Increase In Normal Load Research Articles

An Assessment of Tribological Characteristics under different Operating Condition

The paper evaluates and compares the friction and wear behavior of SAE-AISI 1060 steel and brass (CuZn37Pb2) at different initial surface roughness and normal load using pin-on-disc test. Tribological behavior of studied materials was analyzed in detail. Variation of coefficient of friction at different initial surface roughness and normal load has been correlated with wear loss, wear rate, track width. Experiments are carried out in normal load 3-5-8-10 N, sliding speed 0.24-0.35m/s and 0.48 m/s, wear track diameter 4-6-8-10 mm. Results show that friction coefficient, wear loss and wear rate of steel increase with track width at high initial surface roughness and normal load. For brass friction coefficient decreases with the increase of normal load. On the other hand, it is also found that wear loss, wear rate and track width increase with sliding distance. Microscopic of worn surfaces for each alloy were carried out and compared.

Experimental Investigations on Pullout Behavior of HDPE Geogrid under Static and Dynamic Loading

This paper describes a series of laboratory pullout tests that were performed to investigate the pullout behavior of high‐density polyethylene (HDPE) uniaxial geogrid subjected to static and dynamic loading. Pullout tests were conducted on HDPE geogrid reinforced coarse sand under normal static loading (60–300 kPa), dynamic loading with different amplitudes (20, 40, and 60 kPa), and different frequencies (2, 4, and 6 Hz) by using the newly developed pullout apparatus. The results indicated that the pullout resistance of geogrid presented different growth patterns with the increase of normal loads under static loading. The amplitude and frequency both had significant effects on the interaction between reinforcement and soil, and the increment of the pullout resistance was 0.6 kN and 0.3 kN, respectively. The effect of dynamic loading on the soil‐geogrid interface can be gradually equivalent to that of static loading corresponding to the balance position of dynamic loading with the increase of frequency compared with the static loading. The results of this study are helpful for the selection of the strength of the reinforcement in different locations and to simplify the study on the stress of reinforcement in reinforced soil structures under traffic loads.

Tribological and electrochemical corrosion performanceanalysis of Hastelloy C276 under different loading conditions

Hastelloy C276, a Ni-Cr-Mo wrought alloy and generally considered as a versatile corrosion resistant alloy, is investigated for dry sliding wear against an EN 31 stainless steel (hardness 60 HRC) at 298 K. The tribological properties such as frictional force, Coefficient of friction and the wear rate on the material surface at different sliding distance are examined under different loading conditions. In the dry wear test at 40 N load, the wear rate increased by 300% as compared to 10, 20, 30 N loading conditions.The experimental results indicated reduction in coefficient of friction values and thus an increase in the frictional force with the increase in normal load. The Scanning Electron Microscope images of worn out surfaces confirm that the delamination and adhesion causes the material removal from the surface in dry sliding. Further, the analysis of the hardness characteristics of worn out surfaces shows surface hardening during sliding wear processunder 40 N loads. The study on the corrosion wear behaviour in the sulphuric acid showed a significantly lower value of corrosion rate (0.0016579 mm/y in H2SO4 solution) in comparison to other alloys frequently used in industries.

Investigation of tribological properties of Al-Mg-Si/SiCp nanocomposites prepared by ultrasonic assisted casting method

In the present study, wear properties on 0, 0.5, 1.0 and 1.5 vol% nano-SiCp reinforced Al-Mg-Si alloy metal matrix nanocomposites (MMNCs) fabricated by ultrasonic assisted casting method. The pin on disc apparatus was used for wear testing. Dry sliding wear behavior of nanocomposites were studied by changing the normal load, sliding distance, sliding velocity, and volume fraction of nano-SiCp. The results showed that the wear rates of MMNCs were drastically lower than the unreinforced alloy and the rate of wear decreases as the reinforcement content in the metal matrix increases. The MMNC containing 1.5 vol% nano-SiCp yielded lowest wear rate. It was also observed that the increase in applied load, sliding velocity and sliding distance increases the wear rate of both nanocomposites and monolithic alloy. The average friction co-efficient decreases gradually, with increase in normal load as well as nano-SiCp content. From the scanning electron microscopic images, it was observed that the worn surface had deep long groove in the sliding direction for the monolithic Al alloy, whereas the worn surfaces of MMNCs possessed narrow grooves with almost a flat surface.

Corrosion and corrosive‐wear behaviors of a high strength and toughness Cu–15Ni–8Sn alloy in seawater

AbstractThe Cu–15Ni–8Sn alloy with high strength and toughness is a common bearing alloy, while it is often subjected to premature failure in service due to corrosion and wear. Therefore, the corrosion and wear behaviors of an ultra‐high‐strength and toughness Cu–15Ni–8Sn (wt%) alloy fabricated by hot isostatic pressing were investigated in this study. The results indicated that intergranular corrosion and pits were observed when the studied alloy was immersed into seawater for 30 days. When the Cu–15Ni–8Sn alloy slid in seawater, there was a synergistic effect between corrosion and wear. With the increase of normal load, the synergistic effect weakened initially and then enhanced the interaction between corrosion and wear changed from negative to positive, and the main wear mechanisms transferred from abrasive wear into delamination.

Strongly adherent Al2O3 coating on SS 316L: Optimization of plasma spray parameters and investigation of unique wear resistance behaviour under air and nitrogen environment

Plasma spray deposition of Al2O3 is a well-established technique for thick ceramic coatings on various substrates to shield them from corrosion and wear. Owing to its high hardness, aluminum oxide is known to protect stainless steel substrates from wear. However, the plasma process requires optimization for desired coating thickness and adhesion strength. It is also necessary to understand the sensitivity of friction and wear resistance of the deposited coating on exposed environment for evaluation of service life. The study offers comprehensive investigation on plasma process parameters for the development of strongly adherent aluminium oxide coatings on SS 316L substrate. Impact of environment like dry air and dry nitrogen on tribological properties of the coatings was also investigated. Dense adherent coatings of alumina could be deposited on SS 316L at a plasma power of 20 kW with an intermediate bond coat of NiCrAlY to enhance the adhesion properties. The effects of stand-off distance and bond coat thickness on adhesion strength were additionally examined. Further, the coatings were characterised for phase composition, microstructure, microhardness and wear resistance potential. Reciprocating wear tests of the coatings were carried out using ball on disc reciprocating tribometer at different loading conditions (5, 10 and 15 N) at constant (5 Hz) sliding frequency. Unlike the coefficient of friction (COF), wear volume was found to increase with an increase in normal load. These adherent coatings revealed promising properties for the applications where the tribological failure of SS 316L in dry air or dry nitrogen environment is to be controlled.

Dry sliding friction and wear of Al 6061 and Al 6082 alloys under different normal loads

The current research work addresses evolution of coefficient of friction over sliding distance. Friction and wear tests were conducted using pin on disk type tribometer. The stabilized friction coefficient values under normal load of 10 N and 15 N for Al 6061 were noted as 0.5 and 0.58 respectively. Corresponding friction coefficient values for Al 6082 were noted as 0.6 and 0.45 respectively. Equation to calculate wear volume was derived for cylinder on flat contact. The dominant wear mechanisms were justified with the images of the disk specimens captured using optical microscope. Increase in wear volume resulting from increase in normal load was observed for Al 6061 and Al 6082 alloys.

Pre-Test Analysis on Reinforced Concrete Beams with Shear Strengthening using GFRP by Finite Element Method

Research on the developments of new materials as well as the methods and techniques of retrofitting structures showed that the Fiber Reinforced Polymer (FRP) is a promising material for use in strengthening reinforced concrete structures. This research aims to model reinforced concrete beams with shear strengthening using GFRP based finite element method. By using computer program Finite Element Analysis (FEA) the modelling was carried out by 2-dimension models on 3 testing material variations namely: the test normal concrete beams without the shear retrofitting (BGN), beams with shear retro fitting using GFRP are continuous on the shear span (BGPF), beams with retrofiting using 3 strips (BGP3S). The research result indicated that generally, the programused can show the behavior closed to the theoretical design result. The ultimate load of results normal concrete beams without the shear retrofiting (BGN) is 76,393 kN, beams with shear retrofitting using GFRP are continuous on the shear span (BGPF) is 77,798 kN, and beams with retrofiting using 3 strips (BGP3S). The results showed that the percentage increase of normal ultimate load of beam with shear reinforcement using GFRP was 1.4%, 11.01%, for reinforced using 3 strips (BGP3S). This indicated that the material behavior response produced from simulation study can well be described by the program.

Hardness Along with Electrochemical Corrosion Performance Examination of Hastelloy C276

Hastelloy C276 a versatile corrosion resistant alloy, is investigated at 298 K. The tribological properties such as frictional force, In the micro-hardness test at 40 N load, the hardness is increased by 25 % as compared to 10, 20, 30 N loading conditions. The experimental results indicated reduction in coefficient of friction values and thus an increase in the frictional force with the increase in normal load. The images of worn out surfaces confirm that the delamination and adhesion causes the material removal from the surface in dry sliding. Further, the analysis of the hardness characteristics of worn out surfaces shows surface hardening during sliding wear process under 40 N loads. The study on the corrosion wear behavior in the sulphuric acid showed a significantly lower value of corrosion rate (0.0016579 mm/y in H2SO4 solution) in comparison to other alloys frequently used in industries.

Microstructural Characterization and Evaluation of Sliding Wear of Hastelloy C276 under Different Loading Conditions

Hastelloy C276 is investigated for dry sliding wear against an EN 31 stainless steel (hardness 60 HRC) at 298 K. The tribological properties such as frictional force, coefficient of friction and the wear rate on the material surface at different sliding distance are examined under different loading conditions. In the dry wear test at 40 N load, the wear rate increased by 300% as compared to 10, 20, 30 N loading conditions. The experimental results indicated reduction in coefficient of friction values and thus an increase in the frictional force with the increase in normal load. SEM images of worn out surfaces confirm that the delamination and adhesion causes the material removal from the surface in dry sliding. Further, the analysis of the hardness characteristics of worn out surfaces shows surface hardening during sliding wear process under 40 N loads.

Probing the effect of grinding-heat on material removal mechanism of rail grinding

Rail grinding is of vital importance for high-speed railway with safe, reliable and comfortable operation. Here, a self-design grinding machine was applied to evaluate the performance of as-prepared grinding stone (GS) vs Rail under normal loads and grinding speeds. Results illustrate that the increase in normal load leads to the wider and thicker wear debris, but the increasing grinding speed is opposite. Friction-induced heat regulated by working parameters determines the grinding properties of the GSs/Rail contact, high grinding-heat causes the plastic deformation and accelerates the wear. The finite element analysis verifies the source/distribution of grinding-heat and heat flux, thereby revealing the material removal mechanism. It is of great significance for long-term safe and reliable operation of rail via grinding regulation.

Wear resistance of graphene nano-platelets (GNPs) reinforced AlSi10Mg matrix composite prepared by SLM

In order to improve the wear resistance of aluminum alloys and expand its applications, the microstructure and tribological properties of nano-graphene reinforced aluminum matrix composites—which were fabricated by selective laser melting (SLM)—were investigated. Experiments were conducted to investigate the effect of slide speeds (0.3–0.9 m/s) and normal loads (10N–30N), which demonstrated the dislocation strengthening and load strengthening resulting from the homogeneous dispersion of graphene nano-platelets (GNPs) enhance the wear resistance of GNPs/AlSi10Mg composites. With the increase of slide speed, the wear rate of composites decreases and the wear regime changes from abrasive wear to delamination wear, which is because the formation of a relatively stable mechanically mixed layer (MML) reduces the contact area between the counterbody material and the wear surface, and the nano-graphene bridges between the subsurface cracks improve the tribological performance. Meanwhile, with the increase of normal load, the predominant wear regime of the reinforced composite is the combination of delamination wear and oxidize wear. And the coefficient of friction (COF) decreases as the slide speed increases, which is because the self-lubricating property of graphene nano-platelets makes it easy to form interlayer sliding and reduce friction effectively.

A Comparative Study on the Tribological Behavior of SAE-AISI 1055 Steel and Brass (CuZn39Pb2) a Pin on Disc Type of Contact

The paper assesses and compares the friction and wear behavior of SAE-AISI 1055 steel and brass (CuZn39Pb2) under dry sliding condition. The tribological behavior was investigated and compared by conducting two different experiments, the first experiment conducted on a CSM tribometer, and the second experiment was carried out on a test bench in horizontal lathe machine where device holder pin is fabricated and mounted on a test bench and a rotating disc, varying the normal load exert on the disc by the pin and the rotation speed of the disc. These tests consisted of measuring friction coefficient and wear loss of samples. Experiments are carried out in normal load 5-10 N, sliding speed 0.24-0.35 and 0.48 m/s. Variations of coefficient of friction during sliding at different initial surface roughness, normal load and sliding speed are investigated. Results show that the two alloys had different friction and wear behavior, for steel friction coefficient increase slowly with the increase of normal load and sliding speed. For brass friction coefficient decreases with the increase of normal load and sliding speed. On the other hand, it is also found that wear loss increase with sliding distance. Microscopic of worn surfaces for each alloy were carried out and compared.

Screening the Main Factors Affecting the Wear of the Scraper Conveyor Chute Using the Plackett–Burman Method

The wear of scraper conveyor chute causes both significant economic and environmental losses by shortening the service life. The life of the chute under coal abrasive wear situations is primarily decided by operating conditions and the materials properties. The comprehensive analysis of the influence factors had not been studied before. In this paper, the Plackett-Burman design (PBD) method was used to screen the main influence factors and a regression equation was developed to predict the wear loss. The steel was tested on a modified pin-on-disk apparatus in which coal abrasive was filled in the disk. The influence factors included water content, gangue content, coal particle size, Hardgrove Grindability-Index (HGI) of the coal, normal load, and scraper chain speed. The results of the investigation suggested that the significance of water content, normal load, and gangue content on wear loss was relatively higher than the HGI of coal, scraper chain speed, and coal particle size. The wear loss increased with the increase of water content, gangue content, normal load, and coal particle size while it decreased as increase in HGI of the coal and scraper chain speed. Based on the significance of the parameters, the regression equations were derived and verified further with a number of test cases. Optical microscope studies revealed the main wear mechanism of the chute was mainly micro-cutting and corrosive wear and accompanied by fatigue fracture.

Tribological investigation of copper and AISI 304 steel during dry sliding wear

Copper-based metal matrix (CBMM) composite is used in ball bearings and other tribological components due to significant improvement in thermal and mechanical properties. However, copper alloys based bearings are likely to fail due to severe surface fatigue wear in rolling/sliding condition. To understand the fatigue wear of copper-alloy which is dominated by the evolution of asperity characteristics, the study of topography evolution in dry sliding condition is essential. The purpose of this study is to study the tribological behavior of copper-steel material combination in dry sliding condition. The tribological properties of copper are also compared with AISI 304 steel. Experiments are performed on pin-on-disc tribometer. The AISI 52100 steel disc is used as a counter body during the experiments on AISI 304 and copper pin materials. The effect of normal load on friction coefficient and wear is studied. Surface topographies of the worn surfaces are measured using a 3D optical profiler. Scale-sensitive fractal analysis (SSFA) is performed on worn surfaces to analyze the complexity of the surface. It is found that surface complexity increases with an increase in normal load. At low scale, worn surfaces are rough and can be simplified by applying fractal theory. At lower load, an oxide layer is formed on the copper surface which reduces the direct asperity contacts. At higher load, distortion in the shape of autocorrelation is observed due to an increase in adhesion and plowing wear.

Microstructure and Wear Behaviors of Plasma-Sprayed FeCrNiMoCBSi Coating with Nano-Grain Dispersed Amorphous Phase in Reciprocating Sliding Contact

A novel FeCrNiMoCBSi amorphous/nanocrystalline coating was fabricated using a plasma spraying process. The coating was dense with a low porosity of approximately 0.99%. The coating consisted of a 67.8 vol% amorphous phase coupled with many nanocrystalline grains that were approximately 5 nm in diameter. The mechanical properties of the as-sprayed coating were determined by nanoindentation measurement, and the tribological behaviors were systematically investigated in a reciprocating sliding contact. The results show that FeCrNiMoCBSi coatings possess superior wear resistance compared to other typically similar Fe-based amorphous coatings. The tribological behaviors evolve with the combination of normal load and sliding velocity. Herein, the dominant wear mechanisms are delamination wear and oxidation wear. With an increase in normal load and sliding velocity, the abrasive wear is gradually weakened, the formation of oxide films on the worn surfaces is facilitated, and wear debris is ground to powder. The oxide films suffer from fatigue wear with induced cracks undergoing reciprocating sliding effects.

Wear of chromium nitride coating under high loads and speeds

This paper investigates the effect of high loads (up to100 N) and high speeds (up to 3 m/s) on wear and friction behaviour of PVD deposited CrN coatings on cast iron substrate. Uncoated substrate materials were also tests under identical test parameters to compare the friction coefficient, wear rate, temperature generation accompanied with wear mechanism. With the increase of normal loads from 50 N to 80 N the wear rate of coated sample increases from 4.59 × 10−5 mm3/Nm to 6.86 × 10−5 mm3/Nm, while the sliding speed remains constant. Temperature rise due to friction was monitored in wear tracks, and higher wear track temperature (from 65°C to 178°C) simulates higher coating wear as well as degradation of materials. The wear mechanisms of the CrN coatings involve pull out of nitride particles, oxidation of wear particles, adhesive wear and a combination of fatigue delamination as evident from wear track morphology investigated by scanning electron microscope.

Wear of chromium nitride coating under high loads and speeds

This paper investigates the effect of high loads (up to100 N) and high speeds (up to 3 m/s) on wear and friction behaviour of PVD deposited CrN coatings on cast iron substrate. Uncoated substrate materials were also tests under identical test parameters to compare the friction coefficient, wear rate, temperature generation accompanied with wear mechanism. With the increase of normal loads from 50 N to 80 N the wear rate of coated sample increases from 4.59 × 10−5 mm3/Nm to 6.86 × 10−5 mm3/Nm, while the sliding speed remains constant. Temperature rise due to friction was monitored in wear tracks, and higher wear track temperature (from 65°C to 178°C) simulates higher coating wear as well as degradation of materials. The wear mechanisms of the CrN coatings involve pull out of nitride particles, oxidation of wear particles, adhesive wear and a combination of fatigue delamination as evident from wear track morphology investigated by scanning electron microscope.

Tribological Properties of B4C Nano Particulates Reinforced Copper Matrix Nanocomposites

Abstract Pure copper (Cu) matrix composites reinforced with different weight percentages of Nano boroncarbide particles (B4C) were successfully produced through powder metallurgical route. Nano sized B4C particles with 0, 0.5, 1.0 and 1.5 weight % were mechanically mixed with Cu powder of size 125 μm and then compacted at 248 bar pressure. SEM analysis revealed that the B4C nanoparticles were uniformly distributed in Cu matrix. Addition of 1.5 wt.% Nano B4C particles in Cu matrix, increases the Vickers micro hardness from 32 to 93. The wear measurements of pure Cu exhibited high wear loss than the Nano B4C mixed copper matrices. Nano composites reinforced with 1.5 wt.% of Nano B4C showed maximum wear resistance property. In general, increase of normal load and sliding velocity increases the wear rate. The worn surfaces of pure Cu show deep long grooves while Cu-Nano composites show narrow grooves.

A tribological application of the coarse-grained molecular dynamics simulation and its experimental verification

Abstract We developed a method to simulate the polytetrafluoroethylene (PTFE) tribology by estimating the molecular interaction parameters on the basis of experimental verification. We fitted the molecular interaction parameters between coarse-grained PTFE beads using the iterative Boltzmann inversion method and multi-centered Gaussian-based potentials. The fitting parameters were subsequently validated by comparing an all-atom PTFE model and its corresponding coarse-grained model. A two-layer PTFE friction model was then built on the basis of the estimated parameters to study the effect of normal load on the friction coefficient and wear depth of PTFE. The simulation results showed that the friction coefficient decreases and the wear depth increases as the normal load increases. Moreover, the reasonability of the simulation results was verified through experiments.