Worn Surface Morphology Research Articles

A study on friction induced tribological characteristics of steel 316 L against 100 cr6 alloy under different lubricating conditions with machine learning model

The material steadily wears away from touching surfaces when two solid entities are constantly moving against one other. When more parameters and extreme materials are involved in tribological testing, then it is very difficult to analyze and observe the working phenomena. With this aim, this study uses the gaussian process regression (GPR) approach to estimate friction forces when testing SS 316 L against 100 Cr6 alloy under cryogenic and cryo + minimum amount lubrication conditions. The friction forces from ball-on test experiments were used to develop the prediction models. Then, the wear surfaces and surface morphology are analyzed under cryo and cryo+MQL conditions. The results demonstrated that the combination of MQL and CRYO cooling reduced the friction forces more than 10 times for sliding distances above ∼30 m and loads below ∼25 n. Hence, the cryo+MQL conditions are beneficial in enhancing the tribological features due to the dual cooling and lubricating effects.

Mechanical‐wear behavior and microstructure analysis of Al2214 alloy with B4C and graphite particles hybrid composites

AbstractIn the present work, hybrid composites made of Al2214 alloy with B4C and graphite were produced by using a liquid metallurgical process. Al2214 alloy was utilized to create hybrid composites that had 1.5–6 wt% of B4C particles and a constant 3 wt% of graphite particles. Microstructural analysis using scanning electron microscope (SEM), energy dispersion spectroscopy (EDS), and X‐ray diffraction (XRD) was done on the produced composites. The density, hardness, ultimate, yield strength, and elongation as a percentage were carried out using ASTM E8 for tensile and E10 standard for hardness test. The wear behavior of Al2214‐B4C and graphite composites was examined as per ASTM G99 standard using a wear testing device under a variety of loads and rotation speeds. Graphite and boron carbide particles were equally dispersed throughout the Al2214 alloy, according to SEM photographs. Graphite and B4C particles were detected in the Al2214 alloy by EDS and XRD analyses. The density of Al alloy composites was decreased by adding dual particles to the matrix. The Al2214 alloy's hardness, ultimate strength, yield strength, and wear resistance were all enhanced by the inclusion of dual particles, which increased these properties by 15.4%, 40.4%, and 46.7%, respectively. The presence of hybrid particles in the Al2214 alloy was revealed by EDS and XRD patterns. The density of Al alloy composites was decreased by adding dual particles to the matrix. Tensile force micrographs provided further evidence of the unique fracture behaviors shown by the Al2214 alloy and its composites. In order to examine the wear mechanisms and different morphologies of worn surfaces, scanning electron micrographs were taken.

Synergistic enhancement in mechanical properties of graphene/MWCNT reinforced Polyaryletherketone – carbon fiber multi-scale composites: Experimental studies and finite element analysis

This investigation focuses on the synergistic performance improvement in graphene/MWCNT reinforced Polyaryletherketone (PAEK) - carbon fiber (CF) multi-scale composites. FTIR revealed the chemical interactions while HRTEM, XRD and 3D X-ray microscopy gave insight into nanofiller dispersion and microstructural features. The functional groups on nanofillers along with structural features integrated various components of the multi-scale composites by formation of graphene/MWCNT/CF complex network that provided larger interfacial area, bridging effect and physico-chemical interaction with PAEK while restricting its segmental mobility. Multi-scale composites displayed significantly improved strength, fracture toughness, interlaminar shear strength, glass transition temperature and tribological performance. Under dynamic load, graphene/MWCNT reinforcement of matrix and CF synergistically increases the storage modulus and energy absorption characteristics. Wear and fracture surface morphology of nano and multi-scale composites showed ductile failure confirming interfacial adhesion. The failure behavior in experimental studies was supported by Abaqus/Explicit-based FEM models of fracture toughness response. This work provides a promising avenue to develop next generation high performance thermoplastic composites for structural applications.

Development of Novel Wear Equation of AA7050/SiC-Steel Interface for High Temperature Application

AA7050 aluminium alloy used for the main landing gear link was reinforced with SiC particles utilizing stir casting and uniform dispersion of reinforced particles was analyzed through SEM with EDS mapping. Wear test were performed on pin on disc apparatus by varying the process parameters and experimental runs were designed using response surface methodology. The influence of SiC particles on wear resistance at high temperatures was explored and the findings led to the development of a novel wear equation. The hardness of composites increased due to impediments of dislocation movement, and it declines with an increase in temperature owing to a reduction of Pierls stresses. The formation of a Mechanically Mixed Layer (MML) enhances wear resistance with the inclusion of reinforced particles, and the breakdown of this layer swifts the wear from moderate to severe. The mode of wear was a combination of shearing and abrasive at room temperature, shearing and adhesive until the temperature 200ᵒC, and plastic deformation when the temperature exceeded 200 °C, which was confirmed by worn surface morphology.

Post-Wear Surface Morphology Assessment of Selective Laser Melting (SLM) AlSi10Mg Specimens after Heat Exposure to Different Gas Flames

The wear surface morphology of AlSi10Mg specimens, originally manufactured using selective laser melting (SLM), has been analyzed in the context of exposure to heat from gas flames. The first stage of the experimental work included the performance of surface heat-exposure on SLM-prepared specimens through oxyacetylene gas welding. Gas welding was utilized with three different flames, namely; reducing, neutral, and oxidizing on the as-built specimens of SLM. The post-surface-treated specimens were subjected to pin-on-disk wear testing against fixed parameters. After the performance of wear testing at two different radii, the mass loss of each of the four types of specimens was calculated including the three specimens exposed to heat along with the as-built specimens. The results showed that the maximum amount of mass losses at 24 mm and 30 mm radii belongs to the neutral flame specimens and the least was for the as-built condition specimens. Upon analysis, the heat-exposure specimens through all three types of gas flames resulted in an increase in the amount of mass in contrast to the as-built specimens. Moreover, the morphologies of the developed wear tracks at surfaces were examined using the scanning electron microscope (SEM) for the understating of the mechanism.

Investigation of Mechanical and Wear Behaviour of Al5056-Carbon Nanotube -Graphene Hybrid MMCs using Powder Metallurgy Route

Composites containing metal at least in two constituent parts are metal matrix composites. Another material may also be used like organic compounds or ceramics, in addition to a different metal. In the current work Al5056 aluminium powder is used as the matrix material having an average particle size was about 35±5 μm and Carbon Nanotube (CNT) and Graphene (Gr) are used as reinforcement materials. Hybrid composites are developed using an advanced powder metallurgy technique process. Also, in the existing work microstructure characterization was performed using advanced techniques. Hardness, Tensile and wear tests are conducted as per ASTM standards. Mechanical properties improved with the increase in amalgams in the matrix. The wear surface morphology of Al alloy shows a rough surface with more grooves and ridges compared to the wear surface morphology of Al5056/CNT-Gr hybrid composites. Wear debris results of Al alloy show more debris chips out of the material compared to Al5056/CNT-Gr hybrid composites.

Influence of Laser Energy Density on Tribological Properties of AlSi10Mg Manufactured by Selective Laser Melting.

In recent years, much work related to the performance of AlSi10Mg manufactured by selective laser melting (SLM) has been extensively researched. However, the study of tribological performance caused by different laser energy densities is still insufficient. This work concentrates on the relationship between the wear resistance and laser energy density of AlSi10Mg processed using SLM. Moreover, XRD characterization, density, surface roughness and microhardness were also examined since they are closely related to wear resistance. The results revealed that the XRD pattern of AlSi10Mg was mainly composed of the α-Al and Si phases under the conditions of different laser energy densities. In addition, the peak of Mg2Si was also detected. Also, the grain size increased with the increasing of laser energy density. The increase in laser energy density led to an increase in the convection and porous phenomenon in the molten pool. However, when the value was lower, the overlapping area reduced, and the strength between adjacent melting paths was insufficient, resulting in the declination of the sample property. According to the experimental results, a laser energy density of 63.33 J/mm3 was considered to be a relative optimal condition. The relative density, Ra, microhardness and wear volume were 99.2%, 8.86 μm, 128.3 HV0.2 and 2.96 × 10-2 mm3, respectively. The worn surface morphology also confirmed the influence of laser energy density on wear resistance. A regression model was established and analyzed, which showed the reliability of the results. Furthermore, the tribological mechanism was also revealed.

Impacts of chemical short-range orders on nanotribological properties of CrCoNi medium-entropy alloy at room and cryogenic temperatures

Presence of chemical short-range orders (SROs) had a great impact on the property-structure relationships of high/medium-entropy alloys (H/MEAs), but its influence on the tribological performance of H/MEAs has never been reported. This study provides an understanding on the chemical SRO degree dependent nanoscratching response of CrCoNi MEA by hybrid Monte-Carlo and molecular dynamic simulations. Friction coefficient, wear rate, worn surface morphology, phase stability and dislocation activities have been systematically investigated considering different load mode and temperature conditions. CrCoNi MEA exhibited superior nanotribological properties at cryogenic temperature than room temperature. Increasing chemical SRO degree is found to be effective in reducing friction and improving wear resistance and phase stability, regardless of nanoscratching conditions.

Enhanced tribological performance of nanotwinned copper enabled by sliding-induced heterostructure

Nanotwinned metals have many advantages such as high strength, reasonable ductility and high damage tolerance. However, studies on their tribological properties are scarce, especially the tribological performance relative to the counterparts with comparable hardness. Here, dry sliding tests of electrodeposited nanotwinned copper sample (NT-Cu) are carried out in comparison with the nanocrystalline copper (NC-Cu) and coarse-grained brass (CG-Br) samples that have similar initial hardness. Their worn surface morphologies, chemical compositions and worn subsurface microstructures are characterized in detail. At a load of 3 N, the friction coefficient of NT-Cu is 0.25, which is 44 % and 58 % lower than CG-Br and NC-Cu, respectively. The wear rate is 1.4×10−6(mm−3/Nm), which is 3.8 % of NC-Cu and 10.4 % of CG-Br, respectively. When the load is increased to 5 N, their difference in wear rate increases obviously. The superior tribological performance of NT-Cu is attributed to the sliding-induced layered heterostructure that can effectively accommodate frictional work and suppress the cracking and peeling-off of dynamic recrystallized structures.

Tailoring the in-situ formation of intermetallic phases in the self-lubricating Al–WS2 composite for enhanced tribological performance with wear track evolution analysis

Self-lubricating aluminium matrix composites with enhanced tribological properties are sought for weight critical applications. In previous studies, the Al composites incorporating the solid lubricant WS2 have been shown to reduce both the coefficient of friction and wear rate, positioning them as promising candidates in various tribological applications (e.g. automotive industry). However, the impact of interfacial reactions between Al and WS2 during composite production on tribological performance has still not yet been explored. This study highlights the hardening effect of the reaction products. Despite some literature assuming a negative impact of these reactions as they consume WS2 in the composites, this study presents evidence that this cannot be generalised for the overall outcome. Interestingly, a controlled amount is shown to be beneficial for tribological properties. In this work, the tribological influence of the Al–W intermetallic structure forming during spark plasma sintering of the Al–WS2 composites was investigated. The microstructure was tailored by adjusting the manufacturing temperature between 500 and 600 °C. The Al–WS2 fabricated at 580 °C exhibited the lowest coefficient of friction and specific wear rate (reduced by 20 % and 97 %, respectively, compared to the one fabricated at 500 °C. Furthermore, the worn surface morphology in different stages during friction was evaluated by a novel wear track evolution analysis. This study confirmed that offering a balance between the fraction of solid lubricants and in-situ formed hard intermetallic structure is crucial to the effective formation a protective layer on the worn surface.

Triple heat treatment effects of Inconel X-750 superalloy on its microstructure, hardness, and high-temperature fretting wear characteristics

Inconel X-750 alloy specimens were undergone the triple heat treatment process: solution annealing (1149 °C/2h), equalization treatment (843 °C/24h), and precipitation treatment (704 °C/20h). Then microstructure characterization and hardness tests were performed prior to the self-mated pin-on-disk fretting wear tests in the range of 25 °C-650 °C temperature conditions. This type of alloys is widely used in bump-type gas foil bearing applications where complex fretting phenomenon occurs between foils under harsh operating conditions. Conducted investigations revealed that the heat-treated sample developed more precipitated phases in the matrix and along the grain boundaries with higher bulk hardness. Fretting wear surface morphologies indicate that the formation of glaze layer composed of NiO, Cr2O3, and mixed Ni(Fe,Cr)2O4 oxides prevail on the wear scar during the elevated temperatures, harnessing significantly lower friction coefficient and wear loss. Severe material transfers and galling were the dominant wear mechanism in the non-heat-treated alloy interface which caused the stick-slip frictional behavior. On the contrary, the heat-treated alloy surfaces demonstrated the stable coefficient of friction and 3–10 times lower wear rates at high temperatures due to the additional Cr-rich carbides. It is believed that these hard and lubricious Cr2O3 internal oxide precipitates form healing glaze barrier in the interface by protecting against severe material transfer/build-up.

Surface self-nanocrystallization and -lubricating dependent wear resistance of austenitic steels at same initial hardness level

In the present paper, two austenitic wear-resistant steels, namely 110Mn13 and 0Cr17Ni10Mn5Mo2 steels, were cold-rolled to a same hardness level of ∼270 HV. Mechanical properties and wear resistance under various applied loads were tested. The deformed microstructure, worn surface morphologies and wear debris were discussed to analyze the wear resistance. Results showed that a higher density of deformation twins and dislocations were generated in the 0Cr17Ni10Mn5Mo2 steel to reach a same hardness level with the 110Mn13 steel. Consequently, the 0Cr17Ni10Mn5Mo2 steel obtained higher yield strength (736 MPa) but lower ultimate strength (896 MPa), elongation (30.5%) and strain hardening rate than the 110Mn13 steel when the impact absorption energies were at a similar level of ∼170 J. The weight loss of the 0Cr17Ni10Mn5Mo2 steel reduced by over 40% compared to that of the 110Mn13 steel under the selected wear conditions. With the cold-rolled microstructure, the worn surface of both the test steels produced nanocrystalline layers. The nanocrystalline layer thickness of the 0Cr17Ni10Mn5Mo2 steel was over 5 μm, far larger than that of the 110Mn13 steel. Meanwhile, with the wear debris containing Cr-oxide adhering to the worn surface, which could facilitate the self-lubricating effect, the 0Cr17Ni10Mn5Mo2 steel presented better wear resistance than the 110Mn13 steel.

Effect of Ultrasonic Surface Rolling on the Fretting Wear Property of 7075 Aluminum Alloy

This paper investigates the effect of ultrasonic surface rolling (USR) on the fretting wear properties of the 7075 aluminum alloy. A white light interferometer, Vickers hardness tester, and X-ray diffractometer were employed to comparatively analyze the variations in surface roughness, hardness. and grain size before and after the USR treatment. The fretting tests were carried out under oil lubricated and dry fretting conditions, using a ball-on-flat contact tangential fretting tester. The worn surface morphology, wear debris, and chemical composition were analyzed using an optical microscope (OM), a scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS), etc. The results revealed that after USR treatment, the surface roughness was reduced by 90%, the hardness was increased by 13HV, and the grains were refined. Moreover, the wear was reduced under oil lubrication conditions but increased under dry fretting conditions. It can be concluded that the microstructure and mechanical properties of the 7075 aluminum alloy surface can be enhanced by the USR treatment. The improved fretting performance in oil should be attributed to the increased surface hardness, which helps reduce abrasive wear and plastic deformation. However, under dry fretting conditions, the wear was increased due to the presence of hard debris particles that peel off from the USR-treated surface, leading to aggravated abrasion.

Tribological Properties Laser-Cladded Spherical WB-Reinforced Co-Based Coatings under Low-Temperature Friction.

Three groups of spherical WB-reinforced Co-based coatings (Co coating, Co + 15%WB coating, Co + 45%WB coating) were fabricated by laser-cladded technology. The microstructure and constituent phase of spherical WB-reinforced Co-based coatings were examined through scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). The low-temperature tribological properties were analyzed by coefficient of friction, 2D and 3D profiles across the wear track, and wear surface morphology, respectively. The results showed that the phases in the WB-reinforced Co-based coatings are mainly γ-Co, carbides Cr23C6 and Cr7C3, WB, and WO3. Under dry sliding friction at -20 °C, the more spherical WB, the lower the friction coefficient. The wear rate of Co + 45%WB coating was as low as 3.567 × 10-4 mm3/N·m-1, indicating the outstanding wear resistance. Abrasive wear was observed on the rough surface of the WB-added coatings. Compared with dry sliding, due to the plastic deformation of micro-convexes and lubrication function in the 3.5 wt.% NaCl solution, the wear tracks on the surfaces of the three tested coatings were shallower, exhibiting distinct elongated plough grooves.

Investigation of performance characteristics amid nano powder mixed electrical discharge micro-milling on Hastelloy C 276

Powder mixed electrical discharge micro-milling (EDMM) has been introduced as a novel variant of EDM operation, which can generate complex 3D micro features by CNC programming through the rotating micro-tool. It enhances the material removal rate (MRR), decreases the tool wear rate (TWR) and provides superior surface characteristics. The present work investigates the impact of powder concentration, gap voltage, and capacitance on the micro-hardness (MH), material removal rate (MRR), tool wear rate (TWR), surface roughness (SR), overcut (OC), taper angle (TA) and surface morphology during graphene nano powder added EDMM of Hastelloy C 276. The powder concentration of 0.25 g/L significantly enhanced the MRR and decreased the TWR, respectively. A drastic reduction in SR has been observed for 0.4 g/L concentration compared to plain dielectric. Lower OC and higher TA has been found for plain dielectric system. Field emission scanning electron microscopy (FESEM) is used in both cases to examine the surface morphology and recast layer of the milled micro-channels. The MH of the milled micro-channels is raised by 2.3 times at 0.4 g/L concentration. Energy-dispersive X-ray spectroscopy (EDS) confirms the migration of materials from the dielectric and graphene nano powder to the milled micro-channels on HC 276.

The aqueous corrosion and wear responses of HVOF-deposited TiC-Ni3Al, WC-Co, and WC-CoCr coatings on AISI 4130 steel substrates

In prior studies, TiC-Ni3Al cermets have shown an excellent combination of corrosion and wear resistance in comparison to WC-Co, while exhibiting <50 % of the mass. Consequently, it is attractive to assess these materials in coating form. The aqueous corrosion and wear performance of TiC-Ni3Al cermet coatings, deposited by high-velocity oxy-fuel (HVOF) thermal spray onto AISI 4130 steel substrates, is examined in the present work. Two powder feedstock formats were investigated. The first is a conventional agglomerated and sintered powder, which is then compared to a micro-composite powder feedstock fabricated via a novel gelation technology. The HVOF coatings were subsequently examined in terms of their microstructure, corrosion, and wear behaviours. The potentiodynamic polarisation responses of the cermet coatings were assessed in a simulated sea water environment (deaerated H2O with 3.5 wt% NaCl). The reciprocating sliding wear responses were also examined, against a WC-Co counter-face sphere. The post-corrosion and worn surface morphologies were subsequently investigated with optical microscopy, scanning electron microscopy, and associated energy dispersive X-ray analysis, with focused ion beam milling used to evaluate the wear track cross-sections. The TiC-Ni3Al HVOF sprayed cermet coatings demonstrate a combination of high wear and corrosion resistance in comparison to conventional WC-Co and WC-CoCr cermet coatings that were also HVOF deposited and tested under similar conditions.

Developing a steady state wear equation for AA7050 hybrid composites/steel interface at elevated temperature

ABSTRACT In this research work, an attempt was made to reinforce AA7050/5Gr composites with multi-walled carbon nanotube (MWCNT) of varying weight percentages processed through stir casting route. SEM with EDS mapping revealed that the particles were uniformly distributed over the composites. Hardness reduces with increasing MWCNT weight percentage owing to the inverse hall petch effect and increment in void content. A third-body abrasion, which happens when the CNT in the aluminium matrix material detaches from the surface and erodes material from the composites pin as well as the counter face, causes the wear resistance to rise with the addition of CNT particles. A mechanically mixed layer, which avoids direct metal-to-metal contact and thus increases wear resistance, was created at the abraded surface and at high temperature, where the reduction of wear rate was due to the development of oxide protective layer. A steady-state wear equation for the contacting surface at high temperature (R = 1/Y √(ln W/2X)) for AA7050 hybrid composites–steel interface was developed. The enhancement in wear resistance was directly proportional to the proportion of ferrous content present on the surface, which was confirmed on the elemental analysis. Pock marks, micropits, craters and cracks were the features observed on the worn surface morphology, whereas delamination and plasticisation were the observed modes of wear mechanism.

High-temperature wear mechanism of roller cone bit spiral seal

When drilling, the spiral seal of the roller cone bit and the journal are prone to collision and wear, and the friction heat and downhole high temperature will affect the wear process. The friction and wear experiments of the spiral seal material (20CrNiMo–40Cr) at different temperatures were carried out to study the wear mechanism of the spiral seal and journal of roller cone bit at high temperatures to determine the wear amount, friction coefficient and main wear forms. The wear model of friction pairs is established based on the Archard wear model and experimental results; The wear results at different temperatures are obtained by establishing the spiral seal structure model and simulation research of the roller cone bit. The results show that:(1) Through the friction and wear experiment of friction pair materials, the higher the temperature is the greater the wear amount and friction coefficient are. When the temperature exceeds 100 °C, the wear amount and friction coefficient begin to decline with the increase in temperature. By observing the wear surface morphology, abrasive and adhesive wears occur simultaneously, and the main wear form is adhesive wear under high-temperature conditions.(2) The maximum temperature rise caused by friction and the relationship between wear volume and time at different temperatures are obtained through the simulation of the spiral seal structure. Taking the groove depth value as the index to evaluate the sealing effect, the roller cone bit works in the temperature range (25 °C-400 °C), and high-temperature wear does not affect its sealing performance.

Evaluation of tribological process parameters of Al6061 + Nano Sic + Gr hybrid nano composites using Taguchi technique

This paper presents the optimization of tribological process parameter of Al 6061 aluminium alloy reinforced with nano SiC and graphite Gr particles using ultra cavitation method. Dry sliding wear test was performed with different process parameters like sliding distance; applied load, wt% of SiC and wt% of Gr using pin-on-disc and optimized by Taguchi L27 orthogonal array to predict the wear rate and coefficient of friction (COF). Analysis of Variance (ANOVA) and the interaction effect of the process parameters on the wear rate and coefficient of friction are investigated. It was observed that the wt % Gr contribute more influencing parameter for getting minimum wear rate followed by applied load and the wt % SiC contributes to obtain less coefficient friction. The wear surface morphology and wear mechanism of the hybrid nanocomposites were examined through atomic force microscopy(AFM)test.

Correlation between TiO2 nanotubes thickness and their tribocorrosion performance in simulated body fluid solution

Titanium dioxide nanotubes (TNTs) have been extensively researched for their enhanced biomedical characteristics, including biocompatibility, cell apposition, and growth morphology. However, there is a significant concern in metallic medical devices owing to micro-movements between implants and bone in aggressive environments due to wear and corrosion synergies, leading to adverse body responses and implant failure. In this study, TNTs on Commercially Pure titanium (C.P. Ti) with three different thickness layers were grown to correlate their corrosion and wear behavior. Initially amorphous after anodization, TNTs underwent annealing at 450 °C for 2 h to transform the distorted, into a crystalline structure. The characterization included X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX), X-ray Photoelectron Spectroscopy (XPS), and contact profilometry. Potentiodynamic polarization (PD) and tribocorrosion tests were conducted in Simulated Body Fluid Electrolyte (SBF). SEM micrographs showed TNT thickness layers of 314, 691, and 5280 nm, and X-ray Diffraction showed anatase transformation post-annealing. Results confirmed a significant influence of TNT thickness layers on corrosion and tribocorrosion properties, with higher current density obtained from PD for thicker TNTs layers, associated with surface fluorine content. During tribocorrosion, annealed samples demonstrated lower corrosion tendency, potential drop, and coefficient of friction. Morphology of worn surfaces and volumetric wear rate varied with TNT thickness layer and thermal treatment.