Wear Resistance Of Metals Research Articles

Influence of Reinforcing nano-Al<sub>2</sub>O<sub>3</sub> Particles on Microstructure and Hardness Properties of HVOF Sprayed 80Ni20Cr Coatings

80Ni20Cr coatings produced by high-velocity oxygen fuel (HVOF) thermal spray technique are novel and widely used to improve the corrosion and wear resistance of metal and steel components in many applications, especially in coal-fired power plants. The present study investigated the effects of nano-Al2O3 at 0.5 wt.% on the microstructure of HVOF-sprayed 80Ni20Cr coating deposited on AISI 304L steels corresponding to its coating hardness. The coating was successfully sprayed with a thickness of 150 – 180 µm. The microstructure and phase formed by the coating were analyzed by a field emission electron microscope (FE-SEM) and an X-ray diffractometer (XRD). Synchrotron X-ray fluorescence spectroscopy (SRXRF) was used to confirm the Cr solid solution in the Ni-based coating. The presence of the nano-Al2O3 phase in the 80Ni20Cr coating was characterized by electron backscattered diffraction (EBSD). The nano-Al2O3 particles were homogenously distributed in the coating layers. The incorporation of nano-Al2O3 into 80Ni20Cr enhanced coating characteristics by decreasing surface roughness by 23% and increasing coating hardness by around 4%.

Diatomite@MoS2 Nanocomposite Layers as Composite Coating Targeting for Mg Alloys Endowed with Properties of Anticorrosion and Antiwear.

Molybdenum disulfide (MoS2) demonstrates promising applications in enhancing the corrosion and wear resistance of metals, but the susceptibility of this nanomaterial to agglomeration hinders its overall performance. In this study, the externally assisted corrosion inhibitor sodium molybdate (SM) was successfully constructed in diatomaceous earth (DE) and molybdenum disulfide (MoS2). This not only served as a molybdenum source for MoS2 but also enabled the preparation of DE@MoS2-SM microcapsules, achieving a corrosion inhibitor loading of up to 23.23%. The corrosion testing reveals that the composite coating, when compared to the pure epoxy coating, exhibits an impedance modulus 2 orders of magnitude higher (1.80 × 109 Ω·cm2), offering prolonged protection for magnesium alloys over a 40 day period. Furthermore, a filler content of 3% sustains a coefficient of friction (COF) at 0.55 for an extended duration, indicating commendable stability and wear resistance. The protective performance is ascribed to the synergistic enhancement of corrosion and wear resistance in the coatings, facilitated by the pore structure of DE, the high hardness of MoS2, and the obstructive influence of Na2MoO4. This approach offers a straightforward and efficient means of designing microcapsules for use in corrosive environments, whose application can be extended in industrial fields. In particular, we promote the application of nautical instruments, underwater weapons, and seawater batteries in the shipbuilding industry and marine engineering.

ACCELERATED TESTING OF MECHANICAL AND CHEMICAL EFFECT OF THE ENVIRONMENT ON WEAR RESISTANCE OF PARTS OF TRIBOCOUPLES UNDER COMPLEX DYNAMIC LOADING

The wear of tribocouplings parts under complex dynamic loading conditions is considered. A methodology for accelerated testing of friction pairs under multi-component dynamic loading is offered. The designs stand for modeling the processes of contact interaction, and studies of the wear resistance of tribocouplings, which operate under complexdynamic loading conditions with various lubricating and cooling media, are presented. The results of the impact assessment of mechanic and chemical transformations in the contact zone of tribological interfaces for wear resistance according to the developed method are presented. The variable effectiveness evaluation of the degradation influence products of macromolecular compounds in the composition of cutting fluid on wear resistance of metals in the contact zone of tribocouplings are analysed. The use ofthe presented materials allows rationally selecting friction pair materials for given operating conditions, developing new wear-resistant materials and coatings, lubricant composition and cooling mediums.

Features of Increasing the Wear Resistance of Machine Parts by Treatment with a Concentrated Heat Flow

The article discusses the possibility of using surface treatment of parts with a concentrated heat flow to increase the wear resistance of parts. This method provides conditions for the rapid crystallization of the metal structure after zonal surface melting of the sample surface with electric arc plasma. It has been found that the wear resistance of steel increases significantly with increasing scanning speed and decreasing current strength. The near-surface layers on the cross-sectional grinds of the melting areas were studied in comparison with the initial (without melting) state on the basis of diagrams of the method of continuous indenter immersion. The values of a number of micromechanical parameters characterizing the resistance to microplastic deformation and elastic-viscous properties of steel after strengthening heat treatment were obtained. It should be noted that with a fourfold increase in hardness, the wear resistance of the steel increased almost 10 times. This indicates that the wear resistance of metals under friction is determined not only by macroscopic strength and hardness, but also by the ability to relax local peak stresses under dynamic contact interaction

Predicting the Cavitational Wear Resistance of Metals from the Roughness of the Worn Surface

Predicting the Cavitational Wear Resistance of Metals from the Roughness of the Worn Surface

Analysis of Wear-Resistant Materials of Mixer - Pneumosuperchargers Blades Operating under Conditions of Abrasive Wear

We conducted comparative tests of the wear resistance of metals operating under abrasive conditions. Samples were cut from the working parts of mixer-pneumosuperchargers. The chemical composition and mechanical properties were determined. To compare samples under abrasive wear conditions, we designed and assembled a carousel installation. The principle of its operation is based on mixing the abrasive medium by the samples being studied with a given speed. Wear resistance was evaluated by weight loss by samples after several test cycles. To determine changes in the structure of the metal during abrasive wear, metallographic studies of the samples were carried out before and after the tests. It is shown that the best complex of service and mechanical properties is possessed by 110G13L steel.

Acceleration effects of rare earths on salt bath nitriding: diffusion kinetics and first-principles calculations

ABSTRACT Nitriding can improve the surface hardness and wear resistance of metals, and rare earths can speed up this process. To study the mechanism of rare earths promoting salt bath nitriding, GX-8 steel was nitrided at different temperatures in two salt baths with and without rare earth Ce. First, structures and depths of the nitrided layers were investigated by microscopic observation, X-ray diffraction, GD-OES and microhardness tests. Then, the diffusion kinetics were calculated, and the atomic mechanisms of rare earth-assisted nitriding were studied by first principles. The kinetics calculations show that after adding Ce to the salt baths, the diffusion activation energy decreases, whereas the decomposition rate of active nitrogen atoms increases. The first-principles results indicate that Ce increases the energy and volume of the supercell of Fe–Cr alloy with N interstitial dissolution and reduces the stability of the supercell. These results demonstrate rare earths can accelerate nitriding at the atomic level.

Plasma electrolytic oxidation coatings with fungicidal properties

ABSTRACTPlasma electrolytic oxidation (PEO) is a relatively new surface treatment that permits to increase the corrosion and wear resistance of metals. One of the peculiarities of the process is the possibility to incorporate into the produced coating the particles suspended in the electrolyte. In this work, micrometric silver particles were added in the PEO coating to innovatively give a fungicidal effect to the samples due to the presence of silver, whose fungicidal effect is well known. PEO coatings were produced on aluminium alloy 7075 using an electrolyte containing sodium silicate and silver particles. The thickness, morphology, composition and corrosion resistance of the obtained coatings were studied. The fungicidal properties were evaluated with contact tests of 2 and 4 h using Candida albicans ATCC 10231. Silver particles were homogeneously distributed in the coating and the silver-containing samples were characterised by improved corrosion resistance and high fungicidal activity.

Numerical simulation of fatigue life of 2A02 aluminum alloy treated by overlapping laser shock processing

Laser shock processing (LSP) has been now recognized as an efficient surface strengthening technology to improve fatigue, corrosion and wear resistance of metals. In this paper, the effect of residual stress on the fatigue life of 2A02 aluminum alloy specimens subjected to LSP was investigated by the finite element method (FEM). This investigation was split into two parts, numerical simulation of the LSP process and the fatigue analysis. The LSP simulation was performed using the commercial code ABAQUS. The fatigue analysis, using the residual stresses obtained in the previous LSP simulation as input, was performed by the commercial node nCode Designlife. The simulation results indicate that under the fatigue loading of maximum axial stress of 365MPa and the stress ratio of R=0.1, the fatigue life of specimens with LSP was extended up to 205.7% from 12,290 times to 25,280 times. It was observed that the residual compressive stresses induced by LSP can significantly prolong the fatigue life of 2A02 aluminium alloy specimens. It is found that simulation results are well agreement with available experimental data. It indicate that FEM calculation of specimen life with LSP is feasible.

Material Wear Resistace Increase of Tillage Machine Working Tools with Electro-Sparkling Application o Coating Layer

The paper presents the method of metal wear resistance increasing of working surface of heavy loaded working tools of agricultural implements with white unalloyed cast iron by electro-sparkling application of coating layer. Considering experiment of scientist we proposed some ways to solve this problem in the conditions of the Russian Federation, conducted some research and experimental work to perform the data.

High Temperature Sliding Wear of NiAl-based Coatings Reinforced by Borides

The development of composite materials (CM) in the systems “metal-refractory compound” is one of the up-to-date trends in design of novel materials aimed at operating under the conditions of significant loads at high temperature. To design such material, NiAl, which is widely used for deposition of protective coatings on parts of gas-turbine engines, was selected for a matrix. To strengthen a NiAl under the conditions of intense wear and a broad temperature range (up to 1000 °C), it is reasonable to add refractory inclusions. Introduction of refractory borides into matrix leads to a marked increase in metal wear resistance. In order to research the behavior of the designed composites at high temperatures and to study the influence of oxides on the friction processes, the authors carried out high temperature oxidation of CM of the above systems at 1000 °С for 90 min. It was determined that all of the composites were oxidized selectively and that the thickness of oxide layers formed on the boride inclusions is 3 – 7 times that on the oxides formed on the NiAl matrix. The mechanism of wear of gas-thermal coatings of the NiAl – МеB2 systems was studied for conditions of high temperature tribotests using the «pin-on-disc» technique. The obtained results indicate that introduction of TiB2, CrB2 and ZrB2 leads to their more intense oxidation during high temperature tribotests as compared to the matrix. The oxides formed on refractory borides act as solid lubricants, which promote a decrease in wear of the contact friction pairs. For more detailed investigation of the effect of tribo-oxidation products on the friction processes, tribotests were conducted for prior oxidized (at 900 °С) coatings NiAl – 15 wt.% CrB2 (TiB2, ZrB2).DOI: http://dx.doi.org/10.5755/j01.ms.22.1.8093

Protective Coatings on Steel Dies for Wax Injection Process

Protective coatings are used today in many applications for reducing friction and wear of tools in hot-working process e.g. metal die casting, hot forging, metal die plastics injection. The main goal of undertaken investigation was to evaluate usability of those coatings for improving wear resistance of metal die applied in investment casting process for wax injection. The (Ti,Al)N and (Al,Cr)N PVD coatings were deposited onto X37CrMoV5-1 hot-work tool steel and their mechanical and tribological properties are characterized in the paper. Based on the results of microscope examinations, scratch test, hardness measurement the similar properties of (Ti,Al)N and (Al,Cr)N coatings were found. Moreover it was established that type of steel surface machining before coating deposition, i.e. grinding, electrical discharge machining (EDM) and milling, did not affect coating properties. Thin coatings replicate steel base roughness parameters as Ra, Rz and Rmax with over 95% of correlation. Based on tensile test results of wax/coated steel samples and wax/uncoated steel samples the lowest wax adhesion to (Ti,Al)N coating was confirmed.

Single and multiple laser shock processing of materials

Laser shock processing (LSP) is an innovative surface treatment technique. It can impart compressive residual stresses in material for improving the fatigue, corrosion, and wear resistance of metals. This technology has been used successfully for the treatment not only of traditional structural materials, but also for hard materials. FEM simulation is an effective method for the prediction of mechanical effects induced in material treated by laser shock processing. The FEM simulation of the single and multiple laser shock processing has been carried out to predict the residual stress field. The predicted residual stress field for single and multiple laser shock processing is well correlated with available experimental data. The simulation of multiple laser shocks has shown that compressive residual stresses and, thus, the strength properties of processed materials, can be extensively increased (up to 40%) with the increase of the laser shock number up to 5, and then they gradually reach a saturated state.

TRIBOLOGICAL BEHAVIOR OF NANOSTRUCTURED MATERIALS

Abstract. The paper presents literary and own data on comparative behavior of tribological characteristics of bulk samples of pure metals (copper, nickel, titanium) in coarse-grained and nanostructured state processed by deformation and electrochemical methods. The friction tests have been carried out under the scheme ball – disk. The temperature dependence of titanium friction coefficient has been investigated. It has been shown, that at room and higher temperatures the decrease in friction coefficient and wear resistance of metals in nanostructure state can be observed in comparison with coarse-grained counterparts. The temperature dependence of friction coefficient changes according to the grain size. In nanostructure state rise in temperature as a rule leads to the reduction of tribological characteristics, and in coarse-grained state – to the increase. The analytical methods and approaches to modeling of the solid state contact have been considered in view of the surface atomic structure.

A Promising Method for Improving Wear Resistance of Metal Cutting Tools

Abstract. A promising method for improving wear resistance of metal cutting tools including pre-heating and a subsequent impact of the pulsed magnetic field of high intensity on the cutting tool is proposed. The experimental setup and methods of research are described. Experimental studies of surfaces of carbide reversible cutting plates of the VK8, T15K6 alloy and drills of high speed steel R6M5 to assess the effectiveness of the proposed method were performed. An increase in wear resistance of cutting tools made of the T15K6 hard-alloy plates by 30% and made of the VK8 alloy plates by 13% was revealed while wear resistance of drills made of steel R6M5 increased on average by 58% The proposed method can be of practical interest for hardening the surface of other types of tools and machine parts for further experimental verification.

Research about Relation between the Microstructures and Mechanical Properties of Metal Coating Layers

The paper presents the research about the correlation between the microstructures and mechanical properties of metal coating layers after laser heat treatment. The research was made with eight types of electrodes for welding coating. Laser heat treatment was applied after coating. Evaluation of results was made by observing the microstructures with metallographic microscopy, SEM/EDX and the mechanical properties were obtained by microhardness and wear resistance. The goal of this research is to study the influence of the laser heat treatment on wearing resistance of metal coating layers. Results reveal the influence of microstructures and chemical composition of used electrodes on microhardness and wear resistance of metal coating layers.

Research about Wearing Resistance of Metal Coating Layers

The paper presents a research about influence of nitrocarburizing on wear resistance of metal coating layer. The research was made using six types of electrodes (El CrMn2, ElCrW8Co, El CrW2, E Cr25Ni20R, E 3161, El 62 H) for metal coating. After metal coating, were applied three variants of plasma nitrocarburizing, and was study their influence on wear resistance. Evaluation of results was made by weighing loss of samples after wearing.

Numerical simulation of residual stress field induced by laser shock processing with square spot

Laser shock processing (LSP), also known as laser peening, is a novel surface treatment technique in the past few years. Compressive residual stresses which imparted by LSP are very important for improving fatigue, corrosion and wear resistance of metals. Finite element analysis (FEA) simulation using ABAQUS software has been applied to predict residual stresses induced by LSP on Ti-6Al-4V titanium alloy with laser pulse duration 30 ns and water confined ablation mode. The residual stress field generated by different shape laser spots was studied, and the square laser spot is shown the most suitability for avoiding stress lack phenomenon and overlapping LSP. Surface residual stresses and plastically affected depth within single square spot both increased with the increase of laser intensity and laser shock times. Furthermore, compared with circle and ellipse spot, the residual stress distribution in overlapping square spots is very uniform only with small overlapping ratio. LSP with square spot can process advantageous residual stress field, and this technique will be used widely.

Calculating the wear resistance of metals in frictional pairs 4. Determining the frictional coefficient and pressure at abrasive contact

On the basis of experimental data, the pressure at the actual contact spot of a metal plate sliding over soil is determined. The pressure may significantly exceed the hardness of the plate. Equations are derived for calculating the effective frictional coefficient at abrasive contact.

Laser Shock Processing of 6061-T6 Al alloy with 1064 nm and 532 nm wavelengths

Laser Shock Processing (LSP) has been proposed as a competitive alternative technology to classical treatments for improving fatigue and wear resistance of metals. We present a configuration and results in the LSP concept for metal surface treatments in underwater laser irradiation at 532 nm and 1064 nm. The purpose of the work is to compare the effect of both wavelengths on the same material. A convergent lens is used to deliver 1.2 J/pulse (1064 nm) and 0.9 J/pulse (532 nm) in a 8 ns laser FWHM pulse produced by 10 Hz Q-switched Nd:YAG laser with spots of a 1.5 mm in diameter moving forward along the work piece. A LSP configuration with experimental results using a pulse density of 2500 pulses/cm 2 and 5000 pulses/cm 2 in 6061-T6 aluminum samples are presented. High level compressive residual stresses are produced using both wavelengths. It has been shown that surface residual stress level is comparable to that achieved by conventional shot peening, but with greater depths. This method can be applied to surface treatment of final metal products.