Wear Traces Research Articles

Шлифовка камня и усложнённое собирательство в палеолите: есть ли связь? (по материалам Костёнковско-Борщёвских стоянок)

Spectacular finds at some of the Gravettian sites of the Kostenki-Borshevo region on the Don River served for the reconstruction of the economic and technological characteristics of the Middle Upper Paleolithic. The materials of these sites contain large polished stone artifacts, but till recently the technology of their manufacture has not been studied in the context of the whole industry. Quartzite slabs with wear traces indicative of their use as grinders traditionally, following A. N. Rogachev, were considered as tools for processing plant resources obtained in the course of gathering. In addition, many of the salbs in question bear residues of ocher-based colorants. The article discusses the connection between the technological chains associated with the production of polished stone pieces and ocher-based colorants and their relationship with the concept of “complex gathering” proposed by A. N. Rogachev. It is shown that stone polishing was not a sporadic activity, but represented rather a well-developed technological know-how common for the Gravettian sites of Kostenki. Quartzite slabs were used both in grinding and in the production of colorants. Without denying the possibility of using such slabs for processing plant products, we have to stree that such a function definitely was not the only one.

Effect of plasma nitriding on tribological properties of nickel‑boron-nanodiamond electroless coatings

This study is an effort to investigate the synergic effect of nano-diamond (ND) addition and plasma nitriding (PN) treatment on tribological and structural properties of nickel‑boron (NiB) coatings. NiB/ND nanocomposites containing different amounts of NDs (0.0, 0.1, 0.5, and 1.0 g/L) were produced in an electroless bath. Then, plasma nitriding was conducted on the samples for 1 h at 400 °C in an N2-H2 environment. To study phase analysis and examine the surface morphology of the samples, X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) were utilized. The wear behavior and friction were determined under the normal load of 10 N using the pin-on-disk method. The surface roughness, microstructure, and microhardness were also assessed. The results showed that, as the ND concentration increased, the amorphous structure of as-plated (AP) Ni-B transformed to a semi-crystalline one. Moreover, the amorphous structure of the as-deposited NiB/ND coatings changed to a crystalline one after plasma nitriding, which resulted in a higher hardness value. NiB/0.5ND coating showed the highest hardness value (1523 HV0.1) and the highest wear resistance (0.8×10−10 Kg/N.m). The smoothest wear trace with no visible cracks is related to the worn surface of PN NiB/0.5ND sample, suggesting that the NiB/ND nanocomposite can be a promising candidate for surface engineering processes.

Effect of ultrasonic surface rolling process on the surface properties of QAl10-3-1.5 aluminum bronze alloy

The main purpose of this article is to study the effect of ultrasonic surface rolling process (USRP) on the surface properties of QAl10-3-1.5 aluminum bronze alloy under different rolling reduction and rolling times, providing ideas for improving the poor wear resistance of valve stem nuts and sealing rings. SEM, EDS and optical three-dimensional profiler were used to characterize the microstructure characteristics of the surface modified layer and the surface morphology of the wear traces. The results show that the surface layer of the USRPed sample has undergone severe plastic deformation. The α phase is elongated, and the microstructure structure shows a fine and uniform distribution state. And the grain size of α phases decreased, and the number density of β phases increased. Compared with the untreated sample (only cutting and polishing), the surface roughness of the USRPed sample reaches nearly Ra 0.04 μm; the maximum surface micro-hardness is 323.04 HV, increasing by 75%; the maximum depth of surface hardening layer is about 570 μm. The friction coefficient, wear mass loss and the width and depth of the wear traces of the USRPed samples are significantly reduced, while the wear resistance is significantly enhanced. By comparing the surface wear morphology of the samples under different process parameters, it is found that the main wear mechanism of the untreated samples is adhesive wear, while the main wear mechanism of the USRPed samples is abrasive wear. The improvement in wear resistance is attributed to the refined and homogenized surface microstructure, the smaller surface roughness, the larger surface micro-hardness and surface hardness layer depth after USRP.

Каменная индустрия памятника Гвоздевка i

The article covers the exploration of the stone industry of a Mesolithic site Gvozdevka I. The Stone Age man site is located in Moskalenki district of Omsk region, at the southern end of Lake Ebeyty, on the eastern bank of flood plain Amre (Amrinsky beam). It was discovered in 1976, last investigated in 2004. In the course of archaeological work, a representative collection of stone artefacts was formed, among them microplates occupying a considerable place. The manufacturing specificity of site materials is difficult for analysis, but certain aspects of plate production and utilisation can be taken into consideration. The techno-typological method, as part of attributive approach, was used for their analysis. The description and analysis of the stone industry was made according to the parameters characterising the metric indicators of cleavage, cleavage zone and dorsal surface. The basic strategy of stone cleavage is reconstructed, aimed to produce lamellar chipping with the use of pressure flaking technique. The production of inlay blanks - thin plates with straight lateral profile and sharp longitudinal edges - appears to have been the ultimate goal of the cleavage. The quality of the analysed material enables one to study not only the techno-typological aspects of its manufacture, but also the traces of non-utilisation wear, secondary processing of blanks as well as functional wear (which is the subject of further research). This suggests that the monument was used to split pre-nuclei or nuclei brought by people; the obtained plates were actively used in the process of treatment of various materials. On the whole, using the attributive approach to the study of Gvozdevka I site stone industry made it possible to establish the major strategies of stone splitting and to reconstruct the primary splitting system, as well as to create a framework for comparison with other monuments of the same period on the territory of Omsk region and adjacent areas, to outline the prospects for further research.

Microstructure and tribological behavior of Ti3C2Tx MXene reinforced chemically bonded silicate ceramic coatings

MXenes – In recent decades, great attention has been paid to the fast-growing two-dimensional (2D) transition metal carbides and nitrides, in terms of their prominent mechanical and electrical properties. The tribological essence of MXene has not yet been entirely investigated, although researches on MXene were conducted in all aspects of its applications. Hence, a newly compound 2D MXene (Ti 3 C 2 T x ) is exploited to reinforce the wear resistance of the chemically bonded silicate ceramic coatings, which are utilized to protect component surfaces under severe conditions. The structural features, hardness, and tribological behaviors of the targeted coatings are investigated and analyzed. Results show that the micro-hardness of the coatings increases to 156.9 HV 0.5 when added 1.2 wt% MXene. The increment of microhardness extraordinarily reaches 33.3%, compared with the original. The coating with 1.2 wt% MXene also indicates a 31.6% decrement of the coefficient of friction (COF) and a 73% reduction of the wear rate respectively. Furthermore, fatigue is found to be the main reason of the wear mechanism, through exploring the surface morphologies of wear traces and counterpart balls.

Functional use of large stone tool from the Upper Paleolithic site of Kamennaya Balka II (the Northern Azov Sea region, Russia)

The assemblages of many Paleolithic sites on the Russian Plain contain large pebbles of various types of stone, which, due to the natural and unmodified forms, rarely become objects of special study. Some of them retain their natural shape, others are slightly artificially modified. In the course of our research, artifacts from several Paleolithic sites in Russia and the Republic of Moldova were subjected to a comprehensive study. Technical-morphological and experimental-traceological studies made it possible to characterize the methods of their manufacture and use. Among the items studied, there is a trapezoidal slab retrieved in the lower layer of the Late Paleolithic stratified site Kamennaya Balka II (the Northern Azov Sea region, Russia). On its surface, use-wear traces were found, which are characteristic of wear traces on tools used to grind plant materials. To verify the results of the traceological analysis, a series of experiments was performed. The wear traces on the working part of the experimental tool turned out to be similar to those found on the original one. The functional identification of the slab from Kamennaya Balka II as a tool for processing plants was also confirmed by the discovery on the working surface of mineralized starch grains.
 This comprehensive study of an unmodified stone artifact from the Kamennaya Balka II site and its identification as the lower grinding stone indicates the presence of complex foraging strategies among the economic activities of the inhabitants of the site and their successful adaptation to the natural environment in this region.

Influence of surface morphology parameters of steel on tribological properties between glass‐fiber‐reinforced polytetrafluoroethylene composites and steel under dry‐friction and oil‐lubrication conditions

AbstractPolytetrafluoroethylene (PTFE) composites are commonly used engineering materials owing to their good tribological and mechanical properties. In this study, a friction pair was formed by a glass‐fiber‐reinforced PTFE composite and a chromium‐plated nickel‐based stainless steel plate (18Cr2Ni4WA). Under dry‐friction and oil‐lubrication conditions, friction and wear tests were carried out on the metal plate surface in two roughness ranges and three surface‐texture directions. The friction coefficient, wear rate, width and depth of the wear trace, wear morphology, and surface composition were analyzed. The results showed that the 90° texture direction of the steel plate with respect to the moving direction under oil lubrication and the 0° texture direction under dry friction were the texture directions with the best tribological performance. The friction and wear properties of the PTFE composite under dry friction were better than those under oil lubrication. The 0.3–0.5 μm roughness range of the steel plate was the best roughness range for the tribological properties of the matching pairs.

Structural and tribological properties of the re-casted dental NiCrMo alloy

The crisis related to the COVID 19 pandemic caused an increase in nickel prices on the global markets. From this perspective, it seems promising to search for the possibilities of effective recycling of nickel-based alloys as biomaterials. The topic of the recasting of Ni-Cr dental alloys is currently being broadly described in the literature. Nonetheless, there are still no conclusive results on the impact of recasting on the quality of the cast dentures. Considering the aforementioned, for research, the effect of recasting on the wear resistance and microstructure of NiCrMo dental alloy was investigated. The Heraenium NA alloy was used for testing. Abrasion resistance was tested by the ball on disc method. Microstructure and wear trace were observed using an optical microscope and a scanning electron microscope. The tests showed a higher wear resistance of the re-casted material. The average coefficient of friction for the initially cast alloys was 0.664, while for the remelted samples the mean value was 0.441. The tested samples are characterised by an abrasive-adhesive wear mechanism. Piling up of the wear tracks edges was observed – the highest for H100. For the H100 samples, a slightly lower average hardness value (HV10) was observed – 226 compared to 233 (HV10) for the samples made from the re-casted alloy (H0). The presence of a dendritic structure of alloys was demonstrated. Blocky eutectic precipitations are visible against the matrix. The observed growth of interdendritic precipitations constitute a natural barrier for the counterpart material and increases its tribological properties. Obtained results suggest that alloy recasting does not constitute a limitation to its use.

Investigation of Micromechanical Properties and Tribological Behavior of WE43 Magnesium Alloy after Deep Cryogenic Treatment Combined with Precipitation Hardening.

This study investigated the micromechanical and tribological properties of WE43 alloy (Mg-Y-Nd-Zr) alloy subjected to cryogenic treatment and precipitation hardening. Microindentation tests were carried out in the range of load from 100 to 1000 mN. The introduction of deep cryogenic treatment (DCT) was shown to increase hardness and Young’s modulus, and reduce the total indentation work. As the load set during the tests increased, a gradual decrease in the measured values was observed, indicating a significant relationship between the indent size and the value of the measured parameters. Cryogenic treatment used in conjunction with precipitation hardening (after solutioning and after aging) reduces the tribological wear of the alloy. Tests have shown an almost twofold reduction in the area of the wear trace and in the volumetric wear of the alloy, as well as a more than twofold reduction in linear wear, with relatively small fluctuations in the coefficient of friction. Abrasion was the main mechanism of wear. Areas where microcutting, adhesion and plastic deformation occurred were also observed. The results indicate the significant effectiveness of the applied heat treatment in improving the service life of the WE43 alloy containing rare earth metals.

Process optimization for enhanced tribological properties of Al/MWCNT composites produced by powder metallurgy using artificial neural networks

In order to eliminate the agglomeration problem of reinforcement in the nanocomposite, a two-step dispersion process was employed. Under ultra-sonication and ball milling, 1 wt% of multi-walled carbon nanotubes (MWCNTs) were properly dispersed in pure aluminum (Al) (used as the matrix phase). The composite powder mixture was then consolidated in an inert Ar gas atmosphere by hot pressing under certain fabrication parameters. The powder mixture was characterized by Raman Spectroscopy, and it was found that MWCNTs did not cause structural defects in the pre-production process. The microstructural analysis of the sintered composites by Scanning Electron Microscope (SEM) and Energy-Dispersive x-ray Spectroscopy (EDS), revealed that the reinforcement was uniformly distributed in the matrix. Wear test results indicated that the wear resistance of the composites increased with increase of MWCNT reinforcement, and the wear mechanism was determined to be a mixing type by examining the wear traces by SEM. In order to determine the effects of different process parameters on wear loss, a Multilayer Perceptron (MLP) based Artificial Neural Network (ANN) was used, and experimental and predicted values were compared. It was noticed that the MLP based ANN model effectively evaluated the wear properties of the Al/MWCNT composites.

Influence of different hard-facing procedures on quality of surfaces of regenerated gears

Abstract During the process of regeneration of machine parts, certain phenomena occur that have a significant impact on the loss of their working ability. Hereditary properties are expressed by the interdependence of geometric and physical-mechanical-metallurgical parameters of gear teeth created during the technological operations of regeneration of worn teeth by hard-facing. The influence of the type of additional material (electrodes and their combinations) on the tribological characteristics of welded gear teeth was considered, whereby the so-called hard additional materials were applied. Those are the additional materials that give the required surface hardness of the teeth without subsequent thermal or thermochemical treatment. This research did not involve the regeneration of specific worn gears removed from machine systems, but the new gears were made, which were then damaged and then regenerated by hard-facing using the shielded metal arc welding (SMAW) procedure. Thus, all the tested gears were made of the same material, belonged to one batch and were machined on the same machines with the same machining regimes. The tests were performed on samples made of 20MnCr5 steel for cementation, on a tribometer by the “block on disc” method, which was designed to simulate the operating conditions of coupled teeth of concrete gears in the exploitation conditions. Based on the conducted tribological tests, the average coefficients of friction and topography of the surfaces were determined by measuring the wear trace and it was defined which additional materials give the best tribological characteristics of the surfaces of gears regenerated by hard-facing.

Failure Analysis and the Evaluation of Forced-in Joint Reliability for Selected Operation Conditions

In this article, sample damage and wear of forced-in joints is presented, and their reliability evaluated. Compared were shafts without additional finish treatment, rolled shafts and those with a TiSiN coating. Tribological samples under investigation operated in rotational bending conditions. Recorded was the number of fatigue cycles at which damage might occur. Reliability indicators were plotted, which demonstrated that coated shafts are distinguished by the highest reliability and low damage intensity. Macroscopic observations of shaft surfaces demonstrated the traces of adhesive wear and, in the case of shafts without additional treatment and in the case of rolled shafts, fretting wear traces in the form of a ring comprising the entire shaft circumference. Microscopic observations showed numerous build-ups on the surface, microcracks, and the occurrence of wear products in the gap between the shaft and sleeve. The highest fatigue strength was demonstrated by shafts with a TiSiN coating. The shaft section change area was the place where fatigue wear occurred.

Qualitative and Quantitative Evaluation of Different Types of Orthodontic Brackets and Archwires by Optical Microscopy and X-ray Fluorescence Spectroscopy

The wear behaviour and chemical composition of orthodontic components influence the mechanical characteristics of a fixed orthodontic treatment. The purpose of this paper is to evaluate the surface alterations of different types of brackets (aesthetic, metallic, and conventional self-ligating) and archwires (superelastic and thermal) subjected to wear tests through optical microscopy and, subsequently, to identify the chemical elements of accessories by X-ray fluorescence. The cycles (5000 for each bracket and 10,000 for each wire) of the tribological test were carried out in dry conditions inside a machine that allows alternating sliding. The results of the study highlighted different wear behaviours even within the same type of brackets and archwires. The monocrystalline sapphire brackets maintain their aesthetic properties despite traces of wear inside the slots and contain minimal amounts of nickel. Superelastic NiTi archwires have a better overall rating than thermal wires, as they do not show significant surface wear alterations.

Investigation of friction performance and surface integrity of aramid fiber‐reinforced polymer matrix composite

AbstractBecause of its superior properties, aramid fiber‐reinforced polymer (AFRP) composite material is used in many sectors including the aerospace, automotive, and defense industries and maintains a stable and reliable coefficient of friction under the various conditions required by these industries. In this study, the friction coefficient of AFRP composites was determined by tests carried out using a ball‐on‐disc friction tester under 8 and 12 N loads at 300, 450, and 550 rpm. The wear traces were investigated and according to the results, the high friction forces negatively affected the wear and led to more prominent wear traces. It was concluded that oxidation, fatigue (thermal), and delamination wear were effective because the increase in the load increased the forces on the samples. In sample A1, the value obtained under the 8 N load was 287.5% lower than that measured under the 12 N load.

Influence of diamond-like carbon coatings on the wear of the press joint components

• The coatings are distinguished by the low coefficient of friction and wear • Wear traces suggesting fretting appear on the coatings • Coating damage consists in micropullouts, abrasions and material buildups in places • No traces of fretting wear are noted on the CrN-a:C:H:W:Ti coating

Wear behavior of self-propagating high-temperature synthesized Cu-TiO2 nanocomposites

In this paper, the copper-based nanocomposites with TiO2 nanoparticles were synthesized by the self-propagating high-temperature synthesis (SHS) process. The effect of the different amounts of excess copper, in comparison with the stoichiometric ratio (CuO:Ti ratios of 1:1, 2:1, and 3:1), on the phase formation of achieved samples was studied. A thermodynamical study showed that increasing the excess copper powder reduces the adiabatic temperature, which helps the phase formation. The maximum Brinell hardness (89) was obtained for the sample with the CuO:Ti ratio of 1:1. Finally, the wear behavior of the synthesized nanocomposites was evaluated by the pin on disk test, and the variation of friction coefficient and lost weight were measured. The friction coefficient decreased by the formation of phases and distribution of titanium oxide particles during the SHS process in the presence of the stoichiometric ratio of CuO:Ti. Therefore, the wear behavior was improved. The lowest depth of wear trace was measured 0.68 where the ratio of CuO: Ti was 1:1.

Investigation of friction performance and surface integrity of cryogenically treated AISI 430 ferritic stainless steel

In this study, the effect of shallow cryogenic treatment on the friction coefficient of AISI 430 ferritic stainless steel was investigated. The friction coefficient experiments were carried out in a ball-on-disc wear tester under 5 N load at 400 rpm. As a result of the tests, the study examined the surface topography of the wear traces, the abrasion profile, microscopic images of the wear traces, and the hardness change of the wear traces. After applying shallow cryogenic treatment, the friction coefficient of the samples was increased by 7.5%. The micro hardness value around the wear traces of the cryogenic (Cryo) samples was 28.4% higher than the value for the commercial samples. The width of the wear trace of the Cryo samples was reduced by 44%. The average roughness value of the wear trace was 33.3% improved in the Cryo sample compared to the commercial sample.

Tribo-oxidation of Ti-Al-Fe and Ti-Al-Mn cladding layers obtained by non-vacuum electron beam treatment

The research was devoted to studying unlubricated tribological behaviors of γ-TiAl-based coatings in the temperature range 25–400 °C. These γ-TiAl-based intermetallic coatings alloyed with Fe or Mn were formed on CP-Ti workpieces using a non-vacuum electron beam deposition. The microstructure, phase and elemental analyses proved the formation of γ-TiAl and appearance of the ternary phases (Laves and G-phases). It was shown that friction coefficients obtained for three materials were barely different but their fluctuations were strongly dependent on surface oxidation and the phase composition. It was found that the Ti-45Al-8Mn (at.%) coatings consisting mainly of γ and α2 phases had lower wear resistance in comparison with the Ti-42Al-7Fe (at.%) and Ti-57Al-13Fe (at.%) coatings. Whereas the Ti-57Al-13Fe (at.%) coating contained γ and G phases possessed better wear resistance as compared to that of Ti-42Al-7Fe (at.%) coating with the structure represented by the γ matrix and a eutectic (α2 + Laves phases). The microprobe analysis, scanning electron and optical microscopy, and XPS measurements revealed the formation of highly oxidized mechanically mixed layers after the sliding tests. The Ti-45Al-8Mn (at.%) coating subsurface consisted of Al2O3, Al, TiO2, and Ti sub-oxides, whereas for both Ti-Al-Fe coatings the formation of an initial oxide film consisted of a titanium dioxide (rutile structure), alumina, and a low amount of iron oxide (hematite structure) was revealed. Thermal softening of the counter body provoked the iron oxide growth in the wear traces of the coatings alloyed with Fe. Tribooxidation behaviors of Ti-Al-Fe coatings may be interpreted as an example of adaptation the as-deposited structure and phases to high-temperature sliding condition and therefore these coatings can be recommended for protection of the titanium alloy components.

Repair and restoration of shafts, couplings, splined and keyed joints

The article provides an overview of the methods of restoration and repair of various parts of the equipment: shafts, couplings, splined and keyed joints. Recommendations on the choice of methods, equipment and tools are given. In case of wear, the keyway is repaired by welding the face with subsequent milling. At the same time, the keyway size set by the standard is maintained. Such repairs are also possible: the keyway is expanded and deepened, completely eliminating the traces of wear, after which a stepped key is made to it. However, with such repairs, a high-quality connection is not provided and, therefore, it is used in exceptional cases (during inspections and ongoing repairs). When repairing keyed joints, the worn keyed joints are not repaired, but new ones are made, fitting them to achieve a firm contact with the side surfaces of the grooves of the connected parts. The exception is the taper keys: they are driven into the keyway with a hammer blow so that they are jammed in height. The taper key should also be hammered in such a way that, when loosened, it can be deposited. Between the head of the key and the end of the part, there must be a distance equal to the height of the key. The connection with the help of splines is used for fixing gears, gear wheels, and bushings on the shafts. It has a number of advantages over other types of connection. The component parts of this joint are more easily centered. This significantly reduces mechanical deformations at the bushing boundary. During operation, under the influence of various loads, the spline joint loses its properties. In this case, the splines or grooves in which they are placed are restored. Splines of small rollers are usually not repaired; the parts with worn splines are mostly replaced with new ones. Such work is carried out in specialized workshops. In some cases, the repair and restoration of such products is carried out in a small workshop, but equipped with the necessary machines.

The analysis of fretting fatigue in forced-in joint with the induction-hardened shaft

Subject to the analysis was a tribological kinematic pair consisting of shaft and sleeve, both made of C45 steel. The elements were joined by pressing with the 0.02 mm tolerance. The shaft was subjected to the finishing and strengthening treatment consisting in induction hardening. The tribological kinematic pair made in such way was tested on a fatigue testing machine, which permitted obtaining a rotational bending moment. Macroscopic investigations of the unhardened shaft demonstrated, on the shaft surface, the traces of fretting wear in the form of a ring of the uniform width comprising the entire axle seat circumference. Based on the test results, it may be concluded that the use of the shaft induction hardening process has caused the reduction of fretting wear development compared to shafts without additional treatment. In this case, Wear traces in the form of small diameter ring comprising the entire shaft circumference are observed on one side of the shaft axle seat.