共查询到20条相似文献,搜索用时 109 毫秒
1.
2.
3.
通过田间试验研究了旱地全膜覆盖垄作集雨节水栽培方式对旱地花椰菜产量和水分利用效率的影响。结果表明:秋季全膜双垄沟显著提高旱地花椰菜定植时和结球期的土壤贮水量,促进了花椰菜的生长;秋季全膜双垄沟的产量和水分利用效率为69663.42kg·hm-2和245.26kg·hm-2·mm-1,较春季全膜垄上双沟、春季全膜双垄沟、春季垄上单沟、春季全膜微集流沟、春季平覆膜、春季半膜微集流沟、春季半膜垄作(ck)分别提高3.26%~12.33%和1.89~6.57%,差异均达显著水平;秋季全膜双垄沟提高了旱地花椰菜的产量和水分利用效率,可作为旱地花椰菜的主要栽培方式。 相似文献
4.
5.
6.
7.
针对"水窗"波段(280~540eV)对多层膜反射镜的应用需求,在Sb的M5吸收边(525.5eV)附近,选择Co和Sb作为该能点的多层膜材料组合,优化设计膜系结构。采用直流磁控溅射方法制备了Co/Sb多层膜,通过在溅射气体氩气中引入氮气作为反应气体,多层膜界面粗糙度明显减小。利用X射线掠入射反射(GIXRR)测试多层膜结构,并在北京BSRF同步辐射3W1B实验站测量了反应溅射前后的多层膜反射率(SXR),结果表明:氮气含量为25%时的界面粗糙度最小,反射率从无反应溅射的7.2%提高到11.7%。 相似文献
8.
9.
应用化学处理方法对去湿机的蒸发器施行化学处理,使其翅片表面形成一种亲水性膜(厚度为0.5~1μ)。通过在去湿机上进行对比试验的结果表明,采用亲水性膜可以提高去湿量11.5%。本文介绍了对比试验结果,并从理论上对亲水性膜提高去湿量的原因进行了分析。 相似文献
10.
11.
12.
E. E. Feldshtein M. A. Kardapolova R. Gaida B. Khorodyski O. V. Kaval’chuk 《Journal of Friction and Wear》2013,34(2):137-141
The tribological properties of the coatings based on fine-grained VK6-M hard alloy, chromium, and molybdenum have been investigated. The coatings were obtained by the electrospark deposition followed by the laser treatment. The electric spark deposition does not affect the coefficient of friction and temperature in the friction zone of the coated surface in contrast to steel 45 surface. Additional laser treatment reduces the dispersion of the friction coefficients and temperatures, but hardly alters their level. The wear rate of the coatings increases in the direction VK6-M → Cr → Mo → steel 45. A hard alloy coating is most effective, since the wear rate decreases as much as 15 times compared to steel 45. The wear rate of the coatings based on chromium and molybdenum is 1.7 and 1.4 times lower than that of steel 45. The laser treatment reduces the wear rate even more, i.e., by 70% for the coating based on the hard alloy and 3.5 and 3 times, respectively, for coatings based on chromium and molybdenum. 相似文献
13.
半导体激光器腔面全介质涂层的研究 总被引:2,自引:0,他引:2
通过对GaAs/GaAlAs激光器谐振腔前、后腔面蒸镀2rO2和ZrO2、MgF2的工艺过程,从理论和实验上分析涂层特性,透射率、反射率分别由无膜时的68%、32%,镀膜后提高到94%、95.0%以上,提高了激光输出功率和工作寿命,保护了器件端面。 相似文献
14.
Liu Y Gottwald T Havener CC Howe JY Kiggans J Mattolat C Vane CR Wendt K Beene JR 《The Review of scientific instruments》2012,83(2):02A904
This report describes the efforts made to develop a resonant-ionization laser ion source based on tunable Ti:sapphire lasers for nuclear physics and astrophysics research at Holifield Radioactive Ion Beam Facility. Three Ti:sapphire lasers have been upgraded with individual pump lasers to eliminate laser power losses due to synchronization delays. Ionization schemes for 14 elements have been obtained. Off-line studies show that the overall efficiency of the laser ion source can be as high as 40%. TaC surface coatings have been investigated for minimizing surface and bulk trapping of the atoms of interest. 相似文献
15.
Optical coatings for fiber lasers 总被引:1,自引:1,他引:0
1Introduction HighPowerFiberLasers(HPFLs)and HighPowerFiberAmplifers(HPFAs)promise anumberofbenefitsintermsoftheirhighopti calefficiency,degreeofintegration,beamquali ty,reliability,spatialcompactnessandthermal management.Thesebenefitsaredrivingtherap idadoptionofHPFLsinanincreasinglywide rangeofapplicationsandpowerlevelsranging fromafewWatts,forexampleinanalyticalap plications,tohigh power>1kWmaterialpro cessing(machiningandwelding)applications.Insilica,neodymium(Nd3+),ytterbium(Yb3+… 相似文献
16.
为提高钛合金的高温抗氧化性能,采用激光熔覆原位自生技术,在TC4钛合金表面自行设计并制备了原子百分比为Ti∶Al∶Si=41∶41∶18和Ti∶Al∶Si=35∶35∶30的两种涂层。通过XRD、OM、SEM表征了涂层的微观组织和物相组成;借助管式电阻炉测试了涂层和基体试样在800℃×24h×5次循环氧化条件下的高温抗氧化性能;结合氧化增重和氧化动力学曲线分析了涂层的高温抗氧化机理。结果表明,涂层主要由Ti5Si3、Ti7Al5Si12、Ti3Al、TiAl和TiAl3等物相组成。涂层中没有出现一般激光熔覆所产生的外延生长柱状晶组织,全部为细小等轴晶。在800℃×24h×5次循环氧化条件下,TC4基材单位面积的氧化增重约为35.1mg·cm-2,涂层的约为2.8mg·cm-2和3.3mg·cm-2。两种涂层的高温抗氧化性能较钛合金基材分别提高了12.5倍和10.6倍。激光熔覆原位自生Ti-Al-Si复合涂层能明显改善TC4钛合金的高温抗氧化性能。涂层抗氧化性改善的机理,一方面是表面生成了连续致密的TiO2、Al2O3、SiO2氧化层,阻碍了氧扩散;另一方面是提高了氧化层的黏附性,使氧化层不易从涂层表面剥落,对涂层未氧化部分起到了很好的保护作用。 相似文献
17.
Nickel aluminide (NiAl) intermetallic compound coatings were in situ synthesized from pre-placed mixed powders of Ni and Al by laser cladding. The phase composition and microstructure of the NiAl coatings were studied by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The effects of laser cladding parameters on the microstructure and friction and wear behavior of the NiAl coatings were investigated. It has been found that laser power density had a crucial influence on the microstructure and friction and wear behavior of NiAl coatings. Namely, the NiAl coatings synthesized under a lower power density have more dense and fine microstructure, and lower friction coefficient and wear rate. Besides, the friction and wear behavior of the laser cladding NiAl coatings is highly dependent on applied normal load and sliding speed; and the resulting coatings sliding against Si3N4 in a ball-on-disc contact mode is more suitable for tribological application at a moderate normal load of 3–7 N and sliding speed of 0.16–0.21 m/s. 相似文献
18.
激光重熔纳米SiC复合陶瓷涂层组织和性能研究 总被引:8,自引:0,他引:8
研究了WC/Co-NiCrAl等离子复合陶瓷涂层、激光重熔等离子涂层、激光渗入纳米SiC涂层的组织结构、耐磨性能。结果证明:在所定的工艺参数下,等离子喷涂层组织呈层片状,层间为机械结合界面;经激光重熔后,激光作用区涂层组织细化,孔隙率降低,耐磨性能是原等离子涂层的1.3倍;渗入纳米SiC后,组织进一步细化,孔隙率进一步降低,SiC颗粒仍处于纳米尺度,分布在粗颗粒表面及粗颗粒之间,其耐磨性能是原等离子涂层的2.6倍。 相似文献
19.
20.
本文从膜系设计、材料选择、制备工艺及测量,较全面地论述了10.6μm高能激光高反膜的研制过程。研制成一种性能良好的三元混合氟化物(BaF2,SrF2,CeF3)低折射率材料,并对由此材料蒸镀的膜层进行了晶体结构分析。已研制出反射率分别达99.0%、99.3%和99.5%的保护银膜、增强银膜和高增强银膜等三种高能激光高反膜,反射率是用自行研制的测量装置测定的。 相似文献