Low Temperature Ion Sulfuration Research Articles

Structural and tribological properties of sulfonitrocarburizing layers prepared by plasma nitrocarburizing and low temperature ion sulfurizing

The reduction in the friction coefficient and minimizing wear are fundamental characteristics of friction components. Sulfurization effectively enhances the self-lubricating properties of metallic surfaces, while nitriding/carburizing can enhance the resistance to wear. This study explored two methods to create a sulfonitrocarburizing layer on 38CrMoAl. One method involved a simultaneous treatment of ammonia, carbon dioxide, and hydrogen sulfide, while the other employed a two-step process of initial nitrocarburizing, polishing, and sulfurization. The single-step treatment resulted in erratic COF and poor wear resistance. In contrast, the two-step treatment produced a composite structure of FeS polycrystals, sulfur-containing nanocrystals, and a nitrocarburizing layer. Further optimization made the composited structure achieve equilibrium between self-lubrication and binding force, resulting in a significant friction reduction effect exceeding 800 s and good occlusion resistance. This study presents a paradigm for successfully integrating treatments for strengthening metal surfaces, demonstrating the potential to enhance the efficacy of friction components.

Reduction of Friction and Wear for AISI321 Stainless Steel through Surface Modification Using Nanocrystallization.

Through surface nanocrystallization and low-temperature ion sulfurization, the nanocrystalline/FeS thin film with excellent friction-reduction and antiwear properties was fabricated on the surface of AISI321 stainless steel. The nanocrystallization treatment formed the high hardness and active nanocrystalline structure on the surface of AISI321, with the harness increased from 4.6 GPa to 7.56 GPa. Furthermore, the significantly refined nanostructure strongly increased the concentration of S element in comparison with the single-sulfurized layer on the substrate. Tribological tests reveal that both the original AISI321 substrate and the single-sulfurizing-treated samples are subject to severe abrasion. Single nanocrystallization treatment can improve the wear resistance of AISI321, while the compound treatment can obviously improve the comprehensive tribological properties. The compound-modified layer presents excellent tribological properties with the lowest coefficient of friction (COF) of 0.33, which is related to the increased hardness of the substrate and increased thickness, density, and homogeneity of the sulfurized layer. Furthermore, a physical model is developed for the vacuum tribological behavior of the samples after different treatments. This model provides a reference for revealing the tribological mechanism of the compound-modified layer treated using surface nanocrystallization-assisted chemical heat treatment.

Tribological properties and bearing application of Mo-based films in space environment

MoS2 film plays an important role in the field of space lubrication due to its excellent tribological properties, but the complex and changeable space environment has increasingly higher requirements for the lubricating layer. In order to improve the spatial tribological properties of the MoS2 film, the Mo-X (X = Pb, PTFE, C) binary composite films were prepared by radio frequency magnetron sputtering technology. Then, Mo/MoS2–Pb–PbS, Mo/MoS2-PTFE and Mo/MoS2–C films were obtained through the treatment of binary films by “low-temperature ion sulfurizing” technology. The structure, morphology and composition properties of the three films were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS).The tribological properties of the three films were tested through ultraviolet (UV), atomic oxygen (AO) and high-vacuum simulated space environment, and the results showed that the Mo/MoS2–Pb–PbS film has better comprehensive spatial tribological properties. The Mo/MoS2–Pb–PbS film was applied to practical bearings, which were simulated for life test after exposure to space environment. The wear life of the new bearing is an order of magnitude higher than that of the active bearing. Therefore, Mo/MoS2–Pb–PbS film has broad application prospects in the field of space solid lubrication.

Self-lubricating Property of Cu2S Composite Films on Ni60+60%WC Cermet

A novel composite sulfides film was fabricated on the surface of Ni60+60%WC cermet by Low Temperature Ion Sulfurizing. The microstructure and the self-lubricating performance of the composite coating under dry sliding condition were investigated. The results show that the films are composed of Cu2S, FeS, NiS and FeS2, which showed outstanding self-lubricating performance under dry sliding condition by reducing the friction coefficient, the wear depth, and weight loss of the cermet significantly.

Vacuum tribological properties of a composite Mo–MoS2film after atomic oxygen exposure irradiation

A composite Mo–MoS2solid-lubrication film measuring approximately 2-µm thick was prepared using a two-step composite process involving magnetron sputtering of Mo film followed by low-temperature ion sulfurization. Microstructure of the said film was characterized using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Auger electron spectroscopy, and X-ray photoelectron spectroscopy, and nanomechanical properties of the Mo and Mo–MoS2film were tested using a nanoindenter. The Mo–MoS2film and GCr15 substrate were irradiated by atomic oxygen with the self-developed MSTS-1 space tribometer system equipped with an atomic oxygen beam at a flux of 9 × 1019atoms/cm2. Subsequently, vacuum tribological properties of the said substrate and film were examined and compared. Results demonstrated that the Mo film possessed a smooth and dense structure with stable nanomechanical properties. Part of the elemental Mo translated into MoS2post sulfurizing, thereby forming the Mo–MoS2composite film with an alternating soft and hard structure. The Mo–MoS2film demonstrated a low and stable friction coefficient of approximately 0.15 along with only a slight wear in vacuum. The film surface could be oxidized and eroded when exposed to the highly active and energetic atomic oxygen. Post atomic oxygen erosion, the film thickness demonstrated a decrease, and small amounts of MoO3were observed on the surface. However, all structural and property changes were limited to the superficial layer. The excellent tribological performance of the film could be restored when the surface layer was removed after a certain period of sliding friction.

Microstructure and tribological performance of sulfurizing layer prepared on the laser cladding Co-based alloy coating

Laser cladding of Co-based alloy coating owns excellent wear and corrosion resistances. The sulfides film fabricated by low temperature ion sulfurizing technique performs outstanding friction-reducing properties. In this study, the sulfides layer was successfully fabricated on the Co-based laser cladding coating by means of low temperature ion sulfurizing. The surface morphologies, microstructures and phase constituents were investigated by SEM, EDS, XRD and XPS. The results show that the surface of sulfurizing layer is loose and porous. The lubricant phases FeS and WS2 are detected in the sulfurizing composite layer. The thickness of the sulfurizing composite layer is about 3–4μm. Tribological properties were tested by a pin-on-disc tester, and the wear mechanisms were further analyzed. The friction results indicate that the friction coefficients and wear losses of the sulfurizing composite layer are decreased remarkably in contrast to the cladding coating under dry condition. The sulfides layer prepared on laser cladding coating shows excellent performance on wear and friction-reduction. The lubricant phases of FeS and WS2 play an important role in improving the tribological performances of the sulfurizing composite layer.

Syntheses and tribological property of CrMoN/MoS2 multilayer films on piston rings of heavy vehicle engine

In order to prolong the service life of piston rings of heavy vehicle engine and decrease the friction and wear of piston rings and cylinder liner, CrMoN/MoS2 multilayer films were deposited on the surface of rings by magnetron sputtering and low temperature ion sulfuration. FESEM equipped with EDX was adopted to analyze the compositions and morphologies of surface, cross-section, and wear scars of the multilayer films. The nano-hardness and Young’s modulus of the films were measured by a nano tester. Tribological properties of the films were tested by an SRV®4 wear tester. The experimental results indicate that the structures of the multilayer films are dense and compact. The films possess nano hardness value of approximately 26.7 GPa and superior ability of plastic deformation resistance. The multilayer films can activate solid lubricating, and possess an excellent antifriction and wear resistance under the conditions of heavy load, high frequency, high temperature, and dynamic load.

Surface properties of W-implanted TiN coatings post-treated by low temperature ion sulfurization

TiN coatings were implanted with W ions by metal vapor vacuum arc (MEVVA) source at dose of 9×1017ions/cm2, and then they were post-treated by low temperature ion sulfurization (LTIS) at 160°C. The W-implanted TiN samples were characterized before and after post-treatment of LTIS, using Scanning Electron Microscopy (SEM), Scanning Auger Microprobe (SAM), X-ray diffraction (XRD), and Nano Indenter System. Friction and wear properties were evaluated using a ball-on-disc tribometer under dry sliding in air. After post-treatment of LTIS, XRD results showed no diffraction peaks of tungsten sulfides on surfaces of W-implanted TiN coatings; W-implanted TiN coatings were sputtered by the sulfur plasma with about 36% reducing of W depth. Further, the nano-hardness decreased mainly due to the amount decreasing of Ti2N and the formation of more metal oxides on surfaces of W-implanted TiN coatings after LTIS. As a result, LTIS treatment could not well improve tribological properties of W-implanted TiN coatings.

Preparation and Characterization of Sulfurized Tungsten Doped Non-hydrogenated Diamond-Like Carbon Films

A tungsten doped non-hydrogenated diamond-like carbon (W-DLC) film was prepared by ion beam assisted deposition, and then W-DLC film was sulfurized by low temperature ion sulfurization. The structural analyses were performed on the scanning electron microscope, optical profilometer, Raman spectroscope and transmission electron microscope equipped with energy dispersive spectroscope. The results showed that the low temperature ion sulfurization treatment increase ID/IG ratio from 3.5 to 4.0 and 3.4 to 3.8 for sulfurized DLC and W-DLC films, respectively. The microstructures of sulfurized DLC film changed from amorphous to nanocrystalline/amorphous structure after low temperature ion sulfuration. The sulfurized W-DLC film was composed of nanocrystallites β-WC1−X, WS2 and FeS, which uniformly dispersed in the amorphous DLC matrix.

Investigation on Nano‐Self‐Lubricant Coating Synthesized by Laser Cladding and Ion Sulfurization

The composite processing between laser cladding and low temperature (300°C) ion sulfurization was applied to prepare wear resistant and self‐lubricating coating. The microstructure, morphology, phase composition, valence states, and wear resistance of the composite coating were investigated by scanning electron microscopy (SEM), atomic force microscope (AFM), X‐ray diffraction (XRD), X‐ray photoelectron spectroscope (XPS), and friction and wear apparatus. The results indicate that the laser cladding Ni‐based coatings and the maximum hardness of 46.5 HRC were obtained when the percent of pure W powder was 10%, composed of columnar dendrites crystals and ultrafine dendritic structure. After ion sulfurization at 300°C for 4 h, the loose and porous composite coating is formed with nanograins and the granularity of all grains is less than 100 nm, which consists of γ‐(Fe, Ni), M23C6 carbides, FeS, FeS2, and WS2. Furthermore, the wear resistance of the composite coating is better than the laser cladding Ni55 + 10%W coating, and the friction coefficient and mass losses under the conditions of dry and oil lubrication are lower than those of laser cladding Ni55 + 10%W coating.

Effect of Mo Content on the Structural and Mechanical Properties of CrMoN/MoS2 Composite Coatings

CrMoN/MoS2 composite coatings were prepared on the surfaces of the CrMoN composite coatings with different Mo contents by means of a low temperature ion sulfurizing process. The structural and mechanical properties of these coatings as a function of Mo content have been studied. SEM analysis shows that the CrMoN coating reveals a dense and compact surface structure, the CrMoN/MoS2 composite coatings display loose grain structures; In the sulfurizing process, a preferential growth does not happen, the sulfide size is inhibited, The products of the reaction between MoNx and S are the main origin of MoS2. Nanoindentation test shows that the hardness and Young's modulus of CrMoN/MoS2 coatings are higher than that of CrMoN composite coatings.

Excellent Vacuum Tribological Properties of Pb/PbS Film Deposited by Rf Magnetron Sputtering and Ion Sulfurizing

Soft metal Pb film of 3 μm in thickness was deposited on AISI 440C steel by RF magnetron sputtering, and then some of the Pb film samples were treated by low-temperature ion sulfurizing (LTIS) and formed Pb/PbS composite film. Tribological properties of the Pb and Pb/PbS films were tested contrastively in vacuum and air condition using a self-developed tribometer (model of MSTS-1). Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were adopted to analyze the microstructure and chemical construction of the films and their worn surfaces. The results show that a mass of Pb was changed to PbS during the process of LTIS. In air condition, owing to the severe oxidation effect, pure Pb film showed relatively high friction coefficients (0.6), and Pb/PbS composite film also lost its friction-reduction property after sliding for a short time. In a vacuum, the average friction coefficients of Pb film were about 0.1, but the friction coefficient curve fluctuated obviously. And the Pb/PbS composite film exhibited excellent tribological properties in vacuum condition. Its friction coefficients keep stable at a low value of about 0.07 for a long time. If takes the value of friction coefficients exceeding 0.2 continuously as a criterion of lubrication failure, the sliding friction life of Pb/PbS film was as long as 3.2 × 10(5) r, which is 8 times of that of the Pb film. It can be concluded that the Pb/PbS film has excellent vacuum tribological properties and important foreground for applying in space solid lubrication related fields.

Synergistic effects between sulfurized W-DLC coating and MoDTC lubricating additive for improvement of tribological performance

Low temperature ion sulfuration technology was used to obtain sulfurized layer on W doped diamond-like carbon (W-DLC) coating. The tribological behaviors of the pure W-DLC and sulfurized W-DLC coatings were investigated under PAO and MoDTC lubrication conditions. It shows that sulfurized W-DLC coatings can obviously improve their tribological performances under PAO with MoDTC lubrication. The primary reason is due to the formation of WSx on the surface of sulfurized W-DLC coating, the decomposition of additives for formation a higher ratio of Mo sulfide/Mo oxide and the graphitization for a high ratio of sp2/sp3.

The Low-temperature Ion Sulfurizing Technology and its Applications

Abstract A solid lubrication film mainly consists of FeS, which has excellent tribology properties, can be formed on the sulfurized iron or steel surface. The sulfurizing technology has aroused intense attention from the day it appeared. However, the widespread industrial application of sulfurizing technology was promoted by the low-temperature ion sulfurizing (LTIS) process. This paper summarized the phylogeny and sorts of sulfurizing technology firstly; then, the process flow of LTIS technology, the forming mechanism, microstructure and tribological properties of ion sulfurized layer were introduced detailedly; and then, the technological, economic and environmental merits of LTIS technology were generalized; finally, the industrial applications of LTIS technology in various typical rolling, sliding and heavy duty parts were reviewed briefly. LTIS technology, with the advantages of high sulfurizing speed, good performance of sulfurized layer and without sideeffect, has played an important role in the tribology modification of ferrous parts, and the LTIS process will become more green, simple and efficient in the future.

Influence of W content on microstructural, mechanical and tribological properties of sulfurized W-doped diamond-like carbon coatings

A series of sulfurized W doped diamond-like carbon (W-DLC) coatings were prepared using a two-step method as depositing W-DLC coating firstly, and then treated by low temperature ion sulfuration. A designing thought of a composite DLC with sulfide coating with optimized mechanical and tribological properties was realized. The structural analyses were performed on the scanning electron microscope (SEM), X-ray photoelectron spectroscope (XPS), scanning Auger microprobe (SAM), X-ray diffraction (XRD) and Raman spectroscope. The mechanical and tribological properties were evaluated by the nanoindenter and ball-on-disk friction and wear tester. The results show that the microstructures, mechanical and tribological properties of sulfurized W-DLC coatings exhibited a significant dependence on the W concentration. A high fraction of W in W-DLC coating promoted the formation of WC which could prevent the S diffusion and the extent of graphitization for sulfurized W-DLC coatings. The hardness of sulfurized W-DLC coating gradually increased with higher W concentration, and it was lower than that of the untreated W-DLC coating. The coefficient of friction and wear rate of sulfurized W-DLC coating were reduced with the increase of W content. The best tribological properties with the lowest friction coefficient and wear rate were achieved on sulfurized 27.7% W-DLC coating. The tribological mechanism was attributed to the graphite-rich and sulfide composite top layer with lower shear strength and combining a support of the sublayer W-DLC coating with better mechanical property.

Laser quenching and ion sulphidizing complex surface treat technology for diesel engine cylinder

In order to solve the problem of wear-out-failure of diesel engine cylinder, the laser-quenching and low temperature ion sulfurizing complex surface treatment technology was operated on the surface of 42MnCr52 steel. And the tribological properties of the complex layer were investigated. The experimental results indicated that the complex layer was composed of soft surface sulphide layer and sub-surface laserquenching harden layer, and showed excellent friction-reduction and wear-resistance performance at high temperature. The synergistic effect of the complex layer resulted in 20% increase in hardness, 10% reduction in friction coefficient and 50% reduction in wear weight loss, respectively, compared with those of the standard samples. The bench-test further demonstrated that this technology can improve the lubricating condition between cylinder and piston ring, and reduce both abnormity wear when the lubricating oil is deficiency at the time of start-up and sticking wear at high temperature during the operating period, and then prolong the service life of engine.

The Interactions Between Sulfur-Nitrided Layer on Steel Surface and MoDTC Lubricating Additive and Their Effects on Tribological Performance

Low temperature ion sulfuration and ion nitriding technologies were used to treat AISI 52100 steel. The tribological behaviors of the treated surface were investigated under lubrication with different MoDTC additive concentration. The morphologies and composition of worn surfaces were observed, and the valence states of tribofilm were identified. The results showed that the sulfur-nitrided surface was obviously improved in the friction-reducing property and exhibited the best synergistic effect when the concentration of MoDTC reached 1.0 %. The main reason is that MoS2 and FeS were formed on the worn sulfur-nitrided surface.

Microstructure and friction-reducing performance of sulfurized W doped diamond-like carbon film

The microstructure and friction-reducing performance of W doped diamond-like carbon (W-DLC) film treated by low temperature ion sulfuration was investigated in this paper. According to our designing thought a solid lubrication layer of WS2 with gradient distribution and about 100nm depth was successfully prepared on the W-DLC film. The structural analyses were performed using X-ray photoelectron spectroscope (XPS) and Raman spectroscope. The examinations of mechanical and tribological properties were completed using a nanoindenter and ball-on-disk friction and wear tester. The results showed that a soft layer of low content WS2 and a slight increase of sp2-C phase on the hard W-DLC film played an important and beneficial role for improving the friction-reducing performance of DLC film.

Investigation of Microstructure and Tribological Properties of Novel $\hbox{CrN/MoS}_{2}$ Composite Films

The complex plating-sulfurizing process, which fitted magnetron sputtering together with low-temperature ion sulfurizing, was utilized to prepare novel CrN/MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> composite solid lubrication films. The composite films were characterized by means of X-ray photoelectron spectroscopy (XPS) analysis, X-ray diffraction, atomic force microscopy, and friction and wear test machines (UMT-2) friction and wear tester, respectively. The experimental results show that there are CrN, Mo <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> N, MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , and Cr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> phases existing in the CrN/MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> composite films, which was demonstrated by XPS analysis results. The CrN/MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> composite films perform better than Cr-Mo-N films in terms of friction coefficient under oil lubrication condition at room temperature. Then, the lubrication mechanism for CrN/MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> composite films was analyzed.

A comparative study on the tribological behaviors of nitrided and sulfur-nitrided 35CrMo steel lubricated in PAO base oil with MoDTC additive

A nitrided layer on 35CrMo steel was prepared by the ion nitriding process, and then a sulfur-nitrided layer was obtained by low temperature ion sulfuration. The results showed that both the nitrided and sulfur-nitrided surfaces improved the wear resistance efficiently under PAO lubrication, and exhibited the best wear resistance and friction-reducing property under PAO with 0.75% MoDTC lubrication. Compared with the plain and nitrided surfaces, the sulfur-nitrided surface exhibited the best synergistic effect with MoDTC displaying the lowest friction coefficient and wear volume. The mechanism of the best effect was due to MoS 2 and FeS formed on the sulfur-nitrided surface.