/carbonate (CO 3 2−) buffer. Compared to the unimplanted ones, the implanted samples showed an increase of corrosion potentials from 170 to 240 mV in the unbuffered solution and an increase of pitting potentials from 90 to 160 mV in the buffered solution. The surface chemical states and corrosion morphology of the samples were analyzed by X-ray photoelectron spectroscopy and scanning electron microscopy, respectively.

Effects of Ce, Mo and Si ion implantation on the passive layer composition and high-temperature oxidation behaviour of AISI 304 stainless-steel studied by soft x-ray absorption spectroscopy

The influence of Ce, Mo and Si ion implantation on the chemical properties of AISI 304 stainless-steel passive and oxide layers was studied by means of soft x-ray absorption spectroscopy (XAS). Applying this technique at the transition metal 2p absorption thresholds, the composition and chemical state of the passive layer were determined. A surface Cr enrichment is observed for the ion-implanted samples in comparison with non-implanted samples, which can be associated with better corrosion behaviour. To investigate the effects of ion implantation on the high-temperature oxidation behaviour of AISI 304 stainless-steel, the oxide layer formed after an isothermal oxidation at 1173 K for 32 h was also investigated. The XAS data show mainly the presence of Cr and Mn oxides in the surface region of all samples. The Cr/Fe ratio—a parameter that can be associated with the protective character of the oxide scale—is higher for the Si- and Ce-implanted samples than for the as-received sample. The Mo-implanted sample has the lowest Cr/Fe ratio, suggesting a poor oxidation resistance at high temperatures in this case. Copyright © 2000 John Wiley & Sons, Ltd.

Computer simulation of multicomponent ion beam enhanced deposition of (TiMo) N films

Abstract A Monte Carlo computer simulation code has been developed to describe the behavior of incident particles and the growth of (TiMo) N films in the multicomponent ion beam enhanced deposition process, which combines bombardment with a multicomponent ion beam of N + +Mo + and sputter deposition of a Ti film. The film composition profile and intermixed layer between the substrate and the film were studied using a computer simulation method. It is shown that Mo ion implantation has a stronger mixing effect in the film–substrate interface than does N ion implantation. The N profile of the computer simulation conforms to that of the Auger electron spectroscopy results.

High temperature corrosion protection of austenitic AISI 304 stainless steel by Si, Mo and Ce ion implantation

Abstract The influence of implanted silicon, molybdenum and cerium on the oxidation behaviour of a 18Cr8Ni stainless steel was studied at 1173 K up to 144 h in air under isothermal conditions in order to verify the enhanced selective oxidation of chromium by these elements. The implanted surface and the corrosion products formed were characterized by means of AES, SEM, EDS and XRD. Implanted depth profiles were calculated by TRIM96 computational code. The implanted silicon and cerium markedly improved protection against oxidation of the alloy by enhanced chromium transport while molybdenum gave rise to an accelerated oxidation due to the formation of volatile MoO 3 species. Further, ion implantation was found to play a beneficial effect against decarburization of the alloy.

The influence of ion-implanted Mo on the tribological behavior of iron lubricated with oil containing antiwear additives

Wear tests of the unimplanted and Mo ion-implanted pure iron specimens were made on an SRV fretting wear machine under lubricating condition. The lubricants were liquid paraffin with or without additives containing one or more of the active elements Cl, S, P and Zn. After wear tests, the worn surfaces of the specimens were analyzed by means of Auger electron spectroscopy and X-ray photoelectron spectroscopy. The results showed that Mo ion implantation had a marked effect on friction, wear and tribochemical behavior of the specimen. When the specimens were lubricated with oil containing different additives, the increase in wear resistance due to ion implantation showed different values. This is because the physical and mechanical strengthening caused by Mo ion implantation only is one factor influencing wear behavior. Another wear-effect factor will be the lubricating film which is composed of adsorbed additive and reacted products when the wear specimen is lubricated with oil containing additive. However, Mo in the specimen decreased the chemical reactivity of the specimen surface and obstructed its formation.

Effect of Mo and Mo+N implantation on corrosion resistance of austenitic stainless steel

A study has been made of the effects of Mo and Mo + N implantations on the corrosion resistance of AISI 304L stainless steel. Mo ion implantation was performed with doses ranging from 1 × 10 14 to 3 × 10 17 Mo cm −2 at an acceleration voltage of 65 kV, using an MEVVA IV 80-10 implanter. N ion implantation into some Mo-implanted specimens was carried out with a dose of 1 × 10 17 N cm −2 at 65 kV. The corrosion resistance of the implanted steel was investigated by an electrochemical method in 0.5 M H 2SO 4, 0.5 M HCl and 0.6 M NaCl solutions. After both Mo and Mo + N implantations, the free corrosion current density ( I corr) decreased and the breakdown potential ( E b) increased in HCl. Their modification effects saturated with the very low dose of 1 × 10 14 Mo cm −2. Following 1 × 10 17 N cm −2 implantation, the critical and passive current densities in the acid solutions of H 2SO 4 and HCl also declined at the very low dose of 1 × 10 14 Mo cm −2, and increased at a dose of 1 × 10 16 Mo cm −2. These results indicated that Mo + N double ion implantation with a very low Mo dose is useful for improving the corrosion resistance of 304L stainless steel under acidic conditions. In the neutral solution of NaCl, both the I corr and E b characteristics for the 304L stainless steel modified by Mo and Mo + N implantations improved with increasing Mo dose; the improvement caused by Mo + N double ion implantation tended to be greater than that for Mo single ion implantation. In conclusion, we propose that Mo + N double ion implantation into 304L stainless steel can be expected to form a surface resistant to various corrosion conditions, depending on the choice of implantation dose of Mo ions.