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Fabrication and luminous properties of phosphor ceramic for application in automotive laser headlight
摘要： We report on the optimization of fabrication of a ceramic phosphor plate (CPP) using α-Al2O3 as functional materials for an automotive laser headlamp. The prepared CPP shows the high luminous characteristics with increasing α-Al2O3 contents because of the light scattering of the hexagonal structure of α-Al2O3 materials. We investigated the correlation between α-Al2O3 and thickness of CPP. The luminous properties of the CPP are improved and optimized according to the variables of one. We found that the prepared sample is a potential material for future solid-state laser lighting in application as an automotive headlamp.
关键词： α-Al2O3,Luminous properties,Thickness,Laser diode,Ceramic phosphor plate
更新于2025-09-23 15:21:01
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Grain refinement in laser manufactured Al-based composites with TiB2 ceramic
摘要： Al-based composites reinforced with TiB2 ceramics (1 wt.%, 2 wt.% and 5 wt.%) have been manufactured through selective laser melting (SLM). The results show that the densification, microstructure and mechanical properties of the SLM-processed composites are sensitive to the ceramic particle fraction. The average grain size of the composites decreased from ～6.32 μm with increasing TiB2 fraction from 1 to 5 wt.% respectively. Fine equiaxed grains with narrow size distribution were obtained for composites with relatively high amount of TiB2 particles. The effects of TiB2 ceramic fraction on grain refinement and strengthening mechanisms of SLM-processed composites were discussed. Al-based composite with 2 wt.% TiB2 ceramic was determined to be optimum, especially in the view of manufacturing quality, grain refinement and mechanical properties. The composites at an optimum fraction of 2 wt.% TiB2 exhibited high microhardness of ～127 HV0.2, tensile strength of ～444 MPa, yield strength of ～283 MPa and elongation of ～4.2% owing to collective effects of dispersion and grain refinement strengthening as well as high degree of densification. This study can readily offer reference values for laser additive manufacturing of other metal matrix composites to obtain a good compromise of strength and ductility by tuning reinforcement fraction.
关键词： Selective laser melting (SLM),Mechanical property,Al-based composites,Grain refinement,TiB2 ceramic
更新于2025-09-23 15:21:01
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Structural and optical properties of Gd+3 doped Bi2O3-GeO2 glasses and glass-ceramics
摘要： The gadolinium doped Bi2O3-GeO2 glasses and glass-ceramics have been synthesized by melt quenching and heat treatment. Structural and optical properties of prepared glasses and glass-ceramics have been examined by X-ray diffraction (XRD), Fourier transform infrared, absorption and emission measurements. XRD results have shown that the precipitated crystalline phases in glass-ceramics samples are Bi2GeO5, Bi2Ge3O9 and Bi4Ge3O12. [BiO3] and [GeO4] units are the main structural units present in Bi2O3-GeO2 glass and glass-ceramic network confirmed by IR spectra. Optical band gap values of prepared glass and glass-ceramic systems obtained from absorption spectra vary from 2.01 to 3.34 eV. The optical band gap values of glasses are larger than glass-ceramics. Bi2O3-GeO2 glass-ceramics have higher density values than glasses and densities present an increase with the elevated Gd3+ content. It is suggested that the luminescence under 366 nm excitation has been ascribed to different Bi-related emission centers. The CIE color coordinates and CCT values obtained under 366 nm excitation confirm that the Gd3+ doped bismuth germanate glasses and glass-ceramics exhibit white light emission. The most promising material for white light emitting applications within our research is found to be GC-2Gd with coordinates of (0.327, 0.314) and a CCT of 5753 K.
关键词： glass,bismuth,glass-ceramic,Gadolinium,white light,Bi2O3-GeO2
更新于2025-09-23 15:21:01
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai, China (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Batch-Mode μUSM Process for Surrounding Air Cavity and TCV Holes of AlN Ceramic Substrate Application for Patch Antenna
摘要： Narrow bandwidth of miniaturization patch antenna caused by substrate material severely limits its applications, fabricating air cavity on AlN ceramic substrate for decreasing its dielectric constant is a potential method for increasing the bandwidth. But it’s a critical challenge for simultaneous fabricating of surrounding air cavity and TCV holes on AlN ceramic substrate with high precision. This paper presents a patch antenna on AlN ceramic substrate with surrounding air cavity and TCV holes. And its key process of surrounding air cavity and TCV holes fabrication on AlN ceramic is developed by batch-mode μUSM. AlN ceramic simple with step depth of surrounding air cavity and TCV blind hole is machined simultaneously. Its machining feature resolution and surface roughness are below 1μm and Ra 200nm respectively, machining removal rate is higher than 4.5μm/min. The patch antenna property is simulated and analyzed, the results show the increment of bandwidth reach up to 68.42% because of the surrounding air cavity existing.
关键词： AlN ceramic,simultaneous machining,patch antenna,surrounding air cavity and TCV holes,batch-mode μUSM
更新于2025-09-23 15:21:01
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Low-temperature co fired ceramic materials with three different dielectric constants
摘要： A new type of low-temperature co-fired ceramic (LTCC) material with a medium dielectric constant was developed in this study (MK, εr = 20.9). MK can be co-fired with a high-dielectric-constant material (HK, εr = 44.5) and a low-dielectric-constant material (LK, εr = 8.1) previously reported. Glass and ceramic materials similar to HK and LK were used. The compositions of glass and ceramic materials for MK were designed to set the adequate dielectric constant and low-temperature coefficient of the dielectric constant (τεr). The coefficient of thermal expansion (CTE) was matched with those of both the previous materials. MK was confirmed to match well electrically with both the previous materials, had no mechanical defects, and showed minimal inter-diffusion. With the addition of MK, the three types of LTCC material system contribute to the enhancement of the performance and the downsizing of electronic components for high-frequency communication.
关键词： electronic components,high-frequency communication,dielectric constant,co-firing,low-temperature co-fired ceramic
更新于2025-09-23 15:21:01
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ANALYSIS OF MULTIPLICATION CHARACTERISTICS OF COAXIAL WAVEGUIDE LOADED CERAMIC UNDER EXTERNAL ELECTRIC FIELD
摘要： Multipacting is electron discharge that occurs in components operating in RF high-power electromagnetic fields. In this paper, we will study a new coaxial structure with a ceramic window. A similar structure is utilized in many high power devices for power transfer. Due to the multipactor effect, it will generate huge heat and cause damage to the window, ultimately affect the performance of microwave devices. In order to suppress the surface multipactor effect and improve the transmitting power, the application of an external DC bias is analyzed and simulated. A Monte Carlo algorithm is used to track the secondary electron trajectories and study the multipactor scenario on the surface of a ceramic window in a coaxial line by using 2-D particles distribution code. Since secondary electron multiplication needs to meet specific resonance conditions, an appropriate DC bias will generate a compensating trajectory and collision, which can suppress the secondary electron avalanche. The optimal value of this external bias voltage that will avoid the multipactor phenomenon in the coaxial line will be calculated by simulation in MATLAB.
关键词： DC bias,Coaxial waveguide,Monte Carlo simulation,Ceramic window,Multipacting
更新于2025-09-23 15:19:57
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Parameter Studies of Ceramic MEMS Microhotplates Fabricated by Laser Micromilling Technology
摘要： This paper presents a modeling of technology aspects for fabrication ceramic microelectromechanical systems (MEMS) microhotplate and surface mounting device (SMD) packaging for (MOX) gas sensors applications. Innovative claims include: demonstration of flexible opportunities for new fabrication process flows based on laser micromilling tech; modeling of power consumption MEMS microhotplate depending on the thickness and topology; demonstration of necessity changing thick film technology of metallization to vacuum sputtering by reducing of power consumption. The results show possibility to fast fabrication of different topologies for ceramic MEMS microhotplate in form-factor of SOT-23 type SMD package.
关键词： thick film technology,modeling,microhotplate,MEMS,ceramic
更新于2025-09-23 15:19:57
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Handbook of Smart Photocatalytic Materials || Sustainable photocatalytic porcelain gr??s slabs active under LED light for indoor depollution and bacteria reduction
摘要： The photocatalytic performances of TiO2-based and doped Ag-TiO2-based porcelain grés ceramic tiles as self-cleaning materials developed by digital printing process were investigated. The photoactive tiles coated with doped Ag-TiO2 K1077 showed better photocatalytic efficiency than tiles coated with TiO2 K1077 for the degradation of NOx and ethanol due to the better light absorption and higher electron–hole pairs separation caused by Ag nanoparticles. The total mineralization of EtOH to CO2 was proved. The photoactive tiles also exhibited an excellent efficiency for the densification of E. coli and S. aureus. These experimental data manifested the efficient and durable water and air treatment/densification using Ag-TiO2-based porcelain grés ceramic tiles, which may be significant to future use as self-cleaning materials.
关键词： LED light,bacteria reduction,porcelain grés ceramic tiles,photocatalytic,depollution,Ag-TiO2,TiO2,self-cleaning
更新于2025-09-23 15:19:57
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High peak power, high-repetition rate passively Q-switching of a holmium ceramic laser
摘要： We demonstrated a high peak power, high repetition rate Cr2+:ZnS passively Q-switched (PQS) Ho:YAG ceramic laser. Particularly, the influence of the initial transmission of the saturable absorber (SA) on the laser performance was investigated with two kinds of SAs. Finally, the laser generated average output power of 10.3 W and the stable 13.3 ns, 1.02 mJ pulses were achieved at a 10.1 kHz repetition rate. In addition, the highest peak power of 75.9 kW was obtained, to our best knowledge, which was also the highest peak power achieved in a ~2 μm PQS ceramic laser, corresponding to the intra-cavity peak power of 0.23 MW.
关键词： passively Q-switched (PQS),ceramic materials,high-peak power
更新于2025-09-23 15:19:57
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Q-Switched and Mode-Locked Nd/Cr:YAG Ceramic Pulse Laser
摘要： A mode-locked and Q-switched short pulse laser using the Nd3+/Cr3+:YAG ceramic has been constructed with a SESAM and Cr4+:YAG crystal optical switch based on excite state absorption (ESA). Laser oscillations of the pulse laser were observed experimentally. The Nd/Cr:YAG ceramic laser has a high conversion e?ciency from white light (such as lamp light or solar light) to the laser. The Nd/Cr:YAG ceramic has a higher laser gain than the Nd:YAG laser for the same pumping power. The laser oscillation can be obtained very easily. A single-mode-locked laser pulse with fast modulation on the order of 100 ps was obtained in some pump power regimes when using the Cr4+:YAG crystal. The obtained pulse duration of the short pulse was a few hundred ps. A maximum peak power of 60 kW was obtained when using a SESAM. The same level of peak power (60 kW) was also obtained when using the Cr4+:YAG crystal.
关键词： Q-switched,Nd/Cr:YAG ceramic,mode-locked,pulse laser,Cr4+:YAG crystal,SESAM
更新于2025-09-23 15:19:57