Papers by Keyword: Wear

Abstract: The plasma sprayed bronze coatings are widely used for repairing of plain bearing used in different applications. This type of coating was not deeply analyzed in state-of-art publications. In presented article we fill this gap in the case of plasma spraying process. The influence of power current (300/500/700A) and hydrogen flow (0/4/8 NLPM) on microstructure and thickness of aluminium bronze-polyester coating was investigated. The Thermico A60 plasma torch was used for thermal spray process of coating on flat carbon steel samples (grade S355). The Metco 604NS was sprayed with 20g/min powder feed rate. The obtained results showed the presence of local large pores formed by burning of polyester in plasma plume. This gap makes role of oil pockets in bearings. The obtained coatings were characterized by large deviation in thickness in range 200-350 micrometers. It might be concluded that in requires additional milling process after deposition.

Abstract: The composition, structure, and tribological characteristics at 20 °C and 500 °C of coatings obtained by the vacuum arc deposition method using a MAX phase Ti₂AlC based cathode were investigated. These characteristics were compared to those of titanium nitride coating. It was shown that at a potential of -50 V, a composite coating of TiC and Ti₃AlC phases forms. Meanwhile, at a potential of -100 V, a composite consisting of TiC and α-Ti is formed. At 20 °C, the friction coefficient and specific wear rate of these coatings in contact with a ball made of ShKh15 steel under a load of 2 N are comparable to those of TiN coating. At 500 °C, the wear resistance of the composite (TiC+α-Ti) coating is twice as high as that of TiN coatings. There was no clear correlation between microhardness and the tribological characteristics of the coatings.

Abstract: Siliconizing is one of the case-hardening processes used in the enhancement of some carbon-steel based material properties. Gears, rolling engineering parts, and pickling tanks produced with mild steel can offer better wear and hot-corrosion resistance characteristics through siliconizing. However, the cost of silicon hindered the wide usage of siliconized mild steel, which is the motivation for seeking remedy through processing of agro-waste materials. In this work, waste rice husk was used in the production of silicon nanoparticles using the sol-gel method. The silicon nanoparticles produced were used in the siliconizing of mild steel. The microstructure, hardness values, wear and corrosion tests were determined. The work shows that enhanced hardness values with improved corrosion and wear resistance were obtained when using waste rice husk to siliconize mild steel that can be used in the production of gears and storage tanks.

Abstract: A wear test was performed under the long-used machine oil sliding environment on Cu-based alloys Al-bronze and α-brass. A pin-on-disc wear testing method was applied where normal pressure of 0.255 to 2.55 MPa and a constant sliding speed of 0.641 m/s were considered. For the assessment dry and fresh machine oil sliding environments were also conducted. The results from the experiment demonstrated that the wear rate and friction coefficient in dry sliding condition were much greater for their direct contact but lower under machine oil due to the reduced roughness by the sealing effect as oil forms a thin lubricating film between the contact surfaces. Used oil displayed some degree of higher wear rate along with friction coefficient due to heavy and harmful chemical compounds in it. Al-bronze performed the better wear properties with lower wear rate and coefficient of friction for all the environments as it achieved the strength through different intermetallic formations. In case of α-brass, it had little effect on wear characteristics. Examined by optical microscopy and SEM analysis, worn surfaces showed that Al-bronze improved wear resistance through mild and smooth abrasive grooves filled with oxides in dry sliding conditions. In case of oil sliding environment, smooth surfaces were created by the resistance of the oil film to the direct contact between the surfaces. Used oil sliding conditions reduced the surface smoothness of the Cu and Cu-based alloys for the presence of damaging chemical compounds.

Abstract: This work addresses the challenges associated with the development of short neutral sections (SNS) for overhead lines of high-speed moving trains. A crucial function of a short neutral section is to provide electrical isolation between the different phases of AC traction. These sections are typically located in proximity to the traction substation and sectioning posts. The current SNS design presents several issues, including pantograph arcing, wear and tear of the overhead line system, and the need for manual rotation during periodic maintenance. To address these challenges TRIZ is used, a problem-solving methodology that leverages inventive principles to generate innovative solutions. The work outlines the use of several TRIZ tools and techniques, including the Interaction Matrix, Functional Analysis, Function-Body Diagram (FBD), Trimming, and the Contradiction Matrix [1]. With the application of these tools, the author presents several potential solutions for improving the SNS design to eliminate periodic maintenance and services. One proposed solution involves the use of a segmented overhead line system with an insulating cylinder-shaped discrete insulator to ensure smooth contact of the pantograph. Another solution involves the use of a twisted strip-based insulator to replace linear motion with rotating movement, eliminating the need for manual rotation. The work emphasizes the importance of considering various factors, such as design, material, wear rate, maintenance, and creepage distance, when evaluating the feasibility of these solutions. By leveraging TRIZ to generate innovative solutions, the author demonstrates the potential of this methodology to drive innovation and overcome complex challenges in the development of short neutral sections for high-speed rails.

Abstract: Tool wear is an important problem when cutting hard-to-cut materials such as stainless steel and nickel alloys. This unignorable disadvantage is caused by the diffusion of dissociated carbon atoms to the surface layer of the tool tip during the cutting process, and this has been confirmed by SEM/EDS analysis of worn tool tips. In this study, a novel cutting method is proposed in which chemically activated H₂O molecules are introduced to the cutting tool tip in order to prevent tool wear by removing dissociated carbon atoms on the surface layer of the tool tip. In cutting experiments, stainless steel X5CrNi 18-10 (JIS SUS304), a cemented carbide tool tip, cutting oil, steam, and Ar plasma were used. Ar plasma was used for raising the steam temperature around the tool tip and chemically activating H₂O molecules. From the results, the dissociated carbon and constituted knife edge were mostly removed by H₂O steam and cutting oil without Ar plasma. However, in some cases using Ar plasma, the workpiece melted and tightly adhered to the cutting face of the tool tip. This suggests that the H₂O steam temperature should be suitably controlled so as to remove carbon atoms effectively from the cutting face of the tool tip.

Abstract: Metals are prone to wear through the separation of wear debris particles as well as the plastic displacement of surface and near-surface material. Particle sizes range from millimetres to nanometres. Erosion is the gradual, layer-by-layer destruction of a metallic object's surface brought on by mechanical pressure or electrical discharges. Metals erode as a result of surface friction, wear, cavitation, and the influence of powerful gas or liquid currents on a surface. Jet engines, nuclear reactors, steam turbines, and boilers might all suffer damage from erosion. By enhancing process technology or unit design, using better materials, and applying heat treatment, it is possible to strengthen the resistance of components against erosion. AlSi10Mg is a hypoeutectic alloy that may be additively manufactured due to its limited solidification range, which reduces hot cracking susceptibility during cooling. Complex bulk and open-cell structures with outstanding strength ratio (strength-to-weight ratio) and good formability may be created using additive manufacturing of aluminium alloys, particularly AlSi10Mg. Carbon, manganese, sulphur, silicon, phosphorus, chromium, nickel, copper, and niobium are all present in the pH grade of 17-4. This combination of high strength and corrosion resistance benefits a 17-4 PH stainless steel grade. It may be utilised effectively in a variety of applications due to its high tensile strength and exceptional corrosion resistance.Powder bed fusion is one of the most mature metal additive methods, and as such, it benefits from decades of industrial expertise. PBF can satisfy demands of creating a new component and need to iterate on ideas quickly or are searching for a more efficient procedure to produce sophisticated components. Material waste is reduced because building the part layer by layer reduces the majority of the waste associated with subtractive manufacturing processes. Any surplus powder is collected and recycled when the item is finished. This review researches about the wear and erosion behaviour of Al-Si Alloy and steels printed using additive manufacturing methods. Finally, the findings of this review are summarised, and recommendations are made for future research aimed at resolving current issues and advancing technology.

Abstract: We aim at revealing the damage behavior of HAp sprayed coating on the surface of acetabular cup subjected to cyclic loading using AE (Acoustic Emission) method and IR (Infrared thermography) methods. Fatigue test was conducted in SBF(simulated body fluid), and the displacement of acetabular cup embedded in simulated bone was measured by two cantilever pairs. Acoustic emissions from delamination or wear of HAp coating were also measured by AE method, and the temperature change due to friction and wear near the top was measured by IR method. The analysed result could estimate the process in which delamination occurs in the initial stage of test and then friction and wear occur. The rotation displacement of acetabular cup could be associated with cracking or delamination of the HAp sprayed coating, friction and wear at the interfaces between simulated bone and acetabular cup. The subsidence displacement of acetabular cup can be caused by collapse of the simulated bone accompanied by an increase in AE energy as well as an increase in dissipated energy. Combined analyses using AE method and IR method clarified that the inelastic damages in simulated bone at the top of acetabular cups could lead the acceleration of both normal and rotational displacement of the acetabular cup whereas interface damages also attributed to exaggerate the displacement by deteriorated fixation.

Abstract: This project aims to investigate and compare the tribological properties of copper-based alloys produced by the die-casting method. Tribological properties, such as wear resistance and frictional behavior, play a crucial role in determining the suitability of materials for various engineering applications. Copper has many useful properties, such as high thermal and electrical conductivity, corrosion resistance, and antibacterial properties. It is used in a variety of industries, including electrical and electronics, construction, transportation, and healthcare. The study involves conducting wear tests on various copper-based alloys using a linear reciprocating tribometer. These tests were performed under different loading conditions (5N, 10N, and 15N), varied time durations (5 min, 15 min, and 30 min), Wear rates and morphologies of the specimens were determined by SEM. The effect of composition, microstructure, and hardness on the wear behavior of copper-based alloys has been carried out. The correlation between hardness and wear resistance was analyzed. The findings of this study could provide valuable information for the selection and optimization of copper-based alloys for trigolocal applications. The copper alloys has been characterized by an optical microscope, scanning electron microscope, and Energy dispersive X-ray analysis was used to analyze the wear surfaces.

Abstract: Austenitic stainless steels produced by Laser Powder Bed Fusion (L-PBF) are interesting materials because of their excellent corrosion resistance. Due to their relatively low hardness, the tribological response of these materials is poor, which limits their use in applications where control of wear degradation is important. Nevertheless, low-temperature plasma-assisted carburisation is an interesting process for improving the wear resistance of austenitic stainless steels, as has been observed for wrought materials. In fact, the increase in hardness is guaranteed by a surface layer of expanded austenite (S-phase) with a thin top layer of amorphous carbon. In this work, AISI 316 L, produced by the L-PBF technique, was carburised using 5 different plasma gas mixtures (by varying the CH4/H2 ratio) at 475°C for 7 hours. The samples obtained were then subjected to a detailed microstructural characterisation in order to obtain information on surface modification. The morphological features of the surface were examined by SEM observations in top view and in cross-section. The tribological performance was evaluated by pin-on-flat tests (alumina sphere as counter-material) with 2 different applied loads and a stroke length of 5 mm. Friction coefficient, wear rate (stylus profilometer) and wear mechanisms (SEM) were also evaluated. Preliminary results show an increase in wear resistance of all plasma treated materials compared to the untreated material. The improved tribological performance was discussed in relation to the abrupt increase in surface hardness.