Special Issue "Friction and Wear of Materials Surfaces"

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Metals and Alloys".

Deadline for manuscript submissions: 31 December 2021.

Special Issue Editor

Dr. Andrzej Dzierwa
E-Mail Website
Guest Editor
Department of Manufacturing Processes and Production Engineering, Faculty of Mechanical Engineering, Rzeszow University of Technology, Powstancow Warszawy 8, 35-959 Rzeszow, Poland
Interests: tribology; friction; wear; surface engineering; surface metrology; manufacturing processes
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The surface topography is one of the most important factors determining the quality of a surface layer. It defines a set of all overlapping irregularities of surface resulting from the machining processes and wear of materials. Irregularities of surface have varied dimensions, shapes and location. The quality of the surface has a significant impact on the operational properties of machine elements, which are expressed, among others, through: frictional conditions on contact surfaces, corrosion resistance, fatigue strength, contact stresses or tightness of joints. All mechanical, physical, chemical, and geometrical aspects of the surface contact affect the surface interactions and thereby also the tribological characteristics of the system.

A number of scientists studied the effect of surface topography and materials properties on the tribological performance of sliding elements. However accessible papers contain ambiguous and sometimes contradictory opinions about connections between values of surface topography parameters, materials properties and various tribological properties of sliding pairs. In addition a continuous development of measuring equipment makes possible more precision measurement and as a consequence makes possible extended analysis of phenomena taking part on surfaces in frictional contact.

Therefore the aim of this special issue is to collect high-quality research papers that focus on friction and wear of materials surfaces. We are looking forward to receiving your submissions.

Dr. Andrzej Dzierwa
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Friction 
  • Wear 
  • Tribology 
  • Surface topography 
  • Surface engineering 
  • Materials 
  • Surface metrology

Published Papers (18 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Article
Effect of Temperature on the Tribological Properties of Selected Thermoplastic Materials Cooperating with Aluminium Alloy
Materials 2021, 14(23), 7318; https://doi.org/10.3390/ma14237318 - 29 Nov 2021
Viewed by 266
Abstract
This article concerns the tribological properties of three selected polymer materials: polyamide PA6, polyethylene PE-HD and polyetheretherketone composite PEEK/BG during sliding against aluminium alloy EN AW-2017A in the presence of hydraulic oil HLP 68. The tests were carried out under contact pressure p [...] Read more.
This article concerns the tribological properties of three selected polymer materials: polyamide PA6, polyethylene PE-HD and polyetheretherketone composite PEEK/BG during sliding against aluminium alloy EN AW-2017A in the presence of hydraulic oil HLP 68. The tests were carried out under contact pressure p of 3.5–11 MPa at ambient temperature T ranging from −20 °C to +20 °C. The dependence of kinetic friction coefficient μk on the two parameters was determined through tribological tests carried out using a pin-on-disc tribometer. A five-level central composite rotatable design (CCRD) was adopted for the experiment. All the test results were statistically analysed. The microhardness of the surface of the polymeric material was measured before and after the friction process. The surface was also examined under SEM. Temperature and contact pressure have been found to have a significant effect on the tribological properties of the tested sliding pairs. Relative to the applied friction conditions, the surfaces after friction showed rather heavy signs of wear. Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Graphical abstract

Article
Effect of Calcination Temperature on the Phase Composition, Morphology, and Thermal Properties of ZrO2 and Al2O3 Modified with APTES (3-aminopropyltriethoxysilane)
Materials 2021, 14(21), 6651; https://doi.org/10.3390/ma14216651 - 04 Nov 2021
Viewed by 294
Abstract
This paper describes the effect of calcination temperature on the phase composition, chemical composition, and morphology of ZrO2 and Al2O3 powders modified with 3-aminopropyltriethoxysilane (APTES). Both ceramic powders were modified by etching in piranha solution, neutralization in ammonia water, [...] Read more.
This paper describes the effect of calcination temperature on the phase composition, chemical composition, and morphology of ZrO2 and Al2O3 powders modified with 3-aminopropyltriethoxysilane (APTES). Both ceramic powders were modified by etching in piranha solution, neutralization in ammonia water, reaction with APTES, ultrasonication, and finally calcination at 250, 350, or 450 °C. The obtained modified powders were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, particle size distribution (PSD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS), and thermogravimetric analysis (TGA). Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Figure 1

Article
Alumina and Zirconia-Reinforced Polyamide PA-12 Composites for Biomedical Additive Manufacturing
Materials 2021, 14(20), 6201; https://doi.org/10.3390/ma14206201 - 19 Oct 2021
Viewed by 435
Abstract
This work aimed to prepare a composite with a polyamide (PA) matrix and surface-modified ZrO2 or Al2O3 to be used as ceramic fillers (CFs). Those composites contained 30 wt.% ceramic powder to 70 wt.% polymer. Possible applications for this [...] Read more.
This work aimed to prepare a composite with a polyamide (PA) matrix and surface-modified ZrO2 or Al2O3 to be used as ceramic fillers (CFs). Those composites contained 30 wt.% ceramic powder to 70 wt.% polymer. Possible applications for this type of composite include bioengineering applications especially in the fields of dental prosthetics and orthopaedics. The ceramic fillers were subjected to chemical surface modification with Piranha Solution and suspension in 10 M sodium hydroxide and Si3N4 to achieve the highest possible surface development and to introduce additional functional groups. This was to improve the bonding between the CFs and the polymer matrix. Both CFs were examined for particle size distribution (PSD), functional groups (FTIR), chemical composition (XPS), phase composition (XRD), and morphology and chemical composition (SEM/EDS). Filaments were created from the powders prepared in this way and were then used for 3D FDM printing. Samples were subjected to mechanical tests (tensility, hardness) and soaking tests in a high-pressure autoclave in artificial saliva for 14, 21, and 29 days. Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Figure 1

Article
The Effect of Displacement Amplitude on Fretting Wear Behavior and Damage Mechanism of Alloy 690 in Different Gaseous Atmospheres
Materials 2021, 14(19), 5778; https://doi.org/10.3390/ma14195778 - 02 Oct 2021
Viewed by 442
Abstract
The effect of displacement amplitude on fretting wear behavior and damage mechanisms of alloy 690 in air and nitrogen atmospheres was investigated in detail. The results showed that in air, the friction coefficient gradually increased with the increase in displacement amplitude which conformed [...] Read more.
The effect of displacement amplitude on fretting wear behavior and damage mechanisms of alloy 690 in air and nitrogen atmospheres was investigated in detail. The results showed that in air, the friction coefficient gradually increased with the increase in displacement amplitude which conformed to the universal law. In nitrogen, however, it had the highest point at the displacement amplitude of 60 μm due to very strong adhesion. Whether in air or nitrogen, the wear volume gradually increased with the increase in displacement amplitude. The wear volume in air was larger than that in nitrogen except at 30 μm. At 30 μm, the wear volume in air was slightly smaller. With an increase in displacement amplitude, a transformation of fretting running status between partial slip, mixed stick-slip, and final gross slip occurred along with the change of Ft-D curves from linear, to elliptic, to, finally, parallelogrammical. Correspondingly, the fretting regime changed from a partial slip regime to a mixed regime to a gross slip regime. With the increase in displacement amplitude, the transition from partial slip to gross slip in nitrogen was delayed as compared with in air due to the strong adhesion actuated by low oxygen content in a reducing environment. Whether in air or nitrogen, the competitive relation between fretting-induced fatigue and fretting-induced wear was prominent. The cracking velocity was more rapid than the wear. Fretting-induced fatigue dominated at 30 μm in air but at 30–60 μm in nitrogen. Fretting-induced wear won the competition at 45–90 μm in air but at 75–90 μm in nitrogen. Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Figure 1

Article
Differences in Wear and Material Integrity of NAO and Low-Steel Brake Pads under Severe Conditions
Materials 2021, 14(19), 5531; https://doi.org/10.3390/ma14195531 - 24 Sep 2021
Cited by 1 | Viewed by 394
Abstract
In this study, through severe reduced-scale braking tests, we investigate the wear and integrity of organic matrix brake pads against gray cast iron (GCI) discs. Two prototype pad materials are designed with the aim of representing a typical non-metal NAO and a low-steel [...] Read more.
In this study, through severe reduced-scale braking tests, we investigate the wear and integrity of organic matrix brake pads against gray cast iron (GCI) discs. Two prototype pad materials are designed with the aim of representing a typical non-metal NAO and a low-steel (LS) formulation. The worn surfaces are observed with SEM. The toughness of the pad materials is tested at the raw state and after a heat treatment. During braking, the LS-GCI disc configuration produces heavy wear. The friction parts both keep their macroscopic integrity and wear appears to be homogeneous. The LS pad is mostly covered by a layer of solid oxidized steel. The NAO-GCI disc configuration wears dramatically and cannot reach the end of the test program. The NAO pad suffers many deep cracks. Compacted third body plateaus are scarce and the corresponding disc surface appears to be very heterogeneous. The pad materials both show similar strength at the raw state and similar weakening after heat treatment. However, the NAO material is much more brittle than the LS material in both states, which seems to favor the growth of cracks. The observations of crack faces suggest that long steel fibers in the LS material palliate the brittleness of the matrix, even after heat damage. Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Figure 1

Article
Friction Behavior of a Textured Surface against Several Materials under Dry and Lubricated Conditions
Materials 2021, 14(18), 5228; https://doi.org/10.3390/ma14185228 - 11 Sep 2021
Viewed by 397
Abstract
This paper reports research on the frictional behavior of a textured surface against several materials under dry and lubricated conditions, and this is aimed to provide design guidelines on the surface texturing for wide-ranging industrial applications. Experiments were performed on a tribo-tester with [...] Read more.
This paper reports research on the frictional behavior of a textured surface against several materials under dry and lubricated conditions, and this is aimed to provide design guidelines on the surface texturing for wide-ranging industrial applications. Experiments were performed on a tribo-tester with the facility of simulating A ball-on-plate model in reciprocating motion under dry, oil-lubricated, and water-lubricated conditions. To study the frictional behavior of textured SiC against various materials, three types of ball-bearing –elements, 52100 steel, silicon nitride (Si3N4), and polytetrafluoroethylene (PTFE), were used. Friction and wear performance of an un-textured surface and two types of widely used micro-scale texture surfaces, grooves and circular dimples, were examined and compared. The results demonstrated that the effect of surface textures on friction and wear performance is influenced by texture parameters and the materials of friction pairs. The circular-dimple texture and the groove texture, with certain texture parameters, played a positive role in improving friction and wear performance under specific operating conditions used in this research for SiC–steel and SiC–Si3N4 friction pairs; however, there was no friction and wear improvement for the textured SiC–PTFE friction pair. The results of this study offer an understanding and a knowledge base to enhance the performance of bearing elements in complex interacting systems. Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Figure 1

Article
Modeling the Average and Instantaneous Friction Coefficient of a Disc Brake on the Basis of Bench Tests
Materials 2021, 14(16), 4766; https://doi.org/10.3390/ma14164766 - 23 Aug 2021
Viewed by 500
Abstract
This article presents the results of tests conducted on the average and instantaneous friction coefficients of railway vehicle disc brakes. The tests were carried out independently of various states of wear on the friction linings and the brake disc. The requirements of the [...] Read more.
This article presents the results of tests conducted on the average and instantaneous friction coefficients of railway vehicle disc brakes. The tests were carried out independently of various states of wear on the friction linings and the brake disc. The requirements of the International Union of Railways (UIC) regarding the approval of brake linings for use were taken into account. Based on many years of research using a brake bench to test railway disc brakes, the authors developed multiple regression models for the average friction coefficient and fluctuations (tolerances) in the instantaneous friction coefficient and achieved 870 results. The models proposed three types of variables: the input braking parameters (speed, pressure, and mass to be braked), operational parameters (the wear on the friction linings and the brake disc), and design parameters (perforations in the form of holes on the disc surface). The above two models were validated on the basis of 384 brakes, and in subsequent stages a further evaluation was performed. The coefficients were determined to be, respectively, 0.99 for the model of the average friction coefficient and 0.71 for the model of tolerance (fluctuations) of the instantaneous friction coefficient. Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Figure 1

Article
A Design of Partial Textured Surface on Gear Washers for Reducing Friction and Wear under Low Speed and Heavy Load Conditions
Materials 2021, 14(16), 4666; https://doi.org/10.3390/ma14164666 - 19 Aug 2021
Viewed by 478
Abstract
This paper presents the effort to reduce friction and wear of gear washers under low-speed and heavy-load conditions by designing the arrangement of surface textures. The influence of distributional parameters of textures on load-bearing capacity and friction coefficient of gear washers are studied [...] Read more.
This paper presents the effort to reduce friction and wear of gear washers under low-speed and heavy-load conditions by designing the arrangement of surface textures. The influence of distributional parameters of textures on load-bearing capacity and friction coefficient of gear washers are studied numerically to obtain a preferable surface texturing design. Then, experimental tests were carried out to plot the Stribeck curves of the obtained texture arrangement compared with bare surface and another unoptimizable texture distribution arrangement to facilitate the verification of the simulation results. Theoretical predictions illustrate that the annular gear washers with partial surface texturing provide lower friction coefficients than bare washers. Textures having a sector angle of 20°, a coverage angle of 12°, a circumferential number of 8, and a radial number of 6 are selected as the final optimal surface texture distribution design. Experimental results confirm that the obtained texture arrangement moves the Stribeck curve towards the lower left, indicating thickening of oil film thickness and reduction in friction coefficient. In addition, the weight loss caused by wear is also reduced by the optimized texture design. Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Figure 1

Article
Effect of Lubricant Type on the Friction Behaviours and Surface Topography in Metal Forming of Ti-6Al-4V Titanium Alloy Sheets
Materials 2021, 14(13), 3721; https://doi.org/10.3390/ma14133721 - 02 Jul 2021
Cited by 2 | Viewed by 613
Abstract
The aim of the research described in this paper is to analyse the synergistic effect of types of synthetic oil and their density on the value of the coefficient of friction (COF) of Ti-6Al-4V titanium alloy sheets. Lubrication performance of commercial synthetic oils [...] Read more.
The aim of the research described in this paper is to analyse the synergistic effect of types of synthetic oil and their density on the value of the coefficient of friction (COF) of Ti-6Al-4V titanium alloy sheets. Lubrication performance of commercial synthetic oils (machine, gear, engine and hydraulic) was tested in a strip draw friction test. The friction tests consisted of pulling a strip specimen between two cylindrical fixed countersamples. The countersamples were placed in the simulator base mounted on a uniaxial tensile test machine. Due to the complex synergistic effect of different strip drawing test parameters on the COF, artificial neural networks were used to find this relationship. In the case of both dry and lubricated conditions, a clear trend was found of a reduction of the coefficient of friction with nominal pressure. Engine oil 10W-40 was found to be the least favourable lubricant in reducing the coefficient of friction of Grade 5 titanium sheets. The two main tribological mechanisms, i.e., galling and ploughing, played the most important role in the friction process on the test sheets. In the range of nominal pressures considered, and with the synthetic oils tested, the most favourable lubrication conditions can be obtained by using a type of oil with a low viscosity index and a high kinematic viscosity. Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Figure 1

Article
Selected Methods and Applications of Anti-Friction and Anti-Wear Surface Texturing
Materials 2021, 14(12), 3227; https://doi.org/10.3390/ma14123227 - 11 Jun 2021
Cited by 2 | Viewed by 744
Abstract
The constant development of environmental protection causes the necessity to increase the efficiency of machines. By increasing the efficiency of machines, energy losses can be limited, leading to lower energy consumption. Friction reduction leads to an increase in efficiency and a decrease in [...] Read more.
The constant development of environmental protection causes the necessity to increase the efficiency of machines. By increasing the efficiency of machines, energy losses can be limited, leading to lower energy consumption. Friction reduction leads to an increase in efficiency and a decrease in wear. In this paper, selected surface texturing methods, such as burnishing and abrasive jet machining, with their limitations are presented. Thanks to those processes, various surface textures can be obtained. Examples of applications of these methods for friction and wear reduction are shown. Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Figure 1

Article
A Pocket-Textured Surface for Improving the Tribological Properties of Point Contact under Starved Lubrication
Materials 2021, 14(7), 1789; https://doi.org/10.3390/ma14071789 - 05 Apr 2021
Viewed by 713
Abstract
This paper reports a novel pocket-textured surface for improving the tribological properties of point contact under starved lubrication by possibly storing and releasing oil, and homogenizing the surface contact pressure. The ball-on-disk experimental results confirmed the coefficient of friction (COF) and wear reduction [...] Read more.
This paper reports a novel pocket-textured surface for improving the tribological properties of point contact under starved lubrication by possibly storing and releasing oil, and homogenizing the surface contact pressure. The ball-on-disk experimental results confirmed the coefficient of friction (COF) and wear reduction effect of such pocket-texturing. The maximum reduction rate was 40% compared with a flat surface under the same operating conditions. Analyses on experimental results attributed the oil storage effect and enhanced the secondary lubrication effect within the starved lubrication state, to become the main mechanism. In addition, the plate elasticity and the Hertzian contact principles were employed to estimate the pressure and the load acting on the surface. The experimental results and numerical analysis substantiated the design of pocket-textured surface, making it likely to enlarge about 50% of contact surface and to reduce 90% of equivalent stress in comparison to those of conventional surfaces. Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Figure 1

Article
How Good Are the Performances of Graphene and Boron Nitride Against the Wear of Copper?
Materials 2021, 14(5), 1148; https://doi.org/10.3390/ma14051148 - 28 Feb 2021
Cited by 1 | Viewed by 671
Abstract
We investigate the copper-wear-protective effects of graphene and boron nitride in single asperity sliding contact with a stiff diamond-coated atomic force microscopy (AFM)-tip. We find that both graphene and boron nitride retard the onset of wear of copper. The retardment of wear is [...] Read more.
We investigate the copper-wear-protective effects of graphene and boron nitride in single asperity sliding contact with a stiff diamond-coated atomic force microscopy (AFM)-tip. We find that both graphene and boron nitride retard the onset of wear of copper. The retardment of wear is larger with boron nitride than with graphene, which we explain based on their respective out-of-plane stiffnesses. The wear protective effect of boron nitride comes, however, at a price. The out-of-plane stiffness of two-dimensional materials also determines their friction coefficient in a wear-less friction regime. In this regime, a higher out-of-plane stiffness results in larger friction forces. Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Figure 1

Article
Stereometric and Tribometric Studies of Polymeric Pin and Ceramic Plate Friction Pair Components
Materials 2021, 14(4), 839; https://doi.org/10.3390/ma14040839 - 09 Feb 2021
Cited by 1 | Viewed by 572
Abstract
Two complementary approaches should be used for the full characterisation of friction pair components. The first approach consists of stereometric studies of machined as well as worn surface topography of the friction components with multiple measurement methods used. The second approach, tribometric studies, [...] Read more.
Two complementary approaches should be used for the full characterisation of friction pair components. The first approach consists of stereometric studies of machined as well as worn surface topography of the friction components with multiple measurement methods used. The second approach, tribometric studies, enables the tribological characteristics of the friction pair. This work presents the complete characterisation of polymeric pin and ceramic plate friction pair components based on studies with the use of three research instruments: an interference microscope, a scanning electron microscope and a tribological tester. The results of the studies showed that the same treatment conditions used for different but similar ceramic materials did not provide exactly the same characteristics of both the machined and worn surface topography. Moreover, the results showed that the material properties and machined surface topography of the ceramic component significantly affected the friction coefficient and linear wear as well as the wear intensity of the polymeric component. Connecting the two approaches, stereometric studies and tribometric studies, allowed for a better identification of the wear mechanism of the polymeric pin (i.e., abrasion, fatigue and adhesion wear) and the kind of wear products (polymeric material). Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Graphical abstract

Article
The Impact of the Lubricant Dose on the Reduction of Wear Dies Used in the Forging Process of the Valve Forging
Materials 2021, 14(1), 212; https://doi.org/10.3390/ma14010212 - 04 Jan 2021
Cited by 4 | Viewed by 1210
Abstract
The paper presents the results of research on the influence of the settings of lubrication and cooling system parameters (solenoid valve opening time and lubricant feed pressure in terms of its quantity) in order to select the optimal lubricating conditions and thus reduce [...] Read more.
The paper presents the results of research on the influence of the settings of lubrication and cooling system parameters (solenoid valve opening time and lubricant feed pressure in terms of its quantity) in order to select the optimal lubricating conditions and thus reduce the wear of the dies used in the first forging operation of the valve forging made of high-nickel steel. Based on the observation of lubrication in the industrial process, it was found that a significant part of the lubricant fails to reach the die cavity, reaching the outside of it, which causes die wear due to seizure resulting from adhesion of the forging material to the tool surface as well as high lubricant consumption and dirt in the press chamber. The authors proposed their own mobile lubricating and cooling system, which allows for a wide range of adjustments and provided with automatic cleaning procedures of the entire system, unlike the fixed lubrication system used so far in the industrial process. First, tests were carried out in laboratory conditions to determine the highest wettability and the lubricant remaining inside the tool cavity. These tests determined the lubrication system parameter settings that ensured that the greatest amount of lubricant remains in the cold die cavity without the forging process. Then, to verify the obtained results, tests were carried out in the industrial process of hot die forging of valve forgings for short production runs of up to 500 forgings. The results were compared with the measurement of changes in the geometry of tools and forgings based on 3D scanning and surface topography analysis with the use of SEM (Scanning Electron Microscope). For the best results (the variant of the setting of the dose and the time of exposure to lubricant), the forging process was carried out with the use of a new tool up to the maximum service life. Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Figure 1

Article
The Wear on Roller Press Rollers Made of 20Cr4/1.7027 Steel under Conditions of Copper Concentrate Briquetting
Materials 2020, 13(24), 5782; https://doi.org/10.3390/ma13245782 - 17 Dec 2020
Cited by 2 | Viewed by 618
Abstract
This paper defines the wear process of rollers made of 20Cr4. Rollers with a diameter of 1000 mm were installed in a roller press used for the production of drop-shaped briquettes and the copper concentrate was briquetted for 1100 h. Three-dimensional (3D) geometry [...] Read more.
This paper defines the wear process of rollers made of 20Cr4. Rollers with a diameter of 1000 mm were installed in a roller press used for the production of drop-shaped briquettes and the copper concentrate was briquetted for 1100 h. Three-dimensional (3D) geometry analysis, metallographic analysis, macroscopy, scanning electron microscopy, as well as hardness measurements were performed. It was observed that the working surface was non-uniformly worn. The smallest wear affects the molding cavities situated on the outermost edges of the ring. The wear increases as the center of the ring is approximated, and it reaches its maximum at the middle of the ring. The molding cavities also wear asymmetrically. For the shape considered in this study, the lower part of a cavity is subject to a higher wear rate. We found that the material of the working ring was carburized, but its hardness was significantly lower than required. The roller ring microstructure changes depended on the distance from the cavity’s face. An investigation of the wear mechanisms showed different types of abrasive wear, corrosive processes, and plastic deformation. The exact type and course of wear were described, depending on the location on the working surface. Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Figure 1

Article
The Effect of Surface Texture on Lubricated Fretting
Materials 2020, 13(21), 4886; https://doi.org/10.3390/ma13214886 - 30 Oct 2020
Cited by 3 | Viewed by 626
Abstract
Experiments were conducted using an Optimol SRV5 tester in lubricated friction conditions. Steel balls from 100Cr6 material of 60 HRC hardness were placed in contact with 42CrMo4 steel discs of 47 HRC hardness and diversified surface textures. Tests were carried out at a [...] Read more.
Experiments were conducted using an Optimol SRV5 tester in lubricated friction conditions. Steel balls from 100Cr6 material of 60 HRC hardness were placed in contact with 42CrMo4 steel discs of 47 HRC hardness and diversified surface textures. Tests were carried out at a 25–40% relative humidity. The ball diameter was 10 mm, the amplitude of oscillations was set to 0.1 mm, and the frequency was set to 80 Hz. Tests were performed at smaller (45 N) and higher (100 N) normal loads and at smaller (30 °C) and higher (90 °C) temperatures. During each test, the normal load and temperature were kept constant. We found that the disc surface texture had significant effects on the friction and wear under lubricated conditions. When a lower normal load was applied, the coefficient of friction and wear volumes were smaller for bigger disc surface heights. However, for a larger normal load a higher roughness corresponded to a larger coefficient of friction. Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Figure 1

Article
Dry Rolling/Sliding Wear of Bainitic Rail Steels under Different Contact Stresses and Slip Ratios
Materials 2020, 13(20), 4678; https://doi.org/10.3390/ma13204678 - 20 Oct 2020
Cited by 1 | Viewed by 712
Abstract
This study aims to deeply understand the effect of contact stress and slip ratio on wear performances of bainitic rail steels. The results showed that the wear loss increased as the contact stress and slip ratio increased. Based on the surface damage morphology [...] Read more.
This study aims to deeply understand the effect of contact stress and slip ratio on wear performances of bainitic rail steels. The results showed that the wear loss increased as the contact stress and slip ratio increased. Based on the surface damage morphology and microstructural analyses, it revealed that the rolling contact fatigue wear mechanism played a significant role under the low slip ratio, but the dominant wear mechanism transferred to the abrasive wear at the high slip ratio. Meanwhile, the bainitic steel specifically presented worse wear resistance under the abrasive wear mode. Compared with the influence of a slip ratio, the increase in contact stress led to severer plastic flows and contributed to the propagation of cracks. In addition, the contact stress and slip ratio had the opposite effect on the friction coefficient, that is, the friction coefficient of bainitic steels behaved the inverse proportion with the contact stress, but positive proportion with the slip ratio. At last, the increase in slip ratio had more significant effect on the reduction of retained austenite (RA) than the enlargement of contact stress due to the fact that the RA would probably be removed before the martensitic transformation occurred under the abrasive wear mechanism. Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Figure 1

Article
A Numerical Wear Simulation Method of Reciprocating Seals with a Textured Rod
Materials 2020, 13(19), 4458; https://doi.org/10.3390/ma13194458 - 08 Oct 2020
Viewed by 716
Abstract
Reciprocating rod seals are widely used in the hydraulic actuator to prevent the leakage of fluid. The sealing lip profile changes with the seal wear, resulting in an increase in the leakage. A texturing rod changes the lubrication characteristics of the seal, so [...] Read more.
Reciprocating rod seals are widely used in the hydraulic actuator to prevent the leakage of fluid. The sealing lip profile changes with the seal wear, resulting in an increase in the leakage. A texturing rod changes the lubrication characteristics of the seal, so it affects the wear and leakage of the seal. A numerical simulation method is proposed to investigate the wear of the hydraulic reciprocating seal with textured rods. Several kinds of macro-cavity textures on the rod surface, including circle, square and triangle shapes, have been simulated and discussed. The effects of three shape parameters including area ratio, depth, and ratio of the axial length to the circumferential length on the seal wear are analyzed in detail. The texturing rod slightly increases the seal wear, but decreases the seal leakage. When the rod speed is increasing, the wear time rates of the seal increase, while the wear distance rates decrease, regardless of the texture shapes. When the texture area ratio is increasing, the wear of the reciprocating seal increases. Seal wear decreases with an increasing texture depth during the outstroke, however, it increases during the instroke. The ratio of the axial length of the macro-cavity to the circumferential length has no effect on the seal wear. Full article
(This article belongs to the Special Issue Friction and Wear of Materials Surfaces)
Show Figures

Figure 1

Back to TopTop