In this work, we use the Abbott-Firestone curve as the basis to develop a simple quantitative approach to measure the anisotropy of a surface. The main idea is to measure the difference between the curves for two mutually perpendicular directions over the surface as a function of the orientation of the lines. The approach is tested on a number of isotropic and anisotropic surfaces, both real and numerically generated.

Electroless Ni-B-W coating is deposited on low carbon steel in an alkaline sodium borohydride reduced electroless bath. The mechanical and tribological properties of such coatings are much necessary to be assessed to carry out application-based studies. The present work focuses mainly on the evaluation of hardness and fracture toughness of electroless Ni-B-W coatings using a scratch tester. Coating's response towards scratching is also studied thoroughly. The characteristic short-range order present in its lattice structure causes generation of a specific behavioral pattern. Furthermore, a linear sliding wear test is carried out on the coatings' surface to analyze the wear behavior at different loading conditions. The value of specific wear rate is observed to be minimum at a normal load of 22.5 N against Si 3 N 4 counterbody. The patterns of tribological behavior of the coating at different load values are examined from the worn surface morphologies. But before embarking on the scratch and sliding wear tests, the synthesized coatings are characterized under FESEM and XRD in an exhaustive manner. The growth rates with respect to time and the changes in morphological aspects of the coating are also evaluated. The present study establishes electroless Ni-B-W deposits as a suitable option for protecting mechanical components against wear.

Micro-textured samples with different depths exhibits various contact surface morphology parameters including Sa , Sq , Ssk , Sku , and material ratio curves. In this paper, the relationship between micro-textures and roughness parameters was investigated. The effect mechanism of micro-textures on the friction and wear through the height and functional roughness parameters was elucidated. Micro-textured samples presented more negative Ssk , higher Sku , and larger Svk with the increasing dimple depth. The pin-on-disc reciprocating tribological test results indicated that the more negative Ssk , higher Sku , and larger Svk presented lower friction coefficient under the constant Sa and Sq . The wear topographies for the flat and micro-textured specimens with various dimple depths were examined by laser scanning confocal microscope. X-ray photoelectron spectroscopy was employed to describe the formation of absorbed film and tribofilm on the worn surface of flat and micro-textured samples. It was confirmed that more negative Ssk , higher Sku , and material ratio curves with their relative parameters (smaller value of Spk , Sk , Smr1 and larger value of Svk ) could be used for predicting the tribological performance of micro-textured samples.

Microstructure, hardness, and micro-abrasion behavior of borided H13 tool steel (borided at 1073, 1173, and 1273 K with nanoboron powder for 6 h) were studied. A single-phase boride layer was observed on the borided sample at 1073 K, while a double-phase boride layer was observed on the borided samples at high temperatures. FeB–Fe 2 B phases as well as CrB–MnB phases were determined in the XRD analysis of the samples. The hardness of the borided samples increased up to values above 2000 HV 0.1. The thicker boride layer obtained due to the boriding process at high temperatures provided the retention of high hardness in the inner regions. The highest micro-abrasion resistance was obtained with the borided sample at 1273 K. Depending on the increasing load, volume losses increased on all samples under all conditions. Higher wear losses were determined in the tests performed with high-dimensional SiC. In the tests conducted with SiC F800, the dominant wear mechanism was micro-grooving wear mechanism, while in SiC F1200 tests the wear mechanism was micro-rolling and micro-scratching mechanisms. The abrasion resistance of the untreated sample was attributed to the abrasive particles sinking onto the surface.

Dry sliding wear characteristics of the as-cast Mg–10.1Gd–1.4Y–0.4Zr alloy were investigated at 3.0 m/s within a temperature range of 20–200 °C on a pin-on-disc type wear testing machine. Wear rates were acquired and plotted against load at each test temperature. There existed a turning point on the wear rate versus load curve at each test temperature; it corresponded to the mild-severe wear transition. The wear mechanisms were confirmed through morphological and compositional analysis of worn surfaces. An elevated-temperature wear mechanism transition map was drawn, in which mild and severe wear regions were indicated. The differences in microstructure as well as microhardness in subsurfaces were compared between samples worn in the two different regions. The dynamic recrystallization (DRX) softening of the surface material was found to be responsible for mild-severe wear transition. An approximately linear relationship was found between the transition load and test temperature, suggesting that mild-severe wear transition of the alloy still follows a surface temperature criterion even at elevated temperatures. The critical surface temperature is thought of to be the DRX temperature of the alloy. It is approximately 279.3 °C based on the linearly fitting analysis of the transition load versus test temperature.

Hydrophobic and self-cleaning photocatalytic ceramics and concrete with potential for the superhydrophobicity are promising novel materials for civil engineering applications including buildings, bridges, road pavements, and airport runways. Due to embedded liquid-repellent properties, such materials have low water and salt absorption and, therefore, enhanced durability. However, in applications requiring high traction (e.g., tire and pavement), there is a concern that reduced adhesion may compromise the friction. This paper reports on wetting, dry friction, and roughness properties of TiO 2 coated (hydrophilic) and polymethyl hydrogen siloxane (PMHS) coated (hydrophobic) self-cleaning ceramic tiles. The coefficient of friction values of the tile–rubber interface do not change significantly with the applications of the coatings up to 0.67 for hydrophilic TiO 2 based and up to 0.46 for hydrophobic TiO 2 + PMHS coatings versus 0.45 for uncoated reference. Friction has adhesion and roughness-related components and this response can be attributed to the roughness component of friction due to TiO 2 coating. The challenges related to hydrophobic coatings, including the durability and future research, are also discussed.

The objective of this work is to study the tribological properties of natural fiber based composites using nanotechnology. The naturally available banana plant fibers were treated with nanoclay particles, and these treated fibers were then reinforced in an epoxy polymer to form composites. The friction and wear properties of nanoclay-treated banana fiber (NC-BF) reinforced composites were compared with untreated banana fiber (UT-BF) reinforced composites. Short NC-BF- and UT-BF-reinforced composites with fiber concentration ranging from 20 wt % to 60 wt % were prepared by the vacuum resin infusion processing method. The result indicates that the NC-BF-reinforced composites have shown improved friction and wear properties. Microscopy examination revealed that NC-BF-reinforced composites were able to form a transfer layer between the wear test specimen wear surface and counter face, resulting in improved wear properties. The nanoclay particles also induce increased hardness and friction to the composites and improve braking properties.

This study describes the development of a multicomponent composite system consisting of thermoplastic epoxy resin reinforced with E-glass fiber and silicon dioxide (SiO2) particles and investigates its erosion behavior under different operating conditions. Due to the increasing importance of composites in engineering applications and the need to tackle solid particle erosion in various industrial sectors, the study aims at finding how these composites behave in such type of wear. The composite specimens used for the tests were classified into three types; pure glass fiber (GF)–epoxy, those with addition of SiO2 particles at an amount of 15% and the last group had SiO2 particles added at 30% of the resin used for the materials. The experiments were carried out by selecting three different impact velocities, three different impingement angles, and angular alumina abrasive particles having approximate sizes of 200 μm. The fiber directions used were 0/90/0 and 45/ − 45/45. SEM views belonging to the specimens were taken before and after the tests in order to investigate the differences and the causes of the surface damages. Moreover, it is found that the Taguchi's robust orthogonal array method provides a simple, systematic, and efficient methodology for the optimization of the erosion wear parameters. At the end of the tests, the most significant factor in affecting the erosion rate is found to be the impingement angle, followed by the impact velocity, fiber direction, and filler material.

In the present work, the slurry erosion behavior of friction stir processed (FSPed) hydroturbine steel (CA6NM) was investigated. For comparison, the erosion performance of unprocessed CA6NM steel was evaluated under similar conditions. Friction stir processing (FSP) is a microstructural refinement tool which is useful in enhancing the bulk and surface properties of materials. An in-depth characterization of both steels was done using an optical microscope (OM), a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS), the electron backscatter diffraction (EBSD) technique, and micro- and nano-indentation techniques. The FSP of the steel helped in reducing the erosion rates by 50% to 60%, depending upon the impingement angle. The improved performance of the FSPed steel in comparison to unprocessed steel was attributed to microstructural refinement, which increased the hardness and yield strength. At an oblique impingement angle, plowing, along with microcutting, was observed to be the dominant erosion mechanism. At a normal impingement angle, the material removal process was controlled by the platelet mechanism of erosion. A modified form of the mathematical model for predicting the erosion rates of the ductile materials, proposed by authors earlier, was also presented. This modified model based upon the theory of plasticity was able to predict the erosion rates with an accuracy of ±20%.