CSM Instruments Research Articles

Investigation of the tribological characteristics of Ta–Zr–Si–B–C–N coatings

Ta–Zr–Si–B–C–N coatings were deposited by magnetron sputtering using a TaSi2–Ta3B4–(Ta, Zr)B2 composite target. Ar, as well as Ar + N2 and Ar + C2H4 gas mixtures, were used as the working gas. The structure and composition of the coatings were studied by scanning electron microscopy, glow-discharge optical emission spectroscopy, and X-ray diffraction. A Calowear tester was used to measure the thickness and abrasion resistance of the coatings. Erosion resistance tests were carried out using a UZDN-2T (Russia) ultrasonic disperser. Tribological tests in the sliding friction mode were carried out on an HT Tribometer (CSM Instruments, Switzerland) automated friction machine. The wear zone after tribological testing was examined using a Veeco Wyko 1100 (Veeco, USA) optical profiler. The results showed that the Ta–Zr–Si–B coating was characterised by a columnar structure with an h-TaSi2 crystallite size of 11 nm. The introduction of nitrogen and carbon into the composition of the coatings led to the suppression of columnar growth and a ~2–4-fold decrease in the size of h-TaSi2 crystallites. Carboncontaining coatings demonstrated the best abrasive resistance. The sliding friction tests showed that the Ta–Zr–Si–B coating is characterised by a stable coefficient of friction of 0.3 at a temperature of 25 °C up to the maximum working temperature of 250 °C. The introduction of nitrogen led to an increase in the coefficient of friction up to 0.8–1.0 at a t = 50÷110 °С. The coating with the minimum carbon concentration showed a stable coefficient of friction of ~0.3 up to a maximum temperature of 250 °C. The best result was demonstrated by the sample containing the maximum amount of carbon, with its coefficient of friction remaining at the 0.25 level up to a temperature of 350 °C.

Structural-phase states and micromechanical properties of nanostructured TiAlCuN coatings

TiAlCuN coatings were deposited by reactive magnetron sputtering on substrates of single-crystal silicon, and Titanium Grade2 wafers. To control and manage the coating deposition process by reactive magnetron sputtering, a previously developed modular gas flow control complex (MGFCC) was used. The elemental composition was studied by energy-dispersive X-ray spectroscopy (EDX). The structural-phase state of coatings was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical properties, such as hardness and Young’s modulus, were investigated by the nanoindentation using a CSM Instruments Nanohardness Tester NHT2 (Switzerland). The influence of deposition parameters such as: Ti and Al content, reactivity degree α, and nitride concentration on structure and mechanical properties was considered. It was found that a decrease in the reactivity degree α from 0.605 to 0.474 leads to a 23 % increase in the deposition rate of TiAlCuN coating. It was detected that adding Cu to the coating content decreases the mean sizes of crystallites and growth columns in comparison with the TiAlN analogues due to its segregation along crystalline boundaries and thus advances better mechanical characteristics. The hardness of TiAlCuN coatings varies in the range of H = 29.3–35.4 GPa, Young’s modulus E = 235.9–267.6 GPa. The impact strength index as the H / E∗ ratio and the plastic deformation resistance index H3 / E∗2 were calculated. The formed nitride coatings are suitable for use in space technologies.

Nanostructured TiAlCuN and TiAlCuCN coatings for spacecraft: effects of reactive magnetron deposition regimes and compositions.

Spacecraft are exposed to a number of factors in the outer space: irradiation by electron flows, high-energy ions, solar electromagnetic radiation, plasma irradiation, and a stream of meteorite particles. All these factors initiate various physical and chemical processes in spacecraft materials, which can eventually lead to failure. To ensure reliable operation of spacecraft, it is necessary to use protective coatings and special radiation-resistant materials. TiAlCuN and TiAlCuCN coatings were formed by reactive magnetron sputtering on different substrates: single-crystal silicon and Titanium Grade 2 wafers. Nitrogen was used as a reactive gas to form nitride coatings and acetylene was used to form carbonitride coatings. The elemental composition was studied by energy-dispersive X-ray (EDX) spectroscopy. The structural-phase state of the coatings was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical properties, such as hardness and Young modulus, were investigated by nanoindentation using a CSM Instruments Nanohardness Tester NHT2. The influence of deposition parameters, such as Ti and Al contents, the degree of reactivity α, and carbonitride formation on the structure and their mechanical properties were considered. It was detected that Cu addition to the coatings has effects on crystallite and growth column size refinement in comparison with the TiAlN and TiAlCN analogues due to its segregation along crystalline boundaries, and thus, imparts better mechanical characteristics. The hardness of TiAlCuN and TiAlCuCN coatings varies in the range of H = 25-36 GPa and Young modulus - E = 176-268 GPa. The impact strength index and the H/E* ratio, as well as the plastic deformation resistance index H3/E*2, were calculated. Due to their high mechanical properties, the formed nitride and carbonitride coatings are promising for use in space technologies.

ВЛИЯНИЕ ЛАЗЕРНОЙ МОДИФИКАЦИИ ПОВЕРХНОСТИ НА ФИЗИКО-МЕХАНИЧЕСКИЕ И ТРИБОЛОГИЧЕСКИЕ СВОЙСТВА ШТАМПОВОЙ СТАЛИ

The effect of laser modification of the surface on the value of the coefficient of elasticity, hardness, coefficient of friction and the amount of wear of the counterbody when testing pro­ducts made of tool die steel H12MF was investigated. The SVAROG-1-5DR laser complex (Russia) was used for laser processing. When setting different modes of laser processing, the power of laser radiation, the speed of movement of the laser beam relative to the treated surface and the focal length were varied. The measurement of Vickers hardness and wear resistance indicators was carried out using the MicroCombiTester and Tribometer units of the firm CSM Instruments (Switzerland). Rockwell hardness was measured using a TN 301 hardness tester from Time Group (China). The alloy structure was studied by metallography and X-ray diffractometry. It was found that the indicators of hardness and wear resistance of the surface layers of steel H12MF strongly depend on the laser treatment modes. These dependencies are extreme in nature, have maximums and minimums. The paper presents quantitative values of hardness and wear resistance indicators before and after laser treatment of the surface of this steel according to different modes. The reasons for the change in the hardness and wear resistance of the surface layers of steel H12MF after laser treatment according to various modes have been established. The results of the work were used to optimize the modes of laser surface treatment of steel H12MF in order to obtain maximum values of hardness and wear resistance. It has been shown that laser treatment of steel H12MF without melting is promising in terms of increasing hardness and reducing friction. The mode of laser modification of the SVAROG-1-5DR complex was obtained, which allows increasing the hardness by 55.5% while reducing the coefficient of friction by 12.9% and reducing wear by 27.3%.

Tribotechnical Properties of Materials for Cultivator Sliding Bearings

Agricultural machinery is stated to break down mainly due to the wear of structural parts. Thus, there is a necessity to apply new materials for manufacturing individual machine units whose characteristics will not be inferior to those of their prototypes. The paper primarily focuses on the components that work in movable joints, in particular, on the sleeve type bronze plain bearings which are exposed to high wear and often need replacing. The use of polymers for manufacturing such parts is supposed to solve the problem of untimely failure of machine components. (Research purpose) To compare the tribotechnical properties of cultivator sliding bearings made of bronze and polyamide. (Materials and methods) Two samples were made: one was made of the sliding bearing (BrO10F1 grade bronze) of the SunGarden GT10 cultivator, the other – of a PA-6 polyamide type rod. Special equipment was used such as: X-ray fluorescence spectrometer Thermo Scientific Niton XL3t 900 GOLDD+, TRB-S-DE Tribometer CSM Instruments. (Results and discussion) Comparative tribotechnical ball-disk tests were carried out. It was found out that polyamide sample has certain advantages over a bronze standard: it has a 4-times better friction coefficient and a 12-times better wear intensity. (Conclusions) It was determined that the use of polymer plain bearings will result in 2 times longer service life of agricultural cultivators and their 1.5 times increased efficiency.

ANALYSIS OF DEFORMATION AND FORMS OF DESTRUCTION OF COATING-SUBSTRATE SYSTEMS

The paper presents the results of fracture testing of a coating-substrate system subjected to a concentrated contact load and during a scratch test. A diamond indenter with rounding radii in the range 20-500 µm was used under the tests. Systems with CrN coatings in the range of 1 to 5 µm applied to austenitic steel X5CrNi18-10 were analysed. In the paper, the effect of coating thickness on deformation and fracture of the coating and substrate in the load range of 1 and 3 N is analysed. Cohesion and adhesion sites of the coating to the substrate were determined. Optical profilometer images, scanning microscope images, and Micro Combi Tester images – CSM Instruments were used to analyse Lc1, Lc2, and crack locations. It was observed that, as the indenter radius increases, cracks in the coating-substrate system develop at increasing loads. Average critical forces are also higher with indenters of 200–500 µm. In the case of indentation only, with the indenter’s radius of 500 um, it is 750 Nm for the thinnest 1 µm coating and 1750 Nm for the 5.2 µm coating.

Investigation of physical, mechanical and tribological properties of corrosion-resistant steel with laser surface surfacing of WC100Co4Cr

The article investigated the effect of laser surfacing of WC100Co4Cr powder on the surface of corrosion-resistant steel on hardness, tensile strength and yield strength, coefficient of friction and the amount of wear of products made of alloy structural cryogenic steel. The SVAROG-1-5DR laser complex (Russia) was used for laser processing. Various modes of surface laser surfacing were set. For this purpose, the power of the laser radiation, the speed of movement of the laser beam relative to the treated surface and the focal length were varied. The measurement of physical, mechanical and tribological characteristics was carried out using the equipment of the company “CSM Instruments” (Switzerland). The structure of the alloy was studied by metallography and X-ray diffractometry. The results showed a significant increase in hardness, tensile strength and yield strength and a decrease in the coefficient of friction.

Effect of Chromium Addition and Regimes during Electrospark Alloying with Aluminum Matrix Anode Material of Steel 45

Introduction. Electrospark alloying is used to produce hardening coatings. Anodic materials with unique properties include metal matrix composites based on aluminum. The aim of the work is to develop new aluminum matrix anode composite materials with high efficiency indicators during electrospark alloying of carbon steel 45. Materials and Methods. Structural carbon steel 45 was used as the substrate (cathode). Aluminum matrix materials are chosen as the anode materials. The value of the cathode weight increment and the anode erosion were determined by the gravimetric method on the Shinko Denshi HTR-220 CE electronic scale with an accuracy of ±∙10–4 g. To study the microstructure and metallography of the surface of the anode materials, the microscopes EVO-50 XVP and Altami MET 3 APO from S. ZEISS were used. The device CALOTEST CSM Instruments was used to study coatings for microabrasive wear. Results. There is developed a methodological scheme for achieving the efficiency of the electric spark alloying parameters and the properties of the doped layer depending on the composition of the anodic metal matrix composite material based on aluminum with the addition of chromium and processing modes. The mode of Institute of Materials Science electrospark installation with pulse energy of 14.4 J was set for anode material application during electrospark alloying. It is established that after electric spark alloying of steel 45, the hardness and wear resistance of the surface increase by 2-3 times, and the heat resistance ‒ by 5–18 times. Discussion and Conclusion. The series of increasing the cathode mass, the erosion resistance of the electrode materials, mass transfer coefficient, heat resistance, hardness and wear resistance of the alloyed layer are obtained. The obtained series are a convenient tool for achieving various efficiency parameters in electric spark alloying depending on the selected anode material and processing modes.

A Study on Material Properties of Intermetallic Phases in a Multicomponent Hypereutectic Al-Si Alloy with the Use of Nanoindentation Testing.

The paper concerns modeling the microstructure of a hypereutectic aluminum-silicon alloy developed by the authors with the purpose of application for automobile cylinder liners showing high resistance to abrasive wear at least equal to that of cast-iron liners. With the use of the nanoindentation method, material properties of intermetallic phases and matrix in a hypereutectic Al-Si alloy containing Mn, Cu, Cr, Ni, V, Fe, and Mg as additives were examined. The scanning electron microscope equipped with an adapter for chemical composition microanalysis was used to determine the chemical composition of intermetallics and of the alloy matrix. Intermetallic phases, such as Al(Fe,Mn,M)Si, Al(Cr,V,M)Si, AlFeSi, AlFeNiM, AlCuNi, Al2Cu, and Mg2Si, including those supersaturated with various alloying elements (M), were identified based on results of X-ray diffraction (XRD) tests and microanalysis of chemical composition carried out with the use of X-ray energy dispersive spectroscopy (EDS). Shapes of the phases included regular, irregular, or elongated polygons. On the disclosed intermetallic phases, silicon precipitations, the matrix, values of the indentation hardness (HIT), and the indentation modulus (EIT) were determined by performing nanoindentation tests with the use of a Nanoindentation Tester NHT (CSM Instruments) equipped with a Berkovich B-L 32 diamond indenter. The adopted maximum load value was 20 mN.

ОЦЕНКА ТРИБОТЕХНИЧЕСКИХ СВОЙСТВ ПОКРЫТИЯ, ПОЛУЧЕННОГО ЭЛЕКТРОИСКРОВЫМ УПРОЧНЕНИЕМ

When applying coatings using various methods on the surfaces of moving parts that work in joints, it is important to make sure that the coatings are strong and wear-resistant in order to return them to their original resource. All existing hardening technologies and materials used to perform coatings have their own characteristics, therefore, the quality of the resulting coatings can be judged only after specific tests. (Research purpose) The research purpose is in evaluating the properties of the coating obtained by the method of electric spark hardening, and its ability to resist friction and mechanical wear. (Materials and methods) Authors conducted tests on the basis of the "Nano-Center" center for collective use. A coating was applied on the BIG-4M unit with a VK-8 hard alloy electrode, tribological properties were evaluated on a CSM Instruments TRB-S-DE-0000 tribometer, the width of the friction track was measured after the test using an inverted OLYMPUS gx51 optical microscope, and samples were weighed before and after the test on a VLR-200 analytical balance. Conducted research in accordance with GOST 23.224-86 and RD 50-662-88 guidelines. (Results and discussion) The article presents performed tests on the run-in and wear resistance of the coating. The samples were worked on with a step-by-step increase in the load. During the tests, the friction force was drawed on the diagram. Authors compared the results with the reference sample, an uncoated surface. (Conclusions) The resulting coating has better run-in and wear resistance compared to the standard, and the increase in wear resistance in dry friction conditions is very significant.

Multiple-factor model of hardness of steel 40H13 after laser processing

The multiple-factor experiment is planned and made, and the hardness of the chromic steel 40H13, which is subjected to laser processing on a multibeam laser complex, is determined. Samples in the form of a cylinder 7 mm long and with a diameter of 30 mm are exposed to laser processing. Hardness of the processed surface layer of samples was measured by means of the Micro-Combi Tester installation of CSM Instruments (Switzerland). The independent entrance factors of process, which significantly impact on operational indicators of the processed surface layer, are chosen: power of laser radiation, longitudinal feed of laser beam and a distance from protective glass of a focusing head up to the processed surface. As a result of performance of the plan of a multiple-factor experiment and statistical data processing of a planning matrix the regression equations, which connect the optimization parameter with independent factors, having the interactive and dominating impact on formation of physic-mechanical characteristics of quality of the processed surface layer are received. On the basis of the received multiple-factor model and its graphic interpretation the appointment and optimization of modes of the laser processing, which provides the required values of hardness of a surface layer, is possible.

Improving Tribological Properties of Stainless Steel Surfaces by Femtosecond Laser Irradiation

A possibility of improving tribological properties by femtosecond laser irradiation on an example of a steel surface by creating regularly arranged micro-grooved textures that contain self-organized microstructures and nano laser-induced periodic surface structures (LIPSS) was determined. The friction coefficient of the treated surface of a sample of cold-rolled 1.4301 stainless steel was evaluated using a CSM Instruments SA tribometer according to a Pin-on-disk test scheme at a specific pressure of 1 MPa. It was found that the coefficient of friction was reduced by 35% compared to the initial grinded surface. Such laser treatment can find application for using parts in conditions of dry or boundary friction, mainly in units, in which the use of lubricant is unacceptable or extremely undesirable.

Effect of Laser Shock Peening on the Microstructure and Properties of the Inconel 625 Surface Layer

The aim of this work was to investigate the influence of laser shock peening on the topography, microstructure, surface roughness and the mechanical properties of the Inconel 625 nickel alloy. Examination of the topography and microstructure of the nickel alloy after laser treatment was carried out by means of scanning electron microscopy as well as atomic force microscopy. The roughness of the surface was measured by WYKO NT9300 equipment. Nanohardness test was carried out using a nanoindenter NHT 50-183 of CSM Instruments equipped with a Berkovich diamond indenter. Additionally, transmission electron microscopy was used to examine the microstructural changes on the surface layer after laser treatment. The investigations showed that the laser process produced an ablation and melting of the surface layer and, hence, increased the surface roughness of the Inconel 625. On the other hand, the presence of the slip bands on the surface and on the cross section of the treated material, a high density of dislocations and a higher hardness of the treated region indicated that the laser shock processing caused severe plastic deformation of the surface layer. Additionally, due to the high plastic deformation, cracking of the carbide precipitates was observed.

Analysis of Wear Resistance Characteristics of Additive Products Made from Electroerosive Cobalt-Chromium Powders

Purpose of research of this research is to study wear resistance characteristics of additive products made from electroerosive cobalt-chromium powders. Methods . Wastes of cobalt-chromium CELLIT alloy were used for the research [27]. Butyl alcohol was used as a working fluid. A unit for layer-by-layer application of powder materials with plasma was used for experimental samples production. The intensity and wear rate of the sample surface and counterface were measured on Tribometer automated friction machine, CSM Instruments. The sample was mounted in a holder. A rod was fixed perpendicular to the surface of a sample. A 6 mm diameter ball made of Stainless Steel AISI 420 (Vickers hardness 5000-8000 HV) was at the end of the rod. Radius of wear curvature was selected by adjusting the displacement sensor. Another sensor compensated the friction force and allowed to set the friction coefficient value at a certain time. The condition of friction surfaces was studied with the help of optical inverted microscope Olympus GX 51 equipped with SIMAGIS Photolab automated image analysis system and Quanta 200 3D electron ion scanning microscope. Results . According to the performed analysis of wear resistance characteristics of additive products made from electroerosive cobalt-chromium powders friction coefficient varies from 0.144 to 0.602. An average friction coefficient is 0.526. A wear factor of the sample is two times higher than the wear factor of counterface. Conclusion . Performed research allows expanding the information about properties of additive products made from electroerosive cobalt-chromium powders and reducing production cost.

Study of biodegradability of the vegetable oil modified epoxy coatings

АBSTRACT
 Introduction. For solving environment protection problems and reducing the volume of ‘polymer waste’, the study of biodegradability of polymer materials by means of their modification without impairing main performance is of practical importance. This is achievable by application of biodegradable natural additives. The radical solution is the development of polymer materials that are capable of retaining their performance throughout their service life only.
 Materials and methods. To modify compositions, APh-2 aminoalkylphenol-cured ED-20 epoxy diane resin was used. Liquid fraction of rubber tree oil (RTO) and Vietnam-produced soybean oil (SO) were used as the modifiers. Biodegradability of the materials was evaluated by Sturm’s method checking respirometric activity of soil in their presence. Resistance of the epoxy materials to microbiological putrefaction in soil was investigated by mass loss value. Thermal stability of the epoxy coatings was tested by simultaneous thermal analysis on Netzch-Gerätebau GmbH apparatus at the heating rate 10 °C/min when the temperature varying within the range of 25 °C to 600 °C. Water absorption was evaluated as per GOST 4650-2014 standard. Sol-gel analysis was implemented in boiling acetone in the Soxhlet apparatus. Abrasion hardness of epoxy materials was carried out on the IZV-1 vertical optical caliper. Hardness was checked by Barcol impressor. Frictional factor was determined by means of the CSM Instruments Tribometer automated friction machine.
 Results. Applying vegetable oils governs a significant growth of the abrasion resistance and enhancement of antifriction characteristics of epoxy materials. The vegetable oils exercise a plasticizing effect on epoxy compositions, accelerate processes of epoxy material biodegradation in soil and reduce their resistance to micromyces. Epoxy resin is characterized with high funginertness and its modification by the RTO results in enhancement of biodegradability when exposed to mouldy fungi.
 Conclusions. Applying the RTO as a modifier of the epoxy materials accelerates processes of their biodegradation in soil and decreases their resistance to micromyces. The higher biodegradation of vegetable oil-modified epoxy films takes place at complex exposure to bacteria and mycelian fungi as a part of soil microbiocenosis.

Microhardness of Coal from Near-Fault Zones in Coal Seams Threatened with Gas-Geodynamic Phenomena, Upper Silesian Coal Basin, Poland

Near-fault coal displays some specific structural and textural features. As the distance to the fault diminishes, one can observe ever stronger, gradual degradation of coal, demonstrated by the emergence of structural distortions exogenic in their origin, visible under a microscope. The process of gradual degradation of coal—manifested by the appearance of structural distortions exogenic in their origin—takes place. This can be observed under a microscope. The measurements of the microhardness of structurally altered coal carried out using the Vickers hardness test. For the purpose of this research, a microhardness tester by the CSM Instruments was used. The microhardness of particular structural types of coal was measured. The procedure encompassed both structurally unaltered and altered coal. The tested objects were exogenically fractured fragments, cataclastic, and mylonitic structures. Each of the analyzed structural types displayed a different range of the microhardness, with the highest values confirmed for the structurally unaltered coal. In the case of fractured coal, the microhardness values were somewhat lower. Finally, the lowest values were ascertained for cataclastic coal. Mylonitic coal, in turn, displayed microhardness values similar to those found in the unaltered coal. It was also observed that, in the case of the unaltered, fractured, and cataclastic coal, cracks propagated in the manner typical of brittle materials, whereas the mylonitic coal revealed some degree of elasticity. The analyzed microhardness parameters expose the structural–textural features of coal, particularly when it comes to the degree and character of destruction of the rock’s original matrix. The specific structural–textural composition of particular types of near-fault creations influences both their sorption parameters and the compactness of coal in a seam.

Evaluation of the Friction Coefficient of Antifriction Coatings Based on Ti-Cu Obtained by the Ion-Plasma Deposition in Vacuum

Ion-plasma antifriction coatings based on Ti-Cu were deposited by the method of ion-plasma sputtering in vacuum with the aim to gain a coating with a low coefficient of friction. To protect steel part from wear intermetallic, nitride and conglomerate coatings based on Ti-Cu with thickness of the coating h ≈ 2-5 μm obtained at different regimes of deposition. Thickness of the antifriction coatings and proportion of the chemical composition varied by deposition time, voltage and current of the magnetron, current of evaporators, pressure of gas in a vacuum chamber. This paper presents the results of the tribotest carried out on CSM Instruments pin-on-disk type tribometer. Comparing with uncoated samples microhardness and roughness of the coated samples increased two to three times, coefficient of friction of coated samples was twice lower.

Friction of dental resin composite exposed to lactic acid

Introduction: Lactic acid concentration in the blood and saliva increases during physical exercise [1], leading to dental erosion and the degradation of restorative dental materials [2]. Our goal is to evaluate the effect of lactic acid exposure on the surface of a composite resin Materials and methods: 16 discs were made from Filtek ™ Z250. Every disc was divided into three distinct areas, resulting in a total of 48 samples that were randomly distributed into four groups (n = 12). Group A and B were placed in 5 mL of artificial saliva while group C and D were placed in 5 mL of lactic acid (pH =4.0). Intermittent exposure to the acidic solution (8 hours) alternated with artificial saliva (8 hours), till complete 1 day (group C) or 7 days (group D). All samples were submitted to nanotribological wear tests with a Nano-Tribometer (CSM Instruments SA, Peseux, Switzerland), using as counter-body a zirconia ball. Statistical analysis via one-way ANOVA with Tukey HSD Post Hoc test and independent samples t-tests were performed. Results: The highest friction coefficient (Table 1) was obtained with the acid lactic group at both timings (0.188 at 1 day and 0.144 at 7 days). Statistically significant differences between solutions were found with time: friction coefficient decreased in all groups when the exposition time increases from 1 to 7 days. (p < 0.05). Discussion and conclusions: The resin exposed in an intermittent way to lactic acid for 1 day presented the highest friction coefficient. The obtained results showed that lactic acid led to an increase of the friction coefficient, which was more significant for the lower exposure time. This may be attributed to the acid effect on the surface of the resin that wears the resin making it smoother, thus reducing friction.

Epoxy antifriction wollastonite-filled materials

Introduction. Domestic mineral natural-origin filler ‘wollastonite’, also known as calcium methyl silicate, is widely used as a base for wear-resisting epoxy antifriction materials. Due to anisodiametric shape of its particles, wollastonite functions as a micro reinforcement fibre enhancing adhesion strength and wear resistance of epoxy compositions, improving their antifriction properties, especially when organomodifying by quaternary ammonium salts. In this regard, the investigation of the impact of chemical composition of such surfactants as quaternary ammonium salts on the properties of epoxy compound materials presents utmost interest for researchers developing low-friction materials. Materials and methods. Epoxy diane resin ED-20 was hardened with aminoalkylphenol AF-2. Content of epoxy hardener was determined by equimolar ratio of epoxy groups to amine groups. Domestic wollastonite of the grade Miwoll 10-97 was used as filler, particle length to the diameter correlated as 15:1. The wollastonite surface was activated with surfactants belonging to domestically produced quaternary ammonium salts. Wear resistance of specimens was tested by means of the vertical optical caliper IZV-1. Friction coefficient was estimated with the assistance of the computer-automated frictional machine CSM Instruments Tribometer. Adhesion strength of glue joint was determined as per GOST 28840-90 standard. Two bars of sheet aluminium were used as glued surfaces as per GOST 14759-69 standard. Results. Reduction of wear of epoxy coatings when modified with micro reinforcing wollastonite can be explained by the increase of cross-linking degree of the polymer. The length of alkyl radical of quaternary ammonium salts used for wollastonite surface activation affects the intervals between the epoxy links. As the quaternary ammonium salt chain length is growing, wear of epoxy materials is reducing. Introduction of the wollastonite containing metallic oxides in the epoxy composites increases wear resistance and adhesion strength and reduces coating friction coefficients. Conclusions. Hardened with the AF-2 and filled with the wollastonite of the Miwoll 10-97 grade, the epoxy compound materials have enhanced wear resistance and adhesion strength and lower friction coefficient. The best result is observed when applying wollastonite modified with a surfactant belonging to the class of quaternary ammonium salts. The wollastonite can be used for practical purposes as a perspective reinforcing agent for epoxy materials with improved wear resistance, enhanced adhesion to metals and reduced friction coefficient.

Wear behavior of Diamond-like Carbon Deposited on Ti6Al4V Prepared with Surface Mechanical Attrition Treatment

Surface modification by deposition of hard coatings is a way to overpass the poor wear resistance of some metallic materials and one potential material is the Diamond-Like Carbon (DLC). We investigated the wear behavior, and the adhesion of the DLC deposited on a Ti6Al4V (Ti64) alloy after Surface Mechanical Attrition Treatment (SMAT). The SMAT was applied using 100Cr6 steel balls, and the DLC was deposited through the sputtering method. The nano-hardness was evaluated using a MTS Nano Indenter XP. The adhesion of the DLC was evaluated using a CSM Revetest, and the wear tests was performed in a reciprocating linear tribometer from CSM Instruments. The mean wear rate for the Ti64 was 437x10-6 mm3/N/m against 5x10-6 mm3/N/m for the Ti64+SMAT+DLC. The SMAT reduced the wear rate of the DLC coating, showing that the SMAT might be a viable treatment with promising results regarding the DLC wear resistance.