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Anti-escaping of incident laser in rare-earth doped fluoride ceramics with glass forming layer
摘要： Adaptive fluoride ceramic with glass forming layer (GCZBL-Er) used in laser anti-escaping has been prepared by one-step synthesis, and the thickness of glass layer is identified as ~0.41 mm. Blue, green and red emissions of Er3+/Yb3+ codoped fluoride ceramic (CZBL-Er) and glass layer (GZBL-Er) have been investigated under ~980 nm laser pumping. With the forming of thin glass layer on ceramic surface, the absorption intensities on diffuse reflection of GCZBL-Er at 974 nm and 1.53 μm increase by 48% and 53% than those of CZBL-Er. Excited by a 979 nm laser, the presence of the glass layer increases the absolute absorption rate in spectral power from 75% in CZBL-Er to 83% in GCZBL-er, which is consistent with the improvement in the absorbed photon number. In addition, the quantum yield of GCZBL-er complex is raised by 28.4% compared to the case of ceramic substrate by photon quantification. Intense absorption-conversion ability and efficient macroscopical anti-escaping effect confirm the superiority of ingenious structure in the fluoride ceramics with glass forming layer, which provides a new approach for developing the absorption-conversion materials of anti-NIR laser detection.
关键词： fluoride ceramic,absorption-conversion,Er3+/Yb3+ codoped,laser anti-escaping,glass forming layer
更新于2025-09-16 10:30:52
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Photopolymerization of acrylate resin and ceramic suspensions with benzylidene ketones under blue/green LED
摘要： Finding novel photoinitiators with photobleaching properties suitable for long-wavelength LED light sources is important for their potential use in the photocuring ceramic suspensions containing acrylate resin. Two D-π-A-π-D conjugated benzylidene ketones with visible light absorption (TPAK and CZK) were synthesized and evaluated as photoinitiators in the photocuring of acrylate resin and ceramic suspension under blue (460nm) / green (520nm) LED sources. Results showed that the two photoinitiators have high photoinitiating activity and can effectively produce thick-layer curing in acrylate resin and ceramic suspension due to their quick photobleaching properties under 460nm and 520nm LED light sources. The curing depth of the ceramic suspensions was measured as a function of the concentration of TPAK and CZK and the energy level of the LED light source. Jacob’s equation was used to determine the critical energy Ec and depth sensitivity Dp of every suspension with different concentrations of benzylidene ketones.
关键词： benzylidene ketones,blue/green LED,acrylate resin,Photopolymerization,ceramic suspensions
更新于2025-09-16 10:30:52
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Continuous-wave laser performance of 10 at% Yb:YSAG transparent ceramics
摘要： We report on the continuous-wave and tunable laser operation of transparent 10 at% Yb:Y3Sc1.5Al3.5O12 (Yb:YSAG) ceramics, which have a dense and homogenous microstructure after being sintered at 1820 °C for 10 h. The Yb:YSAG ceramics have excellent optical in-line transmittance characteristics. The broad absorption and emission spectra of Yb:YSAG demonstrated that these ceramics are suitable for laser-diode pumping solid-state lasers. For the 2-mm thick ceramic, a continuous-wave output power of 1.79 W at 1031 nm was measured with a slope ef?ciency of 18.3%, and a smooth tunable spectra ranging from 1021 nm to 1040 nm has been obtained, with a tunable wavelength exceeding approximately 19 nm.
关键词： laser materials,ceramic,solid-state laser
更新于2025-09-16 10:30:52
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Study on laser-stricken damage to alumina ceramic layer of different surface roughness
摘要： This study examines the laser-stricken damage to different alumina ceramic surfaces of different roughness through multi-physical field coupling simulations and laser-striking experiments. The surfaces of different morphologies can be described by waves of different frequencies and amplitudes, and the waves which are discretized can be described by rectangular microstructures of different heights. In this paper, we found that the reaction of roughness surfaces to gauss lasers stricken on them could be simulated by the reaction of rectangular microstructures of different heights to laser strike. The simulation was carried out through the multi-physical field coupling method. The distribution of temperature and stress on rectangular microstructure were examined after being treated by high energy laser. It was found that overhigh temperature and stress were the main causes of laser-stricken damage, but there existed a critical rectangular column height value. The microstructure became increasingly prone to damage and fall-off with the increase of the rectangular column’s height, but it became decreasingly prone to damage after the rectangular column reached the critical value. In the experiments, seven roughness zones of alumina ceramic layer were chosen as sample surfaces for laser-striking experiment. The results showed that there was a critical roughness value at a fixed laser energy density. As a result, the amount of particles falling off the surfaces caused by laser strike was rising when the roughness was increasing. However, the amount of particles falling off the surfaces was decreasing after roughness reached the critical value. The critical rectangular column height value in the simulation corresponded to the critical roughness value in the experiment. Therefore, an appropriate selection of roughness is an important factor for obtaining high laser-stricken damage threshold.
关键词： simulation and experiment,surface roughness,rectangular microstructure,laser-stricken damage,alumina ceramic layer
更新于2025-09-16 10:30:52
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Effect of repeated laser surface treatments on shear bond strength between zirconia and veneering ceramic
摘要： Statement of problem. Delamination failure may occur between ceramic frameworks and veneering ceramics, shortening the lifetime of ?xed dental prostheses in load-bearing areas. Purpose. The purpose of this in vitro study was to compare the effect of different repeating CO2 laser treatment methods and conventional approaches on the shear bond strength of zirconia frameworks and veneering ceramics. Material and methods. Zirconia disks (N=110) were prepared and divided into 5 groups: milling without surface treatment (group M), airborne-particle abrasion (group APA), single laser treatment (group LX1), 2 laser treatments (group LX2), and 3 laser treatments (group LX3). The specimens in the ?rst 2 groups were treated before the framework was coated using the spraying technique. Specimens in the remaining groups were coated with veneering ceramic using the spraying process, and then subjected to laser treatment. Surface roughness and topography, interface properties, phase transformation, shear bond strength, and fracture modes were investigated. Outcomes were analyzed using a pro?lometer, a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS), X-ray diffractometry (XRD), a stereomicroscope, and a universal testing machine for mechanical testing. Results. The XRD showed that phase transformation from tetragonal to monoclinic occurred after airborne-particle abrasion. This phenomenon was not observed in laser-treated specimens. Groups LX2 and LX3 had the highest surface roughness values, 1.18 ±0.23 mm and 1.21 ±0.22 mm, among all groups, and group LX3 had the highest shear bond strength values for unaged and aged conditions, 32.08 ±2.45 MPa and 31.43 ±2.07 MPa. The mixed-fracture mode was the most common type of fracture observed. Conclusions. The results indicated that the shear bond strength between the zirconia framework and veneering ceramic was higher after laser surface treatments than after milling alone or after airborne-particle abrasion. Laser treatment methods, particularly LX2 and LX3, could be considered reliable approaches for zirconia surface treatment.
关键词： veneering ceramic,laser treatment,zirconia,shear bond strength,surface roughness
更新于2025-09-12 10:27:22
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Error Tolerant Method of Dielectric Permittivity Determination Using a TE?? Mode in a Circular Waveguide at the W-Band
摘要： We propose a new method for the precise measurement of dielectric permittivity of ceramics and polymers at millimeter-wave frequencies that employs the TE01 mode of a circular waveguide. At higher frequencies, accurately measuring the dielectric permittivity of materials becomes extremely challenging by using the fundamental TE10 mode of a rectangular waveguide. As the frequency increases, the dimensions of the dielectric sample that has to be fit into the waveguide become very small. Therefore, small fabrication imperfections that produce air gaps between the sample and the wall of the waveguide result in significant errors during measurements. In contrast, the TE01 mode of the circular waveguide that does not have an electric field at the surface of the waveguide is insensitive to small imperfections during fabrication. We measured the dielectric permittivity in small samples of alumina (Al2O3), magnesium calcium titanate (MCT) ceramics, and Teflon placed in a circular waveguide. The results showed that the method was very robust with respect to manufacturing imperfections: when dimensions of the alumina and Teflon samples varied by as much as 10% and 20%, the differences in the computed dielectric permittivity of the alumina were only 1.26% and 3.06%, respectively, and those of Teflon were 1.98% and 2.12%. In addition, when the high-dielectric permittivity material MCT samples were deformed by 5% and 10%, the differences were just 0.04% and 0.14% each, respectively. We believe that this new proposed method is also applicable to even higher frequencies in the THz regime and at a very high relative dielectric permittivity of larger than 10.
关键词： millimeter waves,Ceramic materials,measurement,resonant-based method,dielectric permittivity,waveguide
更新于2025-09-12 10:27:22
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Hybrid laser assisted machining: a new manufacturing technology for ceramic components
摘要： Silicon nitride is a high-performance ceramic used for high-temperature structural applications due to its elevated strength, fracture toughness and corrosion resistance. These properties make this material extremely difficult to machine, leading to component costs that can be prohibitive in many fields where its characteristics could provide improvements in performance. In order to overcome manufacturing limitations, a new technique is proposed in this paper: a hybrid solution that combines laser and conventional cutting tools where the laser source induces controlled cracking into the surface of the material. By properly selecting the laser parameters (laser power, scanning speed, etc.), the crack depth can be smaller than the machining depth of cut. Cracking can be performed in a preceding phase so that no thermal load is induced in the inserts, while maximum cutting load is reduced, thus increasing tool life.
关键词： Silicon Nitride,laser treatment,hard ceramic components,hybrid machining,grinding
更新于2025-09-12 10:27:22
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Evaluation of a real-time optically stimulated luminescence beryllium oxide (BeO) fibre-coupled dosimetry system with a superficial 140?kVp X-ray beam
摘要： The purpose of this study was to investigate the potential of real-time optically stimulated luminescence (rtOSL) measurements of a beryllium oxide (BeO) ceramic fibre-coupled luminescence dosimetry system. By pulsing the stimulation laser during the exposure to ionizing radiation, an rtOSL dose-rate measurement can be obtained which could be stem effect free. A portable rtOSL BeO ceramic fibre-coupled dosimetry system is presented and characterized using a constant dose-rate superficial 140 kVp X-ray beam. The rtOSL was measured for dose-rates between 0.29 and 3.88 Gy/min, controlled by varying the source to surface distance. After correcting for OSL decay during the exposure, a linear dose-rate response of the change in rtOSL (ΔrtOSL) was observed. The ΔrtOSL was also observed to be stem effect free.
关键词： Optically stimulated luminescence,Fibre-coupled luminescence dosimetry,BeO ceramic,Stem effect
更新于2025-09-12 10:27:22
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Output current ripple reduction of LED driver using ceramic‐capacitor‐input circuit and buck‐boost converter
摘要： This article proposes an LED driver that consists of a ceramic-capacitor-input rectifier and a buck-boost converter. The LED driver has an advantage of long life because it does not contain any electrolytic capacitors. However, the issue with electrolytic capacitor-less LED driver is that the ripple of the smoothed voltage becomes large due to insufficient capacitance of the smoothing capacitor. The proposed method, which uses the discontinuous current mode of a buck-boost converter, reduces the output current ripple under such conditions. Experimental results using a 5.7 W LED driver prototype demonstrate that the proposed method reduces the output current ripple and that the percent flicker becomes 4.4%, which is smaller than the recommended upper limit of 8%.
关键词： ceramic capacitor,LED driver,buck-boost converter,electrolytic capacitor-less,discontinuous current mode
更新于2025-09-12 10:27:22
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Tribological performance of metal-reinforced ceramic composites selectively structured with femtosecond laser-induced periodic surface structures
摘要： The impact of femtosecond (fs) laser-induced periodic surface structures (LIPSS) on tribological properties was investigated for metal-reinforced ceramic composites (Al2O3-ZrO2-Nb). For this purpose, the metallic niobium (Nb) phase was selectively structured with LIPSS in an air environment with different values of the fs-laser peak fluence by near-infrared fs-laser radiation (λ = 1,025 nm, τ = 300 fs, frep = 1 kHz), taking advantage of the different light absorption behavior of ceramic and metal. The tribological performance was evaluated by reciprocating sliding tests in a ball-on-disc configuration using Ringer’s solution as lubricant. The surfaces were characterized before and after laser irradiation by optical microscopy, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy and by measuring the contact angle with Ringer’s solution. The LIPSS formation resulted in an increased wetting of the surface with the lubricant. Moreover, the selectively structured composite surfaces revealed a coefficient of friction significantly reduced by a factor of ~ 3 when compared to the non-irradiated surface. Furthermore, the formation of a laser-induced oxidation layer was detected with NbO as the most prominent oxidation state. Selectively structured composites with outstanding mechanical properties and enhanced tribological performance are of particular interest for biomedical applications.
关键词： femtosecond laser-induced periodic surface structures (LIPSS),tribology,wettability,ceramic matrix composites,coefficient of friction,selective surface structuring
更新于2025-09-12 10:27:22