Search Results (37)

To address the inherent defects in the fabrication of AlCrN titanium alloy coatings and enhance interfacial bonding strength as well as tribological performance, an AlCrN coating was employed as an absorption layer and subjected to laser shock processing to form an AlCrN/TC4 transition layer. Subsequently, a secondary AlCrN coating was deposited to construct a gradient coating architecture. The surface and cross-sectional morphologies and elemental distributions under varying laser energies were systematically investigated, and the influence of laser energy on the adhesion and wear resistance of the gradient coatings was analyzed. The results demonstrate that with increasing laser impact energy, the thickness of the AlCrN/TC4 transition layer gradually decreases from 3.75 μm to 1.32 μm, accompanied by significant changes in elemental distribution across the surface and cross-section. The interfacial bonding strength of the gradient coating increases substantially from 13.6 N to 43.3 N, while the average friction coefficient rises from 0.436 to 0.507. Concurrently, the wear track depth is reduced, and the wear rate decreases from 86.46 × 10⁻⁵ mm³/(N·m) to 7.67 × 10⁻⁵ mm³/(N·m). Laser shock peening promotes elemental diffusion, enabling the formation of a diffusion-aided interlayer. The incorporation of this diffused zone facilitates the successful construction of a high-quality TC4 titanium alloy gradient coating, effectively broadening the film–substrate interface, enhancing surface hardness, and significantly improving both interfacial adhesion and wear resistance. Full article

In this study, Cr/CrN and Mo/MoN alternating multilayer coatings with pure metal interlayers were deposited on 316 L stainless steel substrates via physical vapor deposition to systematically investigate the corrosion resistance, wear resistance, and tribocorrosion behavior of the multilayer coating systems in physiological saline environments. Microstructural characterization revealed that the CrN layer consists of mixed CrN and Cr₂N phases, whereas the MoN layer exhibits a highly densified microstructure along with the presence of MoO₂ phase, which collectively contribute to the superior corrosion resistance of the Mo/MoN coating. Furthermore, compared to the CrN layer, the MoN layer demonstrates enhanced nanomechanical properties and improved resistance to crack initiation, due to the greater hardness and higher H/E and H³/E² values. Consequently, the Mo/MoN coating exhibits significantly better wear and tribocorrosion performance than its CrN counterpart. This work provides a theoretical foundation for the design of tribocorrosion-resistant hard coatings for artificial joint materials. Full article

In this paper, the achieved state-of-the-art understanding regarding the wear behaviour of various PVD (physical vapour deposition) coatings deposited on TiB₂/Ti composites produced by SPS (spark plasma sintering) is presented. The objective of this paper is to investigate the wear behaviour of various PVD coatings deposited on TiB₂/Ti composites manufactured by SPS, when lubricated with hexagonal boron nitride (hBN) as an external solid lubricant in the range from room temperature up to 900 °C in friction contacts under extreme pressure and with oscillation relative motion. Four multicomponent and multilayer coatings were investigated based on AlCrN and TiCrN coatings with TiCrN-AlCrN/AlCrTiN/Si₃N₄ interlayers and various external layers (AlCrN, Si₃N₄, AlCrTiSiN, and AlCrTiSiN gradient with increasing oxygen gradient replacing nitrogen). The wear tests were performed by means of a ball-on-disc SRV friction and wear tester using reciprocating motion of the Si₃N₄ ball sliding against a coated disc from room temperature up to 900 °C. The best protection against wear and oxidation at higher temperatures (even up to 900 °C) was achieved for coatings with AlCrN and AlTiCrN external layers, and hBN lubricant was used simultaneously. Full article

This study presents an experimental investigation of steels used in special knife applications, focusing on the interrelationship between chemical composition, microstructure, heat treatment, and mechanical properties. Four representative materials were analysed: VG10 (stainless steel with nickel-laminated edges and a VG10 core), RWL₃₄^TM (powder-metallurgical steel), laminated steel K110+N695 (with a nickel interlayer), and forge-welded steel K600+K720. The steels were characterised using OES, optical microscopy and SEM, supported by EDS for local chemical analysis. Microhardness testing was applied to individual structural regions to correlate carbide morphology, layer interfaces, and heat-treatment response with hardness values. The results reveal pronounced differences in structural homogeneity and defect occurrence. Powder-metallurgical RWL₃₄^TM exhibited the most uniform microstructure with finely dispersed Cr carbides, achieving high hardness and absence of structural defects. In contrast, laminated and forge-welded steels contained large primary carbides, carbide precipitation at grain boundaries, porous cavities, and insufficient cohesion in interlayers or weld zones, which may compromise toughness. VG10 and K110+N695 showed carbide coarsening caused by inadequate heat treatment, whereas K600+K720 revealed weld-related defects and heterogeneous phase structures. Overall, the study demonstrates the critical role of heat treatment and processing route in determining blade quality and performance. The findings provide guidance for optimising steel selection and processing technologies in advanced cutlery engineering. Full article

This study systematically investigates the effects of aging treatment (AT) on the microstructure and properties of Cr/DLC coatings deposited via cathodic arc ion plating onto the surface of ECAP-7075 aluminum alloy. Utilizing a comprehensive approach combining performance tests (nanoindentation, nanoscratch testing, dynamic polarization analysis) with characterization tests (scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy), the synergistic effects of equal channel angular pressing (ECAP) and aging treatment(AT) were elucidated. The results demonstrate that the combined ECAP and AT significantly enhance the coating’s performance. Specifically, AT promotes the precipitation of η’ phase within the 7075 aluminum alloy substrate, increases the size of Cr₇C₃ crystallites in the Cr-based interlayer, improves the crystallinity of the Cr₇C₃ phase on the (060) or (242) crystal planes, and elevates the sp³-C/sp²-C ratio in the diamond-like carbon(DLC) top layer, leading to partial healing of defects and a denser overall coating structure. These microstructural transformations, induced by AT, result in substantial improvements in the mechanical properties (hardness reaching 5.2 GPa, bond strength achieving 15.1 N) and corrosion resistance (corrosion potential increasing to -0.698 V) of the Cr/DLC-coated ECAP-7075 aluminum alloy. This enhanced combination of properties makes these coatings particularly well-suited for high-performance aerospace components requiring both wear resistance and corrosion protection in demanding environments. Full article

Chromium–aluminum nitride (CrAlN) coatings were deposited on polished H13 tool steel substrates using direct current (DC) magnetron sputtering. The Cr/Al composition in the target was varied by inserting either four or eight chromium (Cr) plugs into cavities machined into an aluminum (Al) plate target. Nitrogen was introduced as a reactive gas to facilitate the formation of the nitride phase. Coatings were deposited at substrate bias voltages of −30 V, −50 V, and −60 V to study the combined effects of composition and ion energy on coating properties. Compositional analysis of coatings deposited at a −50 V bias revealed Cr/Al ratios of approximately 0.8 and 1.7 for the 4- and 8-plug configurations, respectively. This increase in the Cr/Al ratio led to a 2.6-fold improvement in coating hardness. Coatings produced using the eight-Cr-plug target exhibited a nearly linear increase in hardness with increasing substrate bias voltage. Cross-sectional scanning electron microscopy revealed a uniform bilayer structure consisting of an approximately 0.5 µm metal interlayer beneath a 2–3 µm CrAlN coating. Surface morphology analysis indicated the presence of coarse microdroplets in coatings with the lower Cr/Al ratio. These microdroplets were significantly suppressed in coatings with higher Cr/Al content, especially at increased bias voltages. This suppression is likely due to enhanced ion bombardment associated with the increased Cr content, attributed to Cr’s relatively higher atomic mass compared to Al. Coatings with lower hardness exhibited greater scratch resistance, likely due to the influence of residual compressive stresses. The findings highlight the critical role of both Cr/Al content and substrate bias in tailoring the tribo-mechanical performance of PVD CrAlN coatings for wear-resistant applications. Full article

Plasma nitriding (PN) is often used to enhance the mechanical properties (surface hardness, wear and corrosion resistance) of bulk alloys. High-quality AlCrN hard coatings were obtained using high-power pulsed magnetron sputtering (HiPIMS) technology. This study proposes a combination of two surface treatment methods (plasma nitriding and hard coating deposition) in a continuous plasma process to optimize the application and service life of cutting tools. The main feature of this study is to verify the mechanical properties and adhesion strength of nitride tungsten carbide (WC-Co) bulk at a lower temperature (∼300 °C) and shorter time (0.5 to 1.5 h) of PN treatment. After 1.5 h of PN treatment on the WC-Co substrate without subsequent coating, the ultra-thin WN_x diffusion interlayer (thickness ∼11.5 nm) on the subsurface was directly observed via TEM analysis, and the types of chemical bonding were confirmed by XPS analysis. Vickers analysis indicated that the surface hardness of the nitrided WC-Co substrate was enhanced by PN treatment from 1534 to 2034 Hv. The AlCrN coating deposited on the nitrided WC-Co substrate significantly enhances the surface mechanical properties, including adhesion strength (increasing from 70 to 150 N), hardness (rising from 2257 to 2568 HV), and wear resistance (with the wear rate decreasing from 14.5 to 3.4 × 10⁻⁸ mm³/Nm). Composite surface technology has a high commercial application value because it enhances the value of products under the existing equipment of manufacturers. Full article

In this study, we analyze the extent to which thin hard coatings can serve as tribological protective layers for the selected plastic substrate materials PA12 (polyamide 12) und PEEK (polyetheretherketone), with and without fiber reinforcement. The approximately 1 µm thick coating variants ta-C, ta-C:N, and ta-C:B, which were applied using the laser arc process, are investigated. In oscillating sliding wear tests against a steel ball in an air atmosphere without lubricant, the wear of the coating and counter body is compared to analogous coating variants applied in parallel to AISI 52100 steel. The ta-C-based coatings show good adhesion strength and basic suitability as wear protection layers on the plastic substrates in the tribological tests. However, there are variations depending on the coating type and substrate material. The use of a Cr interlayer and its thickness also plays an important role. It is demonstrated that by coating under conditions where the uncoated plastic substrate would normally fail, a similarly good performance as with analogously coated steel substrates can be achieved by ta-C:N. Full article

Ensuring adequate reliability of the production process of packaging closures has made it necessary to study the effect of annealing and varnishing variants on the strength and structural properties of the stock material. As a test material, EN AW-5052-H28 aluminium alloy sheets with a thickness of 0.21 mm were used. The surface treatment of the test material involved varnishing the sheet metal surface using various varnishes and soaking the sheet metal. The coefficient of friction and the abrasion resistance of the coatings were determined using the T-21 ball-and-disc tribotester. The tested sheets were subjected to tribological analysis by the T-05 roller-block tribotester using countersamples made of Caldie and Sverker 21 tool steels. The results of the tests showed differences in mechanical and structural properties depending on the method of sample preparation. Based on the test results, significant differences in the adhesion of anti-wear coatings were found. The results revealed that the most favourable friction conditions are provided by the CrN coating. The (AlTi)N interlayer in the (AlTi)N/(AlCr)N coating adheres to the substrate over the entire tested area and no detachment from its surface was observed, which proves good bonding at the substrate/coating interface. The tested AlTiN/TiAlSiXN coating is characterised by a more homogeneous, compact microstructure compared to the (AlTi)N/(AlCr)N coating. Full article

The high chemical activity, low thermal conductivity, and high strength of titanium alloys lead to severe tool wear during cutting. The coating applied to the tool surface insulates the effect of heat and chemical reactions. TiAlSiN coating and AlCrN coating are two representative coatings with excellent properties in TiN-based and CrN-based applications, respectively. Three types of nanocoatings—TiAlSiN monolayer, AlCrN monolayer, and TiAlSiN/AlCrN multilayer—were prepared, and the microstructure, mechanical properties, oxidation resistance, diffusion properties with titanium alloy, and cutting performance of the coatings were investigated utilizing SEM, TEM, XRD, TGA, GD-OES, nanoindentation, and scratching instruments. The hardness, elastic modulus, and adhesion strength of TiAlSiN/AlCrN multilayer coatings are between TiAlSiN monolayer and AlCrN monolayer coatings, which meet the “law of mixtures”. Adhesion strength is the primary condition for cutting applications and should have a minimum threshold value. Ti and N elements are the most significant in the diffusion between coatings and titanium alloys. The nitride coating containing Cr aggravates the loss of N in contact with the titanium alloy. In addition, multilayer structural coatings can lead to more severe diffusion than monolayer coatings due to their inherent interlayer defects. Although diffusion between titanium alloys and coated tools is more severe than with other workpiece materials, the main factor affecting tool cutting life is still the H³/E*² value determined by the hardness and modulus of elasticity together. Full article

A nano-multilayer Ti_0.2Al_0.55Cr_0.2Si_0.03Y_0.02N/Ti_0.25Al_0.65Cr_0.1N PVD coating was deposited on Kennametal carbide K 313 inserts. These coatings are widely used to protect cutting tools under severe exploitation conditions. Under equilibrium conditions, it was found that the Al₂O₃ oxide possessed better adhesive properties than the TiO₂. The addition of chromium further enhanced the oxidation resistance of the coatings. Silicon significantly increased the oxidation resistance of this type of coating. The properties of the diffusion process in this coating have not been sufficiently investigated, despite the considerable number of articles published on this topic. For the purpose of this study, a multilayer ion-plasma (TiAlCrSiY)N/(TiAlCr)N coating was oxidized under equilibrium conditions; its chemical inhomogeneity was studied by time-of-flight mass spectroscopy using a TOF SIMS5-100 instrument. The data was collected from an area of 100 × 100 µ. A D-300 profilometer (KLA-Tencor Corp., Milpitas, California 95035, USA) was used to determine the rate of ion etching. It was found that oxidation commenced at the surface nanolayer of a TiAlCrN nitride, forming loose films of Cr₂O₃, TiO₂, and Al₂O₃ oxides. This passivating film had a thickness of around 140 nm. For the first time, the interlayer diffusion coefficients of Si and Y were determined in multilayer coatings based on Ti_0.2Al_0.55Cr_0.2Si_0.03Y_0.02N/Ti_0.25Al_0.65Cr_0.1N, under open air annealing at 700 °C. The physical nature of the differences in the diffusion of these elements is discussed. The diffusion rate in the near-surface volumes was lower than in the deep layers of the multilayer coating, most likely due to the formation of passivating oxide films on the surface. Full article

Tribological investigations are of great importance, especially in the case of novel combinations of materials used for the tribosystem. In the current research, multilayer diamond-like carbon coating deposited by plasma enhanced chemical vapour deposition on an X42Cr13 plastic mould tool steel is studied with two different surface conditions of the substrate. On the one hand, it is secondary hardened; on the other hand, it is additively plasma nitrided preceding the diamond-like carbon coating. This latter combined treatment, called duplex treatment, has an increasingly wide range of applications today. However, its effectiveness largely depends on applying the appropriate nitriding technology. The tribological behaviour was characterised by an instrumented scratch test and a reciprocating ball-on-plate wear test. The results demonstrate better scratch resistance for the duplex-treated samples, while they show weaker performance in the applied wear type of loading. The current comparative study reveals the reason for the unexpected behaviour and highlights some critical aspects of the heat treatment procedure. The architecture of the tested multilayer DLC coating is unique, and no tribological results have yet been published on tribosystems combined with an X42Cr13 steel substrate. The presented results may particularly interest tribologists and the materials research community. Full article

Bimetallic layered double oxide (LDO) NiM (M = Cr, Fe) catalysts with nominal compositions of Ni/M = 2 or 3 were tailored from layered double hydroxides (LDH) using a coprecipitation method to investigate the effects of the trivalent metal (Cr or Fe) and the amount of Ni species on the structural, textural, reducibility, and catalytic properties for CH₄/CO₂ reforming. The solids before (LDH) and after (LDO) thermal treatment at 500 °C were characterized using TGA-TD-SM, HT-XRD, XRD, Raman, and IR-ATR spectroscopies; N₂ physical adsorption; XPS; and H₂-TPR. According to the XRD and Raman analysis, a hydrotalcite structure was present at room temperature and stable up to 250 °C. The interlayer space decreased when the temperature increased, with a lattice parameter and interlayer space of 3.018 Å and 7.017 Å, respectively. The solids fully decomposed into oxide after calcination at 500 °C. NiO and spinel phases (NiM₂O₄, M = Cr or Fe) were observed in the NiM (M = Cr, Fe) catalysts, and Cr₂O₃ was detected in the case of NiCr. The NiFe catalysts show low activity and selectivity for DRM in the temperature range explored. In contrast, the chromium compound demonstrated interesting CH₄ and CO₂ conversions and generally excellent H₂ selectivity at low reaction temperatures. CH₄ and CO₂ conversions of 18–20% with H₂/CO of approx. 0.7 could be reached at temperatures as low as 500 °C, but transient behavior and deactivation were observed at higher temperatures or long reaction times. The excellent activity observed during this transient sequence was attributed to the stabilization of the metallic Ni particles formed during the reduction of the NiO phase due to the presence of NiCr₂O₄, opening the path for the use of these materials in periodic or looping processes for methane reforming at low temperature. Full article

The microstructure and surface topography of PVD hard coatings are among the most important properties, as they significantly determine their mechanical, tribological and other properties. In this study, we systematically analyzed the microstructure and topography of a TiAlN/CrN nanolayer coating (NL-TiAlN/CrN), not only because such coatings possess better mechanical and tribological properties than TiAlN and CrN monolayer coatings, mainly because the contours of the individual layers, in the cross-sectional STEM or SEM images of such coatings, make it easier to follow topographic and microstructural changes that occurred during its growth. We investigated the effects of the substrate rotation modes on the microstructure and surface topography of the NL-TiAlN/CrN coating, as well as on the periodicity of the nanolayer structure. The influence of the substrate material and the ion etching methods were also studied, while special attention was given to the interlayer roughness and influence of non-metallic inclusions in the steel substrates on the growth of the coating. The topographical features of the NL-TiAlN/CrN coating surface are correlated with the observations from the cross-sectional TEM and FIB analysis. Selected non-metallic inclusions, covered by the NL-TiAlN/CrN coating, were prepared for SEM and STEM analyses by the focused ion beam. The same inclusions were analyzed prior to and after deposition. We found that substrate rotation modes substantially influence the microstructure, surface topography and periodicity of the NL-TiAlN/CrN layer. Non-metallic inclusions in the substrates cause the formation of shallow craters or protrusions, depending on their net removal rates during the substrate pretreatment (polishing and ion etching), as compared to the matrix. Full article

In tribological applications, the degradation of alloy nitride coatings is an issue of increasing concern. The drawbacks of monolayer hard coatings can be overcome using a multilayer coating system. In this study, single-layer TiAlNbN and multilayer TiAlNbN/AlCrN coatings with AlCrN layer addition into TiAlNbN were prepared by cathodic arc evaporation (CAE). The multilayer TiAlNbN/AlCrN showed B1 NaCl structure, and the columnar structure continued from the bottom interlayer of CrN to the top multilayers without interruption. After AlCrN addition, the TiAlNbN/AlCrN coating consisted of TiAlNbN and AlCrN multilayers with a periodic thickness of 13.2 nm. The layer thicknesses of the TiAlNbN and AlCrN were 7 nm and 6.2 nm, respectively. The template growth of the TiAlNbN and AlCrN sublayers stabilized the cubic phases. The introduction of bottom CrN and the TiAlNbN/CrN transition layers possessed com-position-gradient that improved the adhesion strength of the coatings. The hardness of the deposited TiAlNbN was 30.2 ± 1.3 GPa. The TiAlNbN/AlCrN had higher hardness of 31.7 ± 3.5 GPa and improved tribological performance (wear rate = 8.2 ± 0.6 × 10⁻⁷ mm³/Nm) than those of TiAlNbN, which were because the multilayer architecture with AlCrN addition effectively resisted abrasion wear. Full article