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Abstract: A comparative investigation of the structure and properties of TiAlC(N), TiCrAlC(N), and CrAlC(N) coatings deposited by sputtering of МАХ-phase Ti2− х Cr х AlC targets (where x =0, 0.5, 1.5, and 2) in an Ar atmosphere or in a gaseous mixture of Ar+N2 is presented. The coatings were characterized in terms of their structure, elemental and phase composition, hardness, elastic modulus, elastic recovery, thermal stability, friction coefficient, wear rate, corrosion, and high-temperature oxidation resistance. The structure of the coatings was studied by means of X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, glow discharge optical emission spectroscopy, electron energy loss spectroscopy, and Raman spectroscopy. To evaluate the thermal stability and oxidation resistance, the coatings were annealed either in vacuum or in air at temperatures 600–1200 °C. The results obtained show that the TiAlCN coatings possess high hardness of 32–35 GPa, low friction coefficient against WC–Co well below 0.25, high thermal stability up to 1200 °C, and superior performance in dry milling tests against high Cr steel. Meanwhile, the coatings with high Cr content demonstrated improved oxidation resistance up to 1000 °C and superior electrochemical behavior, but their mechanical and tribological properties were deteriorated. [Copyright &y& Elsevier]

Abstract: One binary Al–40Zn and five ternary Al–40Zn–Cu alloys with different copper contents were prepared by permanent mould casting. Their microstructure and mechanical properties were investigated in as-cast state. Friction and wear properties of the ternary alloys were studied using a conforming block-on-disc type tester. The results obtained were compared with those of SAE 65 bearing bronze. The microstructure of Al–40Zn–Cu alloys consisted of aluminium-rich α dendrites surrounded by eutectoid α+η phases and θ (CuAl2) particles. Hardness of the ternary alloys increased continuously with increasing copper content, but their tensile strength decreased above 3% Cu. Friction coefficient and temperature of the Al–40Zn–Cu alloys and bronze increased in the initial period of run. This was followed by a reduction in the properties and attainment of constant levels afterwards. However, volume loss of the alloys increased rapidly at the beginning of the test run and reached almost constant levels after a sliding distance of approximately 400km. The Al–40Zn–Cu alloys were found to be much superior to the SAE 65 bronze, as far as their wear resistance is concerned. Among the alloys tested, highest strength and wear resistance were obtained with the Al–40Zn–3Cu alloy. [Copyright &y& Elsevier]

Abstract: Films of Ti–Ca–P–C–O–(N), Ti–Ca–C–O–(N) and Ti–Zr–C–O–(N) were deposited by DC magnetron sputtering or ion implantation-assisted magnetron sputtering of composite targets TiC0.5+10%Ca10(PO4)6(OH)2, TiC0.5+20%(CaO+TiO2) and TiC0.5+10%ZrO2 in an Ar atmosphere or reactively in a gaseous mixture of Ar+14%N2. The microstructure, elemental and phase composition of films were studied by means of X-ray diffraction, transmission electron microscopy, scanning force microscopy, X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. The films were characterized in terms of their hardness, Young''s modulus, elastic recovery, adhesion strength, and friction and wear both in air and under physiological solution. Particular attention was paid to the analysis of deformation and fracture for various film/substrate systems during scratch testing. The biocompatibility of the films was evaluated by both in vitro and in vivo experiments. In vitro studies involved the investigation of adhesion, spreading, and proliferation of MC3T3-E1 osteoblasts and IAR-2 epithelial cells, morphometric analysis, actin cytoskeleton, focal contacts staining, alkaline phosphatase activity and von Kossa staining of osteoblastic culture. Cell culture experiments demonstrated an increase of osteoblastic proliferation on Ca- and P-incorporated films. In vivo studies were fulfilled by subcutaneous implantation of Teflon plates coated with the tested films in mice and analysis of the population of adherent cells on their surfaces. The results obtained show that multicomponent nanostructured Ti–(Ca, Zr)–(C, N, O, P) films possess a combination of high hardness, wear resistance and adhesion strength, reduced Young''s modulus, low friction coefficient and high biocompatibility. [Copyright &y& Elsevier]

Abstract: A comparative investigation of Ti–B–N, Ti–Cr–B–N, Ti–Si–B–N, and Ti–Al–Si–B–N coatings deposited by DC magnetron sputtering and ion implantation assisted magnetron sputtering of composite targets TiBN, TiCrB, TiSiB, and TiAlSiB in an Ar atmosphere or reactively in a gaseous mixture of Ar+N2 is presented. The targets were manufactured by means of a self-propagating high-temperature synthesis method. The microstructure and phase composition of coatings were studied by means of X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The films were characterized in terms of their hardness, Young’s modulus, elastic recovery, adhesion (critical load), friction and wear. The lifetime of drills coated with Ti–Cr–B–N and Ti–Si–B–N coatings as well as the productivity of the drilling process were examined. [Copyright &y& Elsevier]

Individual hard thin film materials such as TiN, SiN1.3, SiC and CNx exhibit attractive mechanical, tribological, optical and electronic properties related to their microstructure and chemical bonding. In the present work, we combine the characteristics of such materials, while systematically studying quaternary thin films prepared by plasma enhanced chemical vapor deposition (PECVD) from TiCl4/SiH4/N2/CH4 mixtures with different concentrations of CH4. Detailed structural and chemical characterizations using transmission electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and elastic recoil detection suggest formation of a TiCxNy/SiCN nanocomposite structure. Depth-sensing indentation, static indentation and curvature measurements, on samples prepared under optimal conditions, reveal a hardness of 55 GPa, reduced Young''s modulus of 302 GPa, a compressive stress of 2.0 GPa, an elastic rebound of more than 80 %, H3/Er2 coefficient of 1.8 GPa and a high toughness. The friction coefficient and the wear rate, measured against diamond, are 0.13*10-6 and 12*10-6 mm3/Nm, respectively. We compare the properties of the present nanocomposite TiCxNy/SiCN coatings with the performance of PECVD films from our earlier studies: these include TiN/SiN1.3 nanocomposites and SiCN, for which we obtained a hardness of 45 and 33 GPa, and a reduced Young''s modulus of 350 and 200 GPa, respectively. [Copyright &y& Elsevier]

Hard amorphous DLC films were deposited onto ultra high molecular weight polyethylene (UHMWPE) and metallic substrates (Ti, Co–Cr–Mo, stainless steel 138F) used as biomaterials by pulsed arc discharge using a carbon source accelerator in 2×10-4 Pa vacuum. DLC films were analyzed by Auger electron spectroscopy, electron energy loss spectroscopy, nanoindentation, scratch test and Rockwell indentation. Dry friction coefficient of films deposited on UHMWPE and stainless steel were also investigated. The results obtained are discussed with literature data. [Copyright &y& Elsevier]

In the present work multicomponent thin films based on the systems Ti–Ca–C–O–N and Ti–Zr–C–O–N have been deposited and evaluated. TiC0.5+10% CaO and TiC0.5+10% ZrO2 targets were manufactured by means of the self-propagating high-temperature synthesis (SHS) method. The synthesized targets were subjected to DC magnetron sputtering in an atmosphere of argon or in a gaseous mixture of argon and nitrogen. The films were characterized in terms of their structure, surface topography, mechanical properties and tribological behavior. The films deposited on Si substrates under optimal conditions showed high hardness in the range of 36–40 GPa, low Young''s modulus 260–300 GPa and high percentage of elastic recovery 70–75%. The CaO- and ZrO2-doped Ti–C–N films showed significantly lower friction coefficient and wear rate against WC+6% Co alloy in comparison to conventional magnetron–sputtered TiC and TiN films. The biocompatibility of the films was evaluated by both in vitro and in vivo experiments (in mice). In vitro studies involved the investigation of the proliferation of fibroblasts Rat-1 and epithelial cells IAR-2 at the tested films and morphometric analysis of the cells cultivated on the films. Fibroblasts and epithelial cells were seeded on the coverslips, coated with examined films and incubated at 37 °C for 24, 48 and 72 h. We did not detect statistically significant differences in the attachment, spreading and proliferation of cultured cells on the coated and the uncoated substrata. The adhesion and proliferation of cells was good at all investigated films. We also did not observe any inflammatory reactions on the implants, inserted under the mouse skin. [Copyright &y& Elsevier]

TiN coating was deposited on high-speed steel, cemented carbide and TiCN-based cermets using arc evaporation. The variation of substrates was to evaluate the effect of tool materials on the coating's microstructure, composition, hardness, adhesion and tribological properties. The TiN coating on all tool materials had a strong preferred TiN (111) orientation. The TiN coating on high-speed steel grew so fast in the vertical direction that the columnar crystal structure was noticeable. The columnar structure of TiN coating on TiCN-based cermets weakened for the reduced vertical growth rate. The Ti/N atomic content ratio of the TiN coating on high-speed steel was 0.84, and some N atoms formed an interstitial solid solution, which contributed to the increased hardness of the coating. However, the Ti/N atomic content ratio of TiN coating on TiCN-based cermets increased to 1.04. Due to the low residual stress, the adhesion of TiN coating on TiCN-based cermets and cemented carbide was noticeably higher than that of coating on high-speed steel. The wear mechanism of TiN coatings on all tool materials tested against with steel balls was mainly abrasive wear. An iron oxide film appeared on the coated TiCN-based sample, which directly caused the friction coefficient to decrease from 0.8 to 0.6. Therefore, the TiN coating on TiCN-based cermets had the best wear resistance. • Microstructure and properties of TiN coating were affected by the tool materials. • TiN coating on high-speed steel had high hardness and H 3/ E *2 ratio. • TiN coating on cemented carbide and TiCN-based cermets had high adhesion. • Iron oxide formed in the wear process exhibited a good anti-friction effect. • TiN coating on TiCN-based cermets possessed the best wear resistance. [ABSTRACT FROM AUTHOR]

• The effect of sintering temperature on the mechanical and friction properties of GNPs/TC21 composites were investigated. • A model of the relationship between the interfacial evolution of composites and sintering temperature was established. • The strengthening mechanism of GNPs/TC21 composites was revealed using TEM microstructural analysis. Schematic diagram of microstructure evolution with increasing sintering temperature. (a)Spherical particle sintering model, (b) TC21 spherical particle bonding at lowtemperature sintering, (c) interfacial bonding at medium temperature sintering,(d) interfacial bonding at high temperature sintering. Schematic illustration of the strengthening mechanism of TiC@GNPs bands and TiC particles/plates. (a) Synergistic strengthening mechanism of TiC@GNPs bands and TiC particles/plates, (b) Strengthening mechanism of TiC particles/plates [Display omitted] Graphene nanoplates (GNPs) have been adopted in titanium matrix composite manufacturing and design due to its superior mechanical properties. In this study, Graphene nanoplates reinforced Ti-6Al-2Sn-2Zr-3Mo-1Cr-2Nb-Si alloys (named as GNPs/TC21 composites) were prepared by using spark plasma sintering (SPS), and the effects of sintering temperature on the microstructure, mechanical and wear properties of GNPs/TC21 composites were systematically investigated. The results indicate that the sintering temperatures show a great influence on the interfacial structure. With the increase of sintering temperature from 850 °C to 1050 °C, the interfacial microstructures exhibit three morphographies: (1) The original TC21 particles coated with GNPs (850 °C); (2) A special TiC@GNPs band (900 °C−1000 °C); (3) A discontinuous network structure wrapped by TiC particles/plates (1050 °C). Mechanical and tribological properties of the GNPs/TC21 composites were investigated at room temperature. The optimal SPS temperature was 1000 °C, at which the GNPs/TC21 composites show the best comprehensive mechanical properties i.e. the ultimate tensile strength and yield strength are 1167 MPa and 1041 MPa, the friction coefficient is 0.16275 and the wear loss is 0.0179 g. The improvement of mechanical properties can be attributed to the synergistic strengthening of the load transfer effect of TiC@GNPs bands and the pinning effect of TiC particles/plates. The excellent wear resistance is mainly attributed to the pinning of TiC particles on the surrounding metal matrix and the strengthening and lubrication of GNPs. [ABSTRACT FROM AUTHOR]

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 1 N H2SO4 and 3.5%NaCl solutions. The oxidation resistance of the coatings was investigated in the 600–800 °C 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 1 N H2SO4 solution up to 3.5 and 5 times, correspondingly. The superior corrosion resistance of Zr-B-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 °C) 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

• Aqueous PAI-MoS 2 -graphite bonded solid lubricating coatings are novel green lubricated materials. • Aqueous coating with the MRGM of 0.3 exhibits more excellent mechanical and tribological properties. • Tribological mechanisms of aqueous coatings are systematically investigated concerning the morphology, structure and chemical compositions of wear scars. In this paper, a series of the environmental-friendly aqueous PAI-MoS 2 -graphite bonded solid-lubricating coatings (BSLCs) are prepared depending on the design concept of the recombination of two-component lubricant and aqueous resin, and the mechanical strength and wear resistance of the coatings are deeply optimized by virtue of the synergy of the components of coatings. The experimental results demonstrate that the successful preparation of aqueous BSLCs greatly reduces the utilization of toxic organic solvents and is conducive to environmental protection and resource conservation. Doping an appropriate amount of graphite into the aqueous BSLCs is beneficial to maximize the promotion of the mechanical and tribological properties of the coating, and when the mass ratio of graphite to MoS 2 (MRGM) is 0.3, the mechanical strength, friction reduction and wear resistance of the coatings display the comparable level as that of the organic-solvent based BSLCs. Based on the analysis of the variations of the morphology, structure and chemical composition of the wear scars, the corresponding active mechanisms on the mechanical and tribological properties of the coating are investigated in depth. [ABSTRACT FROM AUTHOR]

Based on the advantage of rapidly fabricating parts with complex geometric shapes, selective laser melting (SLM), an additive manufacturing technology, is utilized to process 3 wt.% TiC/Ti6Al4V composites. A TiC-reinforced Ti6Al4V composite with directionally grown unique microstructures is prepared by SLM. The effect of the laser power and scanning speed on the relative density, constitutional phases, and microstructure features is investigated systematically. The microstructure evolution mechanism is clarified. Moreover, the influence of the unique microstructure on the mechanical and tribological properties is investigated. The results indicate that the relative density of the SLM-processed TiC/Ti6Al4V composite can reach 98.7%. Because of the special processing technology used in SLM, unique nanoscale lamellar and needle-like eutectic TiC reinforcement phases, which have never been observed in TiC/Ti6Al4V composites prepared by other flexible laser additive manufacturing technologies, are formed. Furthermore, the composites are dominated by extremely small grains. The nanoscale eutectic TiC and refined grains significantly enhance the hardness and tensile strength of the composites. The microhardness and ultimate tensile strength reach 487 HV and 1565 MPa, respectively. More importantly, the nanoscale reinforcement promotes the migration of C and the formation of a dense solid lubricant film during friction, leading to excellent tribological properties at different applied loads. As the applied load increases from 5 N to 15 N, due to the enhancement of the effect of the nanoscale reinforcement, the tribological properties of the SLM-processed TiC/Ti6Al4V composites are further improved. At an applied load of 15 N, the friction coefficient and wear rate reach 0.303 and 1.221 mm3/m∙N, respectively. • TiC/Ti6Al4V composites with unique nanoscale eutectic TiC reinforcement are prepared by SLM for the first time. • The microstructure formation condition and corresponding evolution mechanism under different parameters are clarified. • The SLM-processed Ti6Al4V/TiC composite shows excellent mechanical and tribological properties. • Mechanical and tribological properties reinforcement mechanism of the SLM-processed Ti6Al4V/TiC composite is established. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

• Technological advancements in functionally graded materials. • Comparison of various homogenization schemes. • Review on analysis of functionally graded structures. • Suggested future scope in the analysis of functionally graded structures. • Review on various fabrication methods of functionally graded materials along their mechanical and tribological performance. This paper discourses an overview of the recent advancements in functionally graded materials (FGMs) research. The paper also disseminates on the key researches that are carried out in the scientific community on the development of manufacturing and modelling of functionally graded materials. The rationale of the current work is to emphasize the selection of materials, processing techniques and analytical modelling and applications of FGMs. Alongside, challenges involved in developing these materials towards various aspects of scientific and technological fields will be addressed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Mo-Si-B and Mo-Hf-Si-B coatings are deposited by magnetron sputtering in two regimes (direct and pulsed current) using composite ceramic cathodes. The structure of the coatings is investigated by XRD, SEM, EDS, and GDOES. Mechanical and tribological properties are measured by nanoindentation and tribological pin-on-disc testing. The short-term oxidation resistance of the coatings in the air is evaluated at 1500 °С. Results show that pulsed current deposition decreases the coating's growth rate and the grains size of coating's main constituent h-MoSi 2 phase while promoting the formation of MoB 2. The introduction of hafnium increased the coating's density and suppressed the formation of unwanted columnar structure. The highest hardness of 28 GPa, Young modulus of 366 GPa, and elastic recovery of 64% were achieved for the Mo-Si-B coating deposited at direct current. Optimal tribological performance, including a stable friction coefficient and low wear rate of 6.9х10−6 mm3/(Nm), was determined for Mo-Hf-Si-B coating also obtained using direct current. All coatings were oxidation-resistant at 1500 °С, but the Mo-Hf-Si-B composition demonstrated oxidation resistance superior to that of Mo-Si-B coatings because of the formation of two-layered HfO 2 /SiO 2 protective film. The thickness of the oxide layer was higher for the coatings deposited using pulsed current. Unlabelled Image • Hard Mo-Si-B and Mo-Hf-Si-B coatings obtained by magnetron sputtering in d.c. and pulsed modes • Mo-Si-B exhibit maximal hardness of 28 GPa and elastic recovery of 64%. • Mo-Hf-Si-B possess higher tribological properties and oxidation resistance. • Coatings withstand short-term oxidation at 1500 °C. • Oxidation is accompanied with formation of SiO 2 and HfO 2 /SiO 2 protective layers. [ABSTRACT FROM AUTHOR]

Metal-matrix composite (MMC) coatings are advanced materials, composed of two or more phases that can be tailored based on the industrial needs such as lightweight and wear-resistance. Cold spray (CS) technology is highly suitable to develop these MMC coatings as it is a low temperature deposition method, which does not involve particle melting, hence retaining the original properties of the materials. Ti–6Al–4V (Ti64) is a common alloy used in aerospace applications owing to its lightweight and high yield strength. Recently, cold sprayed Ti64 coatings have shown promise to repair damaged or enhance surfaces of Ti components. However, there are still several issues with cold sprayed Ti64 coatings, such as relatively high porosity level and low wear-resistance. To solve these, a novel approach is to incorporate CoCr (ASTM F75) as reinforcing metal alloy particles into the Ti64 matrix to form a Ti64–CoCr composite coating. Pure Ti64 and pure CoCr coatings were also deposited as a comparison. The Ti64–CoCr composite coating achieved low porosity level (0.9%), high hardness (434 HV) and high wear resistance (1.7 × 10−4 mm3/Nm) compared to the Ti64 coatings. These properties were obtained while maintaining the original phases of the feedstock Ti64 and CoCr powders and achieving adhesion strength above 60 MPa. A 20 nm thick Ti–Co interdiffusion layer was also observed at the interface of CoCr and Ti64 particles under TEM. These results showed that Ti64–CoCr composite coating is a promising lightweight and wear resistant metallic coating for aerospace application. [ABSTRACT FROM AUTHOR]

Hf-Mo-Si-N films with a series of Si contents were prepared by magnetron sputtering in a mixed Ar/N 2 atmosphere. Microstructure and surface morphologies of films were characterized by XRD, XPS, TEM and AFM. Besides, mechanical and tribological properties were evaluated. With increasing of Si addition, the phase of films transforms from single fcc Hf-Mo-N to nanocomposite structure consisted of Hf-Mo-Si-N crystalline and amorphous Si 3 N 4 phases. The Hf-Mo-Si-N film with 5.4 at.% Si content exhibits improved hardness of 38.6 GPa and enhanced toughness of 3.6 MPa·m1/2, which is ascribed to the synergistic effect of the solid solution strengthen, fine grains and interface strengthening in nanocomposite system. The precipitated amorphous Si 3 N 4 phase could hinder the cracks propagation, which results in higher fracture toughness. The low average friction coefficient of 0.37 and wear rate of 1.8 × 10−6 mm3/N are obtained from the Hf-Mo-Si-N film with 5.4 at.% Si, which is also accompanied with high value of H/E (0.14) and H3/E*2 (0.61 GPa). • Quaternary Hf-Mo-Si-N films were synthesized by DC and RF magnetron co-sputtering. • Hard yet tough nanocomposite films with dispersed a-Si 3 N 4 phases can resist crack propagation. • The proper Si-addition greatly improves tribological properties of films. [ABSTRACT FROM AUTHOR]

Since obtaining a highly oriented structure based on a large-scale commercial ultra-high molecular weight polyethylene (UHMWPE) is considered very difficult due to its high molecular weight and melting index, modifying the structure of these cheap commercial UHMWPE brands into a supra-molecular structure with fiber-forming properties by adding a small amount of polyethylene wax (PE-wax) will provide the possibility to obtain highly oriented UHMWPE products with enhanced mechanical and tribological properties. In this work, highly oriented UHMWPE/PE-wax films were prepared. The PE-wax affected the UHMWPE as an intermolecular lubricant. The obtained lamellar structure of the UHMWPE/PE-wax composites had a better processability. The UHMWPE and UHMWPE/PE-wax structures for the xerogels and the films were studied by using differential scanning calorimetry and scanning electron microscopy. The PE-wax presence enhanced the mechanical properties of the UHMWPE/PE-wax films to a high degree. The highest average value of the tensile strength was 1320 MPa (an increase of 78%) obtained by adding a PE-wax content of 1.0 wt.%, and the highest average value of the Young's modulus was 56.8 GPa (an increase of 71%) obtained by adding a PE-wax content of 2.0 wt.%. The addition of the PE-wax increased the work of fracture values of the UHMWPE/PE-wax films up to 233%. The formation of the cavities was observed in the virgin UHMWPE films more than in the UHMWPE/PE-wax films, and the whitening of the oriented films was related to the crystallization process more than to the cavitation phenomenon. The coefficient of friction of the oriented UHMWPE/PE-wax films improved by 33% in comparison with the isotropic UHMWPE, and by 7% in comparison with the oriented virgin UHMWPE films. [ABSTRACT FROM AUTHOR]

• Two kinds of aqueous PTFE based coatings are green lubricating materials. • The basic physicochemical properties of two aqueous PTFE based coatings are comparable to that of organic-solvent based coatings. • Aqueous PTFE-ADPs based coatings exhibit superior mechanical and tribological performances to that of PTFE-PPs based coatings. • Tribocorrosive properties and active mechanism under diversified environments are thoroughly investigated. In the paper, the two kinds of environment-friendly aqueous PTFE based bonded solid lubricating coatings were prepared via facial paint spraying method, significantly reducing the waste of organic solvents. The basic physicochemical properties of two kinds of aqueous PTFE based coatings are comparable to that of organic-solvent based coatings. In addition, the tribocorrosive properties and active mechanism of two kinds of aqueous PTFE based coatings were thoroughly investigated under diversified environments, and the results illustrate that aqueous PTFE-ADPs based coatings exhibit superior mechanical and tribological performances to that of PTFE-PPs based coatings, and the tribocorrosive properties of two PTFE based coatings show major variation under different environments, which provides valuable references for environmental adaptability of the aqueous PTFE-based coatings, and further promotes the development of bonded solid lubricating coatings toward the direction of low carbon and environmental protection. [ABSTRACT FROM AUTHOR]