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Abstract

W-B-C films were deposited on Si(100) substrates held at elevated temperature by reactive sputtering from a W target in Kr/trimethylboron (TMB) plasmas. Quantitative analysis by Xray photoelectron spectroscopy (XPS) shows that the films are W-rich between ~ 73 and ~ 93 at.% W. The highest metal content is detected in the film deposited with 1 sccm TMB. The C and B concentrations increase with increasing TMB flow to a maximum of ~18 and ~7 at.%, respectively, while the O content remains nearly constant at 2-3 at.%. Chemical bonding structure analysis performed after samples sputter-cleaning reveals C-W and B-W bonding and no detectable W-O bonds. During film growth with 5 sccm TMB and 500 oC or with 10 sccm TMB and 300-600 oC thin film X-ray diffraction shows the formation of cubic 100-oriented WC1-x with a possible solid solution of B. Lower flows and lower growth temperatures favor growth of W and W2C, respectively. Depositions at 700 and 800 oC result in the formation of WSi2 due to a reaction with the substrate. At 900 oC, XPS analysis shows ~96 at.% Si in the film due to Si interdiffusion. Scanning electron microscopy images reveal a fine-grained microstructure for the deposited WC1-x films. Nanoindentation gives hardness values in the range from ~23 to ~31 GPa and reduced elastic moduli between ~220 and 280 GPa in the films deposited at temperatures lower than 600 oC. At higher growth temperatures the hardness decreases by a factor of 3 to 4 following the formation of WSi2 at 700-800 oC and Si-rich surface at 900 oC.

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... Precursor development, however, is much less explored in the PVD community. It has been shown that reactive magnetron sputtering of tungsten target in krypton/trimethylboron (B(CH3)3) plasmas results in growth of W-rich 100-oriented WC1-x with a potential boron solid solution [160]. Moreover, there is an interesting process development in hybrid sputtering using typical CVD precursors such as B2H6, pentaborane(9) (B5H9) decaborane(14) (B10H14) as further discussed in section 7. We anticipate that a similar approach can be developed for TMB2 thin films. ...
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Article
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... This, in turn, could give a real opportunity to promote ternary binding configuration, which might be formed directly within the impulse of neon plasma flux [50] Table 2. Figure 4a and b shows the W 4f and C 1s core-level XPS spectra, while Fig. 4c and d depicts the B 1s and O 1s spectra of W-B-C coatings, which were synthesized from the surface-sintered cathodes and differ in their chemical compositions. The W 4f high-resolution spectra (Fig. 4a) exhibit a double-peak structure due to the spin-orbit splitting (~2.2 eV) of the W 4f7/2 and 4f5/2 peaks of W-B-C-1, which are located, respectively, at 31.4 eV and 33.6 eV, indicating metallic W bonds [51,52]. Following, if the expected boron content increases, the double peaks tend to shift toward lower binding energies that result from the formation of W-B bonds, as indicated by recent studies [53,54]. ...
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... It can be attributed to the presence of WC 1-x particles, which harden the surface layer. studies for thin films (nanoindentation hardness values in the range from~23 to~31 GPa and Young's modulus between~220 and 280 GPa [43]). The average electrical resistance values of the coatings on copper substrates were determined at the value of flowing current equal to 105 · 10 −3 A by the four-probe cell method. ...
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With contributions by Paul F. Fewster and Christoph Genzel. While X-ray diffraction investigation of powders and polycrystalline matter was at the forefront of materials science in the 1960s and 70s, high-tech applications at the beginning of the 21st century are driven by the materials science of thin films. Very much an interdisciplinary field, chemists, biochemists, materials scientists, physicists and engineers all have a common interest in thin films and their manifold uses and applications. Grain size, porosity, density, preferred orientation and other properties are important to know: whether thin films fulfill their intended function depends crucially on their structure and morphology once a chemical composition has been chosen. Although their backgrounds differ greatly, all the involved specialists a profound understanding of how structural properties may be determined in order to perform their respective tasks in search of new and modern materials, coatings and functions. The author undertakes this in-depth introduction to the field of thin film X-ray characterization in a clear and precise manner.
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Tungsten–carbon thin films have been reactively sputter deposited in various Ar–CH4 gas mixtures and the growth kinetics of the reactive deposition process have been elucidated. The films are amorphous as-deposited with partial crystallization of W2C and WC occurring following a 1100 °C–1 min rapid thermal anneal. Carbon incorporation within the W–C films is attributed to the flux of CH3 radicals impinging on the growth surface. Although they have a significantly lower concentration (∼0.1%) than the CH4 molecules contained within the plasma, their sticking coefficient is significantly larger than that of CH4. In addition, the change in the incorporation rate of carbon in the W–C films at higher CH4 (and subsequently CH3) concentrations has been shown to be due to the changes in the growth surface; as the CH3 flux increases, the growth surface becomes carbon terminated and decreases the incorporation of carbon because of the low CH3–C sticking coefficient. © 2001 American Vacuum Society.
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Tungsten carbide films were prepared by rf magnetron sputtering of a tungsten carbide target onto high-speed steel (HSS), stainless steel, silicon and platinum. During deposition the substrate temperature remained below 100°C. The substrate potential was varied between 0 and - 120 V. From 0 to -40 V substrate bias we observed a decrease of the deposition rate whereas the intrinsic stress increased from 3 to 8 GPa. Simultaneously, the composition changed from WC1 to ca. WC0.5. The drastic variation of the chemical composition at low plating energies can be explained by a simple sputter model. With higher negative substrate potentials the films became harder (ca. 4500 HV 0.025) and denser. The adhesion to the substrates increased as well. SEM micrographs of such films deposited onto a non-biased substrate showed a less dense zone I structure. The crystal structure of the films, investigated by X-ray diffraction, was found as that of β-WC1-x and α-W2C. The stress can be reduced by adding approx 1% C2H2 to the working gas.
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Tungsten carbide coatings were deposited onto molybdenum and cemented carbide substrates using d.c. and r.f. magnetron sputtering. Tungsten targets were used in reactive (argon plus acetylene) atmospheres and tungsten carbide targets were used in non-reactive (argon) atmospheres. Substrates were r.f. biased with d.c. potentials of up to -1000 V. Sputtering from WC targets produced carbon-deficient mixed-phase structures with β-WC1-x as the main component. Reactive deposition led to highly disordered W-C films which X-ray studies showed to be almost amorphous. Fractograms revealed very fine-grained to fractured amorphous film structures in all deposition modes. Hardness values higher than 3000 HV 0.05 were reached using non-reactive d.c. sputtering.
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Instrument-size gas-bearing applications demanding hard wear-resistant coatings on lightweight thermally conductive substrates frequently require that properties such as electrical resistivity, magnetic susceptibility and adhesion integrity be evaluated. Titanium carbide and tungsten carbide coatings, approximately 1 to 2 μm thick, were sputter deposited on beryllium oxide substrates. In addition, titanium carbide coatings approximately 50 μm thick were prepared on beryllium oxide substrates by activated reactive evaporation. Electrical resistivity was measured at various locations on the coating surface with a square four-point probe array. Magnetic susceptibility was measured using the Gouy test method in which a specimen is partially suspended in a magnetic field and the resulting force of attraction is measured. Since adhesion integrity is essential to the success of any coating application, a direct tensile pull test was performed on each specimen. The resulting fracture surface showed coating thickness, and the structure and characterization was accomplished by scanning electron microscopy and X-ray analysis.
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The feasibility of using organoboranes as precursors for the deposition of boron-carbon thin films in a hot-wall CVD furnace was investigated. The reagents studied include trimethylborane, triethylborane, and tributylborane. Triethylborane was the most suitable reagent in that higher boron to carbon ratios were obtained.
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The method we introduced in 1992 for measuring hardness and elastic modulus by instrumented indentation techniques has widely been adopted and used in the characterization of small-scale mechanical behavior. Since its original development, the method has undergone numerous refinements and changes brought about by improvements to testing equipment and techniques as well as from advances in our understanding of the mechanics of elastic–plastic contact. Here, we review our current understanding of the mechanics governing elastic–plastic indentation as they pertain to load and depth-sensing indentation testing of monolithic materials and provide an update of how we now implement the method to make the most accurate mechanical property measurements. The limitations of the method are also discussed.
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The synthesis of tungsten monocarbide (WC) thin films has been performed by physical vapor deposition on various substrates including glassy carbon, carbon fiber sheet, carbon foam, and carbon cloth. The WC and WâC phase contents of these films have been evaluated with bulk and surface analysis techniques such as x-ray diffraction, x-ray photoelectron spectroscopy, and scanning electron microscopy. These characterization techniques were also used to determine the effects of synthesis by nonreactive and reactive sputtering. The synthesis of WC particles supported on the carbon fiber substrate has also been accomplished using the temperature programmed reaction method. Overall, the results demonstrate that the phase purity of tungsten carbides can be controlled by the deposition environment and annealing temperatures.
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Tungsten carbide films have been deposited by CVD from a WF~/C~HS/H~ gas mixture on several different substrate materials (Ta, Si, Sic and C). Single-phase WC films could easily be obtained on Ta substrates at 900 "C using a total pressure of 100 mTorr and a high linear gas flow velocity (7 mls). It was found that the low pressures favoured the growth of carbon-rich films and made the deposition zone for WC longer. The phase composition of the films and deposition rates were also strongly affected by the substrate material. The substrate dependence was attributed to the chemical reactivity of WF6.
Article
W1−xCx coatings (with x being in the range of 0.05–0.19) were deposited by reactive magnetron sputtering on to AISI 316 stainless-steel substrates in order to study the influence of the carbon content on the tribological properties of the coating–substrate composite. Knoop microhardness (HK), scratch adhesion, pin-on-disc sliding, ball-on-plate impact and abrasive wheel wear tests were performed to evaluate the mechanical and tribological properties of the coatings. X-ray diffraction (XRD) was used for phase- and peak shape parameter analysis, whilst the coating morphology was evaluated by scanning electron microscopy. It was found that all coatings consist mainly of the b.c.c. αW phase. With increasing carbon content from 5 to 19 at.%, an expansion of the αW lattice occurs progressively, associated with an increase in the peak full width at half maximum (FWHM) and a decrease in intensity. The film density and hardness increased with increasing carbon content up to 15 at.%, where hardness values of 4000HK0.025 were observed. Coatings comprising W1−xCx with x≤0.08 showed the best abrasive wear resistance and adhesion with no through-coating failure in the wear track for dry pin-on-disc sliding and no crack development around the indentation areas in impact tests after 50 000 impacts against both steel and cemented tungsten carbide balls.
Article
Tungsten-carbon coatings have been deposited on stainless steel substrates by reactive magnetron sputtering from Ar–CH4 mixtures. The carbon concentration in the coatings measured by electron microprobe analyses was found to be proportional to the CH4 flow rate. Only the cubic α–W phase with a dilated lattice parameter was identified in W–C coatings having a carbon content lower than 25 at. %. Since the lattice parameter of the α–W phase in these W–C coatings increased with increasing carbon content, these coatings may be assumed to be W–C solid solutions. Only the nonstoichiometric β–WC1−x carbide (cubic phase) was detected in W–C coatings containing 30 to 70 at. % of carbon. The chemical state of the elements was investigated by x-ray photoelectron spectroscopy. The Vickers hardness of the W–C coatings was found to be considerably dependent on the carbon concentration. A maximum microhardness of 26 000 MPa was measured for W–C coatings containing either 14–15 at. % or 40–45 at. % of carbon. The correlation between crystallographic structure and microhardness is analyzed and discussed in this paper.
Article
Epitaxial growth of sp(2)-hybridized boron nitride (sp(2) BN) films on sapphire substrates is demonstrated in a hot wall chemical vapor deposition reactor at the temperature of 1500 degrees C, using triethyl boron and ammonia as precursors. The influence of the main important process parameters, temperature, N/B ratio, B/H-2 ratio, and carrier gas composition on the quality of the grown layers is investigated in detail. X-ray diffraction shows that epitaxial rhombohedral BN (r-BN) film can be deposited only in a narrow process parameter window; outside this window either turbostratic-BN or amorphous BN is favored if BN is formed. In addition, a thin strained AlN buffer layer is needed to support epitaxial growth of r-BN film on sapphire since only turbostratic BN is formed on sapphire substrate. The quality of the grown film is also affected by the B/H-2 ratio as seen from a change of the spacing between the basal planes as revealed by X-ray diffraction. Time-of-flight elastic recoil detection analysis shows an enhancement of the C and O impurities incorporation at lower growth temperatures. The gas phase chemistry for the deposition is discussed as well as the impact of the growth rate on the quality of the BN film.
Article
Epitaxial growth of sp2-hybridized boron nitride (BN) using chemical vapour deposition, with ammonia and triethyl boron as precursors, is enabled on sapphire by introducing an aluminium nitride (AlN) buffer layer. This buffer layer is formed by initial nitridation of the substrate. Epitaxial growth is verified by X-ray diffraction measurements in Bragg–Brentano configuration, pole figure measurements and transmission electron microscopy. The in-plane stretching vibration of sp2-hybridized BN is observed at 1366 cm–1 from Raman spectroscopy. Time-of-flight elastic recoil detection analysis confirms almost perfect stoichiometric BN with low concentration of carbon, oxygen and hydrogen contaminations. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Article
Tungsten-carbon thin films have been deposited by reactive (Ar + C6H6) DC magnetron sputtering onto various substrates. Deposition onto glass, monocrystalline silicon, tantalum and stainless steel at room temperature yielded W–C films, having XRD patterns corresponding to the structure of heavily disordered W2C or WC1–x carbides. The samples deposited upon the Au or Cu foils were nanocrystalline cubic WC1–x with the grain size of 2.9 nm. Disordered tungsten-carbon films were stable up to 1200°C. Microhardness of the films with disordered W2C phase was about 5–6 GPa while that of the films with disordered WC1–x phase was about 17 GPa. The characteristics of films can be understood considering the effects of the incorporation of free carbon and/or carbon-hydrogen fragments into the tungsten carbide layer.
Article
Tungsten carbide was obtained by chemical vapor deposition from a mixture of WCl6, C3H8, H2, and Ar on a graphite substrate in the temperature range of 1200 to 1500 °C. The influence of various factors on the crystal growth was investigated. The geometry in the furnace proved to be an important factor for the process of crystallization. The adherent coating of α-W2C could be obtained at relatively high flow rates of H2 and WCl6. The appropriate gaseous concentrations for the growth of WC were as follows: WCl6: 1.0–1.5 mole%; C3H8: 1.7–2.8 mole%; H2: 10–20 mole%; and Ar: 75–85 mole%; and the total flow rates was 1.78 ml/sec. Various crystal morphologies composed of uniform films, networks, dendrites and pillars with diameters of 2 to 40 μm were deposited on the WC-plated graphite. The dendritic or pillar crystals were obtained at temperatures between 1250 and 1400 °C, while the network-like crystals were formed at lower temperatures of 1200 to 1300 °C on the substrate surface.
Article
Thin films in the W–C system were prepared by magnetron sputtering of W with coevaporated C60 as carbon source. Epitaxial deposition of different W–C phases is demonstrated. In addition, nanocrystalline tungsten carbide film growth is also observed. At low C60/W ratios, epitaxial growth of α-W with a solid solution of carbon was obtained on MgO(001) and Al2O3(001) at 400 °C. The carbon content in these films (10–20 at.%) was at least an order of magnitude higher than the maximum equilibrium solubility and gives rise to an extreme hardening effect. Nanoindentation measurements showed that the hardness of these films increased with the carbon content and values as high as 35 GPa were observed. At high C60/W ratios, films of the cubic β-WC1−x (x=0–0.6) phase were deposited with a nanocrystalline microstructure. Films with a grain size <30 Å were obtained and the hardness of these films varied from 14 to 24 GPa. At intermediate C60/W ratios, epitaxial films of hexagonal W2C were deposited on MgO(111) at 400 °C. Polycrystalline phase mixtures were obtained on other substrates and hexagonal WC could be deposited as minority phase at 800 °C.
Article
It is shown that small variations of the deposition parameters during magnetron sputtering of tungsten carbide thin films may result in drastic changes of film properties. An increasing working gas pressure for example lowers stress and hardness values. Simultaneously, the texture of the WC1–x cristallites turns from 200 preferential orientation to 111, whereas the composition of the films does not change. In reactive sputtering with a tungsten target there is a narrow range from 2 to 3% C2H2 gas admixture to the working gas where the films are stochiometric (WC) and hard, and grain size and morphology are similar to that of non-reactively sputtered films. The generation of different crystallite structures and orientations in the range of 0–3% C2H2 admixtures are used to produce a multiphase thin film with extremely low crack propagation.
Article
In this study, tungsten carbide, with its hardness, chemical inertness, thermal stability and low resistivity (25 μΩ cm)1 is shown as a reliable contact material to n- and p-type 6H-SiC for very high temperature applications. WC films with thicknesses of 100–150 nm were deposited by chemical vapor deposition (CVD) from a WF6/C3H8/H2 mixture at 1173 K. A method to pattern CVD-tungsten carbide is suggested. TEM analysis of as deposited samples displayed a clear and unreacted interface. The electrical investigations of the p-type 6H-SiC Schottky contacts revealed a high rectification ratio and a low reverse current density (6.1 × 10−5 A cm−2, −10 V) up to 773 K. On n-type, a low barrier (ΦBn=0.79 eV) at room temperature was observed. The low ΦBn value suggests WC to be promising as an ohmic contact material on highly doped n-type epi-layers. We will show a temperature dependence for the barrier height of tungsten carbide contacts that can be related to the simultaneous change in the energy bandgap, which should be considered when designing SiC devices intended for high temperature operation.
Article
Superhard nanocomposite coatings are currently of great interest for wear protection of tools. Within this work, after some consideration of the design and failure of nanocomposites, results on nanocomposite Ti–B–N and Ti–B–C films are presented and discussed. Coatings with different compositions in the quasi-binary systems TiN–TiB2 and TiC–TiB2 were deposited onto austenitic stainless steel and molybdenum sheets by means of unbalanced d.c. magnetron co-sputtering using segmented TiN/TiB2 and TiC/TiB2 targets. Coating chemical, structural and mechanical properties were investigated using electron-probe microanalysis (EPMA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray diffraction (XRD), and depth-sensing nanoindentation. Coatings with elemental compositions of about 35–45 at.% Ti, 18–44 at.% B and 20–36 at.% N or 22–40 at.% C consist of a nanocrystalline arrangement of TiB2 and TiN or TiC, respectively, with crystallite sizes of 1–5 nm. Coating hardness varies between 50 and 70 GPa and elastic moduli are close to 500 GPa.
Article
The electrical characteristics of W‐Si(100) Schottky barrier junctions formed by sputter deposition of W on both n‐ and p‐type Si(100) have been measured in the temperature range 95–295 K using current‐voltage and capacitance‐voltage techniques. Auger electron and Rutherford backscattering spectroscopies were used to characterize the Si(100) surface prior to metal deposition, and to monitor the reaction between W and Si upon annealing. The results showed that initial silicide formation has very little or no effect on the barrier height. Annealing after initial silicide formation caused the junction characteristics to strongly deviate from the ideal thermionic emission behavior. For junctions with ideal thermionic emission behavior the barrier height was found to decrease with increasing temperature with a coefficient consistent with the predictions of recent models of barrier formation based on Fermi‐level pinning in the center of the semiconductor indirect band gap.
Article
Tungsten carbide films have been deposited on stainless steel substrates held between 300 to 500 °C in a planar rf magnetron sputtering system at rates as high as that of pure tungsten (825 A°/min). The effect of substrate temperature on formation of WC x films has been investigated. A mixture of hexagonal WC, A‐15 W 3 C and carbon in graphitic and diamond form have been observed by AES and XRD techniques. The microhardness of these films has been found to be as high as 2365 kgf/mm<sup>2</sup>. The adhesion of these films as measured from indentation crack patterns has been found to depend on substrate temperature as well as on the amount of dispersed carbon in the film.
Article
Tungsten and tungsten–carbon thin films have been produced from a W target sputtered in argon and argon–methane mixtures, respectively. The deposition rate of W films was measured as a function of the sputtering power and argon pressure varying in the range of 0.3–3 Pa. The crystallographic structure and composition of W films deposited on silicon and carbon substrates were investigated by x‐ray diffraction and Rutherford backscattering spectroscopy. The electrical resistivity of the W films was minimum (12 μΩ cm) when the internal stresses in the films were negligible. The carbon concentration in the W–C films determined by nuclear reaction analyses and Rutherford backscattering spectroscopy was varied from 10 to 95 at. % with increasing CH 4 content in the gas phase. The crystallographic structure of the W–C films was found to be dependent on the carbon concentration. Below 25 at. % of carbon, the structure of the W–C films was that of the cubic α‐W phase with a dilated lattice parameter. For higher carbon concentrations, the bcc α‐W phase disappeared and the structure was that of the nonstoichiometric cubic β‐WC 1-x phase. The structure of W–C films with a carbon content greater than 65 at. % was nearly amorphous. Internal stresses and electrical resistivity of W–C films were determined as functions of the carbon concentration. The experimental parameters suitable to produce W and W–C films with low resistivities and reduced internal stress level are reported in this article.
Article
Tungsten carbide films have been deposited by low-pressure chemical vapour deposition from a WF6/C3H8/H2 mixture on Ta and Ni substrates. Single-phase WC films could be deposited on Ta in a broad vapour composition range at 900 °C. A mixture of WC and W2C was deposited in the temperature range 700–850 °C, while an amorphous film was obtained at 650 °C. The temperature behaviour suggests that deposition of carbon is a limiting factor in the growth process. The deposition process on Ta could be separated into two parts: a fast substrate reduction step of WF6 leading to the formation of metallic W followed by a slower formation and deposition of WC. The growth behaviour on Ta was also affected by tantalum carbides at the film-substrate interface. A different growth behaviour was observed on Ni. It was found that several η-carbides (i.e. Ni2W4C and Ni6W6C) were formed during a fast initial growth stage. Later on, the η-carbides reacted with carbon under the formation of WC and free Ni particles. It was also found that the carbon deposition rate on Ni substrates was higher than on Ta. This was explained by a catalytic process where Ni particles on the film surface favoured carbon deposition.
Article
Tungsten-carbon coatings have been deposited on stainless steel substrates by reactive magnetron sputtering in ArCH4 mixtures. The composition of coatings was determined by electron microprobe analyses. Only the cubic α-W phase with an expanded lattice parameter was detected by X-ray diffraction in the W-C coatings containing less than 25 at% of carbon. Since the lattice dilatation of the α-W phase increased with increasing carbon content these coatings were assumed to be tungsten-carbon solid solutions. The dilatation of the W crystal lattice and Vickers hardness of the solid-solution-type W-C coatings were measured as functions of the carbon concentration. A lattice dilatation-microhardness relationship was established.
Article
Instrument-size gas-bearing applications frequently require hard wear- resistant coatings on lightweight thermally conductive substrates. Titanium carbide and tungsten carbide coatings approximately 1–2 μm thick were prepared for this purpose on both beryllium and beryllium oxide substrates by sputter deposition. Titanium carbide coatings approximately 50 μm thick were also prepared using activated reactive evaporation techniques. Test fixturing was developed using a vertical-axis turbomolecular vacuum pump to provide both a vacuum atmosphere and a high speed spindle for specimen motion. Coated specimens having beryllium substrates were mounted directly on the pump spindle, while specimens with beryllium oxide substrates were brought into contact with the rotating member at a specified load for a given length of time. Specimen contact was made at a sliding velocity of approximately 7.0 × 103 cm s-1 in a vacuum pressure of less than 5.0 × 10-6 Torr. Specimen surfaces were completely characterized before and after testing using surface profilometery, light microscopy and scanning electron microscopy with X-ray analysis and X-ray diffraction techniques.
Article
The refractory compounds TiC, ZrC, HfC, VC, NbC and TaC comprise a family of materials characterized by high melting point, great hardness and low chemical reactivity. These properties, which are exploited in tribological applications, are reviewed and discussed in terms of models taken from solid state physics. Particular attention is given to the important role of non-stoichiometry in these compounds and its influence on bonding and on transport properties. It is argued that the non-stoichiometry is a metastable condition, however, in view of the presece of ordered phases at certain values of carbon-to-metal ratio. The substantial impact of order-disorder transformations on transport properties is analyzed. The partially covalent bonding is discussed in terms of mixing of 2p and metal 3d or 4d atomic states, and the high Peierls stress resisting dislocation motion is thereby justified.
Article
The electronic structure of nanocrystalline (nc-) TiC/amorphous C nanocomposites has been investigated bysoft x-ray absorption and emission spectroscopy. The measured spectra at the Ti 2p and C 1s thresholds of thenanocomposites are compared to those of Ti metal and amorphous C. The corresponding intensities of theelectronic states for the valence and conduction bands in the nanocomposites are shown to strongly depend onthe TiC carbide grain size. An increased charge transfer between the Ti 3d-eg states and the C 2p states hasbeen identified as the grain size decreases, causing an increased ionicity of the TiC nanocrystallites. It issuggested that the charge transfer occurs at the interface between the nanocrystalline-TiC and the amorphous-Cmatrix and represents an interface bonding which may be essential for the understanding of the properties ofnc-TiC/amorphous C and similar nanocomposites.
High-resolution characterization of the forbidden Si 200 and Si 222 reflections
P. Zaumseil, High-resolution characterization of the forbidden Si 200 and Si 222 reflections, J. Appl. Cryst. 48 (2015) 528-532.
Comparion of WCl 6 -CH 4 -H 2 and WF 6 -CH 4 -H 2 systems for growth of WC coatings
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M. Fitzsimmons, V.K. Sarin, Comparion of WCl 6 -CH 4 -H 2 and WF 6 -CH 4 -H 2 systems for growth of WC coatings, Surf. Coat. Technol. 76-77 (1995) 250-255.
Metallic materials -Instrumented indentation test for hardness and materials parameters
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Centre for Diffraction Data of hexagonal W 2 B 5 , Ref ID
  • Jcpds -International
JCPDS -International Centre for Diffraction Data of hexagonal W 2 B 5, Ref ID: 38-1365.