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Influence of Al2O3 addition on the hardness and in vitro corrosion behavior of laser synthesized Ti-Al2O3 coatings on Ti-6Al-4V
摘要： Titanium alloy (Ti-6Al-4V) has been mostly used for medical implants due to its good chemical and mechanical properties. However, this alloy has tendency to emanate toxic V and Al due to its low corrosion resistance in body conditions. In this work, an experimental study of laser cladding Ti-Al2O3 coatings with different Al2O3 fractions (5 wt.% Al2O3, 8 wt.% Al2O3, and 10 wt.% Al2O3) was carried out to establish a coating which could improve the hardness and corrosion resistance of Ti-6Al-4V alloy. Laser parameters of 900 W power, 0.6 m/min laser scan speed, and 2 l/min powder feed were used in this research. The microstructure, phase constituents, microhardness, and corrosion of the resultant coatings were characterized by scanning electron microscope (SEM), optical microscope (OPM), X-Ray Diffractometer (XRD), Vicker hardness tester, and potentiostat respectively. Results showed that a defect free coating was achieved at a coating with less Al2O3 content. Increase in Al2O3 addition resulted in increment of hardness with Ti-10 wt.% Al2O3 coating achieving an optimum hardness of about 2.2 times greater than that of the substrate. Moreover, considerable increment in corrosion resistance of Ti-6Al-4Valloy was achieved after laser deposition of various Ti-Al2O3 admixed coatings. An optimal corrosion rate reduction of about 81% and polarization resistance increment of 709% over the substrate were achieved at Ti-5 wt.% Al2O3 due to low porosity within the coating layer. It has been established that fabricating Ti-Al2O3 on Ti6Al4V through laser could be used in improving the surface hardness values and corrosion resistance.
关键词： Ti-Al2O3 coatings,Corrosion behavior,Laser cladding,Hardness properties,Ti-6Al-4Valloy
更新于2025-09-19 17:15:36
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Analysis of laser cladding of Titanium alloy
摘要： In this study, laser cladding of Grade 5 Titanium alloy Ti6Al4V was investigated with the main goal being to optimize the cladding process by specifically optimizing the scanning speed. The scanning speed was varied from 0.5m/min to 3.5m/min in increments of 0.5m/min; while the other parameters were kept constant. Thereafter, a geometrical analysis, porosity analysis, microscopic analysis in the form of optical microscopy and SEM, atomic force microscopic analysis, Vickers microhardness testing and corrosion testing were all performed to ascertain the integrity of the clads and to optimize the process. These tests were corroborated and it was revealed that a scanning speed of 1.5m/min yielded the best all-round clad, i.e. most efficient while maintaining the quality at a relatively high level and can therefore be recommended for typical cladding processes.
关键词： titanium,Laser-metal deposition,laser cladding,scanning speed
更新于2025-09-19 17:13:59
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Control and prediction of forming quality in curved surface multi-track laser cladding with curve paths
摘要： This research investigated the influence of different processing parameters in curved surface multi-track laser cladding with curve paths. Mathematical models of flatness ratio, incomplete fusion, and pore area in the clad were developed by central composite design with altering the input laser power, scanning speed, gas flow, and overlapping rate. Response surface methodology was used to analyze the correlation of different processing parameters affecting the selected responses. A clad with better flatness ratio was achieved by properly increasing the laser power and gas flow while reducing the overlapping rate. Appropriately increasing the laser power and overlapping rate while reducing the scanning speed and gas flow effectively diminished the incomplete fusion. Less pore area in the clad was obtained by appropriately increasing the laser power and overlapping rate while reducing the scanning speed and gas flow. Afterwards, desired processing parameters set was obtained by the optimization with the target of maximizing the flatness ratio and also minimizing the incomplete fusion and pore area. Experimental validation with this processing parameter setup provided satisfactory clad, and the error rate for the flatness ratio, incomplete fusion, and pore area was 1.708%, 5.714%, and 6.522%, respectively. This paper provides the theoretical guidance for the prediction and control of the flatness ratio, incomplete fusion, and pore area in curved surface multi-track laser cladding with curve paths.
关键词： Central composite design,Response surface methodology,Curved surface,Laser cladding
更新于2025-09-19 17:13:59
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Fiber Laser || Laser Surface Modification — A Focus on the Wear Degradation of Titanium Alloy
摘要： Over the years, engineering materials are being developed due to the need for better service performance. Wear, a common phenomenon in applications requiring surface interaction, leads to catastrophic failure of materials in the industry. Hence, preventing this form of degradation requires the selection of an appropriate surface modification technique. Laser surface modification techniques have been established by researchers to improve mechanical and tribological properties of materials. In this chapter, adequate knowledge about laser surface cladding and its processing parameters coupled with the oxidation, wear and corrosion performances of laser-modified titanium has been reviewed.
关键词： Titanium,Laser surface cladding,Wear,Surface modification technique
更新于2025-09-19 17:13:59
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Oxygen gain and aluminum loss during laser metal deposition of intermetallic TiAl
摘要： For manufacturing turbine parts for the aeronautical industry, lightweight structural materials like titanium aluminides are used. One well-known example is the alloy Ti-43.5Al-4Nb-1Mo-0.1B (atomic percent) with the commercial name TNM. In previous studies, experiments on laser metal deposition of TiAl were performed to evaluate the potential of the technology to repair defective, damaged, or worn blades. Process conditions including postprocess heat treatment were successfully adjusted. However, oxygen pick-up is still a crucial aspect in laser-based additive manufacturing of Ti- and TiAl-based alloys. In this work, approaches were made to analyze the oxygen pick-up as a function of processing parameters and the powder particle size. The results show that the build rate and the powder particle size affect the oxygen content in the consolidated material.
关键词： laser processing and cladding,intermetallics,phase transformation,aero-engine components,microstructure
更新于2025-09-19 17:13:59
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Study on laser cladding and properties of AZ63-Er alloy for automobile engine
摘要： Aiming at the problem of the poor corrosion resistance of magnesium alloys for automobiles, Al-TiC and Al-TiC-Y2O3 cladding layers were prepared on the AZ63-Er alloy by laser cladding technology, studied the effects of Al:TiC mass ratio and Y2O3 addition on the microstructure, phase composition, hardness and corrosion resistance of the cladding layer. The results show that the Al-TiC laser cladding layer with different mass ratios has metallurgical bonding with AZ63-Er alloy substrate, and there are no pores or cracks at the interface. The main phases of the Al-TiC laser cladding layer are Ti3AlC, TiC, Mg2Al3, Al3Mg2, Al, Mg, AlMg and Ti6O. The hardness of laser cladding layer with the mass ratios of Al:TiC are 8:1, 4:1 and 2:1 are about 2.75, 3.24 and 3.94 times of the substrate. The corrosion resistance of Al-TiC cladding layer is higher than that of the AZ63-Er alloy substrate, and the corrosion resistance of the Al:TiC cladding layer with the mass ratio of 8:1 is the best. Al3Y and Al4MgY phases are formed in the Al-TiC-Y2O3 cladding layer after Y2O3 addition. The hardness of the Al-TiC-Y2O3 cladding layer is significantly higher than that of the Al-TiC cladding layer. The Al-TiC-Y2O3 composite cladding layer has the best hardness and corrosion resistance when the Y2O3 content is 0.6%.
关键词： surface modification,laser cladding,hardness,AZ63-Er alloy,corrosion resistance
更新于2025-09-19 17:13:59
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Residual stress in laser cladded heavy-haul rails investigated by neutron diffraction
摘要： Residual stress is one of the critical parameters affecting the fatigue behaviour of tribological components, which can be introduced by a thermo-mechanical process such as laser cladding. In this study, the residual stress distribution of laser cladded rails was evaluated using a neutron diffraction technique. The substrate rail for the laser cladding was hypereutectoid rail steel used in Australian heavy-haul railway track, and the cladding materials were 410L (a low carbon content stainless steel alloy) and Stellite 6 (a Co-based alloy). The cladding materials were selected based on their high wear, corrosion and fatigue resistance properties. This study measured the residual stress in full-scale laser cladded rails where the residual stresses were measured in the cladding layer, heat affected zone (HAZ) and substrate zone of the railhead. A new sample preparation strategy was developed to quantify the residual stresses in the full-scale rails with high spatial resolution. Higher compressive residual stress was found in the cladding layer, which may have resulted from the martensitic transformation occurred in that region. Tensile stresses occurred in the HAZ to a depth of 4 mm, which might be mainly caused by thermal contraction and volumetric change in the microstructure. The addition of a second cladding layer did not significantly affect the magnitude of the residual stresses, but the peak tensile residual stress shifted to a deeper location from the surface, which is beneficial in resisting wear. Post-cladding heat treatment significantly reduced the undesirable high residual stress from the cladding layer and HAZ.
关键词： Post-cladding heat treatment,Residual stress,Neutron diffraction,Laser cladding,Heavy-haul rail
更新于2025-09-16 10:30:52
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Modeling of thermal behavior and microstructure evolution during laser cladding of AlSi10Mg alloys
摘要： An improved three-dimensional finite element model has been proposed for studying the thermal behavior and microstructure evolution during laser cladding of AlSi10Mg alloys. Different material properties between AlSi10Mg powders and AlSi10Mg alloys are distinguished from the experiment and theoretical calculation to provide more reliable material parameters for simulation. In order to investigate the melting and solidification process during the formation of cladding layers, a temperature selection judgment mechanism is established to simulate the evolution of AlSi10Mg powders from the powder state to melting state and alloy state. In addition, to simulate the complex thermal behavior associated with powder particles and the voids between particles, a simplified exponential attenuation model is used for correcting the heat source. A complex asymmetric heat source considering about the different material properties and laser absorptivity on both sides of the remelting zone is used for multi-track cladding process. By simulating the temperature distribution of molten pool, the improved FEM could be used to predict the geometric shape of cladding layers (ignoring the effect of melting flow) and the temperature history. The simulation results show that the heat tends to diffuse to the unmelted powder owing to the asymmetric heat source during multi-track cladding, which leads to the asymmetry of cladding layers along the width direction. Based on the results of the temperature field simulations and the solidification characteristics of AlSi10Mg powders, the temperature gradient (G), solidification growth rate (R), cooling rate (G*R) and G/R are investigated to predict the morphology and size of the solidification microstructure under different laser scanning parameters. The scanning speed mainly determines the cooling rate during the laser cladding process, which results in different microstructures. Higher scanning speed leads to higher cooling rate, corresponding to a finer microstructure. Coarse dendrites are generated at the bottom of the molten pool, while finer dendrites are formed at the top.
关键词： Simulation,Microstructure evolution,AlSi10Mg alloy,Laser cladding,Thermal behavior
更新于2025-09-16 10:30:52
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Single-step Laser Plastic Deposition (LPD) using a near-infrared Thulium fiber-laser
摘要： Additive Manufacturing of thermoplastic polymers is typically carried out using techniques such as Selective Laser Sintering (SLS) or Fused Layer Modeling (FLM), both of which require the use of support structures that have to be removed after the production process. The laser welding of thermoplastic polymers using laser sources with a wavelength of around 1 μm and thus also Direct Selective Laser Melting (SLM) in the same wavelength spectrum requires the admixing of additives such as carbon black in order to improve the absorption of laser light within the polymer and hence poses an additional process step that has to be performed. Laser sources like Thulium fiber-lasers with a wavelength of around 2 μm enable the absorber-free welding of thermoplastic polymers and therefore promise to be a new source for the SLM of thermoplastic polymers as well as a possible adaption of the known Laser Metal Deposition (LMD) to plastics, the so called ?Laser Plastic Deposition“ (LPD). In the present paper, the feasibility of a single-step LPD process using irradiation of a 1,94 μm Thulium fiber-laser is investigated through the manual deposition of unfilled and absorber-free polyamide-12 powder on polyamide-6 substrates. Powder material and the created structures are characterized by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). In addition to that, optical microscopy and computer tomography analysis (CT) are carried out and discussed for the created LPD structures. From the experiments, it is to be concluded that a single-step LPD process can be carried out using a 2 μm Thulium fiber-laser.
关键词： Fiber laser,Thulium laser,Polymer cladding,Laser polymer deposition,Laser plastic deposition,Additive manufacturing
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Highly-Birefringent Solid-Core Bragg Fiber with a High-Index-Contrast Cladding
摘要： We propose a highly-birefringent solid-core Bragg fiber (SC-BF) with a high-index-contrast cladding by symmetrically introducing two air holes into the solid core. The birefringence properties of such a SC-BF and their influencing factors are numerically investigated by using the finite element method. The numerical results show that the modal birefringence can be effectively improved by optimizing the refractive index, size and position of the air holes. We numerically demonstrate a highly-birefringent SC-BF with the 2.43 10?× modal birefringence of at 1550 nm.
关键词： high-index-contrast cladding,high birefringence,Solid-core Bragg fiber
更新于2025-09-16 10:30:52