影响Ni—P合金镀层结合力因素的研究

本文用自制的划痕试验机研究了影响Ni-P合金镀层结合力的因素,分析了划痕试验时锭层开裂、剥离的情况,观察了镀后加热温度、基体硬度等对划痕形貌的影响规律,并用B-W公式计算了试样的结合力。结果表明,镀后加热温度越高,镀层厚度越厚,基体硬度越高,结合力越大。     

Understanding Spray Coating Process: Visual Observation of Impingement of Multiple Droplets on a Substrate

Spray coating is a facile deposition process with numerous existing and emerging applications. However, spray coating is a stochastic process comprising impingement of many droplets which upon impact on a heated substrate may dry or solidify individually or coalesce first to form a thin liquid film and then dry to yield a thin solid film. There is very limited knowledge on how this process occurs; therefore in this work, high speed imaging is used to visualize the spray coating process. Two model solutions including food-dye with properties like those of water, and poly (3, 4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT:PSS), a polymeric solution, are sprayed onto permeable glossy paper and regular impermeable glass substrates. Substrates are kept at room temperature and 80 °C elevated temperature. In some cases, a vertical ultrasonic vibration is imposed on the substrate to study its effect on the coating process. It is observed that the spray coating process is highly random and stochastic. A higher substrate temperature results in a better coating process in that a more uniform and defect-free coating forms. Imposed vibration in the case of glossy paper substrates results in better droplet spreading and more uniform coating. The results also show that under the conditions of these experiments, impinged droplets dry individually or as islands of multiple coalesced droplets to form a coating. In other words, at used spray flow rate and spray droplet size, a continuous thin liquid film does not form prior to drying even at room temperature. Further systematic studies and high magnification lenses are required to visualize and understand the details of the process.     

用划痕法测定TiN涂层结合力的影响因素

研究了影响划痕法测定 Ti N涂层结合力的因素 ,结果表明 :离子氮化处理能提高 Ti N涂层的临界载荷。随基体硬度提高和涂层厚度增加 ,Ti N涂层的临界载荷 Lc增高。而表面粗糙度增大 ,则临界载荷降低 ,当粗糙度大于0 .70 μm( Ra)时 ,则临界载荷无法得到确定值。以 M2钢为基体的 Ti N涂层的结合力高于以 3Cr2 W8V为基体的 Ti N涂层的结合力。     

Simulation of temperature distribution in hot filament chemical vapor deposition diamond films growth on SiC seals

In this study, the temperature and gas velocity distributions in hot filament chemical vapor deposition(HFCVD) diamond film growth on the end surfaces of seals are simulated by the finite volume method. The influence of filament diameter, filament separation and rotational speed of the substrates is considered. Firstly,the simulation model is established by simplifying operating conditions to simulate the temperature and gas velocity distributions. Thereafter, the deposition parameters are optimized as 0.6 mm filament diameter, 18 mm filament separation and 5 r/min rotational speed to get the uniform temperature distribution. Under the influence of the rotational speed, the difference between temperature gradients along the directions perpendicular to the filament and parallel to the filament becomes narrow, it is consistent with the actual condition, and the maximum temperature difference on the substrates decreases to 7.4?C. Furthermore, the effect of the rotational speed on the gas velocity distribution is studied. Finally, diamond films are deposited on the end surfaces of Si C seals with the optimized deposition parameters. The characterizations by scanning electron microscopy(SEM) and Raman spectroscopy exhibit a layer of homogeneous diamond films with fine-faceted crystals and uniform thickness. The results validate the simulation model.     

Mechanical properties and residue stress of four kinds of ZrC coatings prepared by chemical vapor deposition

Four kinds of ZrC coatings with nearly the same thickness have been successfully prepared on graphite substrate by chemical vapor deposition (CVD) through controlling the ratio of inlet reacting gases. From backscattered electron images, it can be inferred that ZrCIII coating has the best tightness of all coatings. Meanwhile, line energy spectrum curve shows that zirconium and carbon elements distribute uniformly along the normal direction of the ZrCIII coating. As for varied microstructures, the coatings show different mechanical properties and residue stress. The strength and elastic modulus of ZrCIII coating were up to 89.57 and 1 192.5GPa, respectively. Those make it near the level of diamond. Value of residue tensile stress of ZrC+C composite coating was only 7.729MPa and that of ZrCIII coatings was 349.632 MPa. The strong combination of small-size grains in ZrCIII coating plays a decisive role to the best mechanical properties. However, strong misfit of lattice between ZrCIII coating and substrate can induce high residue stress.     

高硬度耐热搪瓷的制备与性能

介绍了制备高硬度耐腐蚀搪瓷层的方法和提高搪瓷层硬度与耐腐蚀性的措施,在对钢板进行脱碳和酸洗预处理的前提下,采用一次涂搪法制备搪瓷．用金相显微镜和扫描电子显微镜观察搪瓷层与基板结合界面处的显微形貌,用X-射线衍射仪（XRD）分析搪瓷层的相结构,用显微硬度仪测试晶化处理前后搪瓷层的硬度,考察晶化处理对搪瓷层硬度的影响．实验结果表明：随烧结温度的提高,搪瓷层与基板的结合性增强;瓷的最佳烧结工艺是在970℃烧结5min．根据XRD分析结果可知,搪瓷层通过在920℃保温14min的晶化处理后出现NaAlSiO4和NaAlSi2O6相．在970℃烧结5min的搪瓷具有优异的性能,其硬度为7．30GPa高于一般搪瓷的硬度;耐热温度为700℃是化工部规定的搪瓷耐热温度的2倍;同时其热震温度为500℃是搪瓷化工设备标准规定耐温急变温度的2倍;耐酸等级为A级,耐碱质量损耗为1．793mg／cm^2．     

不同厚度下船舶板材高频感应自由弯曲成形

应用ANSYS软件建立高频感应自由弯曲有限元模型,研究了船板高频感应成形板厚对可加热温度、变形角度、应力、变形及冷却后的残余应力的影响。结果表明:不同厚度的船舶板材可加热温度皆在860℃以上进入奥氏体温度区。在无约束、忽略船板自重的情况下,不同厚度的船舶板材单面弯曲角度在10-2数量级;加热结束后,不同厚度的船舶板材的应力都达到屈服应力,发生了塑性变形。冷却结束后残余应力主要集中在线圈正下方。随着板厚的增加,可加热温度下降,并在中厚板区有波动;弯曲角度先增加,后减小;最大残余应力先减小,后增加。在给定加热频率和功率条件下,船板的高频感应加热变形的最有效厚度为14 mm。     

热障涂层应力场的微拉曼光谱技术测试研究

采用等离子体喷涂工艺制备了热障涂层实验样品,在不同高温下进行热循环氧化实验。再应用微拉曼光谱法测量了热障涂层样品内残余应力场大小,并分析了试样尺寸、热处理温度和陶瓷涂层厚度对残余应力的影响。经历20次热循环氧化实验后,测得陶瓷涂层内残余应力由初始压缩应力值(-30~-20 MPa)逐渐变化到(-15~15 MPa),与文献[3~7]结果比较一致。最后,用扫描电镜观察了试样截面形貌的变化。     

反射隔热涂料对轨道板温度及应力的影响

为了降低无砟轨道板板温及板内应力，缓解夏季高温期无砟轨道胀板导致的各类病害，使用钛白粉、玻璃微珠等组份配置了一种无砟轨道用反射隔热涂料；探究了各组份使用量的合理性，并在红外光及自然光下测试了其降温性能；分析了轨道板板表及内部温度差对轨道板内部应力的影响. 研究结果表明:该种涂料可在夏季高温期降低轨道板板表温度最高达16 ℃，可使轨道板板表与180 mm深处温度差由24 ℃下降至12 ℃，降幅约50%，并可有效降低轨道板应力0.4 MPa；该种涂料可有效降低因温度应力产生的各种轨道病害风险.      

真空镀膜技术在塑料表面金属化上的应用

塑料表面金属化将改善塑料的表面性质，使其具有塑料和金属两者的独特功能，真空镀膜技术是现代塑料表面金属化的主要技术之一．介绍了塑料真空镀膜技术原理及其常见的镀膜方法。分析了塑料作为真空镀膜基体材料的特殊性，阐述了真空镀膜技术在塑料表面金属化上的应用情况，并提出了目前的研究热点．     

Predictive Model for Corrosion Rate of Oil Tubes in CO_2/H_2S Coexistent Environment Part Ⅰ: Building of Model

Introduction　　Sincethecorrosionofoiltubesinbrinesolutionscontainingcarbondioxide (CO2 )andhydrogensulfide(H2 S)gasesisasevereprobleminengineering ,itisveryurgenttobuildapredictivemodelofthecorrosionrate(rcorr)foroiltubesinCO2 /H2 Scoexistentenvironment …     

复合式路面层间剪应力分析

复合式路面的常见病害常表现为层间剪切滑移破坏.选取典型的水泥混凝土下面层、黏结层、沥青混凝土上面层为一整体,应用BISAR3.0程序,计算分析了复合式路面层间最大剪应力、剪切角及其对温度、结构层厚度、材料模量、行车荷载等参数的敏感性.结果表明:AC层厚度、黏结层模量、行车荷载对层间剪应力、剪切角影响显著,当黏结层厚度由...     

水泥砼路面的修理

水泥砼路面在温差和车辆荷载作用下会出现各种各样的病害,需要及时修理。最常用的修理办法是在砼路面上方加铺沥青层,但随之而来的一道难题就是如何防止在沥青层上出现反射裂缝。鉴于此,提出一系列反射裂缝处治对策,以供相关工程人员参考应用。     

正常成人腰骶段椎管内脂肪的MRI研究

目的评价正常成人腰骶段椎管内脂肪的分布特征和厚度范围的临床价值,探讨与脂肪厚度相关的影响因素。方法在MR正中矢状面T1WI上观察了260例正常成人腰骶段椎管内脂肪的分布特点,并测量脂肪厚度及椎管前后径,对测量结果行统计学分析。结果MR正中矢状面上硬膜外腹侧脂肪多呈带状或新月状,背侧脂肪呈梭形节段性分布。不同水平脂肪厚度正常值范围不等,但在性别和年龄组间均无统计学差异。体质量指数、椎管前后径与硬膜外背侧脂肪厚度呈正线性相关关系。结论正常成人腰骶段椎管内脂肪的分布特征和厚度范围可为临床诊断某些椎管疾病提供参考依据。     

列车撞击荷载的有限元数值分析

为获得列车脱轨撞击荷载,分析列车撞击时盾构隧道的动力响应,建立了列车编组的三维撞击有限元模型,探讨了不同列车编组、不同撞击速度和撞击角度下列车近似撞击力时程曲线,分析了列车撞击力最大值和撞击时间与列车撞击速度和角度的关系,并将典型撞击荷载用于分析不同厚度二次衬砌管片衬砌的动力响应.结果表明:列车编组数量一定时,列车斜向撞击力最大值随撞击速度和撞击角度增大而增大;当撞击角度增大到7.5后,撞击力作用时间随撞击速度增大而延长;根据列车撞击力最大值出现时刻不同,可将撞击力时程曲线划分为2类特征曲线,其中第1类特征曲线(撞击瞬间撞击力达到最大)总体上符合高斯多峰拟合公式,可用10个参数近似拟合.二次衬砌厚度增大能有效减小管片衬砌应力、速度、加速度等动力响应以及拉、压损伤区域.      

Lift distribution based design of two-dimensional sections

A lift distribution based section design method has been proposed. Through Newton-Raphson iterations, the section geometry is efficiently designed to meet the requirements for total lift and lift distribution. The effect of fluid viscosity on total lift is taken into account by coupling Reynolds-averaged Navier-Stokes (RANS) simulation with the potential-flow based design procedure. The present method avoids the difficulty of assigning velocity or pressure distributions on section surfaces. As the loading and thickness distributions are expressed in parametric forms, it is easy to ensure that the designed geometry is continuous and smooth. The effects of lift and thickness distributions on cavitation bucket are numerically investigated. A shift of lift loading towards the aft part of section tends to decrease the margin of back cavitation, while the width of cavitation bucket can be kept almost unchanged. To have a wider cavitation bucket, one can increase the leading edge radius, move properly the location of maximum thickness towards the leading edge, or decrease the curvature at the location of maximum thickness.     

三碘季铵酚对琥珀酰胆碱引起肌梭传入放电增加的抑制作用

目的研究三碘季铵酚(GT)对琥珀酰胆碱(SCh)引起肌梭传入放电增加的影响。方法以大鼠为对象,在支配腓肠肌的胫神经上分离神经细束,引导肌梭的传入放电。先注射一定剂量的GT,4min后再注射SCh,以放电频率峰值(DPF)、放电频率最大增值(MIF)和峰频率(PF)出现时间为指标,定量计算出GT对SCh引起肌梭传入放电增加的抑制效应。结果①当GT的剂量分别为0.005、0.010mmol/kg和0.020mmol/kg,SCh的剂量为0.005mmol/kg时,DPF分别降低到对照值的67.2%、52.5%和37.1%,MIF分别降低到对照值的61.4%、40.2%和25.4%,PF出现时间分别较对照值后移43.9s、64.3s和80.4s;②当GT的剂量为0.005mmol/kg,而SCh的剂量为0.010mmol/kg时,DPF和MIF分别降低到对照值的83.3%和77.8%,PF出现时间较对照值后移22.5s。结论GT对SCh引起的肌梭传入放电增加有明显的抑制作用,且呈一定的剂量依从性。     

Microstructure of hot-dip galvanized Zn-Al-Mg alloy coating

The microstructure of hot-dip galvanized Zn-11%Al-3%Mg-0.2%Si alloy coating was studied in this article. X-ray diffraction analysis revealed the coating is composed by Zn, Al and MgZn₂ phase. Optical microscope (OM) and scanning electron microscope (SEM) observations showed the coating is occupied by snowflake-like dendrite, double hexagonal organization and eutectic. The coating backbone was the dendrite considered to be a phase of hexagonal close-packed (HCP) structure judging form its morphology according to the crystal growth way in the coating. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) researches on the dendrite suggested that an intermediate Zn-Al phase was formed at high temperature, then decomposed into a type of Zn-Al granular eutectoid after cooling down to room temperature, while the eutectoid Zn and Al had a certain crystallographic relationship. The coating solidification process and the grain crystal structure were discussed.     

基于主动热成像技术的苹果表面缺陷分类方法

针对苹果在分级中缺陷检测及缺陷种类的判断,提出了苹果的擦伤、撞伤、虫孔及腐烂等缺陷检测方法,利用红外热像图中的线轮廓温度曲线来判断果梗、花萼;主动加热过程中虫孔处与果体外温差相对较小,擦伤、撞伤及腐烂处的导热系数不同,从而导致其在红外热像图中对应表面上的点的温度随时间的变化曲线也不相同,据此提出了利用温度变化曲线来区分不同缺陷种类的方法。     

钢铁表面热浸镀铝技术回顾

综述了热浸镀铝技术的发展现状和热浸镀铝的工艺过程及特点，分析了镀铝层的结构和形成机理，阐述了镀铝层、Fe-Al金属间化合物层厚度及铝中Fe含量的控制方法，对镀铝层的表面质量控制、热浸镀铝件的主要性能特点及其热浸镀铝技术的应用都进行了介绍。