Papers by Keyword: Wear

Abstract: Dry machining of gears demands advanced coating technologies to withstand high thermal and mechanical stresses. In this study, AlCrN coatings were deposited using the newly developed Focused Magnetron Sputtering (FMS) process and compared with conventional Cathodic Arc Evaporation (CAE)-AlCrN and boroncontaining CAE-AlCrBN coatings. XRD analysis showed that FMS produced a finegrained crystal structure with half the full width at half maximum (FWHM) of CAE-AlCrN. Stressoptimised deposition allowed a 60 % higher coating thickness with improved adhesion. Analogy gear hobbing tests (fly cutting tests) demonstrated that FMS-AlCrN had 52 % lower crater wear than CAE-AlCrN, while CAE-AlCrBN also improved crater wear resistance due to boroninduced grain refinement. However, both finegrained coatings exhibited increased flank wear compared to the coarse-grained CAE-AlCrN coating. The results show that FMS enables the production of dense, fine-grained coatings with superior adhesion and crater wear resistance, highlighting its potential for dry gear hobbing. Further optimisation of hardness and microstructure is required to balance crater and flank wear behaviour.

Abstract: Geared components increasingly require higher torque density, driving the use of high-strength steels and necessitating stable machining processes, particularly in small and medium-sized enterprises that rely on cutting fluids. This study evaluates the performance potential of various cutting fluids in gear hobbing using a fly-cutting analogy test setup, which enables controlled and reproducible analysis of wear mechanisms of a single hob tooth. Water-based and oil-based cutting fluids, different tool substrate materials (PM-HSS, MC90, and tungsten carbide), and workpiece steels of different strength levels were systematically investigated. The results show that PM-HSS is unsuitable for machining the highest-strength material. Dry machining improved tool life, whereas the application of cutting fluids led to increased tool wear.

Abstract: This study investigates the effect of deep cryogenic treatment on the tribological and electrochemical performance of X46Cr13 martensitic stainless steel, with a particular emphasis on the synergistic interaction between wear and corrosion and its microstructural origins. The material was subjected to conventional quenching and tempering and compared with heat treatment routes incorporating cryogenic processing. Hardness measurements, wear tests, and electrochemical characterization by Tafel polarization were combined with quantitative microstructural analysis. Cryogenic treatment induces a pronounced microstructural refinement through the transformation of retained austenite into martensite and the enhanced precipitation of fine chromium-rich carbides, predominantly M₂₃C₆ and M₇C₃. This process results in an increased carbide number density and a reduced average carbide area, leading to a more homogeneous carbide distribution within the martensitic matrix. The refined carbide population contributes to increased hardness and significantly improved wear resistance by effectively hindering plastic deformation and abrasive damage. Simultaneously, the stabilization of the martensitic matrix and the modified carbide–matrix interface promote the formation of a more uniform and stable passive film, improving corrosion resistance. The combined improvement in wear and corrosion behavior reduces the degradation rate under coupled mechanical and electrochemical loading, demonstrating a clear tribocorrosion synergy controlled by carbide characteristics. These findings highlight cryogenic treatment as an effective strategy for tailoring the microstructure of martensitic stainless steels to enhance their performance in aggressive and mechanically demanding environments.

Abstract: Nickel coated steel is used in the industry to produce battery shells. These shells are typically produced in several process steps: drawing, redrawing and several ironing steps at high production rates. The nickel plated steel sheet is subjected to a large range of deformations andpressures. Sometimes scratches in the longitudinal direction of the shell (hairlines) occur, due to the build-up of particles on the tooling (i.e. galling). Cleaning of the tools will be necessary and will bring additional costs. In this paper, analyses are performed on tribological behaviour of nickel plated steel sheet with the focus on tool wear. Adhesive wear has been observed to be the main wear mechanism. The adhesive layer build up consists mainly of compacted particles (often in the shape of flakes) of nickel and iron. The Slider on Sheet Test (SOST) is found to be a relevant set-up to study tribological behaviour of nickel plated steels in battery production.

Abstract: In this study, the mechanical and tribological properties of 3 mol. % yttria-stabilized tetragonal ZrO₂ (3Y-TZP) prepared by spark plasma sintering (SPS) were investigated. Nanoindentation revealed a high hardness of 16.51 ± 0.86 GPa and an elastic modulus of 250 ± 8.8 GPa. The low scatter of these values provides strong evidence for a homogeneous, fine-grained microstructure. Vickers microhardness at a 5 N load was 1382 ± 14 and indentation fracture toughness (K_IC, Niihara) was 5.2 ± 0.03 MPa·m¹ᐟ², confirming the material’s high mechanical resilience. Dry reciprocating sliding against a SiC counterface exhibited a stable coefficient of friction (COF) of 0.37–0.39, with a slight decrease to 0.37 at 25 N load attributed to the formation of a thin protective tribolayer. Wear track depth increased from ~0.8 µm (5 N) to ~2.8 µm (25 N), and width from ~1.400 µm to ~ 1.600 µm, while the specific wear rate rose only marginally from 9.28 × 10⁻⁸ to 5.05 × 10⁻⁷ mm³/N·m, demonstrating excellent wear resistance. SEM/EDX analysis revealed predominant abrasive wear with microcracking, alongside tribochemical oxidation layers rich in SiO₂ and carbon that contribute to surface protection. Stabilization of the tetragonal phase and a fine-grained microstructure are key factors enabling the superior hardness, elasticity, and tribological performance of 3Y-TZP for applications demanding low friction and high wear resistance.

Abstract: This study investigates the tribological behavior of composites based on Al₂O₃–ZrO₂ stabilized with 3 mol. % Y₂O₃ (ZTA – zirconia-toughened alumina), prepared using spark plasma sintering (SPS) technology. The composites were characterized in terms of microstructure, mechanical properties, and wear resistance in a dry ball-on-flat configuration. SEM analysis confirmed a homogeneous and fine-grained microstructure without porosity, with Al₂O₃ grain sizes of 200–400 nm and ZrO₂ grain sizes of 100–200 nm. Measurements revealed high Vickers hardness (1566.7 ± 133.6 MPa), fracture toughness (6.4 ± 0.29 MPa·m¹ᐟ²), nanoindentation hardness (25.94 ± 2.35 GPa), and Young’s modulus (365.9 ± 18.2 GPa). The coefficient of friction ranged from 0.40 to 0.53 depending on the load, and the specific wear rate was extremely low (4.81 × 10⁻⁷ to 5.08 × 10⁻⁷ mm³/Nm). Analysis of the wear track revealed predominantly abrasive wear without significant fragmentation or delamination. The results demonstrate that optimized microstructure, proper phase stabilization, and a high degree of densification enable the preparation of composites with an excellent combination of hardness, toughness, and tribological resistance. These materials are suitable for demanding applications in industry, energy, and biomedicine.

Abstract: Abrasive properties of selected rocks and their influence on button bit wear were investigated. Rock samples were obtained from three locations in Southwest, Nigeria. These samples were tested in the laboratory for grain size and circularity factor. Also, porosity, Equivalent Quartz content (EQC), Rock Hardness Number (RHN), Rock Abrasivity Index (RAI) and Uniaxial Compressive Strength were determined. Bit button lengths consumed were measured at regular interval as drilling operation progresses. Results of grain size revealed that medium feldspar granite has least average grain size varying from 0.12 – 0.14 mm. There is possibility that rate of drilling may be low while drilling through this rock. The values of circularity factor varied from 0.624 for medium feldspar granite to 0.786 for coarse muscovite granite. The mean values of porosity varied from between 0.85 and 1.33% for medium feldspar granite and coarse muscovite granite respectively. Biotite hornblende granite has the highest mean uniaxial compressive strength value of 119.48 MPa while coarse muscovite granite has the least mean value of 90.65 MPa. The values of free silica, EQC, RHN, and RAI varied from 35.93 – 51.35%, 45.60 – 67.21%, 575.52 – 821.64 kg/mm³ and 4133.64 – 7003.71 respectively. It was observed that grain size affects the void size in these rocks, which accounted for least porosity value obtained in medium feldspar granite. Average bit button length consumed varied from 15.56 – 24.54 mm for gauge button while length of centre button varied from 13.00 – 19.61 mm. Higher gauge button length consumption could be inferred that it effects the cutting, crushing and wedging of rock mineral components at rock-bit interface. The understanding of grain size, circularity factor and abrasive properties will provide adequate information for quarry to select appropriate bit and drilling machine.

Abstract: In this work, an experimental methodology is presented for investigating the kinetics of competing oxidation and metal-plating processes that occur on friction surfaces under variable load conditions. The aim of the study was to determine the critical parameters for the transition between the formation of dissipative secondary structures (DSS) and metal-plating films (MPFs), as well as to evaluate the contact electrical resistance (CER) as an indicator of the structural state of the surfaces. A universal tribometer with adjustable load (0.2–40 MPa) was used to test friction pairs of steel 45 and bearing steel Shkh15, employing a vaseline oil as an inert lubricant and CIATIM-201 grease with 7% copper powder as a metal-plating additive. A clear correlation was observed between the CER, the friction coefficient (μ) and the wear intensity (I) across four operating modes. The maximum CER values (up to 40 Ω·cm²) were recorded in the DSS formation regime, whereas the minimum values (below 1 Ω·cm²) corresponded to the metal-plating regime. The results demonstrate that the structural-energetic approach enables effective diagnosis of the tribological state and that the CER parameter serves as an informative criterion for distinguishing between friction regimes.

Abstract: The automotive industry has been challenged by the rising need for lighter, environmentally friendly, low-emission, and low-energy consumption vehicles. Aluminium is regarded as a viable alternative to the heavier materials presently used in manufacturing automobiles due to its desirable characteristics. A review of the application of hybrid aluminium matrix composites (HAMCs) and aluminium matrix composites (AMCs) in the automotive sector is discussed in this paper. An overview of the properties and applications of fiber-reinforced, discontinuous, and particle-reinforced AMCs and HAMCs is given. Due to their superior mechanical, tribological, and physical properties, aluminium composite materials have emerged as the material of choice for most engineering applications. A discussion of the importance of proper selection of materials is also presented. The potential applications of AMCs and HAMCs in the automotive industry, i.e., brake discs and drums, cylinder blocks and liners, pistons, crankshafts, connecting rods, brake calipers, turbo heat exchangers, and others, are also addressed in this review. Recent trends and trends forming in aluminium use in automotive applications are also determined through the assessment.

Abstract: This research examines the friction and wear characteristics, as well as the mechanical properties, of EPDM (ethylene propylene diene monomer) rubber filled with oleamide. The friction measurements are done in contact with PA66GF30. The goal is to determine the suitability of this material combination for usage in dynamic sealing applications on the cathodic side of PEMFC (Proton Exchange Membrane Fuel Cell) systems. The EPDM rubber, specifically designed for reduced friction, underwent aging procedures such as heat aging and water-glycol soaking to assess its long-term performance. The pin-on-disk tests demonstrated a rapid initial rise in the coefficient of friction (CoF) and notable wear, but the hot water extraction experiments showed inadequate chemical stability with substantial ion leaching. The tensile tests demonstrated a significant decrease in mechanical characteristics during the aging process. The findings indicate that the EPDM containing oleamide has promise for dynamic sealing. However, its performance is greatly affected by aging and exposure to the environment, which highlights the need for more material optimization.