Lubricants

Research

14 pages, 5358 KiB

Open AccessArticle

Depletion of Reflectance of Silicon Surface Textured Using Nano Second Fiber Laser

by S. Oliver Nesa Raj and Sethuramalingam Prabhu

Lubricants 2023, 11(1), 15; https://doi.org/10.3390/lubricants11010015 - 3 Jan 2023

Cited by 2 | Viewed by 2047

This paper characterizes the surface modification on silicon surfaces with different patterns (circle, pyramid) using a nanosecond fiber laser with different parameters, which enhances its anti-reflection property. The influence of textured and untextured silicon surfaces and their structural properties were evaluated. It has [...] Read more.

This paper characterizes the surface modification on silicon surfaces with different patterns (circle, pyramid) using a nanosecond fiber laser with different parameters, which enhances its anti-reflection property. The influence of textured and untextured silicon surfaces and their structural properties were evaluated. It has a long absorption path (200–1000 nm) and a rougher surface due to surface modifications, which results in a 40% decrease in incident light reflectance, especially in pyramid-shaped dimples with 70 µm size, helping to trap more light in solar cells where the anti-reflecting surface is a crucial need for devices used in optical and photovoltaic applications to operate more effectively. Scanning electron microscope (SEM) and atomic force microscopy (AFM) are used to examine the surface features to determine the process’s effectiveness and recognize the development of patterns that are deep enough to trap light. XRD and micro-Raman spectroscopy were used to examine the irradiated surface’s crystallographic structure and crystallinity change. Full article

(This article belongs to the Special Issue Surface Engineering for Wear Protection and Friction Reduction)

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14 pages, 8817 KiB

Open AccessArticle

Effect of Micro-Dimple Geometry on the Tribological Characteristics of Textured Surfaces

by Saood Ali, Rendi Kurniawan, Moran Xu, Farooq Ahmed, Mohd Danish and Kubilay Aslantas

Lubricants 2022, 10(12), 328; https://doi.org/10.3390/lubricants10120328 - 23 Nov 2022

Cited by 6 | Viewed by 2067

Abstract

The introduction of external surface features on mating contact surfaces is an effective method to reduce friction and wear between the contact surfaces. The tribological properties of the contact surfaces can be improved by controlling the geometrical parameters (shape, size, depth) of the [...] Read more.

The introduction of external surface features on mating contact surfaces is an effective method to reduce friction and wear between the contact surfaces. The tribological properties of the contact surfaces can be improved by controlling the geometrical parameters (shape, size, depth) of the surface texture effectively. In the present study, the tribological properties of Al6061-T6 cylindrical workpieces with various micro-dimple-texture geometries and an AISI 52100 steel stationery block are tested experimentally, in a rotating cylinder-on-pin configuration of the friction test. The dual-frequency surface texturing method is employed to create micro-dimple textures using a polycrystalline diamond tool. The effect of a hierarchical micro-dimple texture is then investigated under boundary lubrication conditions. Hierarchical micro-dimples, with an increase in length, show a lower friction coefficient under high load and sliding speed conditions. Secondary hierarchical nano-structures help in improving the tribological characteristics by generating an additional hydrodynamic lift effect. Full article

(This article belongs to the Special Issue Surface Engineering for Wear Protection and Friction Reduction)

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12 pages, 5065 KiB

Open AccessArticle

Effect of Sintering Parameters on the Mechanical Properties and Wear Performance of Alumina Inserts

by Abdul Aziz Adam, Hadzley Abu Bakar, Umar Al Amani, Lailatul Harina Paijan, Norfariza Ab Wahab, Mohd Fauzi Mamat, Mohd Basri Ali, Safarudin Gazali Herawan and Zulkifli Ahmad

Lubricants 2022, 10(12), 325; https://doi.org/10.3390/lubricants10120325 - 22 Nov 2022

Cited by 4 | Viewed by 1701

Abstract

The sintering temperature and holding time have a significant impact on the densification of a ceramic compact. In this study, alumina inserts were made with varying sintering temperatures and holding times. The procedure began with the compacting of alumina powders inside a mould [...] Read more.

The sintering temperature and holding time have a significant impact on the densification of a ceramic compact. In this study, alumina inserts were made with varying sintering temperatures and holding times. The procedure began with the compacting of alumina powders inside a mould with trapezium and round shapes. These inserts were then sintered between 1200 °C and 1400 °C for 5 to 9 h holding time. The sintered samples underwent analysis based on the shrinkage size, density, and microstructure. The sample with the highest density was chosen for additional machining tests. The results showed that the alumina shrinkage ranged from 3 to 6%, with a maximum relative density of 91.3% recorded when the sintering parameter was applied at 1400 °C and a 9 h holding time. The transition of the grain growth was observed depending on the sintering temperature and heating duration. When machined with AISI 1045 carbon steel, the sintered alumina inserts achieved a maximum tool life of 35 s at a cutting speed of 350 m/min. The sintered inserts exhibited brittle characteristics with a dominant notch wear and abrasive mechanisms. Full article

(This article belongs to the Special Issue Surface Engineering for Wear Protection and Friction Reduction)

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14 pages, 7076 KiB

Open AccessArticle

Tribological Properties of Ti6Al4V Titanium Textured Surfaces Created by Laser: Effect of Dimple Density

by Akshay Gaikwad, Juan Manuel Vázquez-Martínez, Jorge Salguero and Patricia Iglesias

Lubricants 2022, 10(7), 138; https://doi.org/10.3390/lubricants10070138 - 30 Jun 2022

Cited by 17 | Viewed by 2512

Abstract

The loss of energy due to friction is one of the major problems industries are facing nowadays. Friction and wear between sliding components reduce the mechanical efficiency of machines and have a negative impact on the environment. In recent years, surface texturing has [...] Read more.

The loss of energy due to friction is one of the major problems industries are facing nowadays. Friction and wear between sliding components reduce the mechanical efficiency of machines and have a negative impact on the environment. In recent years, surface texturing has shown tremendous ability to reduce friction and wear. Micro-features generated on surfaces act as a secondary reservoir for lubricants and wear debris receptacles to further reduce abrasion. In addition, surface texturing boosts hydrodynamic pressure, which increases the elasto-hydrodynamic lubrication regime of the Stribeck curve, reducing friction and wear. Amongst all different techniques to texture surfaces, laser texturing is the most popular due to its advantages such as high accuracy, good consistency and celerity as compared to other techniques. This study investigated the effect of laser texturing on the tribological properties of Ti6Al4V in contact with a ceramic ball. The effect of varying the dimple density on friction and wear was studied using a ball-on-flat reciprocating tribometer under lubricated conditions. Results show that friction and wear were reduced for all the textured samples as compared to an untextured sample, with important friction and wear reductions for the samples with the highest dimple densities. For samples with intermediate dimple densities, the friction coefficient stayed low until the dimples wore out from the surface and then increased to a value similar to the friction coefficient of the untextured surface. The dimple wear-out time observed in these specimens was greatly influenced by the dimple density. Full article

(This article belongs to the Special Issue Surface Engineering for Wear Protection and Friction Reduction)

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12 pages, 3281 KiB

Open AccessArticle

Evolution of the Geometric Structure of X39Cr13 Steel upon Thermochemical Treatment Specific to Medical-Grade Steels

by Monika Gwoździk, Mirosław Bramowicz and Sławomir Kulesza

Lubricants 2022, 10(6), 114; https://doi.org/10.3390/lubricants10060114 - 3 Jun 2022

Cited by 1 | Viewed by 1747

Abstract

This paper presents the results of the multi-aspect surface characterization of X39Cr13 steel samples subjected to technological processes specific to medical instrumentation, such as heat and thermochemical treatment, as well as sterilization, which are implemented in corrosion resistance measurements. The application of numerical [...] Read more.

This paper presents the results of the multi-aspect surface characterization of X39Cr13 steel samples subjected to technological processes specific to medical instrumentation, such as heat and thermochemical treatment, as well as sterilization, which are implemented in corrosion resistance measurements. The application of numerical methods of fractal analysis to averaged profiles obtained from SEM images resulted in double-log plots of structure function, from which the determination of the fractal parameters of interest was possible. The discussion was focused on the fractal dimension D, which governs relative height variations upon scaling in length, and corner frequency f_c, which separates the scaling behavior of different-order structures (particles and their aggregates). The obtained results show that the heat treatment leaves behind a granular structure of steel (D₂ = 2.43; f_c2 = 1.97 nm), whereas corrosion tests reveal the appearance of pits (D₁ = 2.17; f_c1 = 0.303 nm; D₂ = 2.59; f_c2 = 4.76 nm). In turn, the ion nitriding improves the resistance of steel X39Cr13 to local corrosion. The fractal analysis also shows that the structure of the nitrided layer differs insignificantly from that of the untreated material, seen only as a shortening of the radius of the self-similarity area by a factor of two (f_c2 = 1 nm). Full article

(This article belongs to the Special Issue Surface Engineering for Wear Protection and Friction Reduction)

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15 pages, 4271 KiB

Open AccessArticle

Effect of Surface Texture on the Sliding Pair Lubrication Efficiency

by Bogdan Antoszewski and Piotr Kurp

Lubricants 2022, 10(5), 80; https://doi.org/10.3390/lubricants10050080 - 2 May 2022

Cited by 7 | Viewed by 2503

Abstract

The paper presents certain problems related to the lubrication of textured surfaces. It was noted that for a specific load, the lubrication effectiveness will depend on the shape, size and mutual distribution of the texture’s elements. Proposals for determining the lubrication irregularity parameters [...] Read more.

The paper presents certain problems related to the lubrication of textured surfaces. It was noted that for a specific load, the lubrication effectiveness will depend on the shape, size and mutual distribution of the texture’s elements. Proposals for determining the lubrication irregularity parameters were presented for textures with a rectangular mesh and round recesses. The experimental part presents the laser texturing methodology, tribological testing methodology and preliminary test results where the significant role of the relationship between the trajectory of motion and the texture mesh was demonstrated. Full article

(This article belongs to the Special Issue Surface Engineering for Wear Protection and Friction Reduction)

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14 pages, 3483 KiB

Open AccessArticle

On the Stiffness and Damping Characteristics of Line Contacts under Transient Elastohydrodynamic Lubrication

by Congcong Fang, Anyuan Zhu, Wei Zhou, Yongdong Peng and Xianghui Meng

Lubricants 2022, 10(4), 73; https://doi.org/10.3390/lubricants10040073 - 18 Apr 2022

Cited by 9 | Viewed by 3723

Abstract

The elastohydrodynamic lubrication (EHL) oil film between contact interfaces acts as a spring or damper to reduce wear and vibration for frictional pairs. To analyze the dynamic behaviors of friction pairs in mechanical systems both effectively and accurately, the stiffness and damping parameters [...] Read more.

The elastohydrodynamic lubrication (EHL) oil film between contact interfaces acts as a spring or damper to reduce wear and vibration for frictional pairs. To analyze the dynamic behaviors of friction pairs in mechanical systems both effectively and accurately, the stiffness and damping parameters under EHL contact states are essential. The presented work develops a numerical model to investigate the EHL stiffness and damping characteristics based on the transient EHL system and elastic contact theory of line contact, in which the stiffness force is separated according to the relationship with approach distance of the contact body established in the steady process, and then the damping can be obtained. The results show that the stiffness force plays an increasingly important role over the applied load conditions while the damping effects is gradually weakened. EHL stiffness is obviously smaller than dry contact stiffness, but the discrepancy is decreasing with the increasing load. Moreover, the higher entrainment velocity, lubricant viscosity and larger curvature radii leads to smaller stiffness and damping. The elastic modulus generates little effect on dynamic characteristics when the load is light while dominates the maximum level of the contact stiffness. Full article

(This article belongs to the Special Issue Surface Engineering for Wear Protection and Friction Reduction)

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12 pages, 6900 KiB

Open AccessArticle

Validation of a Multi-Scale Contact Temperature Model for Dry Sliding Rough Surfaces

by Jamal Choudhry, Andreas Almqvist and Roland Larsson

Lubricants 2022, 10(3), 41; https://doi.org/10.3390/lubricants10030041 - 9 Mar 2022

Cited by 4 | Viewed by 2772

Abstract

A multi-scale flash temperature model is validated against existing experimental work. The model shows promising results and proves itself to be a reliable tool for the accurate prediction of the flash temperature development between rough surfaces in sliding systems. Model predictions for the [...] Read more.

A multi-scale flash temperature model is validated against existing experimental work. The model shows promising results and proves itself to be a reliable tool for the accurate prediction of the flash temperature development between rough surfaces in sliding systems. Model predictions for the maximum flash temperatures as well as the bulk temperature fields were in very good agreement with the experimentally measured values. The model was also able to accurately predict the formation of hotspots as well as the temperature variations around the hotspots. From the model predictions, it is concluded that it is sufficient to only assess the flash temperatures on a small portion of the contact area and thus save both computational time and memory. Full article

(This article belongs to the Special Issue Surface Engineering for Wear Protection and Friction Reduction)

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