Difference In Wear Resistance Research Articles

ТРИБОТЕХНИЧЕСКИЕ ИССЛЕДОВАНИЯ ВТОРИЧНЫХ БРОНЗОВЫХ ПОКРЫТИЙ

One of the features of agricultural machines is the use of a sufficiently large number of parts made of non-ferrous metals and alloys in their designs, since they have high antifriction properties, corrosion resistance, withstand significant specific loads and high speed conditions. Most often these are bronze plain bearings of the bushing type. Tribotechnical studies of coated samples based on secondary composite materials on a friction machine is an important direction in the development of technologies for the restoration and hardening of bronze parts and assemblies. Secondary composite materials are obtained from production waste by the electroerosion dispersion, which allows to reduce production costs and reduce the environmental burden. Such powders can be used to create repair coatings with high wear resistance. (Research purpose) The research purpose is performing a comparative analysis of the tribotechnical properties of coatings obtained usng secondary composite materials and electric spark processing. (Materials and methods) Samples with bronze coatings were produced for research. Conducted tests on the friction machine II5018. (Results and discussion) It was determined that coated samples based on secondary composite materials have higher wear resistance and less friction compared to uncoated samples. It was found that with increasing load and sliding speed, the difference in wear resistance and friction between coated and uncoated samples increases. The coating based on secondary composite materials is especially effective in conditions of high loads and sliding speeds. (Conclusions) Comparative tribotechnical studies of coated samples based on secondary composite materials have shown that such coatings can be an effective way to increase wear resistance and reduce friction in various machine components.

Comparison of the relationship between hardness and wear resistance of polycrystalline diamond and cubic boron nitride

AbstractHardness is an important indicator of the wear resistance of tool materials. The study of the effect of hardness on the wear resistance of tool materials has significant practical applications. In this experimental work, a series of polycrystalline cubic boron nitride (PcBN) and diamond (PCD) compacts with different hardness are sintered under high temperature and pressure, and these samples were fashioned into turning tools, used for edge wear testing in the granite turning process. Based on the measurements above, the relationship between hardness and wear resistance in two materials with identical grain sizes (1–2 µm) was examined, and the results reveal a significant positive correlation between the hardness and wear resistance of the two materials. Remarkably, the relationship between hardness and wear resistance in two materials complies with the same type of fitting function. But incredibly, the wear resistance of the two materials exhibits inconsistency as the hardness increases. Specifically, below 40 GPa Vickers hardness, both materials exhibit comparable wear resistance. However, above 40 GPa, the difference in wear resistance between the two materials becomes more pronounced with increasing hardness. At the Vickers hardness of 70 GPa, the abrasion ratio of the PCD is approximately 3.5 times that of the PcBN, and it is anticipated that the disparity between them will continue to expand within the broader range of hardness. Further analysis reveals that the intrinsic hardness of the crystal grains significantly impacts the wear resistance of polycrystalline materials.

3D finite element analysis of a two-surface wear model in fretting tests

This article aims at developing a computationally efficient framework to simulate the erosion of two contact surfaces in three-dimensional (3D), depending on the body resistance. The framework involves finite element (FE) resolution of a fretting problem, wear computation via a non-local criterion including a wear distribution parameter (WDP), as well as updating of the geometry and automatic remeshing. Its originality is based on the capability to capture the damage on each surface and obtain local and global results for a quantitative and qualitative analysis. Numerical simulations are carried out for two 3D contact specimens with different values of WDP. The results highlight the importance of correctly modelling wear: One-surface wear model is sufficient from a global point of view (wear volume), or whenever the wear resistance for a body is much higher than that of another one, whereas a 3D two-surface wear model is essential to capturing local effects (contact pressure, wear footprint, etc.) related to the difference in wear resistance of the bodies.

Crack formation and oxidation wear in (Cr,Y,Al)N and (Mo,Y,Al)N nanolayer coatings with high content of yttrium

The article considers the processes of cracking and oxidation in the nanolayer coatings of (Cr,Y,Al)N and (Mo,Y,Al)N with a high (about 50 at%) content of yttrium (Y). The studies were carried out during the turning of steel with subsequent investigation of the wear area using scanning (SEM) and transmission (TEM) microscopes. Although the main parameters (elemental composition and structure) are identical and the values of hardness and elastic modulus are close, tools with the coatings under consideration demonstrated noticeable difference in wear resistance. The (Mo,Y,Al)N coated tool had a wear resistance 45% higher than the (Cr,Y,Al)N coated tool and 30% higher than the (Ti,Cr,Al)N reference coated tool. Active formation of cracks is detected in the (Cr,Y,Al)N coating, while oxidation wear dominated in the (Mo,Y,Al)N coating. Therefore, coatings containing layers of materials characterized by an increased tendency to oxidize, but at the same time providing a favorable compositional effect, can be effectively used. This is possible provided that the oxidation-resistant layers protect the oxidation-prone layers from active contact with oxygen.

Influence of Materials on Dry Friction and Wear Performance of Harmonic Reducer Circular Spline

Ductile iron and alloy steel are mostly used as the circular spline materials of harmonic reducers. The study of the differences in wear resistance of different circular spline materials is a strong basis for the design of high-precision and long-life harmonic reducers. The dry friction behaviors under room temperature of two ductile iron (low-load SHF and high-load SHG) alloys and steel (40Cr) circular spline materials were studied with a quantitative analysis of the alloy composition, microstructure, hardness and wear resistance. The results showed that the microstructures of SHF, SHG and 40Cr were graphite nodules within a tempered sorbite matrix, graphite nodules within a pearlite matrix and tempered sorbite, respectively. The hardness was inversely proportional to the wear resistance. The wear resistance of ductile iron was better than that of 40Cr, with SHF having the best wear resistance. The microstructure of the SHF and SHG ductile iron had a length of 8.1 μm, 5.9 μm (Ti, V, Mo)/C and Cu/Mg second-phase particles. Compared with tempered sorbite, the self-lubricating layer formed by the graphite nodules can effectively reduce wear. The proportion and average diameter of the SHF graphite were 1.2% and 30.9% higher, respectively, than those of the SHG graphite, providing a higher graphite spalling probability and longer graphite lubrication distance.

COMPARATIVE FRICTION TESTS OF BRONZE COATINGS FROM SECONDARY MATERIALS

Comparative tribotechnical studies of coated samples based on secondary composite materials on a friction machine is an important direction in the development of technologies to increase wear resistance and reduce friction in various industrial sectors. Secondary composite materials are obtained from production waste, which reduces costs and reduces the environmental burden. One of the examples of these materials are coatings obtained by welding and surfacing methods of electroerosive powders based on copper or a hard alloy from waste of tool industries or waste of non-ferrous metals and alloys. (Research purpose) The research purpose is performing a comparative analysis of tribotechnical properties of samples coated by secondary composite materials on a friction machine. (Materials and methods) Samples with a coating based on secondary materials and samples without a coating were produced for comparative studies. A machine was used to test materials for friction and wear AI 5018. (Results and discussion) It was found that coated samples based on secondary composite materials have higher wear resistance and less friction compared to uncoated samples. The coating based on secondary composite materials has a higher hardness and resistance to wear. It was found that with increasing load and sliding speed, the difference in wear resistance and friction between coated and uncoated samples increases. The coating based on secondary composite materials is particularly effective in conditions of high loads and sliding speeds. (Conclusions) Thus, comparative tribotechnical studies of coated samples based on secondary composite materials on a friction machine have shown that such coatings can be an effective way to increase wear resistance and reduce friction in various industrial sectors.

Effect of linear energy density on microstructure and wear resistance of WC-Co-Cr composite coating by laser cladding

To improve the wear resistance of titanium alloy, the WC-reinforced composite coatings were prepared on Ti-6Al-4V substrate by laser cladding. The effect of linear energy density (LED: 73.3 J·mm−1-283.3 J·mm−1) on the microstructure, microhardness and wear resistance of the composite coatings were investigated. The evolution of WC during laser cladding was revealed and discussed. It is found that the WC is dissolved by the forms of releasing W and C with increasing LED, and grows into specific shapes according to the Lifshitz-Slyosov-Wagner model. As the LED increases, the retention index of WC decreases (0.91–0.80) and the grain size increases (1.89 μm–5.81 μm) in the composite coating. The microstructure differences lead to the microhardness and brittleness increasement of composite coating. Compared with the Ti-6Al-4V substrate, the maximum microhardness improvement and wear mass loss reduction are 5 times and 25 times by varying LED. The main wear mechanism of composite coatings is abrasive wear. However, additional forms of wear mass loss such as adhesive wear and WC peeling can occur due to LED variation, and further leads to the difference in wear resistance. It is expected that the evolution of WC, which can regulate the microstructure will provide an effective theoretical foundation for the wear-resistance improvement of the laser cladding coatings.

Hybrid aging and nitriding treatment of nickel aluminum bronze by plasma-based ion implantation

Nickel-aluminum bronzes (NABs) comprise a versatile group of copper-based age hardenable quaternary alloys. Their composition usually comprises aluminum, nickel, iron, and manganese, besides copper. These alloys have a large range of applications, from architectural use to naval propellers. In the present work, a case study of a specific NAB alloy of technical importance was performed aiming to investigate the difference in wear resistance between samples that were aged and samples that received a novel hybrid aging + nitriding treatment carried out on a plasma immersion ion implantation (PIII) apparatus. Both regular aging and the hybrid treatment were carried out for solution-treated coin-shaped specimens, with martensitic matrix, in a PIII chamber under a nitrogen-based atmosphere. Three different voltage biases, 8, 10, and 12 kV, resulted in three distinct treatment temperatures, 370, 400 and 470 °C, for treatment times of 180 and 90 min, being the latter (90 min) used together with the smaller voltage (370 °C) for comparison purposes. From the coin-shaped sample, it was possible to study the two distinct treatments: i) the flat-surface-side exposed to plasma was subjected to the hybrid treatment; ii) the other flat-side (directly supported on the sample holder) was only aging-treated (hereafter termed ‘aged only’). Such methodology allowed to infer the bulk effects on the surface modification process. The XRD patterns of the hybrid-mode treated (hereafter termed ‘aged + nitrided’) surfaces showed formation of nitrogen-expanded phases, these surfaces showing hardness gains varying on the 11%–27% range when compared to the respective surfaces aged only. Scratch tests, in association with hardness and elastic modulus measurements, showed the role of the aging on the elasto-plastic response of both aged only and aged + nitrided surfaces. The nitriding resulted in significant gains of wear resistance for PIII carried out at the lowest temperatures: 43% and 41% less volume loss than the respective aged only surfaces for the treatments at 370 °C for 90 min and 180 min, respectively. Differently, the treatments at the highest temperature (450 °C) resulted in the worst wear performances, since the bulk over-aging surpassed any strength delivered by nitriding.

Investigation of Properties of the Zr,Hf-(Zr,Hf)N-(Zr,Hf,Me,Al)N Coatings, Where Me Means Cr, Ti, or Mo

The article describes the results of the investigation focused on the properties of the Zr,Hf-(Zr,Hf)N-(Zr,Hf,Me,Al)N coatings, where Me means chromium (Cr), titanium (Ti), or molybdenum (Mo). These coatings have three-layer architecture, including adhesion, transition, and wear-resistant layers, while the latter, in turn, has a nanolayer structure. Despite the fact that the coatings under study have close values of hardness and critical fracture load LC2, there are noticeable differences in wear resistance during the turning of steel. The tools with the coatings under study demonstrated better wear resistance compared to an uncoated tool and the tool with the commercial ZrN coating. The best wear resistance was detected for a tool with the Zr,Hf-(Zr,Hf)N-(Zr,Hf,Ti,Al)N coating. The study of the pattern of cracking in the structure of the coatings has found that, during the cutting process, active cracking occurs in the coating with Cr, which leads to the fracture of the coating, while the process of cracking is noticeably less active in the coatings with Ti or Mo.

Efficiency of Application of (Mo, Al)N-Based Coatings with Inclusion of Ti, Zr or Cr during the Turning of Steel of Nickel-Based Alloy

The article compares the properties of multilayer composite wear-resistant coatings of Zr–ZrN–(Zr, Mo, Al)N, Ti–TiN–(Ti, Mo, Al)N, and Cr–CrN–(Cr, Mo, Al)N. The investigation was focused on hardness, resistance to fracture during scratch tests, elemental composition, and structure of the coatings. Experiments were carried out to study the wear resistance of coated carbide tools during the turning of 1045 steel and of NiCr20TiAl heat-resistant nickel alloy. With the elemental compositions identical in the content of molybdenum (Mo) and aluminium (Al), identical thicknesses and nanolayer periods of λ, the coatings being studied demonstrated a noticeable difference in wear resistance. Both during the turning of steel and nickel-based alloy, the highest wear resistance was detected for tools with the Zr–ZrN–(Zr, Mo, Al)N coating (the tool life was 3–5 times higher than for uncoated tools). The good wear resistance of the Zr–ZrN–(Zr, Mo, Al)N coating may be related to the optimal combination of hardness and plasticity and the active formation of molybdenum oxide (MoO3) on the coating surface during the cutting, with good tribological and protective properties.

Mechanism and patterns of wear of chrome steels with a surface-modified layer

The paper presents the results of contact wear studies of surface layers of 6Cr4Mo2VSi steel under the action of pulsating contact stresses. Differences in wear resistance of surface layers of materials are shown, in interrelation with modes of synthesis of their structure and properties. The features of the evolution of the structure of modified layers strengthened by nitrocarburizing are revealed. The modes of thermo-chemical treatment for achieving maximum resistance to the action of pulsating contact stresses are determined.

Effect of Nano-Filled Protective Coating and Different pH Enviroment on Wear Resistance of New Glass Hybrid Restorative Material.

The purpose of the study was to determine the wear rate of Equia Forte HT Fil with Equia Forte Coat or without coating and compare it with Fuji IX GP high-viscosity glass ionomer cement (GIC) in conditions with acid load or at neutral pH. The samples were stored for 7 days: (1) in artificial saliva, (2) in artificial saliva and cyclically exposed to low pH, and (3) in distilled water and cyclically exposed to low pH. Wear was determined by measuring the difference in mass before and after brushing in an abrasion testing device. The wear of Fuji IX GP was significantly higher than that of Equia Forte HT Fil with or without coating (p = 0.000). The difference between Equia Forte HT Fil with and without Coat was not statistically significant (p < 0.803). The differences in wear resistance between samples stored in saliva and in distilled water were not significant (p = 0.588). Periodic exposure to the low pH solution significantly affected the wear resistance of all materials (p = 0.000). Equia Forte HT Fil was more resistant to wear than Fuji IX GP in all storage conditions. A resinous coat did not significantly increase wear resistance.

Design of convex‐hull bionic tire tread compounds and mechanism on collaborative improvement of wet resistance and wear resistance

AbstractThe materials or bionic methods available cannot further solve the contradiction between the wear resistance and wet resistance of tire tread compounds. In this study, a convex‐hull bionic tire tread compound was designed and produced according to the difference in wear resistance between two types of tire tread compounds. The effects of the bionic structure on the wear resistance and wet resistance of the tire tread compounds were explored by analyzing the changes in wear loss, wear surface characteristics, and wet friction coefficient. The wear resistance and wet resistance of the convex‐hull bionic tire tread compound were collaboratively improved. The largest increasing rate of wear resistance was 9%, and the largest increasing rates of wet sliding ability on sand paper surface and on smooth glass surface were 3.4% and 4.2%, respectively. The coupling design of materials and bionic structures offers a new way to improve the overall performances of tire tread compounds.

Evaluation of Zirconia Infused Glass Ionomer Cement Versus Resin Modified Glass Ionomer in Class II Restorations of Primary Molars

Objective of this study to was to evaluate zirconia infused glass ionomer cement versus resin modified glass ionomer in class II restorations of primary molars.Materials & Methods: This study was classified in to vivo and vitro study. I- vivo study: 18 posterior primary molars from 9 children by using split mouth technique was classified equally in to two groups. Group 1: 9 deciduous molars were restored with resin-modified glass-ionomer (RMGI) filling. Group 2: 9 deciduous molars were restored with zirconia infused glass-ionomer (ZRGI) filling. Follow up using the FDI criteria to evaluate the clinical performance of both materials. II- vitro study: 18 freshly extracted human deciduous molars with no crack, decay or structure deformities were collected and stored in normal saline. Group 3: 9 extracted deciduous molars were restored with resin-modified glass-ionomer filling. Group 4: 9 extracted deciduous molars were restored with zirconia- infused glass-ionomer filling. The measures were calculated by Shear bond strength and Wear resistance calculation. Results: It was found that that RMGI is better in shear strength than zirconia infused glass ionomer, while the two materials have the same resistance to wear. Conclusion: Shear Bond strength of RMGI is better than zirconomer. There is no significant difference in wear resistance between the two materials. Clinical performance of RMGI is better than zirconomer.

Polymers for conventional, subtractive, and additive manufacturing of occlusal devices differ in hardness and flexural properties but not in wear resistance

ObjectivesTo investigate the wear resistance of polymers for injection molding, subtractive and additive manufacturing of occlusal devices in comparison with enamel antagonist wear and material properties (i.e., hardness, flexural strength, and flexural modulus). MethodsInjection molding was compared with milling and the additive technologies stereolithography, low force stereolithography, and digital light processing. For each material, eight specimens were produced for wear measurements. Extracted human premolars served as indenters. All samples were subjected to two series of a 2-body wear test consisting of 200,000 circular loading cycles with an applied load of 1) 20 N and 2) 50 N in a thermocycling environment (5/55 °C, 30 s, 3860 cycles, H2O). Wear resistance was characterized by means of maximum depth and volume of the resulting traces. In addition, enamel wear of the indenters and Vickers hardness, flexural strength, and flexural modulus of the polymers were determined. Wear was statistically analyzed with linear general models for repeated measures and material properties with one-way ANOVA with post-hoc Tukey-HSD tests. ResultsWear of the antagonists was not influenced by the material (P ≥ 0.343). Likewise, no differences in wear resistance were found between materials after cyclic loading with 20 N or 50 N (P ≥ 0.074). Material properties investigated revealed decreased values for the resins for the additive manufacturing with the exception of flexural strength of one material. SignificanceWithin the limitations of this in-vitro study, arylates for conventional, subtractive, and additive manufacturing of occlusal devices differ in material properties but not in wear resistance and antagonist wear.

Mechanical properties and wear resistance of ultrafine bainitic steel under low austempering temperature

The mechanical properties and wear resistance of the ultrafine bainitic steel austempered at various temperatures were investigated. Scanning electron microscopy (SEM) and X-ray diffraction were used to analyze the microstructure. The worn surfaces were observed via laser scanning confocal microscopy and SEM. Results indicated that, under low austempering temperatures, the mechanical properties differed, and the wear resistance remained basically unchanged. The tensile strength of the samples was above 1800 MPa, but only one sample austempered at 230°C had an elongation of more than 10%. The weight loss of samples was approximately linear with the cycles of wear and nonlinear with the loads. The samples showed little difference in wear resistance at different isothermal temperatures, whereas the thickness of their deformed layers varied greatly. The results are related to the initial hardness of the sample and the stability of the retained austenite. Meanwhile, the experimental results showed that the effect of austempering temperature on the wear resistance of ultrafine bainitic steel can be neglected under low applied loads and low austempering temperature.

Niobium Additions to a 15%Cr–3%C White Iron and Its Effects on the Microstructure and on Abrasive Wear Behavior

From the present study, niobium additions of 1.79% and 3.98% were added to a 15% Cr–3% C white iron, and their effects on the microstructure, hardness and abrasive wear were analyzed. The experimental irons were melted in an open induction furnace and cast into sand molds to obtain bars of 45 mm diameter. The alloys were characterized by optical and electron microscopy, and X-ray diffraction. Bulk hardness was measured in the as-cast conditions and after a destabilization heat treatment at 900 °C for 30 min. Abrasive wear resistance tests were undertaken for the different irons according to the ASTM G65 standard in both as-cast and heat-treated conditions under three loads (58, 75 and 93 N). The results show that niobium additions caused a decrease in the carbon content in the alloy and that some carbon is also consumed by forming niobium carbides at the beginning of the solidification process; thus decreasing the eutectic M7C3 carbide volume fraction (CVF) from 30% for the base iron to 24% for the iron with 3.98% Nb. However, the overall carbide content was constant at 30%; bulk hardness changed from 48 to 55 hardness Rockwell C (HRC) and the wear resistance was found to have an interesting behavior. At the lowest load, wear resistance for the base iron was 50% lower than that for the 3.98% Nb iron, which is attributed to the presence of hard NbC. However, at the highest load, the wear behavior was quite similar for all the irons, and it was attributed to a severe carbide cracking phenomenon, particularly in the as-cast alloys. After the destabilization heat treatment, the wear resistance was higher for the 3.98% Nb iron at any load; however, at the highest load, not much difference in wear resistance was observed. Such a behavior is discussed in terms of the carbide volume fraction (CVF), the amount of niobium carbides, the amount of martensite/austenite in matrix and the amount of secondary carbides precipitated during the destabilization heat treatment.

DEBRIS-FRETTING TEST OF COATED AND UNCOATED ZR-1%NB CLADDING

Debris fretting is one of the most significant fuel rod failure causes. An approach to mitigate this is to apply special coatings on the surface of the cladding that are supposed to increase the wear resistance. This paper summarizes the experiments performed in Research Centre Rež on fuel cladding tube specimens. The tube segments made of uncoated and coated Zr-1%Nb alloy were exposed to fretting tests simulating the wire-debris vibrations impact on cladding during the reactor operation. The goal of these tests is to obtain results about the differences in wear resistance of uncoated and coated specimens. This paper shows the testing procedure in the air at room temperature and obtained impact markings on the specimens’ surfaces.

Wear resistance and wet skid resistance of composite bionic tire tread compounds with pit structure

This work was aimed to introduce the bionic non-smooth structure of pits into compound preparation by referring to the bionics concept. Four types of highly wear-resistant tire tread compounds (A1, A2, A3, A4) and 4 types of highly wet-skid-resistant tire tread compounds (B1, B2, B3, B4) were made by adjusting the rubber contents and changing the parts per hundreds of carbon black and silica. According to the characteristics of the designed bionic structures and tire treads, A2 and B3 were combined to manufacture composite bionic structured tire tread compounds (C1, C2, C3, C4) through pressured and heated vulcanization. It was found BR showed higher wear-resistance and lower wet-skid resistance than SBR. With the increasing dosages of carbon black and silica, the wear-resistance was first enhanced and then weakened, but the wet-skid resistance was gradually reduced. The wet-skid resistance of tire tread compounds was associated with the hardness and roughness of the friction surfaces, and was improved when the roughness and hardness decreased. Due to the difference in wear-resistance between A2 and B3, pits were formed after wearing, which strengthened the wear-resistance and wet-skid resistance of the tire tread compounds. Compared with A2, the wear-resistance of C2 was increased to the largest extent of 0.98%, but the increasing magnitudes of wet-skid resistance were not significantly between C3 and C4, and the highest increment magnitudes on the diamond piece surface were 20.9% and 21.1%, respectively. The coupling functions of the bionic composites prove the feasibility and practicability of bionic abrication, providing a new way to improve the compound properties.

Solid particle erosion of refractories: A critical discussion of two test standards

Solid particle erosion is a key topic in many industrial applications. Within this work two standardised solid particle erosion test rigs usable for refractories with different working principles will be compared, namely i) the American ASTM C704 standard “Standard Test Method for Abrasion Resistance of Refractory Materials at Room Temperature”, which in fact is a gas blast solid particle erosion test, and ii) the Russian GOST 23.201 “Gas Abrasive Wear Testing of Materials and Coatings with Centrifugal Accelerator” with a centrifugal acceleration disc for the particles. In order to compare the test systems, various ceramic wear protection materials were chosen, featuring heterogeneous microstructures and coarse grain sizes. The particle speed in the ASTM C704 was measured with a high speed camera to be 65 m/s. This speed then was used at both test rigs and samples were impinged at 45° and 90° impact angle with SiC erosive.A comparison of the tests showed similar results at shallow impact angle for materials featuring a slight difference in wear resistance between phases (constituents). For materials containing sufficiently harder phases, the GOST produced lower wear rates.