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901.
Recently, interest in steel alloyed with∼1% Al increased. These materials are expected to show a higher resistance against
oxidation at high temperatures which will improve their performance when used as high-speed-steels. Furthermore, efforts have
been made to combine the advantages of Al-steels with those of powder-metallurgic methods like hotisostatic-pressing (hip).
This should result in a better macro- and microscopic homogeneity of the distribution of all compounds, yielding less waste-production
and a longer life-time of products.
In order to gain deeper insights in the process of “hipping” of the considered material and to see the distribution of both
main as well as trace components, 2D and 3D-SIMS measurements of the material were performed before and after having undergone
the hip process.
The measurements showed enrichments of Na, K, Mg, Ca, and S at the particle boundaries before as well as after the hip-process.
In the hipped material, the enrichments are significantly stronger in the spatial domains in-between larger particles. They
also reveal, that the concentration of C is not equal in all particles and that the particles are covered with an Al2O3-layer which is not dispersed by the hip-process. There were also found small (∼50–100 nm) nitride-precipitates before as
well as after the hip-process. 相似文献
902.
903.
Miniature Boat Fabrication with Striking Loading Capacity in Seawater from Hydrophobic Steel Mesh
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Zai-xing Jiang Ming-qiang Wang Hao Cheng Hai-bao Lv Yong-tao Yao Yong-ping Bai Lu Shao Yu-dong Huang 《化学物理学报(中文版)》2015,28(6):762-766
A superhydrophobic steel mesh film was prepared by combination of macro-scale rough sur-face and low surface energy material treatment through a facile coating method. The contact angle for seawater is measured to be as high as 130.16o. A reformed Cassie-Baxter equation was applied for the theoretical predictions of this novel material for the first time. Good agreement between the predictions and experiments was obtained. The loading capacities of these boats, fabricated from the resulting hydrophobic steel meshes, were also character-ized. The highest loading weight about 17.50 g was obtained by the steel mesh treated by 2.0wt% (heptadecafluoro-1,1,2,2,-tetradecyl)trimethoxysilane solution. The striking loading capacity of this miniature boat may be attributed to the air film trapped around the mesh surface. This novel superhydrophobic steel mesh material have wide applications on medical materials, marine materials and smart materials. 相似文献
904.
针对定向红外对抗系统对中波红外激光器在激光波段、激光功率、激光束散角、激光重复频率以及调制波形等方面的具体要求,通过对光泵半导体激光器、量子级联激光器和基于光学参量振荡的固体以及光纤激光器的技术特点与发展现状的分析比较,和对双折射相位匹配与准相位匹配的特点和最新发展动态的梳理,提出用高功率高光束质量的1 064 nm固体激光器或光纤激光器泵浦基于掺氧化镁的周期极化铌酸锂晶体(PPMgLN)的光学参量振荡器的中波红外激光器方案,其波段转换效率可达到16%以上。 相似文献
905.
906.
907.
A single-longitudinal-mode continuous-wave Ho~(3+):YVO_4 laser at 2.05 μm pumped by a Tm-fibre laser
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We present a single-longitudinal-mode continuous-wave Ho~(3+):YVO_4 laser at 2.05 μm pumped by a Tm-doped fibre laser. Use of a cavity etalon enables spectral selectivity for single-mode operation. The highest power achieved in the single longitudinal mode at 2052.5 nm is 282 mW at a slope efficiency of 6.9%, corresponding to an optical conversion efficiency of 3.0%. These features demonstrate that this single-longitudinal-mode Ho:YVO_4 laser is suitable for use as a seed laser in some Lidar systems(e.g., coherent Lidar or differential absorption Lidar). To the best of our knowledge, this is the first report on such a single-longitudinal-mode Ho:YVO_4 laser at 2.05 μm. 相似文献
908.
Dody Ariawan M. S. Salim R. Mat Taib M. Z. Ahmad Thirmizir Z. A. Mohd Ishak 《Composite Interfaces》2018,25(2):187-203
This paper reports on the comprehensive characterisation of heat treated kenaf fibre (KF) and its composites. The kenaf fibres were modified by heating for 2.5–12.5 h inside a drying oven. Heat treatment produces an increase in the crystallinity index and fibre strength of KF. The highest value of KF strength was recorded by applying heat treatment of 10 h on KF. The heat treatment results in the partial removal of impurities/extractives on the KF surface which is detected by scanning electron microscopy and X-ray photoelectron spectroscopy. Atomic force microscopy results signify the decrease of roughness, the increase in peak area density and the increase of the adhesion force on the surface area of heat treated KF. The effect of the heat treatment in enhancing the interface bonding characteristics between the KF and unsaturated polyester matrix can be reflected by the interlaminar shear strength (ILSS) and dynamic mechanical analysis value of the composites. The flexural properties of the composites showed a similar trend to ILSS. However, the fracture toughness revealed contrasting results. Water absorption induced a drastic loss of the mechanical properties of the composites albeit better retention of properties was observed in the case of heat-treated KF composites. 相似文献
909.
以氧化处理的碳纤维刷(Carbon fibre brush,CFB)作阴极材料,提出海水超级电容溶解氧电池(Seawater battery with electrochemical capacitance, SWB-EC)概念,并制造了3台联用实海测试样机. 分别由循环伏安和稳态恒流放电方法研究了氧化处理前后的CFB和镁合金牺牲阳极的放电性能. 结果表明:氧化处理的CFB具有准电容特性,在动态海水中其氧阴极还原反应(Oxygen reduction reaction, ORR)活性比未处理的CFB有大幅度提高;镁合金牺牲阳极的开路电位为-1.74 V,工作电位高,溶解较均匀. 用以上阴、阳极材料制成3台联用样机作连续实海放电测试,经运行2个月,相关实验数据分析表明:与商品化海水电池SWB1200初步相比,该海水超级电容溶解氧电池具有更高的体积比功率密度. 相似文献
910.
Electrical crosstalk-coupling measurement and analysis for digital closed loop fibre optic gyro
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The phase modulation and the closed-loop controller can
generate electrical crosstalk-coupling in digital closed-loop fibre
optic gyro. Four electrical cross-coupling paths are verified by
the open-loop testing approach. It is found the variation of ramp
amplitude will lead to the alternation of gyro bias. The amplitude
and the phase parameters of the electrical crosstalk signal are measured
by lock-in amplifier, and the variation of gyro bias is confirmed to
be caused by the alternation of phase according to the amplitude of
the ramp. A digital closed-loop fibre optic gyro electrical
crosstalk-coupling model is built by approximating the electrical
cross-coupling paths as a proportion and integration segment. The
results of simulation and experiment show that the modulation signal
electrical crosstalk-coupling can cause the dead zone of the gyro when a
small angular velocity is inputted, and it could also lead to a
periodic vibration of the bias error of the gyro when a large angular
velocity is inputted. 相似文献