Increase In Sliding Distance Research Articles

Wear evolution of graphite asperities on dry-sliding with the squamous textured SiC

The wear evolution of graphite asperities and squamous textured SiC is investigated by wear experiments and numerical simulation. As the sliding distance increases, the SiC/graphite friction pair goes through various wear stages. The accumulation of graphite particles and the formation of adhesive particles with the shear of the graphite asperities, resulting in severe wear, accompanied by adhesion strips of non-textured SiC/graphite pair. In contrast, the graphite exhibits excellent surface sliding with textured SiC resulting from the micro-cutting effect and collection of particles, which is beneficial for the formation of graphite transfer film. Hence, the textured SiC/graphite pair stabilizes wear with a long sliding distance and reduces the friction coefficient by 16%.

Effect of welding process parameters on surface topography and mechanical properties of friction-stir-welded AA2024/AA2099 alloys

The joining of two materials with different chemical composition was a major setback for conventional methods of metal joining. The results of this welding were showing considerably great improvement in the aspects of quality of weld, amount of heat generated, uniform distribution of material, refined microstructure, enhanced tribology, materials flowing pattern, good strength with reduced internal stresses. Optimized parameters were estimated by using Desirabilty approach and Response surface methodology. Optimum parameter combination for dissimilar material welding was observed to be 913.74 rpm, 45 mm min−1 and 8kN. The desirability values for dissimilar welding process were 0.912 respectively. The grain enhancements were decreased in the range of WC > WT > HAZ > Parent material. The wear rate of dissimilar AA2024 and AA2099 were superior as the wear value increases from 0 to 50 μm in the nugget zone. The coefficient of friction value remains constant throughout the wear experiment ranges from 0.3 to 0.55. A steady state friction value of 3N to 5N is observed when sliding distance increases. The wear loss was measured by finding the difference between initial weight and final weight and found as in the range from 0.2283 g to 0.4866 g.

Study on the influence of T4 and T6 heat treatment on the wear behavior of coarse and fine WC particulate reinforced LM28 Aluminium cast composites

This work presents the Influence of T4 and T6 heat treatment on the wear behavior of coarse and fine WC reinforced LM28 cast Composites. Production of the composites was achieved by stir casting method in the presence of inert gas. Fine (0.1–20 µm) and coarse (60–80 µm) particulates of WC were used from 0 to 12 wt.% in a step of 3%. Composites were given T4 and T6 heat treatment in the conventional manner. For T4 heat treatment, composites were heat treated at 450 °C for 2–3 h followed by quenching in oil and then naturally aged for 6–40 days at normal room temperature whereas for T6 heat treatment, similar cycle was employed with the addition of artificial aging at 180–220 °C for 3–7 h followed by normal cooling. T6 heat treated composites showed optimum hardness in comparison to T4 heat treated and non-heat treated composites. Pin on disk tests revealed the optimal wear resistance and coefficient of friction in T6 heat treated composites at varying sliding distance and load. Scanning-electron microscopy examination showed that the surface damage under the influence of load and sliding distance was higher in T4 heat treated and non-heat treated composites as compared to T6 heat treated composites. Abrasive wear mechanism was observed in the initial phase of material removal but gradually as the sliding distance increases, the wear mechanism transformed into adhesive. T6 composites showed superior wear resistance and hardness and therefore can ideally be employed in applications where high resistance to wear is critical.

Mechanical and tribological investigation on Al LM4/TiC composite fabricated through bottom pouring method

Abstract In the present investigation LM4 reinforced 6 wt% Titanium Carbide particles composite was developed by stir casting bottom pouring method. The cast composite specimen was obtained in a cylindrical shape of dimensions 50 mm dia and 100 mm length. The composite specimens were prepared for mechanical and tribological test as per ASTM standards. The obtained results reveal that the mechanical properties are high as compared to the as cast LM4 alloy specimens. Microstructure analysis confirms that the uniform distribution of TiC particles. Tribological test was performed using pin-on-disc machine based on Taguchi’s design of experiments. L27 orthogonal array was selected by changing test parameter like applied load (10, 20, 30 N), sliding distance (600, 800, 1000 m) and sliding velocity (1.5 m/s, 2.5 m/s and 3.5 m/s). The most influencing test parameters were identified by using S/N ratio and ANOVA. The wear results reveled that wear rate increases as applied load increases, and it decreases with decrease in velocity. Also wear rate decreases as sliding distance increases and at some point, it became linear. The applied load was found to be most dominating (77.61%), sliding velocity (10.44%) and sliding distance (4.47%) are less dominating factors. Worn surface morphology was studied to understand the type of wear.

Friction and sliding wear studies on functionally graded Al LM25/WC composite

Functionally graded LM25/15 wt.% Tungsten carbide composite of dimension Øout 150 mm x Øin 110 mm x 100 mm and thickness 20 mm was studied to understand the influence of process parameters (applied load, sliding velocity, sliding distance) on the dry sliding wear rate and co-efficient of friction. A 5-level 3 parameter central composite design was developed using response surface methodology considering applied load (10-50N), sliding velocity (1-3 m/s) and sliding distance (500-2500 m) as input parameters. Dry sliding experiments were performed on pin-on-disk tribometer at ambient conditions. Significance tests, Analysis of Variance and confirmation experiments were done to check the accuracy of generated regression model. Generated surface plots revealed wear rate to be increasing as applied load and sliding distance increases and decrease as sliding velocity increases. Worn surface analysis performed revealed formation of deep grooves at high load, MML formation at high velocities and heavy delamination and particle pull-out at high sliding distances.

Enhancement of tribological properties of pure copper through cold sprayed MoS2 coating

Pure copper chosen as substrate was coated with Molybdenum Disulphide (MoS2) through cold spray coating method. A coating thickness of 123 ± 10 μm was obtained while a hardness improvement of 34.5% was obtained on comparing coated over uncoated substrate. Dry sliding wear analysis performed on coated pin specimens by varying process parameters such as applied load (10, 20, 30 N), sliding distance (750, 1250, 1750 m) and sliding velocity (0.75, 1.5 2.25 m s−1) revealed an increasing wear rate trend as applied load increases whereas an initial increase followed by a drastic decrease trend was observed for sliding velocity. Wear decreased initially followed by a slow rise, as sliding distance increases. ANOVA analysis confirmed highest influence for applied load, followed by sliding velocity and sliding distance. Confirmation experiments validated the regression model generated through RSM, which confirmed adequacy of model. For applied load, a wear mechanism transition from mild to severe wear was observed whereas, for sliding distance, the presence of an oxide layer was observed, which makes it suitable for automotive bearings and cylinder liners.

Fabrication of Cu-Sn/SiC Metal Matrix Composites and Investigation of its Mechanical and Dry Sliding Wear Properties

Requisite for advanced materials with high hardness, high tensile strength and improved wear properties has been drastically increased in recent times. The main objective of this paper is to fabricate unreinforced copper alloy and Cu-Sn/SiC composite with varying wt% of SiC (5, 10, and 15) by liquid metallurgy route and to investigate its microstructure, mechanical properties and dry sliding wear behavior. The hardness and tensile strength of alloy and composites are measured on Vickers micro hardness tester and Universal Testing Machine respectively. Tensile test specimens are further subjected to fractography analysis and the results shows ductile mode of failure for alloy and mixed ductile and brittle mode failure for composites. Based on the test results, it is observed that Cu-Sn/10 wt% of SiC have uniform distribution of particles with optimum mechanical properties. Hence only these 10 wt% SiC composite is considered for dry sliding wear analysis and experiments are conducted using Pin-on-disc tribometer. Analysis of process parameters in three levels such as applied load (15,25,35 N), sliding distance (750,1250,1750 m) and sliding velocity (1,2 and 3 m/s) is done by Taguchi’s Design of Experiments technique based on L₂₇ orthogonal array. From Signal-to-Noise ratio and Analysis of Variance approach, the rank of process parameters as well as its influence on the response is found. The results reveal that the wear rate increases as applied load and sliding distance increases and the wear rate decreases as sliding velocity increases. The load is found to have the highest influence on wear rate (38.5%) followed by sliding distance (7%) and sliding velocity (7%). Interaction between the process parameters also contributed towards wear rate. The worn surfaces were examined using Scanning Electron Microscopy and observed the formation of mechanically mixed layer at high velocity condition. Thus, the fabricated composites can be used in applications like bearings and bushes to improve the wear resistance.

Synthesis of Al LM25/TiC Composite Using Squeeze Casting Method and Investigation of its Mechanical and Adhesive Wear properties

LM25 reinforced with 10 wt.% Titanium Carbide was fabricated using squeeze casting technique and a cylindrical specimen with dimensions of 50 mm diameter and 150 mm length was obtained. The cast composite specimen was subjected to hardness and tensile test using Vicker’s hardness tester and Universal Testing Machine respectively. The hardness and tensile test results revealed 129 HV and 143 MPa respectively. Microstructural analysis was done and uniform distribution of reinforcement particles was observed in the matrix. Dry sliding wear experiments were conducted using pin-on-disc tribometer based on Taguchi’s L27 orthogonal array by varying process parameters such as load (15, 25, 35N), sliding distance (750,1250,1750m) and sliding velocity (1.5m/s, 2.5m/s, 3.5m/s). Signal-to-Noise ratio and Analysis of Variance were used to find out the most influential process parameter. The results revealed that the wear rate increases as applied load increases and it decreases as sliding velocity and sliding distance increases. Load was found to be the most dominating parameter (54.2%) followed by sliding velocity (8.5%) and sliding distance (2.6%). Interaction between wear parameters also had a significant effect on wear rate. Regression model was developed and validated with confirmation experiments with minimum error. Worn surfaces were examined using Scanning Electron Microscope and severe delamination was observed at maximum load.

Design And Manufacturing of a Pin-on-Disk wear Testing Apparatus

The present work is about a design and manufacturing process of a pin-on-disk apparatus which is used as a test method for determining the wear of any two sliding materials. The aim of this paper is to give an information about the design steps and manufacturing procedure for the pin-on-disk apparatus and to discuss the problems follows the design and manufacturing process. It also gives information about wear testing process. Different types of experiments were done with several different test specimens to be able to make a comparison between wear test results of this work and that of another experiment found in literatures. It was concluded, that a pin-on-disk wear testing apparatus which is working properly is successfully designed and manufactured. The results of the wear testing obtained by the apparatus which have been designed and manufactured in this work shows that the wear of the test specimen increases as the speed (rpm) of the motor increases. And also, as the sliding distance increases,the wear decreases at constant load and speed.

Tribological Characterization of Al-bronzes Used as Mold Materials

Abstract Among the copper based alloys, Cu-Al-X bronzes are commonly used as mold materials due to their superior physical and chemical properties. Mold materials suffer from both wear and corrosion, thus, it is necessary to know which one of the competitive phenomenon is dominant during the service conditions. In this study, tribo-corrosion behavior of CuAl10Ni5Fe4 and CuAl14Fe4Mn2Co alloys were studied and electrochemical measurements were carried out using three electrode system in 3.5 % NaCl solution in order to evaluate their corrosion resistance. In tribo-corrosion tests, alloys were tested against zirconia ball in 3.5 % NaCl solution, under 10N load with 0.04 m/s sliding speed during 300 and 600 m. The results indicate that (i) CuAl10Ni5Fe4 alloy is more resistant to NaCl solution compared to CuAl14Fe4Mn2Co alloy that has major galvanic cells within its matrix, (ii) although CuAl10Ni5Fe4 alloy has lower coefficient of friction value, it suffers from wear under dry sliding conditions, (iii) as the sliding distance increases, corrosion products on CuAl14Fe4Mn2Co surface increase at a higher rate compared to CuAl10Ni5Fe4 leading to a decrease in volume loss due to the lubricant effect of copper oxides.

Tribotronic Enhanced Photoresponsivity of a MoS2 Phototransistor.

Molybdenum disulfide (MoS2) has attracted a great attention as an excellent 2D material for future optoelectronic devices. Here, a novel MoS2 tribotronic phototransistor is developed by a conjunction of a MoS2 phototransistor and a triboelectric nanogenerator (TENG) in sliding mode. When an external friction layer produces a relative sliding on the device, the induced positive charges on the back gate of the MoS2 phototransistor act as a “gate” to increase the channel conductivity as the traditional back gate voltage does. With the sliding distance increases, the photoresponsivity of the device is drastically enhanced from 221.0 to 727.8 A W−1 at the 100 mW cm−2 UV excitation intensity and 1 V bias voltage. This work has extended the emerging tribotronics to the field of photodetection based on 2D material, and demonstrated a new way to realize the adjustable photoelectric devices with high photoresponsivity via human interfacing.

The Influence of Velocity Variation on the Adhesive Contact Behavior and the Deformation of Substrate Based on Molecular Dynamics Method

The contact behavior between indenter and single crystal copper substrate is performed to investigate based on EAM and Morse potentials and Verlet algorithm. Effects of different velocities on the contact behavior and substrate deformation are compared and analyzed. The results show that the single crystal copper material’s resist deformation level is limited by low velocity, and more dislocated atoms were accumulated under the direction of indenter moving in higher indenting velocity. During sliding process, lager chip volume is produced in front of the indenter as the sliding speed or sliding distance increases. The dislocated band in basis lies at the angle of 45 degrees with the direction of indenter moving in indenting and sliding process. Furthermore, the contact force, friction force and normal force increase with the rising of speed. On the contrary, the friction coefficient decrease gradually with higher sliding speed.

Sliding wear evaluation of aluminum alloy (7075-T6) on hardened steel (AISI4340) via non-contact technique by I-kaz™ multi-level analysis

Various techniques have been developed in the area of sliding wear evaluation. This paper presents a comparative experimental study on a sliding wear measurement and evaluation system of aluminium alloy (7075-T6) on hardened steel (AISI4340). The system is capable of detecting the wear progression of the aluminium alloy. A microphone is mounted 10mm from the test rig configuration to capture the acoustic emission (AE) generated. The signal is transmitted to the amplifier and then to the data acquisition system. New statistical analysis method was used to characterise the changes in the AE signal captured via non-contact technique. The result showed that the specific wear rate, K′ value increases with the increase in sliding distance, implies that a mild-abrasion wear regime had occurred. Based on the morphology investigation, it was found that under a lubricated test, parallel grooves and craters up to 10μm in size were present, indicating the occurrence of the abrasive action of fresh abrasive particles. New equations were derived from the curve fitting of 7Z∞ as a function of specific wear rate, K׳. The trend of 7Z∞ was consistent with the sliding distance increases which shows that the coefficient is capable to be used as a wear response indicator on the sliding wear operation without having to dismantle the pin inside the test rig to measure the K׳ value.

Experimental study of friction and wear characteristics of titanium alloy (Ti-6Al-4V) under lubricated sliding condition

Purpose– In the present study, an attempt has been made to examine friction and wear behaviour of Ti-6Al-4V alloy sliding against EN-31 steel under lubricative media of common commercial grade oil (hydrol-68). The paper aims to discuss these issues.Design/methodology/approach– Tribological properties of Ti-6Al-4V under hydrol-68 as lubricative media are measured using multi-tribo tester. Lubricating oil samples at different normal loads have also been analysed with the help of laser net fines (LNF) as per ISO 4406:1999. Experiments have been designed by two level full factorial method.Findings– Experimental results indicate that the wear rate of Ti-6Al-4V alloy decreases as sliding speed increases. But it shows typical transition characteristics as the normal load increases; till 30 N wear rate decreases then it increases from 30 to 50 N. Also for all loads and at every speed, the average wear increases as the sliding distance increases. The average coefficient of friction of the Ti-6Al-4V alloy decreases with the increase in sliding velocity and normal load. Lubricating oil analysis indicates that the maximum wear particle size (5-15 μm) was obtained at a normal load of 50 N.Originality/value– This paper shows that considerable reduction in friction and wear is achieved by using common grade oil hydrol-68 as lubricative media. Further, the analysis of lubricating oil using LNF at different normal loads indicates the co-existence of various wear phenomena such as cutting, fatigue, and sliding wear simultaneously.

Molecular dynamics simulation of nanoscale contact and sliding processes for probes with different tip radius of curvature

Three-dimensional molecular dynamics (MD) simulations were carried out to study the contact and sliding processes between diamond points with different tip radius of curvature and surfaces of single crystal copper. The material deformation, abrasion mechanism, lattice defects, the force of contact process, and the sliding friction process were investigated. The simulation results show that the contact force, dislocations, and stacking fault defects, increase during the contact process with increasing contact depth or tip radius of curvature. The dislocations emit along the $$ \left[ {10\bar{1}} \right] $$ and $$ \left[ {\bar{1}0\bar{1}} \right] $$ direction and then a glide band is formed. It was also found that a greater tip radius of curvature results in a larger groove and more material deformation. The normal force and friction increase with increasing tip radius of curvature, but the coefficient of friction decreases. The stacking faults spread along the sliding direction and increase with increasing tip radius of curvature. In addition, the number of upheaval atoms increases as the radius of tip curvature or sliding distance increases.

Effects of Dispersoids on Wear Behavior of Cu-Based Nanocomposite Containing SiO2 Nanoparticles

Solid particles in discontinuous reinforcement metal matrix composites (DRMMCs) drastically improve their strength. Since the strength of DRMMCs is improved by the Orowan mechanism, smaller particles, such as nanoparticles, are effective as dispersoids. In this study, the effects of nanoparticles on the sliding wear behavior of DRMMCs are investigated using Cu-based composites containing 0.6, 1.2, and 1.7 vol % SiO2 particles. Wear resistance of the Cu–SiO2 composite is improved by increasing the volume fraction of SiO2 particles. Moreover, the amount of wear for the Cu–SiO2 composites increases with increasing sliding distance and then becomes saturated beyond about 1000 m. Vickers hardness for all specimens becomes the same regardless of the volume fraction of SiO2 particles as the sliding distance increases. This behavior can be explained by the work-hardening rate of the Cu matrix and the critical hardness for adhesion with a counter-material. It is found that nanoparticles in DRMMCs improve wear resistance by increasing the work-hardening rate of the metal matrix.

Tribological properties of hard chromium coated 1010 mild steel under different sliding distances

The tribological properties of hard chromium coated 1010 carbon steel were investigated under different sliding distances using a pin-on-disc machine. The coefficient of friction was found to decrease as the sliding distance increases. Few thin microcracks initiated at the surfaces of hard chromium layer with a thickness of 7.5 μm. The severity of cracking is increased with increasing the coating thickness. The wear tracks of the hard chromium coated layers also showed similar cracking behavior.

Effect of dry sliding wear conditions on a vacuum induction melted Ni alloy

▶ The microstructure of VIM Ni alloys contains γ-Ni, Ni 3 Si, Ni 3 B, Cr 7 C 3 , and CrB. Also, Ni 3 Si particles were scattered inside the γ-Ni solid solution, Ni 3 B and dendrite Ni 3 Si appeared in the lamellar structures, and Cr 7 C 3 and CrB were scattered in the lamellar structures of Ni 3 B and dendrite Ni 3 Si. Cr 7 C 3 and CrB were more wear resistant compared to other phases. ▶ The wear loss of VIM Ni alloys was lower when the sliding velocity was 0.1 m/s compared to when the velocity was 0.7 m/s. This is due to the fact that the ability of wear at 0.1 m/s is already lower than that at 0.7 m/s. ▶ As the sliding distance increases, the worn surface of 0.1 m/s forms a continuous oxidation layer that protects the original surface. On the contrary, tumorous oxides that result in delamination form on the worn surface of 0.7 m/s. Although this also happens in the case of 0.1 m/s when sliding distance reaches 10,000 m, the quantity of wear loss is still smaller than that in the case of 0.7 m/s. The experiment described in this paper used vacuum induction melting (VIM) to coat Ni alloyNi alloy onto AISI 4140 steel. X-ray diffraction (XRD), scanning electron microscope (SEM), electron probe micro analyzer (EPMA), and transmission electron microscope (TEM) were used to identify the different phases of VIM Ni alloyNi alloys. Then, a ball-on-disc system and different dry sliding wear conditions were used to test VIM Ni alloyNi alloys. Results indicate that Ni 3 Si particles were scattered inside the γ-Ni solid solution, Ni 3 B and dendrite Ni 3 Si appeared in the lamellar structures, and Cr 7 C 3 and CrB were scattered in the lamellar structures of Ni 3 B and dendrite Ni 3 Si. Cr 7 C 3 and CrB were more wear resistant compared to other phases. The wear loss of VIM Ni alloys was lower when the sliding velocity was 0.1 m/s compared to when the velocity was 0.7 m/s. In the former case, the formation of a continuous oxidation layer protected the original surface from direct wear. A further increase in sliding distance caused, in both the cases, the formation of tumorous oxides, which led to delamination. Regardless, wear loss at 0.1 m/s was still lower than at 0.7 m/s.

Experimental Friction Coefficients for Bovine Cartilage Measured with a Pin-on-Disk Tribometer: Testing Configuration and Lubricant Effects

The friction coefficient between wet articular cartilage surfaces was measured using a pin-on-disk tribometer adopting different testing configurations: cartilage-on-pin vs. alumina-on-disk (CA); cartilage-on-pin vs. cartilage-on-disk (CC); and alumina-on-pin vs. cartilage-on-disk (AC). Several substances were dissolved in the phosphate buffered saline (PBS) solution to act as lubricants: 10,000 molecular weight (MW) polyethylene glycol (PEG), 100,000MW PEG, and chondroitin sulfate (CS), all at 100mg/mL concentration. Scanning electron microscopy photographs of the cartilage specimens revealed limited wear due to the experiment. Conducting the experiments in PBS solutions we provide evidence according to which a commercial pin-on-disk tribometer allows us to assess different lubrication mechanisms active in cartilage. Specifically, we find that the measured friction coefficient strongly depends on the testing configuration. Our results show that the friction coefficient measured under CC and AC testing configurations remains very low as the sliding distance increases, probably because during the pin displacement the pores present in the cartilage replenish with PBS solution. Under such conditions the fluid phase supports a large load fraction for long times. By systematically altering the composition of the PBS solution we demonstrate the importance of solution viscosity in determining the measured friction coefficient. Although the friction coefficient remains low under the AC testing configuration in PBS, 100mg/mL solutions of both CS and 100,000MW PEG in PBS further reduce the friction coefficient by ~40%. Relating the measured friction coefficient to the Hersey number, our results are consistent with a Stribeck curve, confirming that the friction coefficient of cartilage under the AC testing configuration depends on a combination of hydrodynamic, boundary, and weep bearing lubrication mechanisms.

Application of BEM and optimization technique to wear problems

In this paper a new method for solving wear problems, using the Boundary Element Method (BEM) is proposed. The proposed method uses a shape optimization technique for rapid calculation of the maximum wear depth and the final geometry of the bodies in contact after a specified service period. The optimization method solves the wear problem directly, without using increments of the sliding distance as in the classical methods. The BEM is used for modelling both bodies in contact, treating the problem as a multi-region problem. The material loss is presented in terms of the applied load and the sliding distance, and is modelled using a linear wear model. The proposed method is shown to be robust as it requires only few iterations to achieve a converged solution. The reduction in computational effort, as compared to the classical incremental method, becomes more significant as the sliding distance increases.