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Photoluminescence of silicon vacancy centres as conceptual indicator for the condition of diamond protection coatings
摘要： Due to the outstanding properties polycrystalline diamond coatings are used for wear protection on tools and work pieces. Thereby adhesive and abrasive wear as well as spalling of the coating can lead to damage and downtimes of the working machines. By depositing silicon doped multilayer diamond coatings, an indication of the condition of the coatings could be achieved. In this study the behaviour and transmission of the zero-phonon line of silicon vacancy centres is investigated in doped multilayer diamond coatings. The in-situ silicon doped diamond coatings were synthesized in use of an atmospheric laser-based plasma chemical vapour deposition. Photoluminescence measurements were performed with an excitation area of 18 mm2 and a wavelength of 248 nm. While the photoluminescence of the doped layers conceptually proves suitability as an indicator for the condition of the coating, the undoped diamond layers in the coatings show a high transmissivity to the zero-phonon line for the used parameters.
关键词： Wear,Luminescent materials,Protective coating,Diamond films,Chemical vapour deposition
更新于2025-09-23 15:21:21
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Surface engineering of a titanium alloy for tribological applications by nanosecond-pulsed laser
摘要： In many applications, surface engineering is needed in order to overcome the poor wear properties of titanium alloys. A fiber laser was used in different operation modes for remelting a Ti6Al4V surface and subsequently smoothing it again, resulting in a smooth, glossy and crack-free surface. The laser treated surface was characterized by tribological experiments, nanoindentation and (transmission) electron microscopy and compared to samples treated by plasma nitridation and thermal oxidation. All surface treatments improved the tribological behavior of Ti6Al4V to different extents. Nanoindentation measurements showed no strict correlation of mechanical properties and tribological behavior. It is hypothesized that apart from mechanical properties, binding of titanium electrons by interstitials plays a role in the occurrence or absence of adhesive wear.
关键词： Titanium alloys,Surface engineering,Adhesive wear,Ti6Al4V
更新于2025-09-23 15:21:01
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Influence of Laser Energy Density on Acquisition and Wear Resistance of Bionic Semisolid Unit of 40Cr Steel
摘要： 40Cr steel is one of the most common materials for manufacturing brake camshaft of trailer. The brake camshaft is subjected to extreme wear during its service life. In order to enhance wear resistance, medium frequency induction hardening (MFIH) treatment is usually conducted on the surface of brake camshaft. However, conventional MFIH technique requires heating of the entire surface, which has the drawbacks of more power consumption, high production cost and easy deformation. Therefore, inspired by the bionic theory, a process named as ‘‘laser bionic semisolid treatment’’ method accompanied by favorable surface roughness and minimum distortion has been proposed herein as an alternative to MFIH method. By this means, bionic units with different surface roughness, sizes microstructure and hardness were manufactured on the surface of 40Cr steel. Then, the wear resistance of 40Cr steel with various laser energy densities was experimentally investigated. The results demonstrated that when the laser energy density was 18:00t3 (cid:2)3 J/ mm2, the bionic semisolid unit was obtained with the arithmetic mean surface roughness Ra of 1046.81 nm. Moreover, in the wear resistance of 40Cr steel due to the microstructure and higher hardness compared with the untreated sample, and its weight loss ratio was decreased by 71.90%. The mechanism of wear resistance enhancement was also discussed.
关键词： bionic semisolid unit,40Cr steel,wear resistance,laser energy density,surface roughness
更新于2025-09-23 15:21:01
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Microstructure and Wear Behaviour of SS420 Micron Layers on Tia??6Ala??4V Substrate Using Laser Cladding Process
摘要： Ti–6Al–4V is commonly used material in automobile, aerospace, biomedical and marine due to its excellent properties. However, their uses are reduced because their its poor tribological performance. In the current study, stainless steel 420 alloy powder was cladded on Ti–6Al–4V base material using high-power Yb: YAG disc laser. Then, the cladded surfaces were evaluated to reveal their new phase formation, hardness changes and improved wear properties. Besides, the various wear mechanisms and their corresponding rough averages were studied. Results showed that the microhardness of laser cladded specimen is 613HV while base material shows 303HV. The wear rate of laser cladded specimen reduces remarkably compared to un-clad specimen. The identi?ed major wear mechanisms are abrasive, adhesive and oxidation wear. The worn-out cladded surface shows lesser roughness than base material.
关键词： Wear mechanism,Microstructure,Ti–6Al–4V,Roughness,Laser cladding,SS420
更新于2025-09-23 15:19:57
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The restoration of the friction surfaces by laser cladding
摘要： The paper deals with laser cladding of wear-resistant coatings for restoring friction surfaces. It describes the modes of cladding technological process, and presents the results of wear tests. Wear-resistant coating based on the Ni-Cr-B-Si and alumina system, which exceeds 30HGSA steel by 11.5 times by wear resistance.
关键词： wear-resistant coatings,alumina,friction surfaces,Ni-Cr-B-Si,laser cladding
更新于2025-09-23 15:19:57
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[Laser Institute of America ICALEO?? 2017: 36th International Congress on Applications of Lasers & Electro-Optics - Atlanta, Georgia, USA (October 22a??26, 2017)] International Congress on Applications of Lasers & Electro-Optics - A composite stellite alloy hardfacing with improved laser cladding behavior and wear resistance
摘要： To solve the existing wear and corrosion problems in power generation industry, this research investigates the wear and corrosion behavior of Stellite alloys in NaOH solution, which simulates the amine media in the feedwater service of power generation plants. The Stellite alloys under this study include Stellite 6 and a composite Stellite alloy. The composite Stellite alloy hardfacing, which consists of 70% Stellite 3 and 30% Stellite 21, is created via laser cladding for control valve seat sealing surfaces, aiming at enhancing hardness and wear resistance, compared with Stellite 6 hardfacing, and improving cracking in laser cladding process, compared with Stellite 3. The composite Stellite alloy hardfacing is made on 316 stainless steel substrate and it does not show any cracking. The microstructure of the hardfacing is analyzed using SEM, EDS and XRD. The hardness, dry sliding wear resistance and cavitation-erosion resistance in NaOH solution are evaluated. Stellite 6 hardfacing is prepared with the same laser process parameters and is also analyzed and tested under the same conditions with the composite Stellite alloy hardfacing for comparison. The experimental results and real industrial test demonstrate superior performance of the composite Stellite alloy hardfacing to Stellite 6 hardfacing for control valve seat sealing application.
关键词： Cavitation-erosion,Hardfacing via laser cladding,Stellite alloy,Dry-sliding wear
更新于2025-09-23 15:19:57
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Study of the effect of surface laser texture on tribological properties of cemented carbide materials
摘要： Surface texturing has become a potential method to obtain a low friction coefficient under dry/lubricated conditions for different mechanical product surfaces. The mechanism of friction and wear reduction from a micro-texture on the surface of cemented carbide cutting tools was investigated by dry cutting a titanium alloy. Three kinds of micro-textures, namely, line, sinusoidal and rhombic grooves, with different area occupancy rates were produced by a laser on the cemented carbide surface. Experiments and finite element simulation of ABAQUS were used to investigate the tribological characteristics of micro-textured cemented carbide. The results indicated that the line-textured cemented carbide with an area occupancy rate of 10% showed a low friction coefficient of 0.076, which is approximately 34% of the non-textured sample. Few adhesives appeared on the textured surface, while a large number of adhesives were attached to the smooth surface after 30 min of dry friction between the cemented carbide and the titanium alloy balls. Moreover, among the three textures, the line-groove texture has the smallest friction coefficient and a good anti-wear effect. The results show that the existence of a groove texture can effectively reserve the wear debris, reduce the bond wear and weaken the furrow effect.
关键词： titanium alloy,friction and wear,Cemented carbide,machine tool and chip contact zone,surface texture
更新于2025-09-23 15:19:57
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Enhancing Hardness and Wear Performance of Laser Additive Manufactured Ti6Al4V Alloy Through Achieving Ultrafine Microstructure
摘要： Refining microstructure is an important issue for laser additive manufacturing (LAM) of titanium alloy. In the present work, the microstructures of LAM-fabricated Ti6Al4V alloy were refined using a low energy density with the combination of a small spot diameter, a low laser power, and a high scanning speed. The microstructure, hardness, wear performance, and molten pool thermal behavior of LAM-fabricated Ti6Al4V coatings were studied. The results show that the grain sizes of both prior β and α phases are strongly dependent on the cooling rate of the molten pool. The fine prior β grains and submicron-scale acicular α phases were obtained under a low energy density of 75 J mm?2 due to the high cooling rate of the molten pool. In addition, the as-fabricated Ti6Al4V sample with submicron-scale acicular α phase showed a very high hardness of 7.43 GPa, a high elastic modulus of 133.6 GPa, and a low coefficient of friction of 0.48. This work provides a good method for improving the microstructure and mechanical performance of LAM-fabricated Ti6Al4V alloy.
关键词： wear properties,hardness,laser additive manufacturing,titanium alloy,microstructure
更新于2025-09-23 15:19:57
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The Relationship between the Model of the Laser Biomimetic Strengthening of Gray Cast Iron and Matching between Different Brake Pads
摘要： When the surface of gray cast iron is subjected to laser irradiation and melted and then re-solidified, a material can be obtained that has a superior structure and properties to the base metal. On the surface of gray iron brake drums, the surface of the raw material can be processed into a bionic coupling surface with different shapes, structures, and soft and hard tissues similar to the surface of an organism. The wear resistance and fatigue resistance of brake drum surfaces can be greatly improved. However, the relative wear characteristics of the friction pairs in brake systems show that performance improvements in brake systems are the result of appropriately matching the brake drum and brake pad. This paper studies the wear relationship between three kinds of commonly-used brake pads (semi-metallic, organic asbestos-free, and ceramic) and different biomimetic models of brake drum samples. The interaction mechanism and failure mode between three kinds of brake pads and bionic samples were determined. According to the wear test results, the matching relationship between the brake pads and the brake drum was analyzed and determined, which provides a basis for the application of bionic brake drums.
关键词： biomimetic model,brake pads,laser melting,surface wear
更新于2025-09-23 15:19:57
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Editorial: Special Issue a??Laser-Induced Periodic Surface Nano- and Microstructures for Tribological Applicationsa??
摘要： Laser material processing is an innovative technology that generates surface functionalities on the basis of optical, mechanical, or chemical properties. In the form of laser surface texturing (LST), it has attracted a remarkable amount of research to tailor surface properties towards various tribological applications. Of this single-step, laser-based technology, the main advantages are the contactless machining, featuring a high flexibility, efficiency, and speed, along with the excellent quality of the processed products. LST can be applied precisely, localized to sub-micrometric areas, but, via laser beam scanning, it is also feasible for structuring large surface areas the size of square-meters.
关键词： microstructure,wear,laser-induced periodic surface structures (LIPSS),lubricant,applications,friction,tribology,nanostructure
更新于2025-09-23 15:19:57