- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Computational and Experimental Investigation of Micro-Hardness and Wear Resistance of Ni-Based Alloy and TiC Composite Coating Obtained by Laser Cladding
摘要： The influence of processing parameters on the micro-hardness and wear resistance of a Ni-based alloy and titanium carbide (TiC) composite cladding layer was studied. Mathematical models were developed to predict the micro-hardness and wear resistance of the cladding layer by controlling the laser cladding processing parameters. Key processing parameters were the laser power, scanning speed, gas flow, and TiC powder ratio. The models were validated by analysis of variance and parameter optimization. Results show that the micro-hardness is positively correlated with laser power and TiC powder ratio, where the TiC powder ratio shows the most significant impact. The wear volume decreased with an increasing TiC powder ratio. The targets for the processing parameter optimization were set to 62 HRC for micro-hardness and a minimal volume wear. The difference between the model prediction value and experimental validation result for micro-hardness and wear volume were 1.87% and 6.33%, respectively. These models provide guidance to optimize the processing parameters to achieve a desired micro-hardness and maximize wear resistance in a composite cladding layer.
关键词： Ni35A + TiC composite,laser cladding,central composite design,wear resistance,micro-hardness
更新于2025-11-28 14:24:20
-
Influence of laser polishing on surface roughness and microstructural properties of the remelted surface boundary layer of tool steel H11
摘要： This work investigates the influence of multi-step laser polishing on microstructural properties of the remelted surface layer of tool steel H11. Four different laser polishing process parameter sets were selected that lead to a significant reduction in roughness. In a sequential process using continuous and pulsed laser radiation (Nd:YAG) a significant reduction of surface roughness was achieved on an initially annealed H11 sample. The remelted layers were analyzed using roughness measurements, white light interferometry, X-ray diffractometry, electron backscatter diffraction, glow discharge emission spectroscopy, and nanoindentation hardness measurements. Laser polishing leads to a grain refinement and a significant increase in hardness. A surface roughness of Ra 50nm was achieved in an Argon process atmosphere with an additional 6vol% CO2. In particular the carbon concentration was more than halved within the remelted layer. The lower carbon concentration is correlated with a decreased maximal surface hardness down to 366HV. High residual tensile stresses of up to 926MPa can be introduced by laser polishing. Overall, high temperature gradients and, in particular, decarburization due to carbon diffusion processes were identified to be the major driving force for significant changes in surface micro-roughness and microstructural properties.
关键词： AISI H11,micro hardness,laser polishing,decarburization,surface roughness,martensite formation
更新于2025-09-23 15:21:01
-
Investigation of hole quality in drilled Ti/CFRP/Ti laminates using CO2 laser
摘要： The machinability of titanium (Ti) and carbon fiber reinforced plastic (CFRP) (Ti/CFRP/Ti) laminates using CO2 laser is presented in this work. The effect of line energy and laser frequency on output responses such as heat affected zone (HAZ), taper angle (TA), metal composite interface (MCI) damage, surface roughness, dross height, and circularity were investigated. Line energy - the most influential parameter - demonstrated a threshold behavior; no drilling was observed below a certain line energy. Scanning acoustic microscopy (SAM), scanning electron microscopy (SEM), micro-computed tomography (μ-CT), and other imaging techniques were used to establish a correlation between laser parameters and CO2 laser machined damage in Ti/CFRP/Ti laminates. The results show that using a higher frequency and lower line energy can significantly improve the hole quality. However, dross free holes with minimum taper can be obtained using higher line energy.
关键词： Surface roughness,Circularity,Micro-hardness,CO2 laser,Dross height,HAZ,Drilling,Ti/CFRP/Ti,MCI damage factor,TA
更新于2025-09-23 15:19:57
-
Luminescence and dielectric properties of Ni2+ ions added to calcio yttria borophosphate glasses for optoelectronic uses
摘要： Glass materials of composition CaO – Y2O3 – B2O3 – P2O5 added with different concentrations of NiO (Ni2+: CYBP) are synthesized by conventional rapid melt quenching method. Various physical properties of these glasses such as polaron radius (rp), molar volume (Vm), optical basicity (Λth) and refractive index (μ) are studied. As an elastic characterization Young’s modulus (Y), Poison ratio (σ) and micro hardness (H) of these glasses are studied. These grades suggest that the prepared materials are mechanically hard and exhibiting covalently interlinked structure. Further these samples are characterized by various techniques such as differential thermal analysis, thermoluminiscence, optical absorption, photoluminescence, Ionic conductivity and dielectric dispersion. The thermoluminiscence grades such as peak temperature maximum (Tm), shape symmetry factor (μsf) and activation energies ( Eτ, Eδ and Eω) are studied at various UV irradiation levels. These results strongly recommended that the both electron and hole trap centers were created at the deeper trap levels and contribute higher orders of thermoluminiscence emission with in these glasses subjected to higher orders of temperature and UV irradiation. The various optical absorption and photoluminescence factor's such as, optical band gap (Eo), nephelauxetic ratio (β), emission cross section (Ω), branching ratio (ζ) and radiative life times (τ) are studied. These grades found to be maximum for the material which has 0.5 mol% of NiO concentration may be most suggestible for optoelectronic application. The dc and ac conductivity (σdc & σac) of these glasses are estimated. The various dielectric parameter’s such as loss tangent (Tan (φ)), temperature region of relaxation (ΔT), density of states near Fermi level (N(Ef)), activation energies of both dipoles and conduction (Ed & Ec) are also calculated. These reports clearly disclose that the octahedrally located Ni2+ ions are increasing with increase NiO concentration with in present calcio yttria borophosphate glasses.
关键词： emission cross section,nephelauxetic ratio,micro hardness,trap depth parameters,Ni2+: CYBP glass materials,temperature region of relaxation
更新于2025-09-19 17:15:36
-
In-situ Monitoring on Micro-hardness of Laser Molten Zone on AISI4140 Steel by Spectral Analysis
摘要： The real-time monitoring technology plays a significant role in the field of laser aided manufacturing. It not only ensures the product quality, but also saves time and expenditure on the subsequent testing. To develop a method to monitor the properties of laser molten zone, in this paper, the AISI4140 steel samples were melted by laser with different parameters. At the same time, the plasma spectra were detected during real-time laser processing. The evolutions for both emission spectra and hardness of molten zone were researched in this work. To correlate the intensity of spectral line with the hardness of molten zone, the method of dimensionless analysis was used in this experiment. As the results shown, in a dimensionless system, there was a linear correlation between dimensionless micro-hardness of molten zone (H*) and dimensionless laser energy density(ln(δ*)); the dimensionless micro-hardness could be expressed by a piecewise function using dimensionless intensity of Fe I spectral lines(I*), dimensionless velocity(v*) and dimensionless laser energy density as variables; depending on the quantitative relation among all dimensionless, a monitoring system of hardness of molten zone was established; by testing under different parameters of laser processing, the mean error of prediction is lower than 3.1%. It means the emission spectroscopy can be a potential way to monitor the properties of parts prepared by laser processing.
关键词： AISI4140 steel,plasma spectra,laser aided manufacturing,micro-hardness,dimensionless analysis,real-time monitoring
更新于2025-09-19 17:13:59
-
A Study of Laser Beam Welding, Gas Tungsten Arc Welding and High Temperature Brazing Processes on Micro hardness and Tensile Strength of AISI Type 316 Stainless Steel
摘要： Thin wall joints for elevated temperature (~550 °C) applications can be prepared by Laser Beam Welding (LBW), Gas Tungsten Arc Welding (GTAW) and High Temperature Brazing (HTB) methods. The joints have been made and tests such as helium leak test (HLT), micro hardness test and tensile test were carried out. A study has been performed on these joining techniques to recognize the suitable method for high temperature applications. No observable leak was identified during HLT. Microstructures shows dissimilarity in solidification morphology due to disparity in heat sources. It has been identified that the joint made by brazing process having higher micro hardness value. Further, it has been observed that LBW joints have better mechanical properties than GTAW joints and HTB joints.
关键词： GTAW,Micro hardness,AISI 316 stainless steels,Tensile properties,High temperature brazing,Microstructures,Nd:YAG Laser
更新于2025-09-12 10:27:22
-
Numerical analysis of multi-layered laser cladding for die repair applications to determine residual stresses and hardness
摘要： Laser cladding provides numerous advantages over the traditional, ad-hoc and imprecise deposition techniques for the repair of critical structural components such as dies and molds used in cold working industries. A necessity of a good quality laser cladding is to offer durable and reliable adhesion to the substrate with reduced dilution and absence of pores, cracks, and delamination. The process can add to complications due to addition of the second layer on the surface of the first clad layer that can generate local variation in shrinkage, layers of additive material are added onto the non-planar domain and the additional distance from the substrate. Consequently, residual stresses previously induced in a first clad layer and substrate region can alter. Largely, tensile residual stresses in the clad layer or clad-substrate interface region can lead to accelerated fatigue failure. Prediction and mitigation of tensile residual stresses still remain important issues in multi-layer laser cladding. Finite element modelling is an appropriate way to estimate the residual stress profile and microstructural changes for the prediction of optimal process parameters. The current work focuses on the development of a coupled metallo-thermomechanical finite element model in ABAQUS? for multi-layered laser cladding of CPM9V powder on H13 tool steel. The residual stress evolution along the cross-section has been characterized at different process conditions and the optimal conditions corresponding to mitigation of tensile residual stresses have been identified. The hardness can be affected due to the deposition of an additional layer and tempering can occur in clad or substrate which needs to be understood. The micro-hardness values are estimated using the numerical model and compared with the measured data using a Vickers hardness tester. It has been observed that the peak magnitude of tensile residual stress in the clad region with multiple layers is lower than the peak residual stresses in single layer clad of the same height along with the hardness.
关键词： residual stress,multi-layered deposition,Additive manufacturing,metallo-thermomechanical model,micro-hardness
更新于2025-09-12 10:27:22
-
Mechanical and tribological performance of fiber laser cladded h-BN + SS316 composite on SS316 surface
摘要： Laser cladding is a unique process for adding one material to the surface of another base material by utilizing high energy and coherent laser beam. For the present investigation, h-BN (hexagonal boron nitride) + SS316 composite coating was applied on SS316 substrate surface by fiber laser cladding operations. Under the influence of various input process parameters, the surface morphology, microstructure, X-ray diffraction, clad layer thickness, micro-hardness, and tribological behaviour of the composite coating were examined. The result showed good metallurgical bonding between the clad powder and substrate surface. Surface morphology did not show any pores and cracks on the clad surface. From FESEM analysis, the clad surface was found to be smooth and free from any crack propagation during laser processing. X-ray diffraction analysis showed formation of Fe3N, Cr2N, CrB, B2C5N2, γ- (Ni, Fe), h-BN phases which are responsible for enhancing mechanical and tribological properties of the clad layer. During the study, the micro-hardness of the clad layer was found to increase with an increase in % v/v of h-BN by 2-2.5 times compared (525 HV0.3) to parent material (220 HV0.3). Further, dry sliding wear test was carried out with Pin-On-Disc, showed that the coefficient of friction value decreased significantly from 0.560 (parent surface) to 0.251 (clad surface).
关键词： solid lubricant,micro-hardness,fiber laser cladding,coefficient of friction,h-BN,microstructure
更新于2025-09-11 14:15:04
-
Sputtering yield measurements of laser ablated Mg-alloy correlated with surface, structural and mechanical modifications
摘要： Sputtering yield of laser ablated Mg-alloy has been measured by Quartz Crystal Microbalance at various fluences ranging from 11.6–44.2 J/cm2, under two different environments of Ar and O2. The sputtering yield initially increases from 14.58 × 1014 to 23.49 × 1014 and from 4.5 × 1014 to 22.60 × 1014 (atoms/pulse) by increasing fluence and then decreases upto a value of 19.78 × 1014 and 19.94 × 1014 (atoms/pulse) at the maximum fluence, under Ar and O2 environment respectively. Scanning Electron Microscope analysis reveals the formation of cones, cavities, droplets, ripples and island like structures on the irradiated Mg surface. Surface profilometry analysis reveals that the crater depth of laser irradiated Mg-alloy ranges from 188 to 209 μm. It initially increases by increasing laser fluence and afterwards, decreases at the maximum fluence. Energy Dispersive X-ray spectroscopy (EDX), X-Ray Diffraction analysis (XRD) and Ultraviolet-Visible (UV–vis) spectroscopy confirm the oxide formation for the laser treated target of Mg in O2. The Vickers Micro-hardness testing reveals that hardness of laser irradiated Mg-alloy is increased by increasing fluence. The surface structures, crater depth and hardness of laser irradiated Mg-alloy are strongly dependent upon laser fluence and are correlated with sputtering yield measurements.
关键词： UV–vis,EDX,XRD,Sputtering yield,Surface modifications,Crater depth,Mg-alloy AZ91D,Micro-hardness
更新于2025-09-11 14:15:04
-
Synthesis, Growth and Characterization of Nonlinear Optical Ce-Doped L-Prolinium Picrate Single Crystals
摘要： A non-linear optical material L-prolinium picrate and cerium doped L-prolinium picrate were synthesized and grown as single crystals by slow evaporation method. The grown crystals were subjected to structural, elemental, thermal, optical and dielectric studies. The structural analysis reveals that pure L-prolinium picrate and Ce doped L-prolinium picrate belongs to the monoclinic crystallographic system with space group P21. Optical transparency of the grown crystals was investigated by UV-visible-NIR spectrum. The thermal analyses reveal that Ce doped L-prolinium picrate is thermally stable up to 162 °C. The dielectric constant and dielectric loss of the crystals were studied as a function of frequency. The non-linear optical property of the doped crystal was confirmed by the Kurtz-powder second harmonic generation test and the result is compared with pure L-prolinium picrate. Mechanical strength of the crystals was also carried out by Vicker's micro hardness test.
关键词： X-ray diffraction,Micro hardness,Growth from solution,Semi organic compound,Non-linear optical crystal
更新于2025-09-04 15:30:14