Development Of Wear-resistant Coatings Research Articles

The tribological properties of two-phase hard and soft composite wear-resistant coatings on titanium alloys

There are still problems associated with the use of conventional modified coatings on titanium alloys despite their attempts to improve wear resistance. These problems include incompatibility of mechanical properties, a poor interface bond, and an abundance of debris. The development of wear-resistant coatings with high reliability and long life is a vital component of expanding the use of titanium alloy in medical implants. The purpose of this study was to produce a composite coating with antifriction and wear-resistant properties by combining the high hardness TiN layer with the soft phase lubricated Cu layer produced by ion implantation and electroless plating. The implantation of Cu ions provided the nucleation sites for electroless copper plating and improving interfacial bonding. There was a reduction in adhesive wear due to the composite coating. By comparing the tribological test results of the composite coating and substrate, the volume loss of coatings decreased by 95 % for the same sliding length, the wear rate decreased from 2.55 × 10−13 m3/N·m to 1.28 × 10−14 m3/N·m, the friction coefficient reduced by 10 % and smoother. As a result of the synergistic effects between the soft and hard phases in the composite coating, titanium alloy exhibited an enhanced wear resistance as the wear process progressed.

Development of wear-resistant coatings for automotive parts after processing in SHS conditions

Methods of obtaining chromium-coated coatings are considered and technology for the formation of boron, silicon and titanium protected layers on steels under conditions of self-propagating high-temperature synthesis is presented. Using the methods of mathematical modeling, when obtaining wear-resistant coatings on machine parts in conditions of self-propagating high-temperature synthesis, optimal compositions of SHS mixtures have been developed. When tested in sliding friction conditions, the best abrasion resistance, among the coatings under consideration, are chromoaluminium-coated coatings. Their wear resistance is 4.8-5 times higher than in uncoated samples, chromoaluminosilicated and chromoalumotated in 2.1-3.5. The gas-transport method of coating with the help of SHS makes it possible to obtain steel 50 and U8A with increased physical and mechanical properties, without requiring high energy costs and time.

DEVELOPMENT OF WEAR- AND IMPACT-RESISTANT COATINGS BASED ON FE-TI-MN-C SYSTEM FOR OIL AND GAS EQUIPMENT

The paper presents the results of research on the development of wear-resistant coatings on the working surfaces of equipment and tools operating in conditions of intense abrasive wear. Titanium carbide alloyed high-manganese steel with a high strain hardening capacity served as the basis for coatings. The coating was made by electric arc surfacing with powder electrodes, the charge of which consisted of ferrosilicomanganese, titanium powder, graphite, and components that protect the arc from the atmosphere. The coatings consiss of manganese austenite and dispersed inclusions of titanium carbide with dimensions of ~ 1 micron. Rockwell hardness was measured my means of TK-2 hardness testers (GOST 3882-74) by indentation of a diamond cone under a load of ~ 150 N (scale C). Before measuring the hardness, the surface deposited layer was deformed using the TS-2 hardness gage. At the same time, a carbide ball with a diameter of 10 mm manufactured according to GOST 3722-81 was used as an indenter. The indentation effort was 3,000 kg. Hardness was measured both in the well and in the undeformed zones. By the difference in hardness, the degree of work hardening was calculated. The developed coatings are characterized by the capacity for strain hardening under plastic deformation conditions. It was found that the hardness of the deformed coatings exceeds the hardness of the coatings in the initial state by 57% higher. Experimental studies of abrasive wear resistance under friction conditions on a fixed abrasive were carried out by comparing the developed coatings and serial materials for surfacing. The results of the comparison of abrasive wear resistance showed that the developed coatings are characterized by wear resistance higher compared to serial high-chromium alloys for surfacing almost 2 times. The wear resistance of coatings under conditions of aero-abrasive erosion was carried out using a Kleis centrifugal accelerator in an environment of quartz sand at angles of attack of 30 °, 60 ° and 90 °. The test results showed that the highest wear resistance of the developed coatings was determined at an angle of attack of 90 °. Analysis of the surface of the coatings carried out by electron microscopy showed no signs of brittle fracture. The developed coatings can be applied to increase the durability of the working surfaces of oil and gas equipment operating in abrasive conditions.

Characterization of High-Velocity Single Particle Impacts on Plasma-Sprayed Ceramic Coatings

High-velocity impact wear can have a significant effect on the lifetime of thermally sprayed coatings in multiple applications, e.g., in the process and paper industries. Plasma-sprayed oxide coatings, such as Cr2O3- and TiO2-based coatings, are often used in these industries in wear and corrosion applications. An experimental impact study was performed on thermally sprayed ceramic coatings using the High-Velocity Particle Impactor (HVPI) at oblique angles to investigate the damage, failure, and deformation of the coated structures. The impact site was characterized by profilometry, optical microscopy, and scanning electron microscopy (SEM). Furthermore, the connection between the microstructural details and impact behavior was studied in order to reveal the damage and failure characteristics at a more comprehensive level. Differences in the fracture behavior were found between the thermally sprayed Cr2O3 and TiO2 coatings, and a concept of critical impact energy is presented here. The superior cohesion of the TiO2 coating inhibited interlamellar cracking while the Cr2O3 coating suffered greater damage at high impact energies. The HVPI experiment has proven to be able to produce valuable information about the deformation behavior of coatings under high strain rates and could be utilized further in the development of wear-resistant coatings.

Research on the tribological properties of a textured lubricating wear-resistant coating modified by nano-SiC at high temperature

Purpose – The purpose of this paper is to investigate the tribological properties of a textured lubricating wear-resistant coating modified by nano-SiC at a high temperature. Its aim is to explore the influence of a new composite method on the organisation and structure of sprayed coatings as well as the evolution rules governing their high-temperature tribological properties. Design/methodology/approach – A KF301/WS2 lubricating, wear-resisting, coating was prepared on matrix material GCr15 by applying supersonic plasma spraying technology. On the basis of this sample, using nano-SiC particles as a filler, the KF301/WS2 nano-modified coating with its round, pit-type texture was prepared by laser re-melting technology and a surface texturing technique. Two kinds of coating micro-organisations and structures were examined by scanning electron microscopy, and the tribological properties of both the modified and conventional coatings were studied at a high temperature. Findings – Results showed that nano-particles could effectively improve the coating micro-structure, and make the structure denser and more uniform, thus significantly increasing the wear resistance of the coating. When the friction and wear processes were stable, the friction coefficient decreased by 13 per cent, while the wear loss decreased by 45.9 per cent. Originality/value – This research concentrating on the study of the process and performance of coatings doped with nano-particles by laser re-melting incorporating simultaneous surface texturing, and studies of their high-temperature tribological properties. That is because applying nano-particle modification technology to the development of wear-resistant coatings, and by applying the nano-particles to such coatings by thermal spraying technology, they can achieve a modification of the coating which makes the structure denser and more uniform.

Effects of atomic ordering on the elastic properties of TiN- and VN-based ternary alloys

Improved toughness is one of the central goals in the development of wear-resistant coatings. Previous studies of toughness in transition metal nitride alloys have addressed the effects of chemical composition in these compounds. Herein, we use density functional theory to study the effects of various metal sublattice configurations, ranging from fully ordered to fully disordered, on the mechanical properties of VM2N and TiM2N (M2=W, Mo) ternary alloys. Results show that all alloys display high incompressibility, indicating strong Me–N bonds. Disordered atomic arrangements yield lower values of bulk moduli and C11 elastic constants, as well as higher values of C44 elastic constants, compared to ordered structures. We attribute the low C44 values of ordered structures to the formation of fully-bonding states perpendicular to the applied stress. We find that the ductility of these compounds is primarily an effect of the increased valence electron concentration induced upon alloying.

Development of wear resistant coatings using LD slag premixed with Al2O3

Linz–Donawitz slag (LDS) is a major solid waste generated in huge quantities during steel making. It comes from slag formers, such as burned lime/dolomite and from oxidizing of silica, iron, etc., while refining the iron into steel in the LD furnace. This work aims at utilization of waste LDS to develop surface coatings by plasma spraying technique. This technology has the advantage of being able to process various low-grade ore minerals to obtain value-added products and also to deposit materials, generating near homogeneous coatings with the desired microstructure. Coatings prepared for this investigation are characterized in terms of their thickness and adhesion strength. Coatability of LDS is assessed by finding deposition efficiency. Erosion wear characteristics of these coatings are also studied. Premixing of Al2O3 powder with LDS is found to substantially improve the interfacial adhesion, and the maximum adhesion strength of 33.77 MPa is recorded in such coatings with 30 wt% of Al2O3 content in the LDS–Al2O3 mix. It is found that the operating power levels of the plasma torch affect the adhesion strength, coating deposition efficiency and mean thickness of the coatings. This work opens up a new avenue for utilization of LD slag as a potential coating material.

Development of Wear Resistant Nano Dispersed Composite Coating by Electrodeposition

This study concerns the development of wear resistant coatings of Ni-Al2O3 composite on steel substrates by electrodeposition. Each of the coating experiments was performed in an electrolytic bath, containing a nano-sized dispersion of Al2O3 particles in nickel sulfate and boric acid solution. Composition of the coating mixture was systematically varied with respect to the contents of the dispersed particles, while the amount of the dissolved nickel sulfate, and boric acid and the applied current were kept constant during the experimental measurements. The coated substrates were characterized for their morphology, Vickers hardness, and scratch resistance properties. It was observed that hardness and scratch resistance of the coated substrates increased with an increase in the Al2O3 content in the coating. It was noted that hardness of the composite coating decreased after heat treatment at 400oC in air atmosphere.

Multifunctional FeCo/TiN Multilayer Thin Films with Combined Magnetic and Protective Properties

AbstractCoatings with thicknesses ranging from a few nanometer up to several micrometer produced by physical vapor deposition (PVD) processes have been established in engineering technologies since the early 1980s. In particular, magnetron sputtered wear resistance coatings are industrially established and capable to enhance tool lifetimes significantly. However, in cases where optical inspection of a coating in use is not possible, an intrinsic sensor function of the film would be beneficial. Therefore, the development of wear resistant coatings with an integrated sensor functionality based on the insertion of a magnetoelastic ferromagnetic phase is suggested. In combination with appropriate read‐out electronics such a film system would be ready for online monitoring of the coatings' actual state (e.g., strain, temperature, volume loss). This paper focuses on the development of wear resistance coatings which simultaneously supply beneficial mechanical properties as well as ferromagnetic properties optimized for online non‐contact read‐out applications. Multilayer coatings obtained through alternate stacking of magnetron sputtered TiN and FeCo layers with a nominal total thickness of 1000 nm were produced as a model system meeting the above conditions. The bilayer period was varied down to 2.6 nm while the individual layer thickness ratio tTiN/tFeCo was determined by the deposition rates and maintained constant at a value of about 3/1. The films were vacuum annealed ex situ in a static magnetic field subsequent to the deposition. The constitution of the as‐deposited and annealed coatings as well as their mechanical (nanohardness, Young's modulus) and magnetic properties (magnetization hysteresis, frequency‐dependent permeability) are described. Finally, the suitability of the coatings for the use in remote‐interrogable wear sensor applications is briefly discussed.