Wear Resistance Of Components Research Articles

Effect of Porosity on Tribological Properties of Medical-Grade 316L Stainless Steel Manufactured by Laser-Based Powder Bed Fusion

The potential of laser-based powder bed fusion (L-PBF) technology for producing functional components relies on its capability of maintaining or even improving the mechanical properties of the processed material. This improvement is associated with the microstructure resulting from the high thermal gradient and fast cooling rate. However, this microstructural advantage may be counterbalanced by the lack of full density, which could be tolerated to a certain degree for applications such as biomedical implants and medical equipment. In this study, medical-grade 316L stainless steel specimens with porosities ranging from 1.7 to 9.1% were additively manufactured by L-PBF using different combinations of laser power and scanning speeds. Tribological properties were evaluated by pin-on-disc testing in dry conditions against a silicon nitride test body and analyzed in the context of microstructural characterization by optical and electron microscopy. The results reveal that higher porosity allows for a diminishing wear rate, which is explained by the capacity of the pores to retain wear debris related with the three-body abrasion. This research provides practical insights into the design of medical wear-resistant components, thereby enhancing our understanding of the potential of L-PBF in the fields of materials science and biomedical engineering.

Tribological performance of 410L martensitic stainless steel parts manufactured by Laser directed energy deposition

The processing of AISI 410L martensitic stainless steel (MSS) by laser directed energy deposition (L-DED) for additive manufacturing (AM) of wear-resistant components is an alternative to the high C-content MSS grade, with difficult processability. This work assesses the tribological performance of low C-content 410L MSS additively manufactured by L-DED. Two sets of L-DED parameters were investigated, one targeting Production and high deposition rates, and the other for Resolution and increased geometric freedom. Half of the multilayer samples were subjected to a post heat-treatment route. Samples were evaluated by the dry-sliding linearly reciprocating ball-on-flat tribological test (ASTM G133) in the as-built and heat-treated states. Commercially annealed 410 MSS was the reference material. In the L-DED as-built, microstructures were composed of ferrite with martensite at the grain boundaries. Heat-treatment provides recrystallization, martensite tempering, and hardness decrease. The more refined microstructure of L-DED resolution as-built led to greater hardness and lower wear coefficient in the ASTM G133 test. Wear tracks revealed wider bands of compact tribolayers on its surface, which reduced the action of adhesive and abrasive mechanisms. The other L-DED as-built and heat-treated conditions, and 410 reference material demonstrated a large amount of free debris, indicating lower wear resistance.

Giant cell interstitial pneumonia: case series with comprehensive ultrastructural analyses of "not only" hard metal pneumoconiosis.

Giant cell interstitial pneumonia (GIP) is a fibrosing lung disease histologically characterized by centrilobular pulmonary fibrosis and cannibalistic intra-alveolar multinucleated giant cells. It is considered a form of pneumoconiosis caused particularly by secondary exposure to hard metals (cemented carbide or tungsten carbide). Hard metals are commonly used in various industrial applications, such as cutting tools, drilling tools, machine inserts, and other wear-resistant components. However, cases with unknown exposure that recurred in transplanted lungs have been described. This has led to the hypothesis of a complex etiopathogenesis, likely multifactorial, involving the coparticipation of immune mechanisms. We aimed to identify all the elements present in a series of GIP lung samples to better understand the pathogenic mechanisms of the disease. We describe five cases of histologically diagnosed GIP in patients with occupational exposure to metallic dust using ultrastructural characterization to identify metal dust and to quantify asbestos fibres. We found that tungsten was present in three cases, albeit in trace amounts in two of them. Numerous elements were identified in all samples, including asbestos fibres in patients with endstage pulmonary fibrosis. Furthermore, in one of the described cases the recurrence of the disease was also observed in transplanted lungs. These findings support the hypothesis that GIP may be due to elements other than hard metals, with asbestos possibly representing a contributory factor in the expression of a more severe fibrotic disease. The recurrence of GIP observed in transplanted organs strengthens the hypothesis of the existence of a not yet fully understood etiopathogenic immune mechanism.

Effect of varying carbon content on microstructure and mechanical properties of (Ti,Ta,Nb,Zr,Mo)C-Co high-entropy ceramic based cermets

The effects of carbon content on microstructure and mechanical properties of the (TiTaNbZrMo)C-Co cermets were investigated in details. Uniform high-entropy carbide powders with different carbon contents were obtained through carbothermal reduction and mixed with a Co binder phase via ball milling for fabricating cermets at the elevated temperature. The increased carbon content makes the hardness of cermets initially rose and then decreased, while the fracture toughness demonstrates an overall decline. Among all high-entropy ceramic based cermets, (TiTaNbZrMo)C0.9-Co cermet (C1) exhibited the optimal combination of hardness and fracture toughness properties, with a Vickers hardness (HV30) of 15.83 GPa and a fracture toughness of 7.74 MPa m1/2. Furthermore, the presence of graphite phases accompanied by the excess carbon content could enhance the wear resistance of cermets. (Ti,Ta,Nb,Zr,Mo)C-Co high-entropy ceramic based cermets have potential applications in the fields of cutting tools and wear-resistant components.

Impact of laser energy density on the structure and properties of laser-deposited Fe‒Ni‒Ti composite coatings

To utilise laser deposition for the preparation of high-strength, wear-resistant components, the service life of components in rail transportation equipment should be improved. Laser deposition technology is used to fabricate Fe‒Ni‒Ti coatings on the surface of AISI 1045 steel substrates. By varying the laser power to adjust the laser energy density, Fe‒Ni‒Ti composite coatings are prepared at various energy densities. The morphology, microstructure, phase composition, tensile strength, microhardness, and friction-wear characteristics of the composite coatings are observed and tested. The influence patterns and mechanisms of laser energy density on the organisational variation and friction-wear performance of composite coatings is investigated. When the laser energy density is 97.2 J/mm2 (1400 W), the residual stresses in the deposition layer are minimised, resulting in fewer cracks and gas pore defects, with a porosity rate reaching its lowest value of 1.2% and a density of 99.1%. With the increase in energy density, both the tensile strength and elongation of the deposited layer exhibited an initial increase followed by a decrease. The hardness and wear resistance of Fe‒Ni‒Ti deposition layers is effectively controlled by regulating the laser energy density.

Characterization of Cr-TiB2 composite coating on AISI 1045 steel using hybrid deep neural network-based sandpiper optimization algorithm

The scope of this study is to enhance the performance of AISI 1045 steel for demanding marine applications like connecting rods, axles, and wear-resistant components. Traditional heat treatment methods, including boriding, surface induction hardening, and tempering, improve the steel’s surface hardness. Additionally, the Tungsten Inert Gas (TIG) coating process develops a novel Cr- TiB2 composite coating on the heat-treated AISI 1045 stainless steel. The investigation explores the influence of varying TiB2 content (10%, 20%, and 30%) on the mechanical properties of AISI 1045 steel. Microhardness and tensile characteristics are analyzed, considering the impact of TiB2 percentage. Surface morphology and interfacial bonding are examined using Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray Analysis (EDAX). Results reveal notable improvements, including a 2.65 times increase in microhardness compared to untreated AISI 1045 steel, uniform TiB2 distribution, and a crack-free coating. The addition of TiB2 particles in the Cr- TiB2 composite coating enhances microhardness. Improved mechanical properties are attributed to surface treatments, incorporation of hard and wear-resistant materials (Cr and TiB2) in the composite coating, microstructure modifications, and crack prevention, collectively resulting in increased hardness, wear resistance, and durability. Furthermore, this study introduces a novel hybrid Deep Neural Network-based Sandpiper Optimization Algorithm (DNN-SOA) for predicting experimental outcomes with superior accuracy. This research not only enhances the understanding of the coated steel’s mechanical properties but also presents an innovative predictive model for future material engineering applications, demonstrating the significance of advanced heat treatment and a novel composite coating in improving AISI 1045 steel performance.

Temperature-induced wear micro-mechanism transition in additively deposited nickel alloys with different solid lubricants

Additive manufacturing of self-lubricating alloys plays a crucial role in the production of complex wear-resistant components and in expanding repair capabilities, especially for intricate wear parts with low tolerances (e.g. with cooling channels). Herein, we report a novel approach providing nickel-based alloy with an excellent tribological performance in dry sliding contacts. Laser-deposited self-lubricating nickel alloys, infused with anti-wear additives of molybdenum disulfide, nickel sulfide, copper sulfide, or bismuth sulfide, were subjected to dry sliding wear tests against an alumina ball counterbody at a temperature range of up to 800 °C. The self-lubricating alloys exhibited a significant decline in friction (43 %) and wear (45 %) at room temperature, 400 °C (friction 40 %, wear rate 55 %), and 600 °C (MoS2-based, friction 58 %, wear rate 75 %). The MoS2-based alloy coating demonstrated excellent performance characteristics up to 800 °C (friction coefficient ⁓0.25, wear rate 11 × 10−6 mm3 N−1 m−1) due to the formation of a ‘glazed’ tribolayer. Wear mapping allowed to identification of a critical condition for self-lubricating alloys where positive transitions in wear mechanisms led to a synergistic lubrication mode involving the formation of tribologically induced new lubricious phases such as silver molybdate or nickel-bismuth intermetallic. This work provides a comparative evaluation of the micromechanisms, surface transitions, and tribochemistry of solid lubricants at a wide temperature range and a variety of applications.

Surface Integrity of Binderless WC Using Dry Electrical Discharge Assisted Grinding

AbstractBinderless tungsten carbide (WC) is preferred for manufacturing tools, mould, and wear-resistant components. However, due to its high brittleness and hardness, the machined binderless WC surface is prone to generate microcracks and the machining efficiency is extremely low. Aiming at this difficulty, a clean and eco-friendly dry electrical discharge assisted grinding (DEDAG) method without any liquid medium was proposed for the processing of binderless WC. DEDAG principle was revealed and the DEDAG platform was first developed. A series of DEDAG, conventional dry grinding (CDG), and conventional wet grinding (CWG) experiments were conducted on binderless WC under different processing parameters. The current and voltage waveforms during the DEDAG process were observed, and the discharge properties were analyzed. The chip morphologies, surface hardness, residual stress, as well as surface and subsurface morphologies were analyzed. The results show that the surface hardness and roughness obtained by DEDAG are smaller than that by CDG or CWG. The measured residual tensile stress after CDG is larger against DEDAG. The ground surface by DEDAG has better crystal integrity than that by CDG. DEDAG can soften/melt workpiece material and diminish grinding chips, thereby promoting plastic removal and increasing processing efficiency. The influences of DEDAG parameters on the ground surface quality are also investigated, and the optimal DEDAG parameters are determined. With the increase of open-circuit voltage or grinding depth, the surface quality improves first and then worsens. The optimal open-circuit voltage is 40 V and the grinding depth ranges from 10 µm to 15 µm. This research provides a new idea for promoting the efficient and low-damage processing of binderless WC.

Additive manufacturing-assisted sintering: Low pressure, low temperature spark plasma sintering of tungsten carbide complex shapes

Tungsten carbide (WC), renowned for its exceptional hardness and wear resistance, plays an essential role in various industrial applications (cutting tools, abrasives, and wear-resistant components). While traditional methods involve hot pressing, Spark Plasma Sintering (SPS) combined with Additive Manufacturing (AM) offers a cutting-edge approach, utilizing high-voltage electric current and mechanical pressure for rapid densification, particularly advantageous for fabrication of complex shape components made from challenging materials like nanosized binderless tungsten carbide. The study encompasses the entire spectrum of the powder's characterization, extending to the development of an intricate finite element simulation tailored for SPS sintering. Sintering cycles underscore the exceptional quality of the powder, demonstrating full density microstructures even under low-temperature (1550 °C) and low-pressure (50 MPa) conditions. The nanosized powder exhibits minimal microstructural coarsening, reflecting the high quality of the initial pure tungsten carbide nano powder. The core of this study revolves around the methodology employed for deriving constitutive parameters, following the Skorohod-Olevsky theory of continuum sintering. The derivation methods include variations in temperature, heating regimes, and stepwise pressure application during SPS. Additionally, a grain growth model is formulated based on microstructural analysis. Critical parameters, including the apparent sintering activation energy (800 kJ/mol) and the creep law stress exponent (n = 4.0), are discussed. The article concludes with the integration of the mechanical sintering model into finite element method (FEM) software, considering thermal and electrical aspects for a comprehensive SPS-AM modeling approach and its application to complex shape production. The research aims to enhance the understanding of SPS for tungsten carbide, providing insights for its application in manufacturing cutting-edge components in challenging environments.

A new wear-resistant component system of copper-based composite materials: Modified sepiolite-complex ceramic powder

To balance mechanical strength, friction stability, and low wear, a novel wear-resistant component system: modified sepiolite-complex ceramic powder, was employed in copper-based composite materials, leading to the successful preparation of samples with outstanding mechanical and frictional performance. The material exhibits high friction stability, low wear, and the simultaneous occurrence of a high friction coefficient, which may be caused by uniquely composed dual friction film. The external layer of the friction film consists of Cu2O, Fe2O3, and CaO metal-films, while the internal layer consists of B2O3 film, graphite, and sepiolite. Additionally, modified sepiolite (composed of sepiolite, CaCO3 and enstatite) plays a dual role in wear resistance and high-temperature lubrication. Furthermore, the Gradient Boosting Decision Tree (Gbdt) model was found to provide more meaningful guidance for predicting friction coefficients.

Characterization of surface properties of TiC ceramic coating developed on AISI 1020 steel

The aim of this research was to develop the TiC ceramic coating on the AISI 1020 steel substrate by a tungsten inert gas cladding (TIG) process and to comprehensively assess the surface properties of deposited TiC coatings. Various TIG currents were employed to deposit the TiC coating. The study included a detailed investigation of the two pivotal aspects: wear rate and microhardness. Additionally, a comprehensive examination of the microstructure and the presence of different phases in the coating layers was done. TiC ceramics were found to be dispersed remarkably and uniformly over the whole coating region, as revealed by scanning electron microscopy (SEM) examinations. Additionally, it was noted that neither the coating area nor the interfacial areas included any harmful flaws like voids or cracks. The results of this experiment clearly showed that the processing current and the subsequent wear resistance and microhardness were directly correlated. In particular, it was shown that wear resistance and microhardness both showed a noticeable increase when the processing current decreased. The coating developed at lower proceeding current 80 A found the most remarkable results, achieving a peak microhardness of 2846 HV0.1 and an impressively low wear rate of only 10.96 × 10−8 g/Nm. These extraordinary results can be directly attributable to the hard TiC phase's significant presence inside the coatings layer. Due to its improved wear behaviour and microhardness as compared to untreated mild steel, pure TiC-coated AISI 1020 steel finds a suitable material for application in wear-resistance components where hardness is considered as a crucial factor. The TiC coating has achieved an exceptionally high friction coefficient, making it particularly valuable for applications within the automobile industry.

Mechanical property analysis and dry sand three-body abrasive wear behaviour of AZ31/ZrO2 composites produced by stir casting

An experimental study of three body abrasive wear behaviour of AZ31/15 vol.% Zirconium dioxide (ZrO2) reinforced composites prepared by stir casting has been carried out. Microstructural analysis of the developed composites was carried out and found out that the microstructure of the composites revealed a uniform distribution of ZrO2 particles with refinement in the grain size of the matrix from 70 to 20 µm. The alterations in the microstructure led to an enhancement in both hardness (68–104 HV) and tensile strength (156–236 MPa) due to Orowan strengthening, quench hardening effect and better bonding. Response surface methodology was applied to formulate the three-body abrasive wear test characteristics such as load, speed, and time. Three body abrasive test results were utilized to generate surface graphs for different combinations of wear test parameters revealed an increase in specific wear rate. The specific wear rate was observed to increase with increase in speed up to a certain level and then started to decrease. The lowest possible specific wear rate was obtained for an optimized load of 20 N and a speed of 190 ms−1. Scanning electron microscopic examination of wear-tested samples showed higher specific wear rate at higher loads with predominantly abrasion type material removal. In conclusion, this study makes a substantial contribution to the field by elucidating the complex relationships among microstructure, mechanical properties, and the three-body abrasive wear behavior of AZ31/ZrO2 composites. The determination of optimal wear conditions and the insights gained into wear mechanisms provide valuable information for designing materials, implementing engineering solutions, and advancing the creation of wear-resistant components across a range of industries.

New strategies based on liquid phase sintering for manufacturing of diamond impregnated bits

Infiltration is an extensively used technique in the production of Diamond Impregnated Bits (DIBs) commonly used for drilling in both mineral exploration and the Oil&Gas industry. This paper describes research into liquid phase sintering (LPS) as an alternative to commonly used infiltration processes. The great wear resistance and high cutting ability necessary for these tools in turn requires a high diamond concentration and a large volume fraction of wear-resistant components, such as tungsten carbide and/or eutectic tungsten carbide particles. With relatively large particles that do not contribute to densification, the LPS system researched was designed with a relatively large amount of permanent liquid phase sintering, with, rearrangement being selected as the primary densification mechanism owing to the stability of the hard phases. After testing various binder phases and evaluating the influence of the liquid phase volume fraction and presence of some sintering aids, results are promising. Bonds with better sintering behaviour were characterized, while hardness, microstructure, abrasive wear resistance, and interaction with diamonds were studied. The proposed 35NiP25Cu40WC bond processed by LPS attained hardness of 66 HRA and wear coefficient of 20 mm3/MPa, levels similar to those obtained by hot pressed components currently used in the diamond drilling tool industry (19 mm3/MPa).

Effect of graphene on the microstructure, thermal conductivity, and tribological behavior of cast B319 Al alloy

In this research, the effect of adding 0.1 – 0.7 wt% of graphene on the microstructure, hardness, thermal conductivity, and tribological response of cast B319 Al alloy was investigated. Addition of 0.1 wt% graphene increased the hardness of cast B319 alloy from 77 to 92 HV, which was the result of grain refinement and the modification of the Si phase. At 0.3 wt% graphene, the composite achieved optimal wear resistance, as the average coefficient of friction (CoF) decreased from 0.42 to 0.20, a ∼52% reduction with respect to the base B319 alloy. Similarly, the average wear volume and specific wear rate of 0.3 wt% graphene composite showed a ∼36% (measured by weight loss) and ∼32% (measured by the laser microscopy) reduction compared to the base alloy. The improved wear resistance of the composite was attributed to its higher hardness caused by microstructural refinement, high stability of the mechanically mixed layer (MML), and the formation of a graphene-rich lubricating layer on the contact surfaces. The results obtained from this study on B319-graphene composites could pave the way for developing lightweight and high-performance wear-resistant components for next-generation automotive applications.

Microstructure evolution and strengthening mechanism of carbides-reinforced Co–Cr–Nb–W alloy under high-temperature stress-rupture

A novel Co–Cr–Nb–W alloy with a carbide-dominant microstructure was designed in view of the excellent characteristics of NbC and γ-Co matrix to use as wear-resistant components on integral shrouds. The actual service conditions of the alloy were simulated using heat treatment experiments to investigate the influence of high temperature on their microstructure and mechanical properties. The stress-rupture property of the alloy was improved by exposing them to high temperatures. Carbides in the matrix bore the main load under external stress. The fracture mechanism of the Co–Cr–Nb–W alloy is ductile combined with localized brittle failure around large carbides. M6C was formed from the degeneration of MC and decomposition of M23C6 during the heat treatment process along with the two carbides transformation as follows: MC + matrix → M6C and M23C6 + matrix → M6C. The elimination of lamellar M23C6 by carbide transformation and supplemental precipitation of fine M6C around skeleton MC were conducive to longer rupture life. Stacking faults (SFs) played a crucial role in the strengthening mechanism of the Co–Cr–Nb–W alloy. The external stress activated different slip planes in the γ matrix to form “X-shaped” crossing stacking faults (CSFs). Lomer-Cottrell (L–C) locks in CSFs were confirmed by transmission electron microscopy (TEM) under two-beam conditions. SFs can interact with precipitates, dislocations, and grain boundaries to enhance the strengthening mechanism. The SF width was increased by heat treatment, which further increased the dislocation accumulation in the matrix and promoted the formation of CSFs and L–C locks. Therefore, the heat treatments were beneficial to the enhancement of the stress-rupture property of the Co–Cr–Nb–W alloy.

Effect of cobalt addition on wear behaviour of TiB2 coating produced by TIG cladding process

In this paper, the mechanical and tribological characteristics of TiB2 ceramic coating with and without cobalt (Co) addition developed using tungsten inert gas (TIG) cladding process on AISI 304 stainless steel (SS) were investigated. The effect of TIG process conditions as well as cobalt (Co) content on the microstructure, microhardness and resistance to wear were investigated systematically. The phase identification, microstructure, and elemental distribution map of the clad layer formed on the surface of an AISI 304SS substrate were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS), respectively. Vickers microhardness testing apparatus and a pin-on-disc tribometer were used to evaluate the microhardness, resistance to wear, and coefficient of friction (COF), respectively. The result demonstrates that a dense and defect-free composite coating with a strong metallurgical bond to the substrate is possible. The average microhardness of the TiB2 ceramic coating without Co addition was 1704 HV, and the average wear rate was 15.1576 × 10−9 g N−1-m−1. In contrast, the TiB2 ceramic coating with Co addition exhibited an improved average microhardness of 1860 HV and a reduced average wear rate of 22.7364 × 10−9 g N−1-m−1, while the AISI 304SS substrate had an average microhardness of 216 HV and an average wear rate of 200.45×10−9 g N−1-m−1. The conclusion is that the TiB2 ceramic coating with Co addition exhibited superior mechanical and tribological characteristics, demonstrating its suitability for use in wear-resistant components. The higher microhardness of the TiB2 ceramic with Co-added coating indicates enhanced hardness and potential resistance to deformation, while the lower wear rate suggests improved durability and the ability to withstand frictional forces. Therefore, the TiB2 ceramic coating with Co addition shows promise for applications where wear resistance is crucial.

Mechanical properties of binderless tungsten carbide enhanced via the addition of ZrO2-20 wt% Al2O3 composite powder and graphene nanosheets

As an alternative to conventional tungsten carbide materials, binerless tungsten carbide (BTC) can be used in a variety of applications, such as high-speed cutting tools, rock drilling and extraction, and wear-resistant components. The absence of the metallic bonding phases solves the problems of oxidative corrosion and softening of the material during high-speed cutting process. However, the fabrication of high strength and toughness BTC ceramics remains a huge challenge. In this paper, ZrO2-20 wt% Al2O3 composite powder and graphene nanoplatelets (GNPs) were used as the reinforced phases to fabricate high performance BTC ceramics. The influence of GNPs contents on the densification, microstructure and mechanical properties of oscillatory pressure sintered BTC ceramics with 8 wt% composite powder was evaluated. The synergistic effect of ZrO2-20 wt% Al2O3 composite powder and GNPs exerted a critical role on the densification process and microstructural evolution. The produced BTC ceramics had the densest microstructure and optimal mechanical characteristics when the GNPs content reached up to 0.2 wt%; the flexural strength, Vickers hardness, fracture toughness and relative density were up to 1480 MPa, 23.72 GPa, 8.68 MPa·m1/2 and 99.8%, respectively.

Impact of Sintering Temperature of the Mechanical Properties of a Fe20Cr20Mn20Ni20Ti10Co5V5 Medium Entropy Alloy

Medium entropy alloys (MEAs) are new emerging engineering alloys comprising four principal elements characterised by a low enthalpy of mixing and entropies of formation between 1 and 1.5 molar gas constant. They have high strength, wear, and thermal properties. MEAs have generated interest as an alternative material in the last two decades in nuclear, aerospace, and high strength engineering applications. In this research a medium entropy alloy Fe20Cr20Mn20Ni20Ti10Co5V5 with principal elements Fe, Cr, Mn, and Ni was fabricated using spark plasma sintering. Elemental powder mixture was sintered at temperatures of 870oC, 900oC and 950oC under 35 bar pressure under an inert argon atmosphere for 45 minutes using an FCT Systeme GmbH spark plasma sintering machine. After sand blasting the densities of the samples were measured before grinding, polishing, and etching for characterisation. Microstructure analysis was carried using scanning electron and optical microscopy. Microhardness was measured using Falcon 507 hardness tester, modulus using by Anton-Paar Nanoindenter and wear using Anton-Paar TRB3 Tribometer. The elements form a solid solution with presence of a hard μ phase and soft γ-phase were observed. The hardness of the alloys sintered at 870oC and 900oC were 397 and 424 Vickers respectively. The alloy sintered at 950oC showed a hardness of 674 Vickers. After annealing the hardness increased to 736 Vickers. The modulus of elasticity and creep resistance increased after heat treatment at 700oC.The other alloys showed a decrease in hardness and other properties after annealing. Unlike in steels, where annealing reduces, in this alloy annealing increased hardness at an appropriate temperature. Fe20Cr20Mn20Ni20Ti10Co5V5 MEA exhibited good thermal stability. Further work on the alloy will involve its crystallography, and feasibility for use elevated temperature energy applications such as fuel cells, turbines and wear resistant machine components.

Study on Mechanical, Wear and Thermal Properties of AL2O3/Graphite Reinforced AA2024 Aluminum Alloy Based Metal Matrix Composites

Abstract: Metal matrix composites (MMC) play a vital role to satisfy global needs for low low-cost and high-performance mechanical, and thermal properties and quality materials in the composite industry.Aluminium MMCs are preferred to other conventional materials in the fields of aerospace, automotive and marine applications owing to theirimproved propertieslike high strength-to-weightratio, good wear resistance, etc. In the present work, an attempt has been made to synthesize metalmatrix composite using AA2024 as matrix material reinforced with Al2O3 and Graphite (Gr) particulates using a liquid metallurgy route in particularstir casting technique. 2024 aluminium alloyis reinforced by different weight fractions of Al2O3 and Gr particles up to 5 wt%. The effect of wt% of Al2O3 and Gr on the properties such as density, hardness, tensile strength, wear rate, flexural strength, and coefficient of thermal expansion were evaluated. Scanning electron microscope and X-ray Diffraction (XRD) were used to examine the microstructure of the produced hybrid MMC composite. The addition of Al2O3 and Gr pronounced improved mechanical properties and wear. Results indicated that aluminium ceramic composites can be considered as an alternate material for AA2024, where high strength and wear-resistant components are of major importance,particularly in the aerospace and automotive engineering sectors.

Corrosion Behaviour of Cemented Carbides with Co- and Ni-Alloy Binders in the Presence of Abrasion

More and more often, cemented carbides are employed for the production of wear resistant components and have to face highly demanding service conditions that combine different damage mechanisms. A key example is the range of tetraphasic (sea water, sand, liquid and gaseous hydrocarbons) flows encountered in the Oil and Gas extraction industry. Notwithstanding the importance of operating regimes of this type, the availability of fundamental and quantitative information on the corrosion performance of cemented carbides in the presence of abrasion is still limited. In this paper, we report a systematic study of the corrosion behaviour of cemented tungsten carbide grades with binders containing different amounts of cobalt (Co), nickel (Ni), chromium (Cr) and noble metal additions, subjected to controlled mechanical abrasion, impacting the stability and nature of pseudopassivation films. In this work, special attention is devoted to Cr, a classical of additive that inhibits the Ostwald ripening of tungsten carbide (WC) particles and notably improves the corrosion resistance of grades with ultrafine-to-fine WC grain size and low-to-medium binder content. We assessed the impact of binder composition on the anodic behaviour by means of linear-sweep voltammetry and chronopotentiometry as well as on the mechanical properties. The application of controlled abrasion conditions under electrochemical control is carried out with an in-house modified ASTM B611 apparatus, equipped with a three-electrode system, enabling the systematic investigation of the synergy of electrochemical and mechanical damaging conditions. Increased corrosion resistance in environments without and with added chloride—both in the absence and in the presence of abrasion—was observed in all the Co- and Ni-based grades to which growing quantities of Cr were added. Moreover, doping with ruthenium (Ru) further enhances corrosion resistance. Regarding corrosion in the presence of abrasion, the addition of Cr and Ru increases the ability of regenerating the pseudopassivation film. The optimized compositions of the binder have been highlighted that open up attractive opportunities of improved service behaviour and deployment in new applications.