Carbonitride Layers Research Articles

Tunable hydrogen generation from sodium borohydride with silicon carbonitride functionalized carbon nanostructure electrode

A novel multilayer carbon nanostructure catalyst (MCNC), composed of carbon fiber (CF), carbon nanotube (CNT), precious metal dispersions (Pt/Pd/Ru) and silicon carbonitride (SiCN) layer derived from a liquid based polymeric precursor, has been developed in this work with the aim to be used as the electrode for decomposing water into hydrogen. The ternary Pt/Pd/Ru catalysts are deposited on the thin film coating of SiCN functionalized carbon nanotube (SiCN/CNT) electrophoretically deposited (EPD) on carbon fiber. The silicon carbonitride layer makes the silicon-transition metal bond form a sub-nanometric layer of metal catalyst to increase the surface-to-volume ratio and catalytic efficiency. Sodium borohydride, NaBH4, solution spontaneously reacts with MCNC to generate hydrogen in a very fast rate, depending on its concentrations. The ternary catalyst shows a higher generation rate compared to the binary and single catalytic systems already prepared with the same synthetic procedure. The reaction mechanism and the catalytic efficiency have been described in terms of the reaction pattern that involves an electric charge transfer, due to the negative charge on the BH4− ion transferred with one hydrogen atom via SiCN/CNT structure, ensuring the generation rate increase. As an electrical potential is applied between two MCNC electrodes in sodium borohydride electrolyte, the generation rate of hydrogen can be tuned by the applied potential. When the concentration of NaBH4 is much diluted, this electrolytic and hydrolytic reaction obeys the Faraday's law. Due to diluted solution, the reaction of hydrogen generation is dominated by electrolytic reaction that can be decomposed at a very low potential ∼0.5 V. This result indicates that the band gap of the semiconductive MCNC electrode can be lowered by the applied potential. The figure-of-merit, FOM can reach 1150 L min−1 [NaBH4]−1gmet−1, as one volt applied. When a constant voltage applied, FOM gradually decreases with [NaBH4] increase till to reach the steady state that the zero order reaction is achieved. The MCNC electrode is robust and re-useable by alcohol rinsing and dry after reaction.

Structural characterization and adhesion appraisal of TiN and TiCN coatings deposited by CAE-PVD technique on a new carbide composite cutting tool

A new composite matrix was developed for a cutting tool based on tungsten carbide ligated with cobalt (WC-Co) using sintering technique. The admixtures of niobium carbide, tantalum carbide, and titanium carbide with the WC-Co matrix aim to inhibit the grain growth of WC and to promote covalent bonding at the interface. The modified WC-Co tools were coated with titanium nitride and titanium carbonitride layers by CAE-PVD technique. To substantiate the performances of the new coating-substrate systems, we have performed X-ray diffraction, atomic force microscopy, and scratch test measurements to estimate: phase content, average crystallite size, average texture coefficient, residual stress level, coating thickness, average roughness, square mean root, fractal dimension, cohesive adhesion, and adhesive adhesion. The results enable the in-depth understanding of the coating growth mechanisms and provide an objective evaluation of the coatings adhesion to the new cutting tools matrix. The results provide evidence to support the potential of TiN and TiCN coatings to enhance the working performances of the composite WC-Co cutting tools and to differentiate their properties. TiCN coating is shown to be superior to TiN coating in terms of adhesion and thus represents a better alternative for coating the modified WC-Co composite matrix.

Duplex ceramic coating produced by low temperature thermo-reactive deposition and diffusion on the cold work tool steel substrate: Thermodynamics, kinetics and modeling

Specimens of DIN 100MnCrW4 steel (type O1 tool steel) have been cut and prepared for performing a duplex surface treatment involving nitriding and low temperature vanadium thermo-reactive deposition and diffusion (TRD) technique. The TRD process was performed in a molten salt bath at different temperatures of 575, 650 and 725°C for 1–30h. The treatment formed a vanadium carbonitride coating with the thickness up to 10.5μm on a hardened diffusion zone. Characterizations by means of an optical microscope (OM), scanning electron microscope equipped with energy dispersive X-ray spectrometer (SEM–EDS) and X-ray diffraction analysis (XRD) indicated that the compact and dense coating mainly consisted of V(C,N) and V2(C,N) phases. All the growth processes of the formed vanadium carbonitride layer obtained by TRD followed a parabolic kinetics while the calculated activation energy (Q) for the treatment was 181.1kJ/mol. An artificial neural network (ANN) based model for predicting the layer thickness of ceramic coatings was presented. Constructing the model, training, validating and testing of experimental results from 72 different specimens were conducted. The data used as inputs in the proposed model were arranged in a format of five parameters that comprised of “pre-nitriding time”, “ferro-vanadium particle size”, “ferro-vanadium weight percent”, “salt bath temperature” and “coating time”. Accordingly, the thickness of duplex coating in each specimen was estimated accurately. Finally, the proposed ANN-based model showed a strong potential for predicting the layer thickness of duplex ceramic coating performed by the TRD technique on the substrate of cold work tool steel.

42CrMo调质钢碳氮共渗组织及性能研究

采用碳氮共渗工艺，对42CrMo调质钢进行表面强化处理，研究了其组织变化对力学性能的影响。结果表明，经碳氮共渗工艺后，工件表面产生了一层0.14 mm厚的碳氮化合物层，芯部转变为隐晶马氏体加铁素体，材料组织得到了进一步细化，42CrMo调质钢的表面硬度达到650 HV，屈服强度达到1120 MPa，冲击韧性达到84 J/cm2。实验结果表明，销轴经碳氮共渗热处理后，42CrMo调质钢具有更好的强韧性，产品质量提高。 Using carbonitriding process, the processing of quenched and tempered 42CrMo steel surface was strengthened, and the effect of its microstructure change on mechanical properties was investi-gated. The results show that, after carbonitriding process, a carbonitride layer of 0.14 mm is pro-duced on the workpiece surface; core is transformed into cryptocrystalline martensite and ferrite; material organization has been further refined; the surface hardness of quenched and tempered 42CrMo steel is 650 HV; the yield strength is 1120 MPa; and the impact toughness can reach 84 J/cm2. The experimental results show that after carbonitriding heat treatment of the pin, quenched and tempered 42CrMo steel has better tenacity, and the product quality is improved.

PECVD Synthesis of Silicon Carbonitride Layers Using Methyltris(diethylamino)silane as the New Single-Source Precursor

Deposition of thin SiCxNy layers from a new single-source organosilicon compound, methyltris(diethylamino)silane (MTDEAS) mixed with helium or nitrogen is studied by using thermodynamic simulation of Si–C–N–H(He)–O system and experimentally by low pressure (10−2–10 Torr) plasma enhanced chemical vapor decomposition (PECVD) in the temperature range of 300–1300 K. Thermodynamic simulation allowed to find the temperature boundaries of solid phase formation. The phase composition, as well as physicochemical and functional properties of the layers has been studied using a complex of modern experimental techniques, including Raman spectroscopy, scanning electron (SEM) and atomic force microscopy (AFM), X-ray diffraction using synchrotron radiation (XRD-SR), ellipsometry and spectrophotometry. The electrophysical parameters were measured using the C-V characteristics. The microhardness and Young's modulus were determined by Nanoindentation method. It was shown that the layers contain crystals of phases belonging to Si3-xCxN4 structures, such as α-Si3N4, α-Si2CN4, α-SiC2N4, and α-C3N4 which, possibly, are embedded in the amorphous matrix of silicon carbonitride layers.

Surface Modification of the Ti6Al4V Alloy with Silicon Carbonitride Layer Deposited by PACVD Method

AbstractFour different layers of various silicon, carbon and nitrogen contents on the Ti6Al4V alloy and (001)Si wafers have been deposited by means of Plasma Assisted Chemical Vapor Deposition (PACVD) method. The layers were obtained from reactive gas mixture containing SiH4, CH4, NH3 and Ar. After deposition the structure and chemical composition of modified surfaces have been analyzed with use of SEM/EDS technique. Based on these results and thermodynamic calculations, the diffusion coefficients, D, for nitrogen and carbon in alloy were discussed. Scratch test shown that silicon carbonitride layers have good adhesion to metal surface. In order to determine atomic structure of obtained layers, FTIR spectra for layer-(001)Si and layer-Ti6Al4V were registered.

Silicon carbonitride layers deposited on titanium and polyurethane by PACVD method

This work reports the results concerning formation and tribological properties of SiCxNy(H) layers deposited on Ti Grade 2 and polyurethane foil. Depending on the substrate, two variants of PACVD were used. The SiCxNy(H) layers on titanium were deposited with application of MWCVD (2.45 GHz, 2 kW). The layers on polyurethane were deposited using RFCVD (13.56 MHz, 400 W). Good adhesion between the SiCxNy(H) layers and polymeric foil was achieved by formation of a transitional C:N:H layer and incorporating Si gradient into the structure of the SiCxNy(H) layer. The chemical composition of the layers was tailored by precise control of the gaseous precursors ratios: [SiH4]/[NH3], [SIH4]/[NH3]/[CH4], [SiH4]/[CH4] or [SiH4]/[N2]/[CH4]. The structure and chemical composition of the obtained layers were subjected to further studies (FTIR, SEM/EDS). The roughness, friction coefficient and wear resistance were also measured. The results show that SiCxNy(H) layers offer attractive tribological properties which make them good candidates for various applications, including biomedical devices.

Effects of Electrolyte Plasma Carbonitriding on Tribological Properties of High Speed Steel

This paper presents research of influence electrolyte plasma carbonitriding on tribological properties of R6M5 high-speed steel. Shows perspectiveness of carbonitriding high-speed steels in electrolyte plasma. The results of research demonstrated increasing wear-resistance of R6M5 steel after carbonitriding in electrolyte plasma. Under the same test conditions by the method of scratch-test have been determined that the depth of the scar of a modified layer has become less in comparison with the original sample, which indicates a significant increase of wear-resistance and hardness of the surface carbonitriding layer R6М5 steel. It was set that after electrolytic-plasma carbonitriding abrasive wear-resistance of the surface layers of R6M5 steel is increased by 25%. Introduction

Use of vacuum carbonitriding for raising the seizure resistance of gears from steel VKS-10

Saturation of heat-resistant steel VKS-10 with carbon and nitrogen in a low-pressure atmosphere is studied. The possibility of increasing the fineness of the carbonitride phase and the content of retained austenite in vacuum carbonitriding is shown as compared to vacuum carburizing. Subsequent aging results in segregation of a still finer excess phase. The factors controlling vacuum carbonitriding are determined. Comparative estimation of the seizure resistance of carbonitrided layers of steel VKS-10 and carburized layers obtained on traditional heat-resistant steels is performed.

Surface Modification of Titanium by Plasma Assisted Chemical Vapor Deposition (PACVD) Methods

One way of obtaining new materials with different properties is to modify existing ones to improve their insufficient properties. Due to the fact that many of the useful properties of materials, including wear and corrosion resistance, friction coefficient and biocompatibility, depend on the state of the surface, modern surface engineering methods are especially helpful. They involve the deposition of the layers with tailored chemical composition and structure. In terms of medical applications, amorphous or nanocrystalline layers containing carbon, nitrogen, silicon and hydrogen appear to be the most suitable. They combine the beneficial properties of silicon carbide SiC and silicon nitride Si3N4, and thus exhibit a strong resistance to oxidation at high temperatures, high modulus of elasticity, low friction coefficient and wear resistance. However, silicon carbonitride compound is not stable thermodynamically in normal conditions and therefore it must be obtained by non-conventional synthesis. One of such method is Plasma Assisted Chemical Vapour Deposition (PACVD). The authors of this paper anticipate that the modification of titanium surface by SiCxNy(H) layers make them proper for use as materials for long-term contact with human body. It contains results of research on titanium Ti Grade 2 surface modification by deposition amorphous carbon layers doped with nitrogen (a-C:N:H) and silicon carbonitride layers SiCxNy(H). What is more, for IR analysis, in the same plasmochemical methods process obtain layers on monocrystaline silicon (001)Si. The layers were synthesis by PACVD with plasma generated by radio waves (RFCVD, 400 W, 13.56 MHz) for a-C:N:H layers and microwaves (MWCVD, 2 kW, 2.45 GHz) for layers containing silicon, carbon, nitrogen and hydrogen. During deposition process metallic surface were ion-etching by argon plasma. The layers were obtained from reactive gas mixture containing CH4, N2or NH3for a-C:N:H layers and CH4, SiH4, N2or NH3for silicon carbonitride compound. In this process argon was used as an inert gaseous. Process conditions allowing obtaining good adhesive layer to the metallic substrate were specified. Obtained systems were subject for further research. Chemical composition of the materials were studied by SEM / EDS techniques with application ETD and BSED detectors. Compared images registered for titanium before surface modification and surfaces covered by a-C:N:H or SiCxNy(H) layers. More information about layers structure provided FTIR spectroscopy. Spectra FTIR was register transmition for (001)Si-layer and reflective for titanium-layer systems. Assessed the impact of different kind of substrate on the layers deposited structure. Operational properties of synergic layer-titanium systems were evaluated in the measurements of tribological parameters. This tests shown that silicon carbonitride layers have the lowest friction coefficient and the highest resistance to wear. Furthermore, it was possible, on the basis of the obtained result, to indicate directions the surface modifications ensuring optimization on their usable properties as medicine and another industries. In previous authors paper the layers were investigated in the aspect of possible application in medicine.

Effect of C/N Concentration Fluctuation on Formation of Plasma Electrolytic Carbonitriding Coating on Q235

The plasma electrolytic carbonitriding (PEC/N) on the Q235 steel was investigated in an aqueous solution containing monoethanolamine and KCl in a very short period of time. The microdischarge characteristics of the voltage/current on the Q235 were observed using real-time imaging during the PEC/N. The microstructure and element distribution of the carbonitriding layer were examined using scanning electron microscope (SEM) equipped with energy dispersive spectroscope (EDS). The effect of microdischarge on roughness, thickness and microhardness was evaluated. The formation of the carbonitriding layer was discussed. Research shows that it is similar in the microstructure and properties between the plasma electrolytic carbonitriding and the traditional gas carbonitriding. The formation of the carbonitriding layer results from the carbon and nitrogen fluctuation in PEC/N process. The microhardness and thickness can be up to HV 779 and 0.360 mm in 180 s, respectively, which is close to the results of the gas carbonitriding in the microhardness. Therefore, the plasma electrolytic carbonitriding has a potential to substitute the gas carbonitriding.

Composition and structure of silicon carbonitride layers grown on Si(100)/(Fe, N, Co) substrates

The phase and chemical composition of silicon carbonitride films obtained by plasma-enhanced chemical vapor deposition on Si(100) substrates and the same substrates covered by a layer of (Fe, Ni, Co) alloy is studied. It is shown that substrate metallization practically does not change the chemical composition of the film, but affects the ratio phases present in the film and the film nanostructure.

On the formation of the crystalline phases and nanostructure of silicon carbonitride layers grown on gallium arsenide substrates

The crystallization of thin silicon carbonitride layers obtained by chemical vapor deposition from silicon organic precursors on gallium arsenide substrates at 973 K in the presence of liquid gallium drops is studied. The layers grown by the vapor-liquid-solid method are studied by IR, Raman, and energy dispersive spectroscopy, scanning electron microscopy, and X-ray diffraction using synchrotron radiation in order to determine their chemical and phase composition, crystal structure, and surface morphology. Their morphology is supposed to be associated with the formation of nuclei in a gallium drop located at the surface of the gallium arsenide substrate.

Tris(diethylamino)silane—A new precursor compound for obtaining layers of silicon carbonitride

Silicon carbonitride layers have been obtained by chemical deposition from the gas phase with thermal (LPCVD) and plasma (PECVD) activation of the gas mixture of helium with the new volatile siliconorganic compound tris(diethylamino)silane (Et 2N)3SiH (TDEAS) in the temperature region 373–1173 K. Thermodynamic simulation of the deposition processes from the gas mixture (TDEAS + He) in the temperature interval 300–1300 K and pressure interval P tot 0 from 1 × 10−2 to 10 mm Hg has revealed the possibility of varying the equilibrium composition of the condensed phase depending on the synthesis temperature and the composition of the initial gas mixture. Physicochemical and functional properties of obtained layers were studied by complex of modern methods. It has been established that the chemical composition of the silicon carbonitride layers obtained by the PECVD method, depending on the deposition conditions, approaches that of silicon oxynitride or nitride, and the composition of those obtained by the LPCVD method approaches that of silicon carbide. The presence of nanocrystals with a phase composition close to the standard α-Si3N4 phase and of carbon inclusions has been found in the layers.

Optical characteristics of nickel and boron carbonitride films in Si(100)/Ni/BC x N y structures

The optical characteristics of nickel films deposited on Si(100) substrates by vacuum thermal evaporation have been studied. The thickness and optical constants of the films are determined using monochromatic zero ellipsometry, while the inverse problems are solved within the three-layer optical model of the samples. It is shown that thermal annealing leads to a change in the optical constants of nickel films in the heating-temperature range of 500–900°C. Boron carbonitride layers deposited on silicon substrates with a nickel sublayer are analyzed within multilayer optical models, which make it possible to determine the refractive index and absorption coefficient distributions along the thickness of the synthesized Si(100)/Ni/BC x N y structure.

침탄질화 처리된 SCM415강의 깊이에 따른 확산 및 마모특성 변화

In this study, the change in diffusion coefficient and wear characteristic with depth in the carbonitriding layer of SCM415 steel was discussed. To determine the diffusion coefficient, depth profile of carbon was measured from the surface using the Glow Discharge Spectrometer. In otherwise, measurements of carbide fraction, micro vickers hardness of surface and observation of microstructure have been implemented through the SEM image. <TEX>$Fe_3$</TEX>(C,N) layer and effective depth were increased as the time for carbonitriding takes longer. According to wear experiment, the results showed that wear resistance was improved by <TEX>$Fe_3$</TEX>(C,N) layer and effective depth.

Plasma-chemical synthesis of silicon carbonitride films from trimethyl(diethylamino)silane

Silicon carbonitride films of different compositions have been synthesized by plasma-enhanced chemical vapor deposition with the use of trimethyl(diethylamino)silane as the initial compound. The conditions used for the deposition of the films have been chosen from the thermodynamic modeling. The properties of the films prepared have been investigated using ellipsometry, scanning electron microscopy, X-ray photoelectron spectroscopy, IR spectroscopy, and synchrotron X-ray powder diffraction. It has been established that the synthesis temperature substantially affects the kinetics of growth and physicochemical properties of silicon carbonitride layers in the range of synthesis conditions under investigation. The films prepared consist of nanoparticles whose size increases with increasing synthesis temperature. The refractive index of the films increases from 1.6 to 2.8 with an increase in the temperature.

Roentgenographic Determination of Residual Stresses in Carbonitrided Layers

The aim of the current investigation is to examine the influence of carbonitriding in low-temperature plasma on forming macroresidual stresses in the surface layer of the materials. Particular modes of ion carbonitriding are considered in which layers of different depth and different surface microhardness are obtained. The residual stresses in the α-Fe in carbonitride layers are determined by the method of “sin2Ψ.” The results show that at different modes of ion carbonitriding, residual macrostresses are obtained that have different values and depend on the qualitative characteristics of the formed carbonitrided layers.

Properties of BC x N y films grown by plasma-enhanced chemical vapor deposition from N-trimethylborazine-nitrogen mixtures

Boron carbonitride films of various compositions have been grown by plasma-enhanced chemical vapor deposition using N-trimethylborazine as a single-source precursor and nitrogen as a plasma gas and an additional nitrogen source. Experiments were performed at various deposition temperatures and rf powers. The films were characterized by ellipsometry, atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, IR and Raman spectroscopies, synchrotron X-ray diffraction, energy dispersive X-ray microanalysis, and spectrophotometry. The results demonstrate that, under the conditions of this study, the growth kinetics and physicochemical properties of boron carbonitride layers are influenced by both the substrate temperature and rf power. Conditions are found for producing boron carbonitride films transparent in the UV through visible spectral region.

Kinetics of V(N,C) coating produced by a duplex surface treatment

A duplex surface treatment has been developed involving the pre-nitrocarburising of annealed DIN 1.2367 die steel followed by vanadium thermo-reactive diffusion (TRD) coating and then hard and temper treatment. TRD process performed by pack method at 1223, 1323 and 1423 K for 1–5 h in an electrical resistance furnace. The TRD process formed a thin (5 to 40 µm) and hard (2220 ± 40 HV) vanadium carbonitride surface layer above a hardened diffusion zone. Characterization of the coating by means of microstructure and X-ray diffraction analysis indicates that the vanadium carbonitride coating consists of V–C–N, V–C and V–N phases which produced a single, undifferentiated layer. Moreover, the results showed a parabolic relationship ( d 2 = Kt) between carbonitride layer thickness ( d) and treatment time ( t). The mean activation energy for the TRD process was estimated to be 145.5 kJ/mol and the growth rate constant ( K) changed between 4.16 × 10 − 10 to 1.02 × 10 − 9 cm 2/s depending on the process temperature.