Dry-sliding Behavior Research Articles

Slurry Abrasion and Dry Sliding Behavior of High-Velocity Oxy-Fuel (HVOF) Sprayed WC-12Co and WC-10Co-4Cr Coatings on EN8 Tillage Material

Slurry Abrasion and Dry Sliding Behavior of High-Velocity Oxy-Fuel (HVOF) Sprayed WC-12Co and WC-10Co-4Cr Coatings on EN8 Tillage Material

Dry Sliding Behaviour Study of Novel Low-metallic Friction Materials by using DoE-Taguchi Method

Dry Sliding Behaviour Study of Novel Low-metallic Friction Materials by using DoE-Taguchi Method

Reinforcing Cold-Sprayed Al Coatings With Boron Nitride Nanotubes and Micro-Boron Carbide and Their Effect on Surface Mechanical and Dry Sliding Behavior

Abstract This investigation explores the reinforcement effects of both boron nitride nanotubes (BNNTs) and micro-boron carbide (μB4C) on the tribological and mechanical properties of aluminum matrix composite (MMC) cold-sprayed coatings. The synthesis process involved high-energy ball milling (HEBM) and cold spraying with helium to create four distinct Al-MMC coatings on a magnesium (AZ31) substrate. These coatings consisted of pure aluminum, a composition containing 4 vol% B4C, a composition with 4 vol% BNNTs, and a composition with 2 vol% B4C and 2 vol% BNNTs. Successful dispersion of nanoparticles within the aluminum matrix was achieved. The hardness of the coatings exhibited significant improvements compared to the pure aluminum coating. Specifically, the Al-BNNT coating showed a hardness increase of 14.1%, the Al-B4C-BNNT coating displayed a hardness increase of 20.8%, and the Al-B4C coating demonstrated the highest increase of 33.3% over the pure aluminum coating. Furthermore, the Al-B4C coating exhibited remarkable reductions in wear volume loss and wear track depth, amounting to eight and two orders of magnitude, respectively. Adhesion testing revealed that the Al-B4C-BNNT coating failed cohesively, while the pure aluminum coating failed adhesively at approximately the same force. The Al-B4C coating experienced a combination of the two failure modes at a 31.2% increase in force compared to the pure aluminum coating. Tensile testing stress versus strain curves indicated that the load was partially supported by the cold spray coating until the coating ruptured.

The Effects of Titanium Dioxide (TiO2) Content on the Dry Sliding Behaviour of AA2024 Aluminium Composite

The low density, low expansion coefficient, and strong corrosion resistance at room temperature of Aluminium alloys have made them a popular choice for engineering applications. In this study, Aluminium AA2024 alloys are prepared with different weight contents of ceramic material, titanium oxide (TiO2) nanoparticles (0%, 2.5%, 5%, and 7.5% wt.) of a particle size of 30 nm using the metal stir casting method. The hardness property and wear resistance with the effect of heat treatment are investigated using a pin-on-disc wear device for both the base alloy and the reinforced alloys. The result shows the prosperity of 5wt.% of TiO2 to attain the optimum hardness and wear resistance. Using the optimum content of TiO2 and heat treatment, the hardness and wear resistance of 5wt.% TiO2-AA2024 nanocomposite has been significantly improved after heat treatment over the unreinforced Aluminium matrix. Statistically, the hardness and wear resistance are improved by 68% and 22%, respectively. This is due to an increased number of fine precipitates besides their uniformly distributed after heat treatment. Furthermore, casting AA2024 Aluminium alloy material mainly has S (Al2CuMg) and Al3TiCu phases. The appearance of a large number of S phases causes a significant improvement in the properties of the alloy.

Influence of Load and Speed on Tribological Performance of A390 and A515 Alloys in Dry Sliding Behavior A Comparative Study

In this study, tribological characteristics and wear debris morphology of A390 and A515 alloys are evaluated and compared. Components with a high wear resistance slide are typically made with alloys are A390 and A515, while components with high hardness requirements are usually made up with SS410. Those alloys were used in brake pads, and SS410 steel is used for the brake disc. Speed and pad force are the two factors that affect tribological characteristics such as friction coefficient and wear rate. Wear debris and wear track were examined by scanning election microscopy and optical microscope, respectively. The effect of sliding speed variations on wear and friction coefficient at various load conditions was also evaluated, and a comparative analysis was reported based on wear rates, coefficient of friction, and debris morphology for both materials. The A515 alloys shows higher friction coefficient under all the process conditions except at very low loads and high speeds due to increased superficial hardness and the composition of the case layer (oxygen-diffused/oxide formed).

Influence of Surface Roughness of Stator on Dry Sliding Behavior against Rotor in Pneumatic Downhole Motor

Influence of Surface Roughness of Stator on Dry Sliding Behavior against Rotor in Pneumatic Downhole Motor

Comparative Studies on the Dry Sliding Behavior of a Low-Metallic Friction Material with the Addition of Graphite and Exfoliated g-C3N4

This study compares the effect of the addition of two types of lubricants on the dry sliding behavior of a simplified Cu-free phenolic resin-based composite material. The lubricants were commercial graphite and exfoliated graphitic carbon nitride (codenamed: TEX6). The graphite particles were rounded and of ‘flaky’ character. The TEX6 particles were not only flaky, but also irregular in shape, and ‘fluffy’. Both lubricants were added individually in the basic formulation and subjected to dry sliding tests on pin-on-disc testing equipment in mild conditions and against a grey cast-iron counterface. The tests with TEX6 observed a stable steady state in the friction coefficient (CoF) with lower scatter and lower average friction coefficient and pin wear magnitude when compared to samples containing graphite. Additionally, the worn surfaces of the TEX6-containing samples had extremely smooth, compact, and continuous secondary plateau coverage when compared to the graphite-containing samples. The counterface paired with the TEX6-containing samples observed much lower abrasive action compared to the graphite-containing samples. Through the wear testing and further evaluation of the secondary plateaus, the possible addition of TEX6 as a lubricant in friction material composition was explained, making it a promising component for automotive braking applications.

Dry Sliding Behavior and Particulate Emissions of a SiC-graphite Composite Friction Material Paired with HVOF-Coated Counterface

Dry sliding wear tests and corresponding particulate matter (PM) analysis were conducted on a newly developed SiC-graphite-based composite friction material, paired with two types of HVOF counterface/discs: WC-CoCr and WC-FeCrAlY coatings, with a conventional martensitic stainless steel counterface as a reference. The trials were conducted on a pin-on-disc testing equipment at room temperature and a constant sliding velocity and contact pressure of 7 m/s and 0.5 MPa, respectively. The coefficient of friction (CoF) curves with the uncoated disc exhibited considerable fluctuations. On the other hand, the coated discs featured an increase in the CoF at the beginning of the tests, followed by either a continuous reduction until the end of the testing duration or the attainment of a steady state regime. The pin wear and emissions with both coatings were appreciably lower when compared to the trials with the uncoated disc. The evaluation of the friction layer observed a significant contribution of the counterface for all the pairings. The PM analysis was conducted on the particles that were lying in the range of 10 μm and 2.5 μm on a scanning electron microscope (SEM), and particles from 2.5 μm and 1 μm on transmission electron microscope (TEM), with an emphasis on the particles that were detached from the pin surface and friction layer to explain the wear mechanisms for each pairing. Through this, the need for the proper selection of both friction material and counterface to avoid the emission of harmful compounds in the environment was highlighted.

Dry Sliding Behavior of an Aluminum Alloy after Innovative Hard Anodizing Treatments.

This work evaluates the dry sliding behavior of anodic aluminum oxides (AAO) formed during one traditional hard anodizing treatment (HA) and two golden hard anodizing treatments (named G and GP, respectively) on a EN AW-6060 aluminum alloy. Three different thicknesses of AAO layers were selected: 25, 50, and 100 μm. Prior to wear tests, microstructure and mechanical properties were determined by scanning electron microscopy (VPSEM/EDS), X-ray diffractometry, diffuse reflectance infrared Fourier transform (DRIFT-FTIR) spectroscopy, roughness, microhardness, and scratch tests. Wear tests were carried out by a pin-on-disc tribometer using a steel disc as the counterpart material. The friction coefficient was provided by the equipment. Anodized pins were weighed before and after tests to assess the wear rate. Worn surfaces were analyzed by VPSEM/EDS and DRITF-FTIR. Based on the results, the GP-treated surfaces with a thickness of 50 μm exhibit the lowest friction coefficients and wear rates. In any case, a tribofilm is observed on the wear tracks. During sliding, its detachment leads to delamination of the underlying anodic aluminum oxides and to abrasion of the aluminum substrate. Finally, the best tribological performance of G- and GP-treated surfaces may be related to the existence of a thin Ag-rich film at the coating/aluminum substrate interfaces.

Dry Sliding Behavior of Qbe-2 Beryllium Bronze against 38CrMoAlA Steel in Pneumatic Downhole Motor under Different Loads

In drilling engineering, the wear of tribo-pairs is the primary cause for the rapid failure of rotating seals in pneumatic downhole tools. In order to reduce the wear of tribo-pairs, a new type of rotating seals was designed in this work, which introduced copper alloys between the stator and rotor. To elucidate the wear and failure mechanism of the copper-steel tribo-pair rotating seals in pneumatic downhole motors, pin-on-disc dry sliding tests with Qbe-2 beryllium bronze pin against 38CrMoAlA steel disc under different loads were thus designed to simulate the friction and wear behavior of such tribo-pair. During the dry sliding process, the friction behavior of the copper pin would go through a running-in period and then become stable. As the load increases, the running-in period will be shortened, while the friction coefficient during the stable period decreases. Interestingly, a false stability occurs when the load is low. However, this phenomenon will disappear under heavy loads. The wear mechanism of the copper pins would change from adhesive wear to ploughing wear as the load increases, which is mainly related to the spalling of asperities and the filling of wear debris into the steel disc. The wear debris consists of copper and copper oxide. The surface roughness of the steel disc and copper pin decreased and the size of the wear debris increased with the increase of the load. The material removal mainly occurs on the copper pin, which will present a relatively small value under 45 N. On contrast, due to the filling of wear debris, the volume of the steel disc increased. Therefore, considering the value and stability of friction coefficients, as well as the wear amount of the sample, it would be better that such tribo-pair could work under 45 N. The present work will provide a fundamental understanding and solid support for systematically designing the tribo-pairs in pneumatic downhole tools under practical working conditions.

Effect of Carbon Addition on Mechanical Properties and Dry Sliding Behavior of Fe-0.65P Alloy Processed by Powder Forging

The present work reports the effect of addition of 0.2 wt.% C on the microstructure, mechanical properties and dry sliding wear of Fe-0.65 wt.% P-based alloy prepared by hot powder forging. The presence of phosphorus (P) leads to loss of ductility in steels which may be overcome by use of the reported powder forging route as well as addition of C in processing of Fe–P alloys. In this study, the iron-phosphate (master alloy) powder containing 5 wt.% P was prepared by a chemical route. The master alloy powder was then mixed with water-atomized Fe powder, while carbon was added in the form of graphite powder. The mixed powders were filled in a mild steel (M.S) capsule and heated at 1323 K in tubular furnace in the presence of flowing hydrogen atmosphere. The heated capsule was hot-forged at 1323 K and further homogenized at the same temperature for two hours. Strength and hardness increased on addition of 0.20 wt.% carbon in Fe-0.65 wt.% P alloy without loss in ductility. Friction and wear properties under dry sliding wear conditions have also been found to improve with the addition of carbon. Wear results have been discussed and correlated with observed microstructure and mechanical properties.

Effect of Molybdenum Disulfide Nano-particles on Dry Sliding Behavior of Carbon Fiber Reinforced Epoxy

Effect of Molybdenum Disulfide Nano-particles on Dry Sliding Behavior of Carbon Fiber Reinforced Epoxy

Plasma Electrolytic Oxidation (PEO) Layers from Silicate/Phosphate Baths on Ti-6Al-4V for Biomedical Components: Influence of Deposition Conditions and Surface Finishing on Dry Sliding Behaviour

Plasma Electrolytic Oxidation (PEO) layers were produced on Ti-6Al-4V in different conditions, so as to assess the influence of layer structure, current mode, duty cycle and surface finishing on microstructural features and tribological behaviour. In DC regime, the double-layer structure (silicate bath followed by phosphate bath) beneficially affected wear resistance. In unipolar pulsed DC (phosphate bath), the wear resistance of single layers improved with increasing duty cycle, due to improved microstructure and adhesion: high duty cycle single layers can be considered an alternative to double-layer deposition. Surface finishing by abrasive blasting with spheroidal glass beads leads to surface roughness decrease and hence to decreased friction and improved wear resistance. The best-performing PEO layers showed promising results in the comparison with reference materials such as CoCrMo (both uncoated and (Ti,Nb)N PVD-coated) and PVD-coated Ti-6Al-4V up to 30 N normal load.

Dry Sliding Behavior of a TiZr-Based Alloy under Air and Vacuum Conditions

In this study, dry sliding tribological properties of a TiZr-based alloy with the chemical composition Ti-20Zr-6.5Al-4V (wt.%) were tested in air and vacuum under different normal loads (10, 20, and 30 N) at various sliding velocities. Results showed that the coefficient of friction in air was lower than that in vacuum, whereas the wear volume at sliding velocity presented an opposite trend. The surfaces and cross-sectional morphology of wear scar on the TiZrAlV alloy was analyzed through scanning electron microscopy to determine the wear mechanisms. The observations showed that abrasive wear and delamination wear were dominant in air. In vacuum, the main wear mechanism changed from slightly abrasive and adhesive wear to severe adhesive wear and delamination wear as the normal load increased. Wear mechanism maps were also constructed and compared. The comparison showed that severe wear (including delamination wear) was prevalent in air.

Effect of Steel Counterface on the Dry Sliding Behaviour of a Cu-Based Metal Matrix Composite

Pin-on-disc testing was used to investigate the friction and wear behaviour of a Cu-based metal matrix composite dry sliding against three different martensitic steels. The tests were carried out at two contact pressures (0.5 and 1 MPa) and two sliding velocities (1.57 and 7 m/s), and the results were explained by considering the characteristics of the friction layers formed on the pin and disc surfaces during sliding. At 7 m/s, pin and disc wear was very mild in every condition, because the high flash temperatures achieved during sliding induced intense oxidation of the disc asperities, irrespective of the steel disc compositions. At 1.57 m/s, the steel composition played an important role. When using a heat-treated steel and a conventional martensitic stainless steel, pin and disc wear was by ‘low-sliding speed tribo-oxidation’, regarded as mild wear. However, when using a martensitic stainless steel with a very high Cr-content and a very low C-content, i.e. by a very high oxidation resistance, pin and disc wear was by adhesion/delamination at 0.5 MPa, and thus severe in nature. The results presented herewith clearly suggest the importance of selecting suitable steel counterfaces in the optimization of the tribological systems tribological involving Cu-based metal matrix composites as a mating material.

Effect of Phosphorus Addition on Dry Sliding Behavior of Fe–P Alloys Prepared by Powder Metallurgy

Iron–phosphorus powder metallurgy (P/M) alloys having 0, 0.35 and 0.65 wt.% P have been prepared by hot-forging technique. Hot forging consists of heating encapsulated powder at a temperature of 1050 °C in the atmosphere of hydrogen gas followed by hot forging. These hot-forged specimens have been subjected to dry sliding adhesive wear test at a normal load of 19.6, 29.4, and 39.2 N, at a constant sliding speed of 2.2 m/s and for a sliding distance of 4000 m using a pin-on-disk wear testing machine. Archard wear coefficient has been found to decrease from 2.5 × 10−7 to 1.4 × 10−7 with increasing phosphorus content in the alloys. The average coefficient of friction has also been found to decrease more or less linearly with increasing load as well as with increasing phosphorus content in the alloy. The mechanism of wear is primarily oxidative in nature, which has been confirmed by SEM–EDS analysis of the worn surfaces.

Synthesis and Dry Sliding behaviour of LM24-TiB₂ Reinforced Particulate Composite

The existing effort deals with synthesis of (LM24) composite developed by reinforcing 3wt % and 5wt % TiB2 particles in the size range of 20-60 μm in the LM24 matrix. Hardness of the alloy and the composites were evaluated to see the changes in the hardness of the materials. The sliding wear tests were performed using pin on disc machine to study the wear properties. Effect of various experimental parameters like sliding distance, and applied pressure were studied on sliding wear response of the alloy and the composite. Micro structural examination of the alloy and composite was done to see the structural changes and distribution of the particles in the matrix. Worn surfaces were examined to see the mechanism of material removal. Results show that reinforcement of TiB2 particles in LM24 alloy increases the hardness and wear resistance. Microstructural study of the base alloy LM24 and composites were performed having special attention to the dispersion of TiB2 particles in LM24 base alloy matrix and interface closeness between TiB2 particles and LM24 alloy matrix. The microstructure of aluminium alloy shows primary Al dendrites and intermetallic phases around in the inter-dendrites region. The TiB2 particles were noted to be more or less uniformly distributed within the metallic matrix and these particles were trapped within the primary aluminium dendrites instead of inter-dendritic region.The importance of this work is to study the importance of TiB2 particles in enhancing the properties of the base alloy. In general, the properties of unreinforced materials show poor mechanical as well as wear properties and there is a need to improve the properties to a certain level so that the material can be extended to a certain level for its usefulness. In the present work, it has been observed that after reinforcing TiB2 particles to the base alloy considerable amount of enhancement in the properties can be achieved. It is quite sure that this project work will certainly help in designing of the various parts.

Influence of Duplex USSP/Nitriding Surface Treatments on the Dry Sliding Behavior of Ti6Al4 V/AISI 316L Tribopairs

This contribution gives the first results of an ongoing research aiming at determining the effect of duplex USSP/Nitriding surface treatments on the dry sliding behavior of an AISI 316L steel against a Ti6Al4V counterpart under quasi-static and dynamic conditions. While the nitriding process, carried out solely, leads to a 8μm thick layer of hard (850 HV) expanded austenite, the effect of the additional USSP pretreatment is also to harden the sub-surface over about 300μm and raise the hardness of the top surface to about 1200 HV. After a quasi-static friction test against the fairly soft Ti6Al4V, the 8μm thick nitrided layer was not worn but was significantly modified. A 1μm thick layer of heavily plastically deformed material was observed at the top surface within which some transverse cracks formed and could sometimes extend throughout the entire nitrided layer. Comparatively, after a dynamic friction test, some additional recrystallization took place in the sub-surface of the USSP + nitrided treated 316L steel at the sliding output located at the end of the pads; indicating thereby that the temperature could reach values above 600°C during friction.

Dry Sliding Behaviour of AlCrN and TiN Coatings

This paper examines the friction behaviour of AlCrN and TiN PVD coatings in atmospheric air and vacuum using a ball-on-disc and a reciprocating tribotesters. Comparative study on the coating sliding in air and in high vacuum environment provides important insight on the effect of oxidation on the friction behaviour of the coatings. Other important factors such as load, sliding velocity, temperature effects on the frictional behaviour of these coatings were also investigated. In the ball-on-disc tests carried out in vacuum, (i) TiN gave lower coefficient of friction (COF) than AlCrN, indicating that TiN was more lubricous, (ii) higher speed resulted in lower COF, and (iii) the COF of both coatings were lower than that produced in air. In ambient air, (i) AlCrN gave lower COF than TiN with high wear debris retention on the sliding interface due to the effect of oxidation, and (ii) higher speed resulted in lower COF, similar to that observed in vacuum. In the reciprocating tests, at low load, increasing the temperature from room temperature to 150 °C resulted in a reduction in the COF. However, at high load, the temperature virtually did not affect the COF. Higher nominal load resulted in lower COF while higher speed resulted in higher COF.

Dry Sliding Behaviors of Polydicyclopentadiene under Elevated Sliding Velocity

Polydicyclopentadiene (PDCPD) was prepared in a simulating reaction injection molding system. Dry friction behaviors of the PDCPD under elevated sliding velocity (5m/s, 10m/s, 15m/s, and 20m/s) against GCr15steel were investigated on a high-speed pin-on-disc tribometer. Their microstructure changes on sliding surface were examined by using scanning electron microscopy (SEM). The results showed that the wear mass loss of PDCPD increased with the increase of sliding velocities. The friction coefficients of PDCPD under a sliding velocity of 5m/s were the most stable, and the friction coefficients were irregular with the further increasing the velocity. The results of SEM analysis showed that the wear mode is typical abrasive wear at a sliding velocity of 5m/s and the wear mode had transformed into typical adhesive wear at a velocity of 20m/s.