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Influence of Vanadium on the Microstructure of IN718 Alloy by Laser Cladding
摘要： A deleterious Laves phase forms in the solidi?ed structure of Inconel 718 (IN718) alloy during laser cladding. However, e?ective removal methods have not yet been identi?ed. In this study, we ?rst added the IN718 alloy cladding layers with a trace amount of vanadium (V, 0.066 wt.%). Then, we studied the solidi?cation structure of cladding layers using a confocal laser scanning microscope and scanning electron microscopy. The microstructure and Laves phase morphology were investigated. The distribution of niobium (Nb) was observed by experiment as well. We found that V is evenly distributed in dendrites and interdendritic zones. A more re?ned dendrite structure, reduced second dendrite arm spacing and lower volume fraction of Laves phase were observed in the solidi?cation structure. The results of linear energy-dispersive X-ray spectroscopy (EDS) indicate that the concentration of Nb decreases with an increasing of the distance from the Laves phase. The V-containing sample displayed a relatively slower decreasing tendency. The IN718 alloy sample was harder with the addition of V. In addition, the porosity of the sample decreased compared with the blank sample. The presented ?ndings outline a new method to inhibit the Nb segregation in IN718 alloy during laser cladding, providing reference signi?cance for improving the performance of IN718 alloy samples during actual processing.
关键词： laves phase,element segregation,vanadium,laser cladding,microstructure
更新于2025-09-11 14:15:04
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Improving Performance and Stability of Planar Perovskite Solar Cells through Grain Boundary Passivation with Block Copolymers
摘要： Al2O3–ZrO2 ceramic coatings were fabricated on titanium alloy substrate by ultrasonic assisted laser cladding. The effects of ultrasonic on the microstructure and mechanical properties of the coatings are investigated through experiments. A novel laser cladding method by ultrasonic assisted is used in this paper. In this method, ultrasonic waves are directly applied on the micro-zone of molten pool. Experimental results indicated that the grain size and mechanical properties of the coatings are improved with the ultrasonic assisted. The amount of coatings cracks are decreased due to the application of ultrasonic vibration in the laser cladding.
关键词： Al2O3–ZrO2 ceramics,ultrasonic,laser cladding,mechanical properties
更新于2025-09-11 14:15:04
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Reactive Fabrication and Effect of NbC on Microstructure and Tribological Properties of CrS Co-Based Self-Lubricating Coatings by Laser Cladding
摘要： The CrS/NbC Co-based self-lubricating composite coatings were successfully fabricated on Cr12MoV steel surface by laser clad Stellite 6, WS2, and NbC mixed powders. The phase composition, microstructure, and tribological properties of the coatings ware investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS), as well as dry sliding wear testing. Based on the experimental results, it was found reactions between WS2 and Co-based alloy powder had occurred, which generated solid-lubricant phase CrS, and NbC play a key role in improving CrS nuclear and re?ning microstructure of Co-based composite coating during laser cladding processing. The coatings were mainly composed of γ-Co, CrS, NbC, Cr23C6, and CoCx. Due to the distribution of the relatively hard phase of NbC and the solid lubricating phase CrS, the coatings had better wear resistance. Moreover, the suitable balance of CrS and NbC was favorable for further decreasing the friction and improving the stability of the contact surfaces between the WC ball and the coatings. The microhardness, friction coef?cient, and wear rate of the coating 4 (Clad powders composed of 60 wt % Stellite 6, 30 wt % NbC and 10 wt % WS2) were 587.3 HV0.5, 0.426, and 5.61 × 10?5 mm3/N·m, respectively.
关键词： tribological behavior,metal matrix self-lubricating coating,laser cladding,microstructure
更新于2025-09-10 09:29:36
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Calculation and experimental determination of the geometric parameters of the coatings by laser cladding
摘要： In the present work the experiments on laser cladding of powder Fe-B-Cr-6-2 on samples of steel 20. Metallographic studies of geometric parameters of deposited layers and the depth of the heat affected zone (HAZ). Using is the method of full factorial experiment (FFE) mathematical dependences of the geometrical sizes of the deposited layers of processing modes. Deviation of calculated values from experimental data is not more than 3%.
关键词： geometric parameters,laser cladding,heat affected zone,full factorial experiment
更新于2025-09-10 09:29:36
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Formation and properties of a Zr-based amorphous coating by laser cladding
摘要： (Zr0.53Al0.1Ni0.05Cu0.3Ti0.02)99Y1 (at%) coating with amorphous layer of about 180 lm thick was prepared on a steel substrate by using laser cladding method. The coating is compact and shows good metallurgical bonding with substrate. The microstructure, microhardness and corrosion behavior along the depth from the coating surface to the substrate were investigated. It is found that a gradient structure consisted of amorphous surface layer, amorphous–crystalline transitional layer and substrate is formed after the laser cladding. The microhardness and corrosion behavior exhibit variation with the microstructural evolution at different depths from the coating surface. The microhardness and corrosion resistance in 3.5 wt% NaCl solution of the amorphous surface layer are comparable to those of the as-cast Zr-based BMG with the same composition, and higher than those of the steel substrate.
关键词： Laser cladding,Hardness,Corrosion resistance,Amorphous coating,Microstructure
更新于2025-09-10 09:29:36
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Laser cladding composite coating on mild steel using Ni–Cr–Ti–B <sub/>4</sub> C powder
摘要： The composite coating was fabricated by laser cladding on Q235 mild steel. The cross-section morphology, microstructure, phase, micro-hardness and wear resistance of the coating were investigated by scanning electron microscope, energy dispersive spectrometry, X-ray diffraction, Vickers micro-hardness tester and dry sliding wear testing machine, respectively. Results showed that composite coating was gained without cracks and bonded with substrate excellently because of the prominent metallurgical bonding. The composite coating was made up of Ni3Ti, Cr2Ti, Ni–Cr–Fe, TiB2 and TiC. Ceramic reinforcements existed in coating with eutectic and independent structures. The micro-hardness of coating was about 5 times the substrate. Compared with substrate, the coating showed superior wear resistance.
关键词： laser cladding,wear resistance,microstructure,Q235 mild steel,Composite coating
更新于2025-09-10 09:29:36
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On the formation features, structure, microhardness and tribological behavior of single tracks and coating layers formed by laser cladding of Al-Fe powder bronze
摘要： In this paper, the effect of the gas flow and pressure on the powder flow, as well as the effect of the conditions of laser cladding on the microstructure, phase composition, microhardness and tribological behavior of an Al-Fe powder bronze coating, is studied. The features of single tracks, single- and double-layer coatings are described. The speed of a laser beam, the pitch of the single track and the distance between the nozzle and the coated surface affect the microstructure and microhardness of the coating. These parameters are more stable for double-layer coatings because a denser coating with better fusing along the grain boundaries is formed as a result of secondary melting. Under dry friction conditions, with deposition speeds less than 140–160 mm/min, the coefficient of the friction is stable and significantly lower compared with cast aluminium bronzes. In such conditions, the wear resistance of the coating increases with the increase in deposition speed. With further speed increases, a substantial rise in the friction coefficient in time and a substantial seizure of friction surfaces are observed. Under lubricated friction conditions, when the load increases from 120 N to 360 N, that is, where the pressure on the contact surface increases from 1.75 to 5.3 MPa, a sharp increase in the wear rate occurs with a deposition speed of 120 mm/min almost 130-fold and for a speed of 140 mm/min ~9-fold.
关键词： Al-Fe bronze,Powder flow,Single- and double-layer coating features,Laser cladding,Tribological behavior,Single track features
更新于2025-09-09 09:28:46
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Finite Element Simulation of Temperature and Stress Field for Laser Cladded Nickel-Based Amorphous Composite Coatings
摘要： In this paper, a nickel-based amorphous composite coating was obtained on the carbon steel surface by the laser cladding process. The thermal ?eld and stress distribution were simulated by using ANSYS ?nite element software where the moving heat source and powder feeding were modelled by the “Element birth and death” method. The simulation results were veri?ed by comparing the cross-sectional pro?le of fusion lines and X-ray stress measurements, respectively. The results on thermal ?eld showed that the cooling rate of the coating could reach up to 10389.15 K/s and it gradually decreased from the outside surface to the interior, which promoted the formation of amorphous phase. The simulated stress ?eld showed that the coating was in the state of tensile stress after cladding and the longitudinal stress was larger than the transverse stress. The coating was experienced with tensile plastic deformation along the laser scanning direction, which resulted in longitudinal residual stress. A higher stress concentration was occurred between the coating layer and substrate, which increased the susceptibility of crack formation. The test results on transverse residual stress were generally consistent with the simulation. On the contrary, the measured longitudinal stress was nearly close to zero, which was not in agreement with the model due to the formation of cracks.
关键词： stress ?eld,temperature ?eld,laser cladding,amorphous,numerical simulation
更新于2025-09-04 15:30:14