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High temperature wear performance of laser cladding Co06 coating on high-speed train brake disc
摘要： Abnormal wear sometimes occurs on the high speed train brake disc surface in winter time. In this paper, Co-based alloy powders were deposited by laser cladding technology to improve the wear resistance of train brake discs. Sliding wear at room temperature, 200℃, 400℃ and 600℃ were conducted to investigate the wear behavior. Microstructure, hardness, and phase composition of Co06 cladding layers were also studied. The results showed that Co06 cladding layer exhibited better wear resistance than the substrate, with different wear mechanisms at high temperatures. Co06 cladding layers also exhibited better high temperature oxidation resistance than the substrate. Cr23C6 played a significant role in anti-friction.
关键词： high temperature wear behavior,laser cladding,high speed train,brake disc
更新于2025-11-28 14:24:20
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Wear and Corrosion Resistance of Al0.5CoCrCuFeNi High-Entropy Alloy Coating Deposited on AZ91D Magnesium Alloy by Laser Cladding
摘要： In order to improve the wear and corrosion resistance of an AZ91D magnesium alloy substrate, an Al0.5CoCrCuFeNi high-entropy alloy coating was successfully prepared on an AZ91D magnesium alloy surface by laser cladding using mixed elemental powders. Optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction were used to characterize the microstructure of the coating. The wear resistance and corrosion resistance of the coating were evaluated by dry sliding wear and potentiodynamic polarization curve test methods, respectively. The results show that the coating was composed of a simple FCC solid solution phase with a microhardness about 3.7 times higher than that of the AZ91D matrix and even higher than that of the same high-entropy alloy prepared by an arc melting method. The coating had better wear resistance than the AZ91D matrix, and the wear rate was about 2.5 times lower than that of the AZ91D matrix. Moreover, the main wear mechanisms of the coating and the AZ91D matrix were different. The former was abrasive wear and the latter was adhesive wear. The corrosion resistance of the coating was also better than that of the AZ91D matrix because the corrosion potential of the former was more positive and the corrosion current was smaller.
关键词： laser cladding,wear,AZ91D magnesium alloy,high-entropy alloy coating,corrosion
更新于2025-11-21 11:24:58
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Microstructure and Wear Resistance of 62Cu-38Zn Brass with Bionic Coupling Units Treated by Laser Cladding
摘要： In order to improve the wear resistance of 62Cu-38Zn brass, bionic coupling units were fabricated by laser cladding using Ni-based, Fe-based and Co-based self-fluxing alloy powders. The microstructures, chemical composition and mechanical properties of the units were studied in this paper. Wear resistance of samples was examined by dry sliding wear. Good metallurgical bonding between the unit and substrate was obtained, and fine dendritic microstructure was resulted in the unit zone, which proved marked availability of laser cladding on brass. Laser cladding treatments with different self-fluxing alloy powders were beneficial to reinforcing the surface of brass and then improved its wear resistance with various results. The Ni-based alloy powders led to the best wear resistance amongst the all samples.
关键词： wear resistance,laser cladding,bionic coupling units,microstructure,62Cu-38Zn brass
更新于2025-11-21 11:18:25
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Effects of three-dimensional vibration on laser cladding of SS316L alloy
摘要： As a widely used approach for surface modi?cation, laser cladding plays a signi?cant role in surface hardening and repairing of metallic parts. However, the defects existing in laser cladding parts, such as cracks, tensile residual stress, and pores, signi?cantly a?ect the performance and the application of the cladding parts. In this study, an SS316L layer was fabricated on a 45 steel substrate using a laser cladding process assisted by three-dimensional vibration. The microstructures and the properties of the coating and the bonding interface with various vibration parameters were analyzed and compared. The microstructures of the cladding layer and the matrix were analyzed by an optical microscope and a scanning electron microscope. The results show that the three-dimensional vibration is able to re?ne the columnar dendrites in the cladding layer. The oscillation accelerates both the liquid ?ow and the thermal transfer of the molten pool, which not only reduces the temperature gradient but also increases the solidi?cation growth rate. Meanwhile, the porosity and the maximum pore size in the cladding layer were signi?cantly reduced by the vibration. The average microhardness of the cladding layer signi?cantly increased assisted by the three-dimensional vibration. Experimental results demonstrate that the e?ects of the three-dimensional vibration are more signi?cant than the single vertical vibration. The proposed approach provides a potential way to improve laser additive manufacturing and remanufacturing.
关键词： laser cladding,microhardness,three-dimensional vibration,microstructure
更新于2025-11-21 11:18:25
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Crack Restraining Methods and their Effects on the Microstructures and Properties of Laser Cladded WC/Fe Coatings
摘要： Laser cladded WC/Fe coatings have the advantages of low cost and high abrasion wear resistance. However, cracks always appear in WC/Fe coatings, which limits their industrial application. In this paper, the co-effects of the re-melting process, heat treatments, and amount of Co element on the cracking susceptibility, microstructures, and mechanical properties of WC/Fe laser cladding coatings were studied. Experimental results show that re-melting process is helpful to improve the surface quality of the coating and to reduce the cracking susceptibility. The hardness of the coating decreases slightly but distributes more uniformly. Cracks in the coating can be inhibited effectively by preheating the substrate to 250 ?C and maintaining the temperature during the laser cladding process, as well as applying an annealing treatment at 300 ?C for 1 h. Heat treatment also results in a slight decrease in the hardness. Crack initiation cannot be restrained completely by applying the above two methods when laser cladding a big area of coating. On the basis of the above two methods, addition of Co element to the coating can further improve its toughness and decrease the crack susceptibility. Crack-free WC/Fe coating can be manufactured when 8% Co is added, and its wear resistance is much better than that of the hardened medium steel, especially when the wear time is long.
关键词： Laser Cladding,mechanical properties,microstructures,WC/Fe coating,crack restraining methods
更新于2025-09-23 15:23:52
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Corrosion study of laser cladded Ti-6Al-4V alloy in different corrosive environments
摘要： Laser cladding of Ti-6Al-4V powder on a substrate with the same chemical composition was performed at different laser powers. The effect of laser power on the microstructure and corrosion behavior was then investigated. Electrochemical studies were performed by potentiodynamic polarization tests in different corrosive environments (3.5% NaCl, 2% H2SO4 and 5% HCl solutions). Microstructural investigation together with phase characterization revealed that laser cladded Ti-6Al-4V coatings were composed of needle-like martensite (ɑ/) and coaxial hexagonal compact (ɑ) phases. The coatings were crack-free; however, some cavities were observed in the coatings produced at high laser powers. In all three corrosive environments, the coatings showed a more noble corrosion behavior compared to the untreated substrate. The results showed that corrosion potential increases from ?410 (mV) to ?130 (mV) in NaCl and from ?50 (mV) to ?20 (mV) in H2SO4 enviroments but decreases from ?60 (mV) to ?270 (mV) in HCl solution. Increasing laser power had a positive effect on the corrosion behavior in NaCl and H2SO4 solutions; however, it had a negative effect on the corrosion behavior in HCl solution.
关键词： Corrosion,Laser cladding,Ti-6Al-4V alloy,Microstructure
更新于2025-09-23 15:23:52
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Microstructure and tribological properties of laser cladded self-lubricating nickel-base composite coatings containing nano-Cu and h-BN solid lubricants
摘要： In the present work, nickel-base composite powder (Ni60), nickel-base composite powder with the addition of h-BN solid lubricants (h-BN/Ni60) and nickel-base composite powder with the addition of nano-Cu encapsulated h-BN solid lubricants (nano-Cu/h-BN/Ni60) were used as raw materials to synthesize three different coatings on Q235 steels by laser cladding. Microstructures of these coatings were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. Tribological properties of these coatings were investigated at the temperatures from 25 °C to 600 °C. High temperature micro-hardness measurement was performed by Vickers micro-hardness tester. The results showed that the h-BN particles survived after laser cladding and displayed a homogeneous distribution in the nickel-base composite matrix. The encapsulation of h-BN by nano-Cu resulted in an increase of h-BN content in the coating. Although the addition of nano-Cu and h-BN led to a decrease on hardness, the nano-Cu/h-BN/Ni60 coating had the lowest friction coefficient and wear rate among the three coatings in a wide range of temperature from 25 °C to 500 °C. The mechanism of wear reduction by addition of nano-Cu encapsulated h-BN solid-lubricants was also discussed in this research.
关键词： Laser cladding,Self-lubricant coating,Steel substrate,Wear,Wide temperature range,Nickel-base composite
更新于2025-09-23 15:23:52
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Comparative investigation into effects of ZrO <sub/>2</sub> and Al <sub/>2</sub> O <sub/>3</sub> addition in fluorapatite laser-clad composite coatings on Ti6Al4V alloy
摘要： Composite coatings consisting of fluorapatite mixed with 20 wt% yttria (3 mol%) stabilized cubic phase zirconia (c-ZrO2, 3Y-TZP) or 20 wt% alumina (a-Al2O3) were deposited on Ti6Al4V substrates using a Nd:YAG laser cladding system. The interface morphology, phase composition, micro-hardness and biological properties of the two coatings were examined and compared. The results showed that the fluorapatite/Al2O3 specimen underwent a greater inter-diffusion at the interface between the coating layer and the transition layer than the fluorapatite/ZrO2 specimen. During the cladding process, the ZrO2 and Al2O3 components of the coating were completely decomposed or underwent phase transformation. In addition, the fluorapatite was partially decomposed. For both specimens, the coating layers contained fluorapatite, CaF2 and CaTiO3 phases. The coating layer of the fluorapatite/ZrO2 specimen additionally contained TTCP, CaO, CaZrO3 and m-ZrO2 (monoclinic phase), while that of the fluorapatite/Al2O3 specimen contained b-TCP, CaAl2O4 and u-Al2O3. The average micro-hardness of the fluorapatite/ZrO2 coating layer (1300 HV) was approximately 200 HV higher than that of the fluorapatite/Al2O3 coating layer (1100 HV). Both specimens generated dense bone-like apatite following immersion in simulated body fluid for 3 days. In other words, both specimens had a good in vitro bioactivity. However, the fluorapatite/ZrO2 specimen showed a better initial attachment and spread of osteoblast-like osteosarcoma MG63 cells than the fluorapatite/Al2O3 specimen in in vitro biocompatibility tests performed for 24 h.
关键词： Ti6Al4V,bioactivity,biocompatibility,alumina,laser cladding,Fluorapatite,zirconia
更新于2025-09-23 15:23:52
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In situ TiN-reinforced CoCr2FeNiTi0.5 high-entropy alloy composite coating fabricated by laser cladding
摘要： The fcc structural CoCr2FeNiTi0.5 high-entropy alloy (HEA) composite coating with TiN particles reinforced was acquired by laser cladding on the commercial 904L stainless steels. The results show that phase structure is mainly composed of fcc solid solution and TiN phases. The coating exhibits excellent structural stability below 850 °C. The microstructure consists of irregular dendrite and TiN particles. Transmission electron microscopy (TEM) results reveal that the close-packed plane of fcc phase is (111) with interplanar spacing of * 0.208 nm. The interface between TiN and fcc matrix is semi-coherent. And the angle of boundary between dendrite and matrix is * 65°. The hardness and corrosion resistance of coating have much improvement compared with those of substrate.
关键词： Semi-coherent interface,High-entropy alloy,Laser cladding,TiN particle reinforced
更新于2025-09-23 15:22:29
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Synthesis and characterization of nickel free titanium–hydroxyapatite composite coating over Nitinol surface through in-situ laser cladding and alloying
摘要： In this study, a high power fibre laser was used to synthesize titanium hydroxyapatite composite coating over biomedical-grade Nitinol surface through laser in-situ formation, cladding and alloying processes. The laser fluence is varied in the range of 2 kJ/cm2 to 8 kJ/cm2 in view of establishing a relationship between various in-situ phase-formation characteristics along with the rate of diffusion of the base material in the cladding zone with molten pool temperature. The alloying with base Nitinol material and subsequent diffusion of titanium to the in-situ formed calcium phosphate cladding layer are observed in the samples treated with laser fluence of 4 kJ/cm2 or above. Double layer configuration of the solidified molten pool is mostly found in all the cladding samples. At the fluence of 6 kJ/cm2 or above, the top layer primarily comprises segregated titanium-hydroxyapatite phase along with diffusion of titanium from the base material. Whereas, the bottom part of the molten pool is dominated with titanium-rich nickel–titanium intermetallic reinforced with nano particles. The steady-state variations of calcium and elemental presence of titanium through the cladding cross-section along with no nickel or oxide presence are confirmed through EDS line scans. The spherical and lamellar structures of formation of titanium-hydroxyapatite on the top surface also help to improve the overall corrosion resistance properties as compared to the bare surface. The modulus of elasticity is controlled by the variation of the top layer and intermediate layer composition and thickness, which varies with laser fluence. It falls in the range of 6–30 GPa which is similar to natural bone. Thus this nickel-free alloying and cladding layer of titanium-hydroxyapatite can serve as one of the potential candidates for use as a coating over the load bearing Nitinol implants to arrest the nickel release phenomena.
关键词： Titanium–calcium coating,Biocompatible functional coating,Hydroxyapatite,Nitinol surface modification,Laser cladding and alloying
更新于2025-09-23 15:22:29