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931.
Surface morphology and photoluminescence properties of ZnO thin films obtained by PLD 总被引:2,自引:1,他引:2
ZnO thin films on Si(111) substrate were deposited by laser ablation of Zn target in oxygen reactive atmosphere, Nd-YAG laser with wavelength of 1 064 nm was used as laser source. XRD and FESEM microscopy were applied to characterize the structure and surface morphology of the deposited ZnO films. The optical properties of the ZnO thin films were characterized by photoluminescence. The UV and deep level (yellow-green) light were observed from the films. The UV light is the intrinsic property and deep level light is attributed to the existence of antisite defects (Ozn). The intensity of UV and deep level light depends strongly on the surface morphology and is explained by the surface roughness of ZnO film. A strongly UV emission can be obtained from ZnO film with surface roughness in nanometer range. 相似文献
932.
Vision-based detection of MAG weld pool 总被引:2,自引:0,他引:2
Weld pool contains significant information about the welding process. The weld pool images of MAG welding are detected by LaserStrobe system. An algorithm for extracting weld pool edge is proposed according to the characteristics of MAG weld pool images. The maximum weld pool length and width are calculated. The measurement data can be used to verify the results of welding process simulation and to provide a good foundation for automatic control of MAG welding process. 相似文献
933.
934.
Superplastic solid state welding of steel and copper alloy based on laser quenching of steel surface 总被引:3,自引:0,他引:3
1 INTRODUCTIONThe copper and copper alloys possess a num ber of superior properties, such as excellent elec trical conductivity, excellent thermal conductivityand forming property, so the complex componentsof the steel, copper and copper alloy have comple mentary advantages on the economy and perform ance[1, 2]. But it is very difficult to realize the goodbonding of them by adopting routine fusion weld ing and braze because of a rather large difference inthe melting point, coefficient… 相似文献
935.
936.
ZHANGGuang-jun DAIJian-qiang WANGHui-ping YANMin-jie XIWen-long ZOUChang-gu GEDa-fang 《材料热处理学报》2004,25(5B):1004-1008
CO2 laser is adopted on the surface of austenitic stainless steel (1Cr18Ni9) to clad nickel based nanometer WC/Co composite coating. SEM, EDAX, XRD, AFM and Scratch Testers are adopted to conduct analysis and research on the microstructure, composition, phase and bonding strength of the coating. Results indicate that the microstructure of coating is metallurgically bonded with stainless steel base, eliminating porosities and cracks. The coating has a considerable quantity of nanometer particles visible with a granularity ≤100nm under a nanoscope atomic microscope. The bonding strength of the laser cladded coating is remarkably improved respectively compared with conventional hot-sprayed coating and spray welding. The nanometer effect of nanometer WC/Co introduced into the coating plays an important role in the laser cladding processes. 相似文献
937.
938.
939.
介绍了激光切割工艺的优点及数控激光切割机的基本构成。在此基础上,重点论述了数控激光切割机主机的构成部件及设计要点。 相似文献
940.
用OM、SEM等手段分析了不同激光焊接工艺参数下焊缝成形和其微观组织特征,并测试了焊缝的力学性能。结果表明:0.8mm厚钛合金板激光穿透焊离焦量范围约在-2mm~+2mm之间,最佳离焦量为-0.5mm。随焊接线能量的增大,焊缝熔宽和背面宽度都呈增大趋势,且背面宽度的增加更为显著。TC4合金焊缝为针状马氏体α′组成的网篮组织。随着焊接热输入量的增加,马氏体的形态由平行的单相针转变为多相针,分布更加密集和散乱。不同焊接工艺参数下接头的强度均高于母材,塑性低于母材。 相似文献