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Being a key component of the transmission system, the needle bearing's performance and service life affects the overall service life of mechanical equipment. This study takes needle bearings composed of AISI 52100 steel as the research object and studies the effect of carbonitriding surface strengthening treatment on the bearing friction, wear, and fatigue life. The carbon and nitrogen co-infiltration surface-strengthening method was employed to prepare cylindrical and disc samples. The surface hardness, residual austenite content, microscopic morphology and organization composition, coefficient of friction, and wear scar were studied to analyze the effect on the wear performance of the material. The bearing fatigue wear comparison test was conducted on a test bench to compare the actual fatigue life and surface damage of the needle bearing through conventional martensitic quenching heat treatment and carbonitriding treatment. The results demonstrate that the carbonitriding strengthening method enhances the toughness of the material while improving its surface hardness. It also improves the wear resistance of the needle roller bearings, and the fatigue life of the bearings is significantly improved. In conclusion, carbon and nitrogen co-infiltration treatment is a strengthening method that effectively extends the service life of needle roller bearings, indicating its high practical value. [ABSTRACT FROM AUTHOR]

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Abstract A Hollow Cathode Plasma Enhanced Chemical Vapor Deposition (HC-PECVD) reactor was used to deposit silver doped Diamond-Like Carbon (Ag-DLC) films on Ti6Al4V alloy employing two methodologies: i) producing a silicon interlayer, using tetramethylsilane (TMS) as silicon precursor, varying the argon flow of the hollow cathode; and ii) carbonitriding the substrate. Profilometry, Raman, and Secondary Ion Mass Spectrometry (SIMS), as well as nanohardness, micro-scratch, scratch, and VDI 3198 indentation tests were used to evaluate the characteristics of the films and their adhesion on the substrates. The results demonstrated that the argon flow can be used for tuning the Ag-DLC film’s hardness, toughness, and adherence on silicon interlayers. The carbonitriding process, in turn, provided an improvement in the film toughness compared with non-carbonitrided samples. Considering the lower cost and easier handling of N2 compared to the silicon precursors commonly available (TMS, HDMSO, SiH4, etc.), the carbonitriding process proved more appropriate to improve the adhesion of the Ag-DLC films on the Ti6Al4V alloy.

This work investigated the effects of thermal aging and shot-peening of carbonitrided 1.6587 steel grade on retained austenite and residual stresses. After carbonitriding samples contained maximum of 0.87% carbon, 0.34% nitrogen and 50 mass. -% retained austenite. Thermal aging conditions investigated were -30°C, 90°C and 150°C while the aging period were 14, 96 and 720 hours. After thermal aging, some of the samples were subjected to shot-peening treatment using standard cut wire shots StD - G3 - 0.6 mm VDFI 8001 with intensity in the range of 0.25 to 0.30 mmA and coverage of 1.00 to 1.24 x 98%. It was found that the quantity and size of finely disseminated precipitates increase with increasing aging temperature and time accompanied by darkening of martensite plates. The magnitude and distribution of hardness in the case layer was highly influenced by aging conditions with an increase of up to 50 HV for peak hardness and up to 120 HV at a depth of 50 µm on aging at -30°C. Aging at 90°C, hardness distribution remains relatively unaffected while at 150°C for 720 hours the magnitude of hardness is slightly improved mainly to decomposition of retained austenite to bainite. Aging at 90°C, retained austenite remains relatively stable and readily transforms on aging at -30°C and 150°C for 720 hours; transformation of up to 20% of the initial retained austenite can be reached which enhances compressive residual stresses of up to -120 MPa in retained austenite and up to -250 MPa in martensite phase. Aging coupled with shot-peening treatment induces transformation of up to 48% of the initial retained austenite and enhances compressive residual stresses of up to -1200 MPa in both phases. It can be concluded that thermally aging coupled with shot-peening treatment reduces retained austenite and significantly enhances residual stresses which is essential to improved ductility and fatigue life of carbonitrided parts. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Gear materials need a more in-depth analysis to verify the conditions of chemical elements and their structural formations. Among them, the focus is often related to the thermochemical treatment process, which should ensure low levels of distortion in micro-geometry due to its high level of mechanical accuracy. In gear manufacturing processes where profile and helix errors are defined in operations prior to thermochemical treatment, process designers are faced with challenges to ensure tooth quality levels. Processes such as hobbing and shaving are important in gear manufacturing. This study addressed the influence of some factors on the gear manufacturing finishing process, as well as the steel alloy microstructure, on the geometric distortion levels in the profile and helix. All stages of the experiments were followed in a controlled manufacturing process, observing the behavior of micro-geometric parameters in each manufacturing phase in the hobbing, shaving, and carbonitriding processes. This analysis was performed on DIN 19MnCr5 alloy steel batches whose microstructures are different, after analyzing them in a laboratory to characterize each one. These observations can lead to important decisions being taken in the manufacturing process to improve a product, regarding the profile and helix parameters. Decisions can also be made about optimizing manufacturing processes. [ABSTRACT FROM AUTHOR]

Nanostructured single-phase hafnium-zirconium carbonitride powders were synthesized using a simple and fast mechanochemical synthesis approach. The critical milling duration, after which a (Hf,Zr)(C,N) solid solution formation inside a jar occurred via mechanically induced self-sustained reaction (MSR), was 10 min. After 30 min of treatment, a solid-gas reaction was completed, and as a result, a homogeneous (Hf,Zr)(C,N) powder consisting of 10–500 nm submicron particles was obtained. The phase and structure evolution of the powders after different treatment durations allowed for the establishment of possible reaction mechanisms, which included the formation of Hf/Zr/C-layered composite particles, their interaction via MSR, and further grinding and nitridization. Spark plasma sintering (SPS) was used to produce bulk hafnium-zirconium carbonitride ceramics from nanostructured powder. The sample had higher values of relative density, hardness, and fracture toughness than those for binary compounds of a similar composition. [ABSTRACT FROM AUTHOR]

an experimental study of the impact of surface hardening on the high-cycle fatigue behavior of an isotropic beam.The beams are made from low carbon steel.The experimental work included mechanical tests, surface heat treatment, fatigue tests, and microscopic inspections.The surface hardening was done by using a pack-carburizing process at atemperature of 925 C holding time variation(2, 4, and 6 hoursfollowed by quenching and tempering process and using the carbonitriding process at a temperature of800 °C and for periods(0.5, 1 and 1.5hour)then quenching directly inwater.an experimental fatigue test indicates that various behaviors depend on surface heat treatment and time soaking.that carbonitriding has a greater impact on fatigue strength and life than the specimen has been treated with pack carburizing.the time soaking increase,the fatigue life will increase for both types of surface heat treatments.the specimens that were hardened using the carbonitriding process achieved a higher surface hardness as the hardness increased to1571.94 HV,while the untreated specimens were293 HV.Compared with the hardening using the pack carburizing process.The cross-sectional area of the treated steel with pack carburizing and carbonitriding is divided into two-part, that is Surface layer and core.The surface layer consists(of carbon, carbon, and nitrogen).The longer the retention time, the deeper the surface layer.

Achieving excellent electromagnetic-wave absorption (EMA) performances and outstanding multifunctional physicochemical properties in complicated application environments is a great challenge for high-entropy alloys (HEAs) absorber. To accomplish this goal, a novel mechanochemical carbonitriding technique is designed. Carbonitriding FeCoNiCu HEAs with flake-like morphology is successfully prepared by a mechanochemical method using the cyano-compound (melamine, C 3 H 6 N 6) and metal powders as raw materials. Through the investigation of phase structure, magnetic properties, corrosion resistance, oxidation resistance and EMA performances of the samples, it can be found that the carbonitriding process optimizes the high-frequency electromagnetic matching of HEAs, and realizes excellent EMA performances. With the introduction of melamine, S003 (FeCoNiCuM 0.03) sample has a reflection loss of −55.8 dB with an effective absorption bandwidth (EAB) of 3.82 GHz, and S006 (FeCoNiCuM 0.06) sample achieves a strong absorption of −61.8 dB. In addition, the carbonitriding FeCoNiCu HEAs exhibit excellent corrosion resistance and mechanical hardness. This work not only demonstrates the potential of carbonitriding HEAs for EMA applications, but also provides a new concept for optimizing the electromagnetic impedance matching of HEAs. [Display omitted] • An efficient and homogeneous carbonitriding process was developed by mechanochemical method using cyano-compound. • The impedance matching was significantly optimized by carbonitriding treatment. • The carbonitriding FeCoNiCu HEAs exhibited excellent adaptability to harsh environments. [ABSTRACT FROM AUTHOR]

Thermochemical surface treatments of steels, such as carburizing and carbonitriding are used to improve mechanical properties, especially resistance to fatigue. Carbonitriding can achieve excellent properties, but the origins remain to be understood, as it has been less studied than carburizing. Fundamental understanding has to be established regarding the formation of microstructures and internal stresses as well as their couplings, during the cooling which follows the enrichment treatment. For this purpose, an original experimental method is introduced to follow in situ by High-Energy X-Ray Diffraction the phase transformation kinetics as well as the evolutions of the internal stresses during cooling, inside laboratory scale, 3 mm-thick samples with C and/or N composition gradients. The usual trends are confirmed regarding carburizing: the carbon-enriched case is the last to transform and the surface ends up with compression residual stresses. Conversely, for carbonitriding, unusual evolutions of microstructure and internal stresses are observed. The presence of nitrogen reduces the hardenability in the enriched case. This modifies the chronology of the phase transformations and this leads to tensile residual stresses at the surface. A coupled thermal, mechanical and metallurgical model predicting the phase transformation kinetics and the evolutions of internal stresses is set up. It achieves quantitative predictions and it shows that, in the studied cases, the phase transformation plasticity strains are the main origin of the residual stresses. [Display omitted] [ABSTRACT FROM AUTHOR]

Friction stir welding (FSW) is extensively used to join aluminium alloys components in space and aircraft industries. Al 2024 is a heat-treatable aluminium alloy with copper as the primary alloying element which has good strength and fatigue resistance. This paper investigates the effect of carbonitriding surface modification on the hardness, tensile strength and impact strength of FSW welded Al 2024 joints. The friction stir welding was performed on three different sets of aluminium alloy (Al2024:Al2024, Al2024: carbonitrided-Al2024, carbonitrided-Al2024: carbonitrided-Al2024) at two different tool rotation speed (TRS) and two welding speed using cylindrical pin tool. The carbonitriding pre-treatment of Al-2024 alloy demonstrated significant improvement in the tensile strength, percentage elongation, abrasion wear resistance and corrosion resistance with the sacrifice of impact strength. The maximum tensile strength of all three sets of samples after FSW was recorded in descending order of (i) carbonitrided-Al2024:carbonitrided-Al2024 (ii) Al2024:Carbonitrided-Al2024 and (iii) Al2024:Al2024. The friction stir welded joint of carbonitrided aluminium alloy exhibited best abrasive wear resistant and corrosion resistant properties.

The work aims to realize low-damage cutting of Alfalfa stalk. The self-sharpening blades of gradient material were prepared by 40 Cr steel, then heat-treating the flank surface by carbon-nitron-boronized with a rare elements catalysis technique. The biological characteristics of Alfalfa incision self-healing and regeneration process were analyzed in order to compare the cutting effects of different blades. After treatment with carbon-nitron-boronized with rare elements catalysis, the flank surface and tip point of blades were coated by boride layer and carbonitriding layer. The composition, microstructure and properties of the carbon-nitron-boronized layer demonstrated a gradient distribution state, and had good wear resistance. A kinetic model for the formation of the carbon-nitron-boronized layer was proposed. The initial stage of heat-treatment was mainly a carbonitriding process. When continuous and compact boride was formed on the surface, it was mainly boridized. The results of field experiment indicated that compared with the commercial blades, the self-sharpening blades have excellent properties as wear resistance and long service life. In addition, the cut damage caused by the self-sharpening blades was less, the self-healing and regeneration process of Alfalfa stalk was normal, and the regeneration duration was greatly shortened. The blades with carbon-nitron-boronized heat-treatment could form the self-sharpening characteristics, always maintaining the cutting sharpness, and realized the low-damage cutting of Alfalfa stalk. [ABSTRACT FROM AUTHOR]

The present paper investigates the friction and wear resistance of carbonitrided AISI 4130 steels using single and multi-pass scratch techniques. The influence of carbon concentration in high-temperature gas carbonitriding on friction, wear, and corrosion behavior was studied. The microstructure and morphological properties of carbonitrided layers were investigated employing optical microscope and XRD. The corrosion performance of carbonitrided layers was also evaluated using potentiodynamic polarization in 3.5 wt.% aqueous solution of NaCl. The results of microstructure showed the formation of an arrangement of carbonitrides, chromium nitride, retained austenite, and F e 3 C carbides phases in the carbonitrided layers. The carbonitrided layer microhardness increased as a function of increasing carbon concentration to attain a maximum value of about 980 HV0.1 at a carbon content between 1 and 1.2%. The microhardness value was more than 3 times than those of the untreated AISI 4130 steels. Moreover, carbon content has a significant influence on the scratch resistance. For single pass, a critical load (LC1) of about 3.5 N was found. The use of multi-pass scratching allowed to examine friction coefficient, wear volume, and damage mechanism. Carbonitrided layers revealed a low friction coefficient (0.06) and a low wear volume that does not exceed 0.16 ∗ 10 6 μ m 3 . Moreover, the multi-pass scratch technique can extract valuable information about the wear behavior of the carbonitrided layers. The results of corrosion test showed that the formation of ε (F e 2 − 3 C N) S , γ ′ (F e 4 N) and chromium nitride phases in carbonitrided layers were at the origin of high electrochemical resistance. [ABSTRACT FROM AUTHOR]

This paper is to present an experimental study of the impact of surface hardening on the high-cycle fatigue behavior of an isotropic beam. The beams made from low carbon steel (St 44-2). Surface treatments used are pack carburizing and carbonitriding. The experimental work included mechanical test, surface heat treatment, fatigue test and Microscopic inspection. The surface hardening was done by using pack-carburizing process at a temperature of 925°C holding time variation (2, 4, and 6hr) followed by quenching and tempering process, and using the carbonitriding process at a temperature of 800°C and for periods (0.5, 1 and 1.5hr) then quenching directly in water. The fatigue test was carried out by a cantilever rotating-bending system. The results of an experimental fatigue test indicate that various behaviors depend on surface heat treatment and time soaking. The findings indicate that carbonitriding has a greater impact on the fatigue strength and life than the specimen has been treated with pack carburizing. In addition, as the time soaking increase, the fatigue life will increase for both types of surface heat treatments. It was found that the specimens that were hardened using the carbonitriding process achieved a higher surface hardness as the hardness increased to 1644.62HV, while the untreated specimens were 293HV. Compared with the hardening using the pack carburizing process. [ABSTRACT FROM AUTHOR]

This paper investigates the evolution of retained austenite and residual stresses during and after tempering of carbonitrided 18CrNiMo7-6 low alloy steel carried out using in-situ X-ray diffraction technique. In this case, two carbonitriding treatments with different surface the retained austenite contents of 20 and 54 mass.-% are investigated. The tempering is carried out in a continuous heating mode to 650°C as well as in isothermal mode at holding temperature of 170, 240, and 300°C for 2 hours. During continuous heating at a heating rate of 10°C/min, the retained austenite started to decompose at 290°C. On isothermal holding at 170°C for 2 hours, the retained austenite remained relatively stable at 20 and 54 mass.-% while readily decomposed to less than 5 mass-% on holding at 300°C. On continuous heating, residual stress in martensite continuously relaxes and reaches full relaxation (0 MPa) at about 400°C. During isothermal holding, residual stresses in martensite are increasingly relaxed with increasing holding tempering. Further relaxation of residual stresses is observed during cooling whereas a cyclic variation of the residual stresses in the retained austenite could be determined. [ABSTRACT FROM AUTHOR]

The work is based on carbonitriding in a fluidized layer with methane and ammonia gas applied to 41Cr4 steel samples. To achieve the best possible results, other factors must be taken into account, than those specific to carbonitring. It was necessary to use a partially factorial working procedure due to the increase in the number of factors. An A18 matrix has been used, with 18 lines of experiments in which three levels have been modified for 6 factors. The objective function was fixed at the final hardness after carbonitriding, hardening and tempering. The carbonitriding was performed in fluidized bed with granular solid ground and sorted to 0.1- to 0.16mm, and brought to fluidization with a mixture of methane and ammonia. The hardening has been done directly after carbonitriding in the fluidized bed. The experiments have been performed according to Taguchi Methods and the results indicate an optimal regime and the influence of the factors considered on the hardness after the thermo-chemical treatment and the thermal treatment. Metallographic analysis has been performed on the carbonitrided layer.

Case-hardening steels (EN36, 16MnCr5, and AISI 4140) are used in applications demanding good surface properties such as precision gears, shafts, and cam rollers. This study explores the formation of microcoatings to improve the surface characteristics of these steels using carbonitriding, which combines the merits of carburizing and nitriding to offer surfaces with enhanced hardness and wear resistance. Taguchi's L18 orthogonal array is used for conducting the carbonitriding trials with replications. The effects of various carbonitriding parameters like carbonitriding time, temperature, and flow rate of ammonia are studied on the treated surface characteristics (Vickers microhardness, diffusion depth, and wear loss). A novel integrated approach of principal component-based grey incidence (PGI) that combines the merits of both principal component analysis and grey incidence theory is effectively used to select the optimal carbonitriding inputs (material substrate AISI 4140, carbonitriding temperature −835°C, carbonitriding time-40 min, and flow rate of ammonia 0.4 lit/min). Microscopic images related to diffusion depths are also analyzed. This study offers the necessary guiding principles for obtaining the desired surface coating on EN36, 16MnCr5, and AISI 4140 steels. [ABSTRACT FROM AUTHOR]

A quenched and tempered and a carbonitrided Fe-Cu-C steel were compared in fully reversed plane bending fatigue with notched and unnotched specimens at different densities. If the notches are characterized by elastic stress concentration factors Kt, the volume around the peak stresses diminishes with increasing Kt. Applying Weibull's survival statistics, the effect of highly-loaded volume on fatigue is quanti- fied to predict the fatigue performance of components. There are competing concepts with the same claim. For the relative stress gradient concept, it is shown that there is a loose, but systematic relationship between relative stress gradient and highly-loaded volume. With regard to the different heat treatments, the carbonitrided steel outperformed the quenched and tempered version up to the sharpest notches, although after carbonitriding all specimens were through hardened and free of compressive residual stresses. [ABSTRACT FROM AUTHOR]

Designing low-cost catalysts that offer both high mass activity and high cycling stability is crucial. Herein, a binder-free 3D self-supporting electrode composed of carbo-nitride tungsten supporting Pt nanoparticles (Pt@3DP-WN x C 1-x /W) has been successfully synthesized for hydrogen evolution reaction in acid electrolyte. The tungsten carbo-nitride synthesized via a one-step heat treatment exhibits enhanced conductivity as a result of the carbonization process and optimizes the adsorption and desorption properties of WC towards H atoms through the incorporation of N atoms, thereby achieving an effective balance. Simultaneously, the N –Pt bond enhances electron transfer efficiency. This electrode exhibits outstanding electrochemical performance with a 219 mV overpotential at a current density of −300 mA cm−2. Its current density and mass activity is up to 75 mA cm−2 and 7.5 A·mg Pt −1 at an overpotential of 100 mV, respectively, which are both 2.6 times higher than those of the 40% Pt/C electrode. In addition, it reveals a low Tafel slope of 38.3 mV dec−1 indicating rapid kinetics. Furthermore, the electrocatalyst shows only 3 mV day at −100 mA cm−2 after 10,000 cycles. Both theoretical calculation and experimental results show the promotion of catalytic efficiency of Pt@3DP-WN x C 1-x /W brought by carbo-nitrition. This study offers a novel, efficient, and stable electrode design strategy. [Display omitted] • Prepared a large-area 3D self-supporting electrode (Pt@3DP-WN x C 1-x /W). • Pt@3DP-WN x C 1-x /W exhibits high current density and excellent long-term stability. • Pt@3DP-WN x C 1-x /W substrate's conductivity increased 15 times. • The electronic interaction between Pt and WNxC1-x resulted in superior HER performance. [ABSTRACT FROM AUTHOR]

In this paper, the antifriction carbonitriding (PEC/N) layers were prepared on pure iron by cathodic plasma electrolytic treatment (PET) in glycerin and carbamide aqueous solution under 360 V for 1, 3 and 10 min. Influence of discharge time on morphology, structure, surface roughness and microhardness of PEC/N layer was analyzed. The tribological performance of the PEC/N layer, growth mechanism and diffusion process during PEC/N treatment was investigated. The thickness of the PEC/N layer grew to 48 μ m for 10 min treatment and the growth of the saturation layer met the parabolic law. The highest microhardness of the surface was up to 811 HV, which was 5 times of that of iron substrate. The PEC/N layer consisted of α -Fe, Fe 2 − 3 N, Fe4N, Fe3C, Fe5C2 phases and a little FeO phase. The wear rate of the PEC/N layer reduced by five-sixes comparing with the iron substrate and the surface of the wear track was much smoother. The temperature close to the surface during PEC/N fitted by the tested temperature values inside the sample was 801∘C (1074 K), and the combination diffusion rate of C and N into pure iron during PET at 360 V reached 4. 0 9 × 1 0 − 1 2 m2/s. The electron temperature fluctuates between 3000 K and 8000 K. The antifriction PEC/N layer displayed a very good wear resistance and the higher diffusion rate makes plasma electrolytic carbonitriding a very effective technique for surface modification of pure iron. [ABSTRACT FROM AUTHOR]

The article provided results of chemical and thermal treatment of high-speed steel R6M5. Carbonitriding of the high-speed steel performed at 1200-1230 °C and tempering at 600-620 °C. The microhardness of the metal surface layer reached 11000 MP at 0.1-0.15mm depth of the surface. Studies were conducted on the effect of quenching and tempering temperatures on the parameters of the steel structure (physical width of the x-ray line, dislocation density, lattice parameters, and hardness of steel R6M5). [ABSTRACT FROM AUTHOR]

In order to increase the fatigue performance of mechanically loaded PM-components, case hardening procedures can be used to improve the surface layer states in terms of hardness and residual stress. In this work, the effects of carbonitriding treatment on two typical PM-steels with multiple densities are investigated in terms of their surface layer state (hardness, residual stress and retained austenite) before and after fatigue testing and their resulting pulsating fatigue performance. The results confirm fatigue strengths that can be formulated linearly as a function of porosity as well as a cyclic stability of the surface layer condition at loads below the fatigue strength. Further optimisation of the fatigue strength can be expected by tailoring the surface layer with respect to residual stresses. Comparisons to other studies are difficult due to many process parameters, different load cases and limited data, but indicate comparable fatigue strengths. [ABSTRACT FROM AUTHOR]

The work is based on carbonitriding in a fluidized layer with methane and ammonia gas applied to 41Cr4 steel samples. To achieve the best possible results, other factors must be taken into account, than those specific to carbonitring. It was necessary to use a partially factorial working procedure due to the increase in the number of factors. An A18 matrix has been used, with 18 lines of experiments in which three levels have been modified for 6 factors. The objective function was fixed at the final hardness after carbonitriding, hardening and tempering. The carbonitriding was performed in fluidized bed with granular solid ground and sorted to 0.1- to 0.16mm, and brought to fluidization with a mixture of methane and ammonia. The hardening has been done directly after carbonitriding in the fluidized bed. The experiments have been performed according to Taguchi Methods and the results indicate an optimal regime and the influence of the factors considered on the hardness after the thermo-chemical treatment and the thermal treatment. Metallographic analysis has been performed on the carbonitrided layer. [ABSTRACT FROM AUTHOR]

A duplex treatment, namely, plasma carbonitriding followed by multi-arc ion plating, was used to improve the high-temperature tribological properties of TiAlCrN coatings on 300M steel in this research. The carbonitriding layer was first prepared on 300M steel substrates by the double glow plasma metallization technique. A corresponding heat treatment was performed, and then the TiAlCrN coating was synthesised on the surface of the carbonitriding layer and 300M steel substrates by multiarc ion plating. The microstructure, element composition and structural variations of the TiAlCrN coating were characterised using XRD, SEM and EDS. Moreover, the adhesion and high-temperature tribological behaviours of TiAlCrN coatings were studied by scratch tests and ball-on-disk wear tests, respectively. It was observed that the PCN + TiAlCrN coating showed gradient hardness support, a good chemical composition gradient and a diffusion effect in the carbonitriding process, which could significantly enhance the adhesion and tribological performance of the composite coating. [ABSTRACT FROM AUTHOR]

We present results of investigations of the physicochemical properties of KhVG steel depending on the method and conditions of carbonitriding in glow discharge. As the optimal version of carbonitriding in glow discharge, we can mention simultaneous saturation of the metal surface with nitrogen and carbon. In this case, on the steel surface, we observe the formation of a composite layer that consists of an outer carbonitride zone (15 μm) with a microhardness of 7480 MPa and a developed diffusion zone (55 μm) without precipitation of the ε-phase on grain boundaries, which decreases the abrasive wear resistance, adhesive wear resistance, and corrosion-fatigue resistance. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to prepare Ti(C,N) coatings on TA15 treated and not treated by shot peening using double glow plasma alloying technique. The effect of shot peening on the wear behavior of Ti(C,N) coatings is discussed. Design/methodology/approach: The Ti(C,N) coatings were prepared by double glow plasma alloying technique on two different TA15 substrate; one is shot peened and the other is not. Findings: Ti(C,N) coating on SP-treated TA15 was thicker and denser, and the grain size was smaller compared with that on original TA15. Compared with the Ti(C,N) coating on original TA15, the wear resistance of that on SP-treated TA15 is improved. Ti(C,N) coating on SP-treated TA15 showed higher nanohardness and bearing capacity than that on original TA15. Originality/value: For double glow plasma alloying technique, surface quality, surface activity and other factors will have influence on the thickness and density of the coating. The wear mechanisms of Ti(C,N) coating on original TA15 are serious abrasive wear and oxidation wear. However, the wear mechanism of Ti(C,N) coating on SP-treated TA15 is slightly oxidation wear. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0283/ [ABSTRACT FROM AUTHOR]

The influence of the process of ion carbonitriding on the micro-hardness and wear resistance of steel 25CrMnSiNiMo and Armco-iron is considered in the present study. The obtained results show the positive influence of the process on the wear resistance of the studied materials. Depending on the chemical composition and on the modes of carbonitriding, their wear resistance varies within different limits. It has been found out that for all modes of ion carbonitriding in ammonia and corgon medium the studied materials obtain a higher wear resistance than that they obtain after ion nitriding; and it has also been proved that steel 25CrMnSiNiMo has a higher wear resistance t han Armco-iron. [ABSTRACT FROM AUTHOR]

We present the results of investigations of the influence of hydrogen-free carbonitriding in glow discharge on the physicochemical characteristics of the hardened layer of 40Kh steel depending on the content of propane and the pressure of gas atmosphere. We consider three versions of saturation: carbon + nitrogen, nitrogen + carbon, and simultaneous saturation with nitrogen and carbon. The analysis of the obtained results reveals the highest efficiency of hardening of the surface of 40Kh steel for the third version of saturation. [ABSTRACT FROM AUTHOR]

Vacuum carbonitriding has recently been attracting attention as a heat treatment to reduce the size and weight of power transmissions. In this study, all of the chromium molybdenum steel test gears were vacuum carbonitrided after hobbing. The roughness of test gears was finished by a gear grinding machine to about 3 μmRz on tooth profile. These gears were called Gear G. Additionally, fine particle shot peening was applied on some of Gear G to improve the bending strength by providing work hardening and compressive residual stress on tooth flank. These gears were named Gear GS. Their load carrying capacity was investigated through running tests using a gear testing machine. The endurance limit of Gear G was about 2150 MPa in maximum Hertzian stress at the pitch point. This is an improvement of about 25 % over that of the carburized gear. However, the endurance limit of Gear GS was lower than that of Gear G. In order to investigate this factor, each of the surface topology were observed using a laser microscope. Comparatively, the rate of contact area was decreased after shot peening. This means that the surface topology of Gear GS must be improved, since failure occurs in shorter cycles on Gear GS. In order to simulate the surface roughness finished by the gear lapping technology which has been developed by the authors, some of Gear GS were polished to about 1 μmRz on tooth profile. These gears were called Gear GSP. According to running tests of Gear GSP, the fatigue life was longer than those of Gear G and GS, because the rate of contact area was improved by polishing. It is concluded that if the vacuum carbonitrided gear was treated by grinding, fine particle shot peening and the gear lapping in turn, the appropriate load carrying capacity may be obtained.

Forging dies have to resist high mechanical and thermal loads. Therefore, they are usually nitrided. Former investigations showed that the abrasive wear at the critical parts of the dies is much higher than the nitriding hardness depth. Carbonitriding offers the possibility to increase the hardness depth in shorter treatment times because of the higher treatment temperature. The (carbo-)nitrided surface region obtains a better hardness at elevated temperatures and a better wear resistance than the untreated steel. In order to create a wear- and corrosion-resistant compound layer at the surface, a nitriding process step can be conducted after carbonitriding. The present work deals with developing a carbonitriding treatment for forging dies and investigations on the wear resistance of the created surface zones in model wear tests and tool life time experiments under industrial conditions. The aim of this work was to produce heat- and wear-resistant precipitation layers in hot working tool steels in economical treatment durations.

Technology for low-temperature carbonitriding combined with high temperature tempering of cold-worked die steel 6Kh4M2FS (DI55) is proposed. The high efficiency of a paste-like coating based on amorphous carbon and nitrogen-containing components (carbamide and potassium ferricyanide) during die steel cyaniding in the temperature range from 500 to 580°C is demonstrated. The effect of thermochemical treatment regimes on diffusion layers formed on steel, their phase composition, and properties is investigated. [ABSTRACT FROM AUTHOR]

In this study, the low-pressure carbonitriding (LPCN) response of four different steel alloys is investigated. The influence of unprotected boron is evaluated by comparing the microstructure and fatigue performance of 20MnCr5 with and without boron additions after LPCN. Similarly, the influence of Nb microalloying is assessed by comparing 8620 steel with and without Nb additions. Low-pressure carbonitriding heat treatments were developed to achieve case depths of 0.65-0.75 mm in each alloy, thus allowing the influence of alloying and microstructure to be explored independent of case depth. The hardness and case microstructure are correlated with bending fatigue response measured with Brugger fatigue specimens, which are designed to simulate the root of a gear tooth. The 20MnCr5 alloys had the highest fatigue strength, and the 8620 alloys had the lowest fatigue strength, despite having the same hardness profile and case depth. Reductions in prior austenite grain size and increased surface hardness appeared to have a positive effect on the endurance limit of the steel alloys. Retained austenite volume fraction on the surface of the steel alloys as well as non-martensitic transformation products subsurface in the case did not have an apparent direct contribution to fatigue performance. [ABSTRACT FROM AUTHOR]

• SiBCN powders were prepared by the carbonitriding of silicon, B 4 C and cornstarch. • Chemical bonds such as C N and B C N with higher binding energy were detected. • BN(C) grains homogeneously distributed around nano-sized α/β-SiC/SiCN grains. • Better oxidation resistance because of the strengthened bonds and BN(C) formation. SiBCN ceramic powders were facilely synthesized from the compacts of silicon, B 4 C and cornstarch by a carbonitriding route. Effects of silicon content in raw materials on phase composition, chemical bond, microstructure and oxidation resistance of as-received products after heated at 1550 °C were investigated. The featured chemical bonds such as C N and B C N in as-received products were detected by X-ray photoelectron spectroscopy (XPS). The microstructure of BN(C) distributed around nano-sized α/β -SiC/SiCN grains was revealed by transmission electron microscopy (TEM). The synthesized products with the Si/B/C ratio of 1:1:1 presented better oxidation resistance than SiC because of the strengthened chemical bonds and BN(C) formation. [ABSTRACT FROM AUTHOR]

Using the transmission electron microscopy of thin foils the paper studies the phase composition and fine structure of 0.18С–1Cr–3Ni–1Mo–Fe steel after plasma electrolytic carbonitriding carried out through the surface saturation with nitrogen and carbon. The steel specimens are studied before and after carbonitriding on the surface and at a ~40 μm distance from the surface. It is found that carbonitriding causes significant qualitative and quantitative changes in the steel structure. Thus, the layers of residual austenite appear along the boundaries of martensitic lamellas, and the particles of alloyed cementite and carbonitrides are observed inside the lamellas. The layers of residual austenite locate at a ~40 μm depth along the boundaries of all martensitic crystals, while inside the crystals there are only particles of alloyed cementite and carbonitride M23(C, N)6. The control parameter of changes in the structure and phase composition is the concentration of interstitial atoms of carbon and nitrogen. Changes in this concentration lead to the system deviation from thermodynamic equilibrium. The transition of system to equilibrium or quasi-equilibrium states is considered to be performed through the transition of crystal lattices, which form a gradient structural-unstable state of the matrix, intermetallics and carbonitride compounds, to a low-stability state. [ABSTRACT FROM AUTHOR]

The intent of this research is to understand the role of interface chemistry on the effective work function and device characteristics of metal gate electrodes on hafnium dioxide (HfO2) gate dielectrics in metal oxide semiconductor field effect transistors. Since multiple factors, including crystal structure, preferred orientation, chemical composition, interface bonding, and reactions or interdiffusions, impact the effective work function, solid-solution carbonitrides of tantalum (TaCxN1-x) have been studied in an attempt to isolate the role of interface chemistry on the effective work function. Tantalum carbonitride films have been carefully deposited with similar Ta/(C+N) ratios to understand how the substitution of N for C on the octahedral interstice in a face-centered-cubic tantalum lattice impacts device performance. Results indicate that the effective work function and device threshold voltage are reduced when the less electronegative carbon atom is substituted for the more electronegative nitrogen atom. This result is in qualitative agreement with the known relationship between metal electronegativity and effective work function and demonstrates the important role that sublattice elements in binary metal compounds have on the effective work function of the gate electrode. [ABSTRACT FROM AUTHOR]

Optimizing the impedance matching via electromagnetic adjustment is considered an effective strategy to accomplish exceptional electromagnetic wave absorption (EMA) performance. Here, we report an efficient and green process to obtain the carbonitriding FeCoNiCr high-entropy alloys (HEAs) with flake-shaped morphology by using organic cyanide (Dicyandiamide, C 2 H 4 N 4 ) as nitrogen and carbon sources. The carbonitriding effects on the phase structure, magnetic properties, mechanical hardness, corrosion resistance, high-temperature oxidation resistance, and EMA performances were investigated systematically. The carbonitriding process optimized the impedance match by decreasing the dielectric constant via introducing the nonmetallic C and N. The #CN10 sample exhibited outstanding EMA performances with a minimum reflection loss of -32.3 dB at 7.89 GHz and a broad effective bandwidth of 4.46 GHz, which covered the majority of X-band. In addition, the carbonitriding FeCoNiCr HEAs had great mechanical properties, excellent corrosion resistance, and high-temperature oxidation resistance, indicating excellent adaptability to harsh environments as well as good EMA performances. This work provides a new idea for the preparation and design of carbonitriding EMA materials.

The potential of carbonitriding treatment of steel with cow horn was investigated in line with abattoir waste to wealth approach of waste management. The objectives of the study included processing of cow horn into different morphologies namely: powder and flakes for carbonitriding heat treatment, and, chemical analyses of cow horn with Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD) techniques to determine the chemical composition and phases of cow horn respectively. The heat treatment was carried out at 850 and 450 °C for carburizing and nitriding dominated processes respectively. Vickers hardness measurement was carried out to determine the hardness profile on carbonitrided samples. Optical metallography was carried out for microstructural examination and to investigate phase contrast between the case and core of carbonitrided sample. The result of hardness test observed is consistent with the case hardening profile with higher hardness value at near surface decreasing towards core. Sample heat treated with horn flakes showed higher hardness than those with horn powder. Microstructural phase contrast showed delineation of the hardened case and soft inner core. The high hardness of case was attributed to diffusion of carbon and nitrogen atoms from the cow horn to iron interstices. This supposition was corroborated by detection of carbon and nitrogen with EDS and XRD tests. It was therefore concluded that cow horn could be processed as candidate materials for carbonitriding of steel. [ABSTRACT FROM AUTHOR]

Abstract In the study, an innovative carbonitriding process was implemented to increase hardness and hardening depth of Ti-6Al-4V alloy via laser irradiation of pure graphite powder in a nitrogen environment. The formation of the carbonitrided layer on the surface depends on the diffusion of carbon and nitrogen atoms and the kinetics of carbonitriding reaction. Dendritic phase transformations within the hardened layer help in determining the overall depth and hardness of the hardened layer. To characterize the proposed carbonitriding process more fundamentally, samples of an Ti-6Al-4V alloy were self-quenched (SQ), laser-carburized (LC), laser-nitrided (LN), and laser‑carbonitrided (LCN) at the same laser irradiation conditions. This was followed by comparing the microstructural evolutions and mechanical properties of the respective samples after laser surface treatments. The hardening characteristics of the respective laser surface treatments were significantly influenced by the reaction compounds and laser energy density. The LCN Ti-6Al-4V alloy was dominated by compounds with mixed structure of carbonitrides and exhibited excellent hardness with increase in hardening depth. The results confirmed that the proposed laser carbonitriding is a feasible and effective process to increase the hardness and hardening depth of Ti-6Al-4V alloy without process-induced cracks. Highlights • Carbonitriding of Ti6Al4V via laser irradiation of graphite powder in N 2 environment • Tailored hardening by controlling the reaction compounds and laser energy density • Enhanced hardening efficiency in laser carbonitriding with pure graphite powder [ABSTRACT FROM AUTHOR]

Abstract The investigation on the microstructure and tribomechanical behavior of hypereutectoid bearing steel AISI 52100 has been carried out during an unconventional thermo-chemical process aiming to improve the wear performance under dry conditions. The effects of NH 3 addition rate on microstructure, hardness and wear performance of the carbonitrided specimen were characterized and the results show that two types of nitride (CrN, (Cr,Fe) 2 N 1−x) are formed in the surface layer. The quantity of the nitride and carbide precipitates increase firstly and decrease subsequently with the increasing of NH 3 addition rate, whereas the fraction of retained austenite increases monotonically. The wear performance of the carbonitrided specimen is improved during the entire stage of the sliding test with the NH 3 addition rate below 0.4 l/min, but it decreases sharply at the initial stage of sliding test and then increases gradually when further raising the NH 3 addition rate. The possible reasons underlying have been discussed and are attributed to the fraction of retained austenite formed during carbonitriding process and the transformation from retained austenite into martensite during sliding test, respectively. Highlights • The microstructure of the carbonitrided layer on the hypereutectoid bearing steel AISI 52100 had been precisely characterized. • The effects of NH 3 addition rate on wear performance of the carbonitrided bearing steel specimen were investigated. • The wear mechanisms of carbonitrided layers were revealed. [ABSTRACT FROM AUTHOR]

Abstract The UC 1-x N x solid solution modified layers that improve corrosion resistance and surface hardness of uranium were prepared by pulsed laser irradiating the surface uranium in the mixed atmospheres where the partial pressure ratios of CH 4 to N 2 are 1:2, 1:1 and 2:1, respectively. The SEM images show that the distribution of micro-cracks in the modified layers decreases significantly with the increase of partial pressure of CH 4 in the mixed atmospheres. The phase structure and chemical composition of the modified layers were investigated by XRD and AES. XRD results show that the composition of the carbonitride modified layers is mainly UC 1-x N x solid solution, only with a small amount of free uranium and uranium dioxide. AES results reveal that the C and N contents in the UC 1-x N x solid solution can be adjusted by the respective partial pressure of CH 4 and N 2. The U 4f, N 1s and C 1s core-level also confirmed that the UC 1-x N x solid solution is the main component in the laser modified layers. Electrochemical polarization tests were conducted in 0.02 mol/L NaCl solution and the results indicated that the carbonitride modified layer prepared in an atmosphere where the ratio of CH 4 to N 2 at 1:2 have excellent corrosion resistance, its self-corrosive potential and self-corrosive current are −2.28 × 10−1 V and 5.56 × 10−8 A/cm2, respectively, while the values of the uranium are −5.67 × 10−1 V and 8.08 × 10−7 A/cm2, respectively. Nano-indentation measurement results show that the average hardness at different depths of these modified layers is between 7 GPa and 9 GPa, while the average value of the uranium is 4.1 GPa. Highlights • The UC 1-x N x solid solutions on uranium were prepared by pulses laser modification. • There is no other uranium nitrides or carbides were found in UC 1-x N x solid solution. • The effect of the ratio of C to N on corrosion and hardness was recognized. • The method of preparing UC 1-x N x solid solution can be applied to the other materials. [ABSTRACT FROM AUTHOR]

Abstract Theory predicts that β-C 3 N 4 with its dense structure is a superhard material. In order to synthesize this material, light-gas gun loading and shock recovery technology were used to perform experiments. The amorphous nitrogen-enriched g-C3N4, produced by the thermal decomposition of melamine, was used as a precursor. The shock synthesis experiment was completed under the pressure of 50 GPa. A high-density phase with a β-C 3 N 4 structure was detected only in the desired product. It is suspected that the elemental composition and synthetic pressure of precursors may be the main factors affecting the phase composition of products. This has significant potential for the synthesis of pure superhard carbonitride compounds. [ABSTRACT FROM AUTHOR]

The isothermal decomposition of austenite between B S and M S was investigated after carburizing and carbonitriding in low-alloy steel 23MnCrMo5. The microstructure of the products differed significantly between carburizing and carbonitriding. The carburized alloy produced an expected bainitic microstructure consisting mainly of bainitic ferrite with some cementite and retained austenite. In contrast, the microstructure of the nitrogen-containing sample showed finer, entangled ferrite plates, retained austenite and nitrides. The ferrite plates contain numerous transformation twins, which can be as thin as only a few nanometers. This original result proves that abundant twinning can be found in bainite as well as in martensite. [ABSTRACT FROM AUTHOR]

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