共查询到20条相似文献,搜索用时 0 毫秒
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Yu. V. Bykov S. V. Egorov A. G. Eremeev I. V. Plotnikov K. I. Rybakov A. A. Sorokin V. V. Kholoptsev 《Technical Physics》2018,63(3):391-397
We report on the results of the analysis of the effect of flash sintering, which is observed upon heating compacted powder materials by high-intensity microwave radiation. Ceramic samples of Y2O3, MgAl2O4, and Yb: (LaO)2O3 were sintered to a density exceeding 98–99% of the theoretical value during 0.5–5 min without isothermal hold. The specific microwave power absorbed volumetrically in the samples was 20–400 W/cm3. Based on the analysis of the experimental data (microwave radiation power and heating and cooling rates) and of the microstructure of the obtained materials, we propose a mechanism of flash sintering based on the evolution of the thermal instability and softening (melting) of the grain boundaries. The proposed mechanism also explains the flash sintering effect observed when a dc or a low-frequency ac voltage is applied to the samples. The microwave heating makes it possible to implement flash sintering without using electrodes for supplying energy to the articles being sintered. 相似文献
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Jirun Luo Christian Hunyar Lambert Feher Guido Link Manfred Thumm Paola Pozzo 《International Journal of Infrared and Millimeter Waves》2004,25(9):1271-1283
Based on electromagnetic induction heating, an interaction model of microwaves with powdered metal has been established. The formulae of attenuation coefficient, heating rate and heating conversion efficiency are obtained and analyzed. The results of calculations show that millimeter waves may be able to overcome the obstacle caused by smaller skin depth and have strong advantages for the microwave heating of powdered metals. Experiments are done for comparison with present theory. 相似文献
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In high power laser system, laser mirror is the core and the most sensitive optical component, which influences the increase of laser power and the quality of laser. Absorption of light at mirrors causes wavefront distortions through the thermal deformations of substrates. The analytical solutions of the two-dimensional transient thermal theory of high power laser mirrors are developed, copious graphical results in our case are presented, and the predicted results are compared with those of the experiment. 相似文献
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JETP Letters - The interaction of an ultrashort (~10 fs) laser pulse with a relativistic intensity (≳1018 W/cm2) with a cluster medium characterized by a random distribution of large,... 相似文献
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简介了激光快速烧结陶瓷技术;测量了采用激光快速烧结技术和传统电炉烧结技术制备的(Ta2O5)1-x(TiO2)x陶瓷的相对介电常数和介电损耗;分析了这两类试样的激光拉曼光谱和粉末XRD谱;发现:(Ta2O5)1-x(TiO2)x陶瓷经激光快速烧结后产生了新相,从而导致相对介电常数大幅度提高。 相似文献
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Basalt is an igneous rock originating from the cooling and solidification of magma and covers approximately 70% of Earth’s surface. Basaltic glass melting in the deep Earth is a fundamental subject of research for understanding geophysics, geochemistry, and geodynamic processes. In this study, we design a laser flash heating system using two-dimensional, four-color multi-wavelength imaging radiometry to measure the basaltic glass melting temperature under high pressure conditions in diamond anvi... 相似文献
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新型电光陶瓷调Q光纤激光器 总被引:2,自引:2,他引:0
报道了基于OptoCeramic(R)电光陶瓷材料的新型调Q光纤激光器.采用976 nm半导体激光器作为抽运源,电光陶瓷调制器作为Q开关,峰值吸收系数1200 Db/m的高掺杂镱纤作为增益介质构成环形腔激光器.增益光纤的高掺杂浓度使得激光器的腔长得到缩短,输出光脉冲的宽度得到压缩.通过调节电光元件的电压,控制材料的折射率,调节谐振腔的损耗,实现Q开关作用.实验中通过改变腔长、抽运功率和重复频率,研究了脉冲的输出特性.获得最窄脉宽104 ns,重复频率3~40 kHz连续可调的调Q脉冲输出. 相似文献
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Leonov S. O. Bastamova M. A. Sidorov N. V. Palatnikov M. N. Gorelik V. S. 《Optics and Spectroscopy》2019,127(4):629-633
Optics and Spectroscopy - Second harmonic generation is studied in samples of LiTaO3 powder ceramics with different lithium concentrations (48.8 and 49.3%) under excitation by a femtosecond laser... 相似文献
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Gozhalskiy D. Kormilina T. Zakharov V. Cherevkov S. Dubavik A. Veniaminov A. 《Optics and Spectroscopy》2018,125(5):769-772
Optics and Spectroscopy - The effect of temperature on luminescence of semiconductor nanocrystals is used for monitoring local heating of specimens studied at laser scanning microscope. The... 相似文献
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Egorov S. V. Eremeev A. G. Plotnikov I. V. Rybakov K. I. Sorokin A. A. Kholoptsev V. V. 《Radiophysics and Quantum Electronics》2022,65(3):219-228
Radiophysics and Quantum Electronics - Using the method of sintering by microwave heating at a rate of 10–100°C/min to a temperature of 1250 °C without isothermal hold, we obtain... 相似文献
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在服役环境中,超高声速飞行器表面与空气剧烈摩擦导致温度极高。超高温陶瓷相较于一般陶瓷而言具有高熔点和良好的抗氧化烧蚀性能,是目前极具前景的热防护材料之一。采用放电等离子两步烧结工艺将ZrB2纳米粉末和SiC粉末在1700℃下制备超高温陶瓷材料ZrB2-20%SiC,通过纳米压痕微观实验、三点弯实验研究其力学性能及其在高温环境下的氧化行为,着重分析1000、1200、1400和1600℃4种不同氧化温度下ZrB2-20%SiC超高温陶瓷的氧化表面、氧化截面和氧化层厚度。结果表明:ZrB2-20%SiC超高温陶瓷的硬度为18 GPa,弹性模量为541 GPa,断裂韧性为5.7 MPa·m1/2;当氧化温度为1600℃时,超高温陶瓷内部的SiC由被动氧化转变为主动氧化,并且随着氧化温度升高,超高温陶瓷氧化层厚度与氧化温度呈正相关。 相似文献
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Yu. A. Pirogov 《Radiophysics and Quantum Electronics》2003,46(8-9):594-603
We briefly review the M. V. Lomonosov Moscow State University developments on the millimeter-wave radio imaging using the super-resolution regime in systems comprising single-channel receivers and sensor arrays. A tenfold enhancement in the spatial resolution in the 8-mm range is achieved by the mathematical processing of some natural radio thermal scenes with allowance for the precisely measured point-spread function of the imaging system. It is shown that the super-resolution is limited by the signal-to-noise ratio of an observed scene. 相似文献