三价铬镀铬工艺初探

传统的镀铬是在含有六价铬的电镀液中进行的,六价铬对环境严重的危害,促进了三价铬镀铬工艺的发展.在铁基体上选取不同的三价铬镀铬配方进行试验,以铅板或石墨为阳极,20钢试片作阴极,对试片除油除锈后,直接进行三价铬镀铬,经过对镀层的外观、厚度及结合力的比较取舍,获得了外观及结合力较好的配方:52g/LCr3 ;40g/L KCl;10g/L KBr;46g/L HCOOH;53g/L NH4Cl;150g/L(NH2)2CO;10g/L H3BO3及少量的添加剂,以阳极石墨为基础,研究了不同种类及不同用量的润湿剂对镀层外观和孔隙率的影响,最终选定了对于三价铬镀铬配方较佳的润湿剂及其用量范围.对镀铬层用碳酸钠和磷酸钠进行中和浸渍,时间为3～5 min,可以减轻三价铬镀层发黄的问题.该工艺条件:DK=10～15 A/dm2,10～20℃带电下槽,pH值为0.5～1.0,电镀液的稳定性为12 A@h/L.镀层细致、光亮、孔隙率低,而且可以在常温下操作,节约能源.  

Zonation and assessment of frozen-ground conditions for engineering geology along the China-Russia crude oil pipeline route from Mo'he to Daqing, Northeastern China

The China-Russia Crude Oil Pipeline (CRCOP), 813 mm in diameter, is designed to transport 603,000 barrels of Siberian crude oil per day across 1030 km of frozen-ground. About 500 boreholes, with depths of 5 to 20 m, were drilled and cored for analyses, and the frozen-ground conditions were evaluated. After detailed surveys and analyses of the permafrost conditions along the pipeline route, a conventional burial construction mode at a nominal depth of 1.5 m was adopted. This paper discusses the principles and criteria for the zonation and assessment of the frozen-ground environments and conditions of engineering geology for the design, construction, and operation of the pipeline system based on an extensive and in-depth summary and analysis of the survey and exploration data. The characteristics of pipelining crude oil at ambient temperatures in the permafrost regions and the interactive processes between the pipeline and foundation soils were taken into account. Two zones of frozen-ground environment and conditions of engineering geology, i.e., seasonally-frozen-ground and permafrost, were defined on the basis of the regional distribution and differentiations in frozen-ground environments and conditions. Then, four subzones of the permafrost zone were classified according to the areal extent, taking into consideration the temperatures and thicknesses of permafrost, as well as changes in vegetation coverage. In the four subzones, 151 sections of engineering geology were categorized according to the ice/moisture contents of the permafrost, as well as the classes of frost-heaving and thaw-settlement potentials. These 151 sections are comprehensively summarized into four types for engineering construction and operation: good, fair, poor, and very poor, for overall conditions of engineering geology. The zonation, assessment principles and criteria have been applied in the design of the pipeline. They have also been used as the scientific bases for the construction, environmental management, operation and maintenance/contingency plans.  

马来酸酐改性天然橡胶对碳酸钙/天然橡胶复合材料力学行为的影响

以过氧化二异丙苯(DCP)为引发剂,在转矩流变仪中自制马来酸酐(MAH)接枝改性天然橡胶(NR)(MNR),将其作为超细碳酸钙/天然橡胶复合材料(CaCO3/NR)的改性剂,研究了MNR对于CaCO3/NR复合材料的力学性能、应力软化效应以及应力弛豫行为的影响。研究结果表明,MNR改性后CaCO3/NR复合材料较之未改性复合材料拉伸强度、撕裂强度和硬度等力学性能均有所提高,应力软化效应加剧,应力弛豫程度和速度降低,力学行为研究结果证实MNR可有效改善CaCO与NR基体间的界面粘合。  

基于嵌入式的视觉巡线机器人系统设计

 常用的巡线方法,如光电检测巡线,易受环境光和场地等影响,适应性不强.因此,提出并设计了一种新型的巡线技术,应用于自主巡线机器人.该机器人系统主要由核心模块、视频图像采集模块、人机交互模块以及电机驱动模块等组成.详细阐述了各个模块的作用、原理以及每个模块的具体实现.该系统经实践验证，实时性强，稳定性好，控制精度高.   

基于工业机器人的电梯厅门立式装箱系统的研制

目的为了提高电梯厅门的包装效率,降低工人劳动强度,应某电梯企业的要求提出一种电梯厅门自动包装装箱方案,并开发基于工业机器人的电梯厅门立式装箱系统。方法该系统主要由门板翻转机、箱体上线输送机、箱体定位输送机及装箱机器人组成,通过门板翻转机将电梯厅门呈立式姿势,空箱通过箱体上线输送机输送至箱体定位输送机进行定位,再由装箱机器人抓取厅门并将其装入空箱内,该系统自动完成空箱的上线、定位以及厅门装箱,实现电梯厅门装箱的自动化。结果根据箱子宽度的不同,装箱成功率也有所不同,成功率最小为95.5%,最大为100%,均满足要求。结论该系统在保证电梯厅门装箱效率的前提下,大大降低了工人的劳动强度,提高了系统的自动化程度。  

运用WITNESS的医院排队模型仿真

根据排队论经验设定医院排队模型分布类型,运用2检验对设定分布类型进行检验,确定医院排队模型最终分布类型,构建完整的统计检验过程,同时运用运筹学排队论相关理论,计算出医院排队模型队长、等待时间等因素,对仿真模型进行验证,最终通过Witness仿真软件对医院排队及服务模型进行仿真分析,得出各岗位工作状况,为医院决策提供依据。  

外腔半导体激光器阵列波长稳定的实验研究

自由运行的半导体激光器列阵输出激光谱线较宽、中心波长易漂移.为此,本文采用体全息光栅(VBG)构成外腔半导体激光器阵列(EcLD)系统,利用体光栅能够稳定波长、压窄线宽的特点,从而克服上述缺点.实验表明:采用了VBG外腔反馈后,在最好的情况下,LDA的输出光谱宽度从自由运行时的2.3 nm压窄到了O.96 nm;在测试的环境温度变化范围内(14～3l℃),LDA的峰值波长稳定在体光栅布拉格波长808 nm处,输出光的线宽维持在1.14 nm之下;并且,在测试的偏置电流变化范围内(7-13A)峰值波长和谱宽无明显变化.  

电化学方法研究腐蚀介质对热浸镀Al-Zn-Si-RE合金镀层腐蚀行为的影响

为研究腐蚀介质对热浸镀Al-Zn-Si-RE合金镀层腐蚀行为的影响,利用电位-时间曲线、Tafel曲线和电化学阻抗谱技术研究了合金镀层在不同盐度、温度和pH值的NaCl溶液中的电化学腐蚀行为,利用扫描电子显微镜(SEM)观察不同腐蚀介质下极化测试后合金镀层的腐蚀形貌.结果表明:随着NaCl溶液温度或浓度的提高,热浸镀Al-Zn-Si-RE合金镀层均出现腐蚀电位负移、镀层腐蚀倾向增大、腐蚀速率增加、腐蚀抗力降低的现象;此外,酸性和碱性条件均会加快镀层在NaCl溶液中的腐蚀速率,其中镀层在pH值为11.0的碱性条件下,腐蚀电流最大,阻抗谱容抗弧幅值最小,说明镀层腐蚀速率最快,耐蚀性最差.  

Numerical and experimental investigations in electromagnetic riveting with different rivet dies

In this work, the numerical simulations and electromagnetic riveting (EMR) experiments were conducted to investigate microstructure evolution and the forming mechanism of adiabatic shear bands (ASBs). And the effects of rivet dies on microstructure distributions in formed heads and mechanical properties of riveted structures were systematically explored. The impact velocity and deformation distribution results demonstrated that the proposed numerical method was accurate and reliable. The simulation results showed the slope angle of rivet dies notably affected the plastic flow of materials, and then determined the microstructure distribution in formed heads. The combined effects of inhomogeneous plastic flow and thermal softening were accounted for the forming of ASBs. The formed heads had two obvious ASBs (upper and lower ASB) for the 40° rivet die and flat rivet die. The formed heads only had the lower ASB and no clear upper for the 60° rivet die and 80° rivet die. The pull-out test results showed that the specific rivet die could improve the mechanical properties of the EMR joints, which contribute to the engineering applications of EMR riveted structures.  

VO2/TiN Plasmonic Thermochromic Smart Coatings for Room‐Temperature Applications

Vanadium dioxide/titanium nitride (VO₂/TiN) smart coatings are prepared by hybridizing thermochromic VO₂ with plasmonic TiN nanoparticles. The VO₂/TiN coatings can control infrared (IR) radiation dynamically in accordance with the ambient temperature and illumination intensity. It blocks IR light under strong illumination at 28 °C but is IR transparent under weak irradiation conditions or at a low temperature of 20 °C. The VO₂/TiN coatings exhibit a good integral visible transmittance of up to 51% and excellent IR switching efficiency of 48% at 2000 nm. These unique advantages make VO₂/TiN promising as smart energy‐saving windows.