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A direct current magnetron sputtering (DCMS) system at room temperature was applied to deposit the Ti/TiN/TiCN films. In order to research the effect of the microstructure of the TiN/TiCN layer on the Ti/TiN/TiCN films, the deposition time ratio of the TiN/TiCN layer ranged from 28.57 to 200%, and the whole deposition time of the films and the deposition time of Ti layer were constant. In this work, the relationship between structure and mechanical properties of films were investigated. The research results showed that the composition and structure of the films only slightly changed, while the crystalline orientation of the TiCN layer was of significant variation with the deposition time of the TiN layer. It is shown that the adhesion strength and internal stresses were 18.6 ± 1.5 N and 140 MPa when the deposition time ratio was 50%. By adjusting the deposition time ratio, the films displayed significant improvement in tribological behaviors. The coefficients of friction (COF) for the films deposited under deposition time ratio of 50% were about only 0.139 when the value of COF was stabilized. This work can provide a good wear-resisting film prepared approach at room temperature.

Dissertação de Mestrado Conjunto Europeu em Tribologia de Superficies e Interfaces apresentada à Faculdade de Ciências e Tecnologia Nos últimos anos, algumas das aplicações promissoras de lubrificantes sólidos em diversos ambientes chamaram muita atenção recentemente. A este respeito, o di-calcogeneto de metal de transição (TMD) pode fornecer algumas soluções favoráveis devido à sua estrutura multicamada altamente anisotrópica. Pure TMD Inharantly tem algumas desvantagens que podem ser otimizadas pela introdução de elementos de dopagem de diferentes compostos metálicos e átomos não metálicos. Neste estudo, um TMD bastante familiar, dissulfeto de tungstênio (WS2), foi ligado com C para melhorar suas propriedades mecânicas e de falha, preservando seu principal atributo de propriedades de baixo atrito a um nível favorável. Neste estudo, foi utilizada uma máquina de deposição de magnetron não balanceado de campo próximo de tamanho semi-industrial, o que nos permitiu depositar os quatro diferentes revestimentos com melhor controle de composição e uniformidade. A caracterização tribológica e mecânica dos revestimentos foi realizada. A morfologia e a cristalinidade foram estudadas. Neste estudo, o uso de viés de substrato nos revestimentos não ligados resultou em melhor desempenho em termos de falha e dureza, que também foi estendido pela adição e aumento adicional da porcentagem de C nos revestimentos. O efeito da temperatura também foi investigado e verificou-se que em uma temperatura mais alta, tanto os tipos de revestimento sem liga quanto os com liga apresentam melhor desempenho em termos de coeficiente de atrito. A fase nanocristalina WS2 foi considerada responsável pelas propriedades de baixo atrito de todos os nossos revestimentos subestequiométricos de enxofre analisados neste estudo. Verificou-se que a relação S/W desempenha um papel importante para melhorar as propriedades de atrito e dificultar as propriedades mecânicas e de falha. Nos últimos anos, algumas das aplicações mais promissoras dos lubrificantes sólidos em diversos ambientes despertaram muita atenção. A este respeito, o dicalcogeneto de metal de transição (TMD) pode fornecer algumas soluções favoráveis devido à sua estrutura multicamada altamente anisotrópica. Ainda assim, o TMD puro tem algumas desvantagens inerentes, que poderiam ser otimizadas através da introdução de elementos dopantes, sob a forma de diferentes compostos metálicos ou atómos não metálicos. Neste estudo, um TMD bastante familiar, dissulfeto de tungstênio (WS2), foi dopado com C tendo em vista a melhoria das suas propriedades mecânicas e de comportamento à falha e a simultânea preservação das suas propriedades de baixo atrito a um nível favorável, aquele que é considerado o seu maior atributo. Quatro revestimentos TMD diferentes foram depositados numa máquina de deposição de magnetrão não balanceado de campo próximo de tamanho semi-industrial, a qual nos permitiu deter um maior controlo sobre a composição e uniformidade dos revestimentos obtidos. A caracterização tribológica e mecânica dos revestimentos foi realizada. A morfologia e a cristalinidade foram estudadas. O uso de polarização do substrato nos revestimentos não ligados durante a sua deposição resultou no seu melhor desempenho em termos de comportamento à falha e de dureza, sendo que a última foi adicionalmente estendida pelo aumento da percentagem de C nos revestimentos. O efeito da temperatura também foi investigado e verificou-se que a uma temperatura mais elevada tanto os revestimentos não ligados como os ligados têm melhor desempenho no que diz respeito ao seu coeficiente de atrito. A fase nanocristalina WS2 foi considerada responsável pelas propriedades de baixo atrito de todos os revestimentos subestequiométricos de enxofre analisados neste estudo. Verificou- se que o rácio S/W desempenha um papel importante na melhoria das propriedades de fricção dos revestimentos, ainda que piore as suas propriedades mecânicas e o comportamento à falha. Outro - European Commission

International audience; In this work, two copper metal matrix composites (MMCs) reinforced with 20 wt.% of Ti(C,N) or Ti2AlN particles were studied. The reinforcement particles were synthesized by flash sintering under 2 bar nitrogen atmosphere causing an SHS reaction ignited by electrical current. This reaction led to produce TiC0.7N0.3 solid solution for the MMC1 reinforcement and Ti2AlN, TiN, and Ti3Al titanium aluminide for the MMC2 reinforcement. Both MMCs were densified by liquid phase sintering. The structural characterization was performed by XRD analysis while the morphology and chemical element distribution of both MMCs were analyzed by SEM and EDS. The structure of the two MMCs was relatively dense and showed good wettability. The mechanical and tribological behavior of MMCs evaluated by nanoindentation and wear testing reveals that the addition of 20 wt.% of reinforcement considerably improves the properties of copper matrix. Indeed, the MMC1 proved to be 3 times harder and 10 times more wear-resistant than the MMC2 composite.

Mechanical and tribological properties of nylon 6 and nylon 6/h-BN composites were investigated in this paper. Tensile, hardness, and impact tests were carried out for mechanical properties, while wear tests on pin-on-disc were carried out for tribological properties identification. Abrasion resistance tests were carried out on the TABER apparatus to analyze the abrasive wear of materials. SEM, XRD, and TGA were used to characterize the materials and to understand the distinctive features of nylon 6 and nylon 6/h-BN composites. Experimental results show that the mechanical properties and tribological behavior of nylon 6 got enhanced by the h-BN fillers. Tensile strength and modulus of elasticity were enhanced by 15.2% and 64.5%, respectively, while hardness and impact strength were enhanced by 3.45% and 6%, respectively. COF and wear rate of composites decreased up to 4 wt% filler reinforcement due to smooth transfer film formation. Coefficient of friction (COF) and wear resistance were improved by 10–15% and 8–10%, respectively, at various testing conditions. h-BN reinforcement in the matrix resulted in more weight loss due to abrasion and it reduced the abrasion resistance of nylon 6 by 5.5 times. Thermal stability was slightly increased, and crystallinity was little affected by the h-BN fillers.

The coatings ZrB2 and Zr-B-N were deposited by magnetron sputtering of ZrB2 target in Ar and Ar–15%N2 atmospheres. The structure and properties of the coatings were investigated via scanning and transmission electron microscopy, energy dispersion analysis, optical profilometry, glowing discharge optical emission spectroscopy and X-ray diffraction analysis. Mechanical and tribological properties of the coatings were investigated using nanoindentation, “pin-on-disc” tribological testing and “ball-on-plate” impact testing. Free corrosion potential and corrosion current density were measured by electrochemical testing in 1N H2SO4 and 3.5%NaCl solutions. The oxidation resistance of the coatings was investigated in the 600–800 °С temperature interval. The coatings deposited in Ar contained 4–11 nm grains of the h-ZrB2 phase along with free boron. Nitrogen-containing coatings consisted of finer crystals (1–4 nm) of h-ZrB2, separated by interlayers of amorphous a-BN. Both types of coatings featured hardness of 22–23 GPa, however, the introduction of nitrogen decreased the coating’s elastic modulus from 342 to 266 GPa and increased the elastic recovery from 62 to 72%, which enhanced the wear resistance of the coatings. N-doped coatings demonstrated a relatively low friction coefficient of 0.4 and a specific wear rate of ~1.3 × 10−6 mm3N−1m−1. Electrochemical investigations revealed that the introduction of nitrogen into the coatings resulted in the decrease of corrosion current density in 3.5% NaCl and 1N H2SO4 solution up to 3.5 and 5 times, correspondingly. The superior corrosion resistance of Zr-В-N coatings was related to the finer grains size and increased volume of the BN phase. The samples ZrB2 and Zr-B-N resisted oxidation at 600 °C. N-free coatings resisted oxidation (up to 800 °С) and the diffusion of metallic elements from the substrate better. In contrast, Zr-B-N coatings experienced total oxidation and formed loose oxide layers, which could be easily removed from the substrate.

The spontaneously self-organizing multilayered graphite-like carbon (denoted as GLC) /TiC films with various bilayer periods in the range of 13.3–17.5 nm were deposited on silicon and 1Cr18Mn8Ni5N stainless steel substrates using closed field magnetron sputtering deposition facility. The microstructures and chemical compositions of the prepared multilayered films were characterized by scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy respectively. The self-organizing multilayered structures in all of the films consisted of titanium carbide layers and sp2-rich carbon layers periodically alternate arrangement. The TiC contents and bilayer periods of the multilayered films can be controlled by means of adjusting of sputtering current of graphite target. Furthermore, the mechanical and tribological performances of the prepared films were appraised by nano-indentor, scratch measures, and ball-on-plate tribometer respectively. The results indicated that multilayer structure endowed the as-deposited TiC/GLC films outstanding mechanical and tribological properties, especially the multilayer film with 15.9 nm bilayer period deposited at 10 A sputtering current showed the excellent adhesion strength and hardness, Simultaneously it also exhibited the lowest average friction coefficient in the humid environment owing to its high content of sp2 hybrid carbon.

Coatings in a Zr-Mo-Si-B-N system were deposited by the magnetron sputtering of ZrB2-MoSi2 targets in argon and nitrogen. The structure of the coatings was investigated using scanning electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, and glow-discharge optical emission spectroscopy. Mechanical and tribological properties were measured using nanoindentation and pin-on-disc testing. Oxidation resistance and oxidation kinetics were estimated via annealing in air at 1000–1500 °C and precision weight measurements. We found that the coatings deposited in Ar demonstrate a superior combination of properties, including hardness of 36 GPa, elastic recovery of 84%, a friction coefficient of 0.6, and oxidation resistance at temperatures up to 1200 °C. High oxidation resistance is realized due to the formation of the protective (SiO2 + ZrO2)/SiO2 oxide layer, which inhibits the diffusion of oxygen into the coating.

Low hardness and poor wear resistance are major limitations of Al alloys, which hinder their application in several fields, especially automotive moving parts. DLC can effectively improve hardness and wear resistance of Al alloys, but high residual stress and poor adhesion limit the film thickness. Multilayer thick films (~10 μm) composed of alternating Ti and Ti-DLC layers were successfully deposited on Al alloys. The influence of Ti content on the microstructure, mechanical and tribological properties of the film was emphasized. As the Ti content decreased from 10.42 to 1.35 at.%, the microstructure evolved from a polycrystalline composite film to a nanocrystalline composite film, and then to an amorphous film. The mechanical and tribological properties of the film depended on the microstructure. The amorphous composite film (Ti >6.06 at.%) exhibited better wear resistance than the polycrystalline composite film (Ti 0.1), H3/E⁎2 (>0.2) and elastic recovery (>60%). When the doped Ti content was 6.06 at.%, the nanocrystalline composite multilayer film showed superior comprehensive performance of high hardness (~23 GPa), high elastic recovery (~69%), low friction coefficient (~0.13) and low wear rate (1.0 × 10−7 mm3/Nm).

As part of the tests, a two-phase NiAl/Ni3Al alloy and a composite based on this alloy with 4 vol% addition of TiB2 were produced by the reactive FAST/SPS (Field Assisted Sintering Technology/Spark Plasma Sintering) sintering method. The sintering process was carried out at 1273 K for 30 s under an argon atmosphere. The effect of reactive SPS on the density, microstructure, and mechanical and tribological properties of a dual-phase Ni-Al intermetallic compound and Ni-Al-TiB2 composite was investigated. Products obtained were characterized by a high degree of sintering (over 99% of the theoretical density). The microstructure of sinters was characterized by a large diversity, mainly in regard to the structure of the dual-phase alloy (matrix). Compression tests showed satisfactory plastic properties of the manufactured materials, especially at high temperature (1073 K). For both materials at room temperature, the compressive strength was over 3 GPa. The stress&ndash, strain curves were observed to assume a different course for the matrix material and composite material, including differences in the maximum plastic flow stress depending on the test temperature. The brittle-to-ductile transition temperature was determined to be above 873 K. The research has revealed differences in the physical, mechanical and tribological properties of the produced sinters. However, the differences favourable for the composite were mostly the result of the addition of TiB2 ceramic particles uniformly distributed on grain boundaries.

As part of the tests, a two-phase NiAl/Ni3Al alloy and a composite based on this alloy with 4 vol% addition of TiB2 were produced by the reactive FAST/SPS (Field Assisted Sintering Technology/Spark Plasma Sintering) sintering method. The sintering process was carried out at 1273 K for 30 s under an argon atmosphere. The effect of reactive SPS on the density, microstructure, and mechanical and tribological properties of a dual-phase Ni-Al intermetallic compound and Ni-Al-TiB2 composite was investigated. Products obtained were characterized by a high degree of sintering (over 99% of the theoretical density). The microstructure of sinters was characterized by a large diversity, mainly in regard to the structure of the dual-phase alloy (matrix). Compression tests showed satisfactory plastic properties of the manufactured materials, especially at high temperature (1073 K). For both materials at room temperature, the compressive strength was over 3 GPa. The stress–strain curves were observed to assume a different course for the matrix material and composite material, including differences in the maximum plastic flow stress depending on the test temperature. The brittle-to-ductile transition temperature was determined to be above 873 K. The research has revealed differences in the physical, mechanical and tribological properties of the produced sinters. However, the differences favourable for the composite were mostly the result of the addition of TiB2 ceramic particles uniformly distributed on grain boundaries.

This work deals mechanical and tribological properties of pure copper, reinforced by various weight percentages of tin, before and after the application of equal channel angular pressing. It is found that the hardness, yield, and ultimate shear strengths are considerably improved through ECAP due to grain refinement. The effect of ECAP process on mechanical properties of dilute copper alloys is more significant than that of the pure condition. Also, the strengthening behavior is slightly intensified by increasing the amount of tin content in pure copper. Additionally, work-hardening potential of CP–Cu is restricted due to the ECAP process and also, through the production of dilute copper alloys. The results showed that the effect of ECAP on friction coefficient reduction is more sizeable than making the dilute alloys. Furthermore, the reduction of electrical conductivity in the deformed materials relies on the lattice distortion increase of copper due to the addition of Sn to Cu and the increment of dislocations density. Finally, ECAP procedure and alloying together, terminate to the better wear response of the materials. © 2019 Elsevier Ltd

The possibility of creating composite bronze reinforced with martensitic and austenitic-ferritic stainless steel dendrites is considered. Compared to BrSn10 bronze, widely used in sliding friction pairs, BrFe12Ni7Al, BrFe12Ni7Cr5Si bronzes have a high complex of mechanical, technological and particularly tribological properties. For similar values of the coefficient of friction, the wear resistance of bronze BrFe12Ni7Al is a higher order. Unlike the classic bronze BrSn10, composite bronzes can be obtained in hot deformed state, deposited on steel and cast iron. The level of mechanical properties: σ0.2 = 220 MPa; σВ = 295 MPa; ψ = 38% is 1.5 to 3 times higher than that of the BrSn10. At the laboratory level for the first time the possibility of creating an industrial variant of composite steel with a particularly high level of tribological properties is based. © 2019 Latin American and Caribbean Consortium of Engineering Institutions. All rights reserved.

The use of nanostructured materials and activated methods of surface engineering for creation of modern technics objects. The principles of control of forming rocesses of structure and phase in the materials and coatings in the presence of nanosized modifying particles are described. The scientific and technological bases of the formation of structure and properties of surface layers under the action of thermal, mechanical, chemical, electrophysical factors in the realization of various surface engineering methods (electrochemical deposition, gas-thermal spraying, microarc oxidation, friction plating, ion beam implantation, tribomechanical modification) are shown. The examples of application of the developed nanostructural materials and coatings with high physico-mechanical and tribological properties for production of friction assemblies of various technical objects are shown.

The present study compares the effect of SiC reinforcement on densification and properties of supersolidus liquid phase sintered 6711Al-SiC composites. The prealloyed 6711 powders were mixed with SiC ranging from 5 to 20 vol.%, compacted at 400 MPa and sintered at 630?C under vacuum. It was shown that better densification, yield strength, wear and corrosion resistance were achieved up to 10 vol.% due to uniform distribution of SiC particles throughout matrix. Beyond 10 vol.%, SiC resulted in clustering and had detrimental effect on densification and mechanical properties. Age hardening of 6711-10SiC composites led to improvement in mechanical properties.

Рассмотрены процессы деформации и разрушения гальванических покрытий Au-Ni при трибологических испытаниях в условиях сухого трения. Показано, что изнашивание покрытий является результатом макроскопического контактного взаимодействия образца и контртела, а также абразивного действия микронеровностей на поверхности контртела и частиц износа. Исследованы механизмы формирования частиц износа и слоя переноса во время трения и продемонстрирована их роль в процессах изнашивания гальванических покрытий Au-Ni. Обоснована значимость сдвиговых напряжений, развивающихся на границе раздела покрытие/подслой, в разрушении покрытий., Deformation and fracture of electroplated Au-Ni coatings subjected to tribological testing under dry conditions were studied. Wear of the coatings is shown to result from macroscopic contact interaction of the specimen with the counterbody, and from abrasive action of microasperities on the counterbody surface and wear particles. The formation mechanisms of wear particles and a transfer layer were investigated, and their contribution to wear of the electroplated Au-Ni coatings was demonstrated. The significance of shear stresses arising at the coating/sublayer interface in coating fracture was substantiated.

TiAlBN films were produced by simultaneously sputtering from TiAl and TiB2 targets in Ar/N2 mixtures at a substrate temperature of 150 °C. The goal of this investigation was to study the influence of the nitrogen content (0-40 at.%) on two sets of four coatings with B/Al ratios of approximately 1 and 5. All coatings showed very dense structures and were mainly found to be only partially crystalline. Evidence of Al, AlN, Ti, TiB2, TiN and BN bonding was observed in the XPS spectra, and correlation of the compositional and mechanical data showed that film hardness and elastic modulus decreased with the presence of a 'soft' phase (Al, Ti or amorphous BN). Hardness and elastic modulus values of up to 25 and 250 GPa, respectively, were found for TiAl0.3B1.7 coatings. Coatings with a similar elastic modulus to that of the steel substrate showed the best adhesion. Friction coefficient values between approximately 0.5 and 0.7 were recorded in sliding wear experiments against SAE52100 and WC/6%Co balls. Although friction coefficients could not be correlated to the amorphous BN contents, it was noted that low combined ball and disc wear rates were found for coatings containing large amounts of BN. Coatings with B/Al 5 and elastic moduli of ≤290 GPa showed two orders of magnitude better sliding wear resistance against WC/6%Co balls compared to commercially available TiN. TiAlBN films were produced by simultaneously sputtering from TiAl and TiB2 targets in Ar/N2 mixtures at a substrate temperature of 150 °C. The goal of this investigation was to study the influence of the nitrogen content (0-40 at.%) on two sets of four coatings with B/Al ratios of approximately 1 and 5. All coatings showed very dense structures and were mainly found to be only partially crystalline. Evidence of Al, AlN, Ti, TiB2, TiN and BN bonding was observed in the XPS spectra, and correlation of the compositional and mechanical data showed that film hardness and elastic modulus decreased with the presence of a `soft' phase (Al, Ti or amorphous BN). Hardness and elastic modulus values of up to 25 and 250 GPa, respectively, were found for TiAl0.3B1.7 coatings. Coatings with a similar elastic modulus to that of the steel substrate showed the best adhesion. Friction coefficient values between approximately 0.5 and 0.7 were recorded in sliding wear experiments against SAE52100 and WC/6%Co balls. Although friction coefficients could not be correlated to the amorphous BN contents, it was noted that low combined ball and disc wear rates were found for coatings containing large amounts of BN. Coatings with B/Al approximately 5 and elastic moduli of ≤290 GPa showed two orders of magnitude better sliding wear resistance against WC/6%Co balls compared to commercially available TiN. 113 126 133 126-133

Using inorganic fullerene-like (IF) nanoparticles and inorganic nanotubes (INT) in organic-inorganic hybrid composite, materials provide the potential for improving thermal, mechanical, and tribological properties of conventional composites. The processing of such high-performance hybrid thermoplastic polymer nanocomposites is achieved via melt-blending without the aid of any modifier or compatibilizing agent. The incorporation of small quantities (0.1–4 wt.%) of IF/INTs (tungsten disulfide, IF-WS2 or molybdenum disulfide, MoS2) generates notable performance enhancements through reinforcement effects and excellent lubricating ability in comparison with promising carbon nanotubes or other inorganic nanoscale fillers. It was shown that these IF/INT nanocomposites can provide an effective balance between performance, cost effectiveness, and processability, which is of significant importance for extending the practical applications of diverse hierarchical thermoplastic-based composites., This work was supported by the Spanish Ministry Economy and Competitivity (MINECO), Project MAT-2010-21070-C02-01. Dr. M. Naffakh would like to acknowledge the Ministerio de Economía y Competitividad (MINECO) for a “Ramón y Cajal” Senior Research Fellowship and Ana Diez-Pascual wishes to acknowledge the CSIC for a JAE Postdoctoral Fellowship cofinanced by the EU., We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)

The structure, mechanical and tribological properties TiN coatings рroduced with PIII&D by using rectilinear filtered vacuum arc plasma system are present. The results of scratch testing and wear reciprocating testing clearly revealed the positive effect of pulse bias (0.5÷2.5 kV) application on tribological behavior of the TiN coatings in comparison the coatings deposited with DC bias (150 V). Application of pulsed bias potential leads to a significant reduction in the friction coefficient and increasing of coatings wear resistance due to a change in their structure. The orientation of crystal planes parallel to the surface changes from (111) to (220) with the application of pulse bias, which is accompanied by a transition from fibrous grains structure to denser columnar grains. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35187

Investigated WC-Co cermets were produced via reactive sintering. In case of reactive sintering the elemental powders of tungsten, carbon black as graphite source and cobalt at first activated throw high energy milling and then the carbide synthesis is taking place in the same cycle with liquid phase sintering of the cermets. Because there is a lack of information about the influence of alloying additives on the reactive sintered WC-Co cermets, small amount of chromium carbide or vanadium carbide was added to the powders. To investigate the influence of carbon content in initial powder mixture on the microstructure and properties of reactive sintered WC-Co cermets alloyed with Cr3C2 and VC cermets with different carbon content were produced. The hardness, transverse rupture strength and erosion resistance of alloyed WC-Co cermets depending on carbon content in initial powder mixture is exhibited.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1347

En este trabajo de investigación se presentan los resultados obtenidos en el proceso de producción y caracterización de recubrimientos en monocapas de Tungsteno (W), Carburo de Tungsteno (WC) y bicapas de (W/WC) sintetizados sobre sustratos de acero inoxidable AISI 316L, por medio de la técnica PAPVD Sputtering DC no reactivo asistida por campo magnético. Los recubrimientos fueron obtenidos usando dos blancos como material de aporte, un blanco circular metálico de W de 2” de diámetro y 99.995% de pureza para la capa inicial de W y un blanco de WC de 2” de diámetro y pureza 99.995% para la capa final de WC, todos los recubrimientos se obtuvieron en una atmosfera de Argón variando la temperatura del sustrato a temperatura ambiente (RT), 100, 200 y 300°C. Los recubrimientos fueron caracterizados mediante la técnica de Espectroscopia de Energía Dispersiva de Rayos X (EDX) donde se observo una disminución en la concentración del porcentaje atómico de Carbono con respecto al Tungsteno, de lo cual se puede inferir la formación de una fase subestequiometrica del compuesto. Los resultados de Difracción de Rayos – X mostraron la presencia de la fase cubica BCC de la capa de W y de la fase FCC de la capa de WC, además se encontró una mayor orientación en la dirección (200), también se calculo el tamaño de cristalito y la microdeformación para los recubrimientos de W/WC en función de la temperatura de crecimiento donde se observo un mejor comportamiento para la bicapa crecida a 300°C. Se realizaron estudios de composición química empleando Espectroscopía Raman y Espectroscopía Auger. Los resultados obtenidos por Raman evidencian la presencia de enlaces W-O, W-C y W=C, lo cual se confirma en los resultados obtenidos por Espectroscopía Auger, además por medio del perfil de profundidad se observo el comportamiento de las monocapas del recubrimiento en función del tiempo de erosión. Por medio de Microscopia Electrónica de Barrido (SEM), Microscopia de Fuerza Atómica (AFM) y Perfilometria se estudio la morfología de las capas a base de W en función de la temperatura de deposición y se observo una leve disminución tanto en la rugosidad como en el tamaño de grano, mientras el espesor de las bicapas presento una leve tendencia a aumentar. Para las capas de WC crecidas sobre el acero 316L se pudo observar por medio de SEM la pobre adherencia que estas capas presentan cuando no se genera la capa intermedia de W. Por otro lado, los estudios de nanodureza revelaron que superficies densas con granos finos y baja rugosidad presentan una mayor de dureza. El comportamiento tribológico de los recubrimientos tanto en monocapa como bicapa fue medido usando un sistema Ball on Disc, donde de observo una disminución en el coeficiente de fricción y la tasa de desgaste para las bicapas, sin embargo no se presenta una influencia significativa con respecto a las temperaturas de deposición (Texto tomado de la fuente) This research presents the results obtained in the process of production and characterization of Tungsten (W), Tungsten Carbide (WC) coatings and (W/WC) bilayers, synthesized on stainless steel AISI 316L substrates by DC nonreactive sputtering technique assisted by magnetic fields PAPVD. Coatings were obtained using two targets, a circular W metal target 2" in diameter and 99.995% purity for the initial layer of W and a WC target 2" in diameter and 99.995% purity for final WC layer. All coatings were obtained in an argon atmosphere by varying the substrate temperature at room temperature (RT), 100, 200 and 300 °C. The coatings were characterized using Energy Dispersive Spectroscopy (EDS) where it was observed a decrease in the concentration of Carbon atomic percentage with respect to Tungsten, infering the formation of a sub-stoichiometric phase of the compound. X-ray Diffraction results showed the presence of the cubic BCC phase of the W layer and the FCC phase of the WC layer and found a major orientation in the direction (200). Also the crystallite size and microstrain were calculated for the W/WC coatings according to the temperature of growth, where An improved behavior is observed for the bilayer grown at 300°C. Studies of chemical composition were realized using Raman Spectroscopy and Auger Spectroscopy. The results obtained by Raman demonstrate the presence of W-O, W-C and W=C linkages, confirmed in the results obtained by Auger Spectroscopy, also by means of the depth of profile behavior of the monolayers was observed according to the time of erosion. Using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Profilometry the morphology of the W-based coatings was studied as a function of deposition temperature. A slight decrease was observed in both the roughness and in grain size, while the thickness of the bilayers presented a slight tendency to increase. For the WC layers grown on the steel 316L it was possible to observe by means of SEM, the poor adhesion that these layers present, when the intermediate layer of W is not generated. On the other hand, studies of nanohardness revealed that dense surface with fine grains and low roughness presented a higher hardness. Tribological behavior of the coatings both in monolayer and bilayer were measured using a Ball on Disc system, where noted a decrease in the coefficient of friction and the wear rate for bilayers, however it does not show a significant influence with regard to the temperatures of deposition Maestría

The tribological behavior of CrN and Al-Cr-N coatings prepared by twin electron-beam evaporation at 450°C was investigated. The composition, structure, mechanical and tribological properties of the coatings were determined using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) in combination with nanoindentation mechanical property measurements, scanning electron microscopy (SEM), and laboratory controlled ball-on-disc sliding experiments. It was found that all of the Al-Cr-N coatings exhibit higher hardness compared to CrN coatings. Also, the compositions of Al-Cr-N coatings with the lower Al content and lower Al/Cr ratios showed better tribological performance than the rest of the coatings. Copyright © 2008 by ASME. 769 771 769-771

Cr(1-x)N(x) coatings were deposited by magnetron sputtering at a substrate temperature of 200°C onto AISI 316 stainless-steel substrates immersed in an Ar/N2 plasma. The goal of this investigation was to study the influence of nitrogen content on the structural, mechanical and tribological properties of the Cr(1-x)N(x) coatings (with x being in the range of 0-0.4). The coating composition and microstructure were evaluated utilizing glow discharge optical emission spectroscopy and glancing angle X-ray diffraction, whereas the morphology was evaluated by scanning electron microscopy. Knoop microhardness, scratch adhesion, pin-on-disc sliding, ball-on-plat impact and abrasive wheel wear tests were performed to evaluate the mechanical and tribological properties. The presence of Cr, Cr2N, CrN (and mixtures of these phases) has been identified and related to the film composition. For Cr(1-x)N(x) coatings with x≤0.16, only the α-Cr phase could be detected. A progression towards a denser microstructure was found with increasing nitrogen content up to x=0.29, associated with an increase in hardness from 700 up to 2400 HK0.025. Cr(1-x)N(x) coatings with x=0.10-0.16 showed good adhesion and the best abrasive and pin-on-disk sliding wear resistance, together with less crack development around the indentation area (and thus improved toughness) in impact test after 50 000 impacts, against both steel and cemented tungsten carbide balls. The hardest coating (Cr0.71N0.29) performed best in terms of reducing the resulting impact indentation volume. Cr1-xNx coatings were deposited by magnetron sputtering at a substrate temperature of 200 °C onto AISI 316 stainless-steel substrates immersed in an Ar/N2 plasma. The goal of this investigation was to study the influence of nitrogen content on the structural, mechanical and tribological properties of the Cr1-xNx coatings (with x being in the range of 0-0.4). The coating composition and microstructure were evaluated utilizing glow discharge optical emission spectroscopy and glancing angle X-ray diffraction, whereas the morphology was evaluated by scanning electron microscopy. Knoop microhardness, scratch adhesion, pin-on-disc sliding, ball-on-plate impact and abrasive wheel wear tests were performed to evaluate the mechanical and tribological properties. The presence of Cr, Cr2N, CrN (and mixtures of these phases) has been identified and related to the film composition. For Cr1-xNx coatings with x≤0.16, only the α-Cr phase could be detected. A progression towards a denser microstructure was found with increasing nitrogen content up to x = 0.29, associated with an increase in hardness from 700 up to 2400 HK0.025. Cr1-xNx coatings with x = 0.10-0.16 showed good adhesion and the best abrasive and pin-on-disk sliding wear resistance, together with less crack development around the indentation area (and thus improved toughness) in impact tests after 50 000 impacts, against both steel and cemented tungsten carbide balls. The hardest coating (Cr0.71N0.29) performed best in terms of reducing the resulting impact indentation volume. 115 222 229 222-229