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Laser in-situ synthesis of high aspect ratio TiB fiber bundle reinforced titanium matrix composite coating
摘要： In this study, coatings are fabricated with laser cladding technique on titanium alloy substrate using TiB2 powder (0.5 μm, 5 μm and 50 μm) as the cladding materials. The effects of different TiB2 particle sizes and different laser powers on the microstructure of laser cladding layer are investigated. The results reveal that the cladding layer of high aspect ratio TiB fiber bundle is formed when using 0.5 μm TiB2 as the cladding material under the condition of high laser power (2.5 kW) of TiB fiber bundle are formed when using 5 μm and 50 μm TiB2 as the cladding materials under the condition of different laser powers. Combined with the evolution of microstructure in the cladding layers, the formation mechanism of high aspect ratio TiB fiber bundle is discussed. Meanwhile, the cladding layer of high aspect ratio TiB fiber bundle exhibits the advantages of high hardness and high wear resistance, and the predominant wear mechanisms of TiB fiber bundle are cutting and fracture.
关键词： TiB fiber bundle,Microstructure,Wear,Laser cladding,Hardness
更新于2025-11-28 14:24:20
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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
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Physical, structural and optical properties of Sm3+ doped lithium zinc alumino borate glasses
摘要： Sm3+ doped lithium zinc alumino borate glasses with composition 15ZnF2–12Li2CO3–10BaO–8Al2O3–(55-x) B2O3–xSm2O3 where x = 0.1, 0.3, 0.5, 0.7 and 1.1 mol% were prepared by conventional melt quenching technique Their optical, physical, structural, mechanical and luminescence properties are investigated. UV–Vis-NIR absorption spectra showed all possible transitions of samarium ion in this glass matrix. Band gap values for all the glass samples were above 3 eV con?rming the insulating nature for the glass. Densities, assessed using the Archimedes rule, were observed to be increasing with increasing samarium concentration. Increase in molar volume with addition of samarium content indicated that the extension of glass network is on account of the increase of number of Non-Bridging Oxygens created by network modi?er samarium ions. Scanning Electron Microscopy (SEM) image showed a smooth surface for the synthezied glass. X-Ray Di?raction (XRD) technique was employed to verify the amorphous nature of the glasses. A Makishima and Mackenzie theoretical model gave acceptable approximation of elasticity constants viz. Young's modulus, shear modulus, bulk modulus and Poisson's ratio. The high Vickers hardness values evaluated with mechanical loads of 50, 100, 300, 500, 1000 g force, proved the stability of the glasses. Emission spectra showed a prominent transition 4G5/2 → 6H7/2 at 598 nm excited with 6H5/2 → 4P3/2 transition at 401 nm. Luminescence quenching e?ect was observed beyond 0.3 mol% Sm2O3 addition. The chromaticity coordinates (x, y) clustered in the orange-red region, making these Sm3+ doped lithium zinc alumino borate glasses suitable candidate for applications in LEDs and solid-state lasers.
关键词： XRD,Photoluminescence,Samarium,Vickers hardness,Radiation shielding,Makishima and Mackenzie,Rare earth
更新于2025-11-21 11:18:25
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Effects of Nd:YAG laser surface treatment on tribological properties of cold sprayed Ti-6Al-4V coatings tested against 100Cr6 steel under dry condition
摘要： The surfaces of cold sprayed Ti-6Al-4V (Ti64) coatings were laser irradiated with different laser powers of 50-200 W to study the effects of Nd:YAG laser surface treatment on their tribological properties. The hardness of the laser treated Ti64 coatings became higher with higher laser power due to the more rapid cooling caused by a larger temperature difference between the coating surface and room temperature. The wear of the laser treated Ti64 coatings tested against 100Cr6 steel balls under dry condition at room temperature decreased with increased laser power as a result of their increased surface wear resistance associated with their increased surface hardness. It could be concluded that the laser surface treatment of the cold sprayed Ti64 coatings improved their surface wear resistance compared to that of the untreated Ti64 coatings.
关键词： Ti-6Al-4V,laser power,hardness,wear,laser surface melting,Cold spray
更新于2025-09-23 15:23:52
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Effect of donor acceptor substitution position on the electrical responsive properties of azulene system: a computational study
摘要： Effect of donor–acceptor substitution position on the electrical responsive properties like polarisability, first hyper polarisability of donor–acceptor substituted azulene derivatives have been investigated using HF and Density functional theory with various hybrid functional and basis. It is observed that among the DFT methods, CAM-B3LYP hybrid functional with correlation consistent polarised triple-zeta, cc-pVTZ basis show less overestimated value of polarisability and first hyperpolarisability compare to other hybrid functional and it is again advantageous than HF with similar basis in term of its price and performance ratio. An apparent violation of minimum polarisability principle among the studied azulene derivatives are observed and it has been explain due to non-constancy of the potential functions upon substitution of donor (NMe2) and acceptor (NO2) groups at different position of azulene ring. Computed βav values are in accordance with the extent of charge transfer character of the azulene with a few exceptions. Position of donor and acceptor group at the five- and seven-member ring also play a big role in determining the electrical responsive parameter has been discussed. It is also observed that 2 and 6 carbon atom of azulene are highly sensitive towards donor acceptor substitution.
关键词： chemical hardness,electronic spatial extent (<R2>),Polarisability,optical gap,first hyper-polarisability
更新于2025-09-23 15:23:52
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Elasticity, Hardness, and Fracture Toughness of Sodium Aluminoborosilicate Glasses
摘要： Due to an increasing demand for oxide glasses with a better mechanical performance, there is a need to improve our understanding of the composition-structure-mechanical property relations in these brittle materials. At present, some properties such as Young’s modulus can to a large extent be predicted based on the chemical composition, while others – in particular fracture-related properties – are typically optimized based on a trial-and-error approach. In this work, we study the mechanical properties of a series of twenty glasses in the quartenary Na2O-Al2O3-B2O3-SiO2 system with fixed soda content, thus accessing different structural domains. Ultrasonic echography is used to determine the elastic moduli and Poisson’s ratio, while Vickers indentation is used to determine hardness. Furthermore, the single-edge precracked beam (SEPB) method is used to estimate the fracture toughness (KIc) for some compositions of interest. The compositional evolutions of Vickers hardness and Young’s modulus are in good agreement with those predicted from models based on bond constraint density and strength. Although there is a larger deviation, the overall compositional trend in KIc can also be predicted by a model based on the strength of the bonds assumed to be involved in the fracture process.
关键词： Vickers hardness,fracture toughness,glass properties,Elastic moduli,crack path
更新于2025-09-23 15:22:29
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Raman Spectroscopy through the Indenter Working as an Optical Objective
摘要： The transparent indenter which can used as an optical objective were tested to obtained a spectra during the indentation. A special device which comprises the transparent indenter and actuator was developed and embedded into the Raman spectrometer. An indentation into the silicon sample was performed and phases that exist under the load and without it were identi?ed.
关键词： transparent tip,hardness,Raman spectroscopy,in-situ observation
更新于2025-09-23 15:22:29
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Growth and study of nonlinear optical P-dimethyl-aminobenzaldehyde crystal for photonic device application
摘要： Pera dimethyl-aminobenzaldehyde (p-DMAB) is a well known aromatic compound with nonlinear optical (NLO) properties in various application fields such as optoelectronics, photonics etc. The single crystal of p-DMAB is grown by slow evaporation technique (Constant Temperature Bath) at room temperature. These grown crystals are good in size with transparent appearance. The grown crystals are characterized using XRD, FTIR spectroscopy, Elemental analysis, UV-Spectroscopy, Second Harmonic Generation (SHG), Optical limiter behaviour, Photoluminescence (PL), Vickers hardness, Scanning Electron Microscopy (SEM). Single crystal XRD provides information about the crystal structure. The powder XRD shows that material is crystalline in nature. FTIR- Spectroscopy provides information about the relevant functional group present in the compound. CHN (Carbon-Hydrogen-Nitrogen) analysis shows appropriate composition of these elements within this material. UV-Vis study reveals that materials have wide window over the entire visible region. The observed order of refractive index points their use in anti-refracting coating devices. Good linear polarisability, susceptibility, optical conductivity data are also appropriate to decide their use in optical device fabrications. Wider optical band gap described dielectric behavior of material. Second harmonic generation test shows that material has 2.03 times greater efficiency than the reference material KDP. Moreover the emission of green light indicates that the material can be used to develop green-blue laser. Optical limiter behavior shows that material is suitable for fabrication of an optical limiter device. In PL study desecrate energy level indicates purity of grown crystals. The Vicker’s micro hardness study was also carried out on the sample. Vickers hardness test shows increment in hardness, yield strength and stiffness of material. SEM images show smooth morphology at different magnifications.
关键词： FTIR,Crystal growth,SEM,XRD,Vickers hardness,CTB method
更新于2025-09-23 15:22:29
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Effect of Nb addition on microstructure and properties of laser cladding NiCrBSi coatings
摘要： NiCrBSi coatings with different Nb additions have been prepared by laser cladding. The microstructure, phase composition, hardness, and wear resistance of the coatings were studied by scanning electron microscopy (SEM), electron probe microanalyser (EPMA), X-ray diffraction (XRD), microhardness tester and M-200 wear tester. The results show that the phases in the NiCrBSi coating without Nb addition include γ-Ni, Cr23C6, Cr7C3, Ni3B, Ni3Si2 and CrB. The NbC phase appears in coatings after the addition of Nb element. When the addition of Nb is 2 wt-%, the NbC particles with a size of about 1.2 μm were found in the coating, and the amount of NbC is about 1.8 vol.-%. With the increase of Nb addition, the size and amount of NbC in the coatings also increased. When the addition of Nb is 6 wt-%, the size of NbC is about 2.3–6.1 μm and the morphology of NbC changed from particle to quadrangular and petaloid shaped. In addition, when the addition of Nb is 2 wt-%, the hardness and wear resistance of the coating are the best, and the wear resistance of the coating is 104% higher than that without Nb addition.
关键词： Nb addition,wear resistance,microstructure,hardness,Laser cladding,NiCrBSi coatings
更新于2025-09-23 15:21:21
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Effect of the photoactivation method on composite resin cure.
摘要： For composite resins to obtain good properties, they must present a high degree of conversion and minimal polymerization contraction. To minimize this contraction, alternative photoactivation techniques have been suggested. The objective of this study was to compare the hardness of a photoactivated composite resin using the pulse-delay, soft start and conventional techniques, in thicknesses of 1, 2 and 3 mm in the irradiated surface and in the opposite surface. Photoactivation was performed with halogen light for 20 seconds in the conventional and soft start techniques. In the pulse-delay technique, each increment of 1 mm was photoactivated for 3 seconds with a final photoactivation of 40 seconds. The samples were stored in an oven at 37°C for one week and submitted to the Vickers microhardness test. The results were submitted to ANOVA and the Tukey’s test with a level of significance of 5%. It was concluded that the hardness was higher with photoactivation of 40 seconds, and for the techniques that had the photoactivation time of 20 seconds (conventional and soft start), there was no difference in terms of hardness. Therefore, the hardness is not influenced by the technique, but rather, by the polymerization time.
关键词： Polymerization,Hardness,Composite Resin
更新于2025-09-23 15:21:21