Tribological Properties Of Metals Research Articles

Effect of laser surface remelting on Microstructure, mechanical properties and tribological properties of metals and alloys: A review

Surface defects like porosity, cracks, coarse grains, surface roughness, etc. have a huge impact on the strength and performance of materials. Due to this, surface treatments have become an important part in the field of materials to attain certain desirable mechanical properties and surface properties. Surface of parts treated with laser surface remelting exhibits excellent surface and mechanical properties. It is a computer-based technique which provides the advantage of treating selective surfaces. Laser surface remelting tends to enhance corrosion resistance, microhardness, wear resistance, fatigue strength, and tensile strength of the materials. To achieve certain mechanical properties with laser surface remelting, an optimized set of laser processing parameters is essential. Laser surface remelting has become a compulsory treatment for parts manufactured by Additive Manufacturing (AM) processes as these processes provide poor surface, porosity, and hot cracking defects which ultimately affect the performance of parts. This paper critically evaluates the advancements which have been made in the field of laser surface remelting to get better surface quality, improved mechanical and tribological properties.

Tribological Behaviour and Microstructure of an Aluminium Alloy-Based g-SiC Hybrid Surface Composite Produced by FSP

In this work, the microstructure and wear characteristics of a surface-reinforced composite based on an aluminium alloy with a mixture of graphene nanoplatelets (GNP) and silicon carbide (SiC), referred to as g-SiC, fabricated by Friction Stir Processing (FSP), are investigated. To further improve the tribological performance, different volume fractions (0 vol%, 5 vol%, 10 vol% and 15 vol%) of g-SiC-reinforced aluminium alloy are prepared by FSP. It is concluded that the Friction Stir Processed (FSPed) AA5083/g-SiC (15 vol%) specimen has optimum reduction in average friction coefficient (61.13%) and optimum reduction in specimen weight (72.97%). In summary, such hybrid reinforcements effectively improve the mechanical and tribological properties of metals with minimal negative impact on the environment and humans, while reducing material loss and overall manufacturing costs.

Effects of constituent layers and interfaces on the mechanical and tribological properties of metal (Cr, Zr)/ceramic (CrN, ZrN) multilayer systems

The influences of constituent layers and interfaces on the mechanical and tribological behaviors of metal (Cr, Zr)/ceramic (CrN, ZrN) multilayer coatings were systematically investigated in the present study. Four sets of multilayer coatings (Cr/CrN, Cr/ZrN, Zr/CrN and Zr/ZrN) with the same number of interfaces were synthesized by multi-arc ion plating technique. The crystalline structures of the multilayer coatings were determined by X-ray diffraction and morphologies were observed by scanning electron microscope and transmission electron microscope. Furthermore, the nanoindenter, Vicker indenter, scratch tester and ball-on-disk tribometer were employed to evaluate the hardness, indentation toughness, adhesion strength and tribological properties of as-prepared coatings, respectively. Results revealed that the multilayer coatings with different constitute layers and interfaces presented different microstructures and properties. Based on the analysis of the cross-sectional indentation topographies, Zr interlayers exhibited higher crack resistances compared to Cr interlayers. Zr/CrN multilayer coating showed the highest hardness of 28 GPa, the strongest strength adhesion (>100 N) and the lowest wear rate. The excellent tribological performance of Zr/CrN multilayer coating was mainly ascribed to the high crack resistance of Zr layer, high wear-resistant layer of CrN as well as the local coherent interface between Zr and CrN sublayers.

Graphene-Reinforced Metal and Polymer Matrix Composites

Composites have tremendous applicability due to their excellent capabilities. The performance of composites mainly depends on the reinforcing material applied. Graphene is successful as an efficient reinforcing material due to its versatile as well as superior properties. Even at very low content, graphene can dramatically improve the properties of polymer and metal matrix composites. This article reviews the fabrication followed by mechanical and tribological properties of metal and polymer matrix composites filled with different kinds of graphene, including single-layer, multilayer, and functionalized graphene. Results reported to date in literature indicate that functionalized graphene or graphene oxide-polymer composites are promising materials offering significantly improved strength and frictional properties. A similar trend of improved properties has been observed in case of graphene-metal matrix composites. However, achieving higher graphene loading with uniform dispersion in metal matrix composites remains a challenge. Although graphene-reinforced composites face some challenges, such as understanding the graphene-matrix interaction or fabrication techniques, graphene-reinforced polymer and metal matrix composites have great potential for application in various fields due to their outstanding properties.

The Influence of Mass Fraction and Size of Glassy Carbon Particles on the Tribological Properties of Metal – Ceramic Composites

This paper presents the manufacturing process and the results of measurements for aluminum – aluminum oxide materials with addition of glassy carbon particles (GC). The composites were manufactured via high energy milling process with hot pressing subsequently. The influence of mass fraction (5, 10 and 15 wt.%) and a size of GC particles (<40, 40-80, 80-120, 120-160, 160-200µm) on the microstructure and properties were analysed. The complex meaning of GC particles for all, milling process, microstructure and final properties were discovered. After based description of materials, the tribological measurement were performed under two loads – 35 and 50N. It was noted, that mass fraction of GC particles have influence on tribological properties of materials. The composite with 5 wt.% revealed the best friction properties without any significant differences between analysed loads. The influence of particles size proved that the most effective fraction for tribological application is 120 – 160µm.

Tribological properties of metals, metal-like compounds, and composite materials under high temperatures

The paper presents the investigation results of tribological properties of metals, metal-like compounds, and composite materials at high temperatures. The factors affecting seizure in like and unlike combinations of materials are discussed along with their adequacy for operation in high-temperature friction joints in various media.

Structure and Properties of Iron Piston Rings Manufactured by Continuous Cyclic Casting

The microstructure and mechanical and tribological properties of metal of piston rings produced from preforms cast into dry sand-clay molds by the method of continuous cyclic casting are described. The dislocation structure and chemical composition of fine surface layers that appear under friction are studied by x-ray diffraction and spectral analysis. It is shown that chemical elements migrate from the metallic matrix of the rings into surface layers plastically deformed by friction. The advantages of continuous cyclic casting in the production of diesel piston rings are analyzed.

Comparison of tribological properties of metal–metal and metal–cermet couples under lubricated and dry conditions

The focus of this paper is on the determination of friction, wear, and film forming characteristics in conventional metal–metal couples and in cermet–metal couples. The tribological behaviour of a WC–Co based cermet applied by the HVOF process to a carbon steel substrate has been investigated in contact with cast iron, and this behaviour has been compared with carbon steel–cast iron couples. A mineral oil, a mineral oil containing zinc dialkyldithiophosphate (ZDDP), and a fully formulated lubricant were used for lubrication. The results show that the behaviour of the lubricant, in terms of its film forming and friction behaviour, is critically dependent on the load. The oil containing ZDDP shows a very significant increase in its ability to form a boundary film as the load increases.

Morphology and tribological properties of metal (oxide)–MoS 2 nanostructured multilayer coatings

Multilayer coatings of metallic (Au, Ni, Pb or PbO) and MoS 2 nanometer-scale layers were deposited by r.f. magnetron sputtering on 440C steel with a Cr adhesion layer. The structure, composition and thickness of the multilayers were studied by Rutherford back-scattering (RBS) and X-ray diffraction (XRD) spectroscopies. Pin-on-disk tribometer tests were performed in humid air of 50% RH. In order to investigate chemical and mechanical aspects of wear in humid air, the worn surfaces of the multilayers and of the counter parts were studied by scanning Auger microscopy (SAM) and scanning electron microscopy (SEM) after different sliding distances. The chemistry of wear was found to be associated with elimination of Mo from the contact surfaces. Relative to pure sputter-deposited MoS 2 coatings, lower values and more stable mean friction coefficients were observed for the metal–MoS 2 multilayers studied at higher loads. A correlation between the morphology and sliding properties of multilayers was found to be associated with an increased preferred basal orientation of MoS 2 in nanoscaled layers. The role of metal is most likely associated with a structural modification of MoS 2 rather than “gettering” of oxygen during sliding. It is concluded that the improvement in the tribological performance of sputter-deposited metal–MoS 2 multilayers in humid air can be generally attributed to the optimization of MoS 2 morphology in nanostructured multilayer coatings.

Tribological properties of metals modified by ion-beam assisted deposition of silicone oil

Silicone oil vapor deposition and Ar+ ion irradiation can form an adhesive carbonaceous film on a steel substrate. The friction coefficient μ of the coated substrate is found to be very low for sliding against a steel ball both in air (μ ∼ 0.04) and in N2 gas (μ < 0.02). The duration of the low friction state is comparatively long and is 5 × 103–1.5 × 104 cycles for a film 0.15 μm thick. X-ray photoemission spectroscopy, infrared reflection spectra, and Raman measurements indicate that the film mainly consists of amorphous carbon containing Si and O.

Comparison between diffusion of 15N N and 14N in implanted iron

It is well known that nitrogen implantations at doses greater than 10 17 ions cm −2 modify the tribological properties of metals. In particular the wear resistance for several types of steel is enhanced. Tribological tests and industrial applications are made with samples implanted with natural nitrogen which contains more than 99% of 14 N. On the other hand, physical properties, such as nitrogen diffusion in steels are measured using the 15 N(p, αγ) 12 C reaction at EP = 429 keV. However, it is also possible to measure depth profiling of 14 N with a narrow resonance at E α = 1531 keV in the 1 4N(α, γ)1 8 F reaction. Both reactions were used in the present work. Pure iron foils were implanted with enriched 15 N (70% 14 N–30% 15 N at different doses. Depth profiles of 14N and 15N were measured on the same sample before and after thermal annealing. The depth distribution was not affected by the isotopic composition of the implanted ions. There is no isotopic effect in the nitrogen diffusion during the implantation or after thermal annealing.