新型高合金齿轮渗碳钢渗层淬透性研究

本文利用端淬试验法和剥层试验法研究了新型高合金钢17CrN iMo6的渗层淬透性,旨在找出参考含碳量的影响因素,绘制出了17CrN iMo6钢的渗碳层的淬透性曲线和参考含碳量曲线,以及不同J距离处的硬度延层深的变化曲线,结果表明,渗碳齿轮淬火后从表面到有效硬化层深度界限硬度550HV相对应的含碳量不是一个固定值,随着合金成分、淬火冷却状况及工件尺寸大小而变化。     

不同淬火温度下NM500/Q345复合板耐磨层的摩擦磨损性能研究

耐磨钢/碳钢复合板不仅具有高强耐磨的双重性能优势,还可以降低能耗及生产成本.针对不同淬火工艺研究该复合板耐磨层NM500的耐磨性,对NM500/Q345复合板进行不同淬火温度下的干滑动摩擦磨损试验.借助显微硬度计测量试样表面的硬度,利用扫描电子显微镜(SEM)、白光干涉三维表面轮廓仪等分析该复合板耐磨层NM500的金相组织、磨痕的宏/微观形貌以及磨损机理.研究结果表明,当淬火温度为860～920℃时,淬火前后的硬度差别很大,淬火后的试样相比淬火前的试样硬度有很大的提高,随温度的上升先增加再降低,在温度为880℃时达到最高;摩擦因数曲线完全符合标准的干滑动摩擦磨损曲线,先快速上升然后有一定程度下降,最后趋于平稳;淬火后的磨损体积相比于淬火前会有很大程度减小,在淬火温度为860℃时,磨损量最少,耐磨性最好.     

维氏硬度计工作台的改进

在检查表面硬化处理的零件时,测量硬化层深度为判定产品合格与否的重要指标。国内大部分工厂常采用金相法测量层深,该方法因人为的因素较多,测量误差较大。国外发达国家对硬化层的测量大部分采用极限硬度法。如我厂引进德国的风冷柴油机零件不论是感应淬火、碳氮共渗,或者是氮碳共渗90％以上都是用硬度法测量层深。近年来国家也相继颁布了上述几个有效硬化层深度的测定标准。工厂现有的维氏硬度计HVA—10A和HV—120型其负荷范围都比较适合采用。但该硬度计的工作台不能前后左右移动,所以测层深时只能用手指轻微移动试样,有时因试样薄小用手指无法移动而只得将试样置于较大铁垫块上来进行,这样不但测量精度差且操作也很不方便,当需要测量一个完整的硬度梯度时就更显得困难。为此,我们自己做了一个既简单又实用的维氏硬度计工作台。自制工作台基本部件有三个:1.底座,它类似于原来工作台中间铣一槽。     

基于油轴温测量的减速机故障诊断方法研究

针对目前国内减速机行业的发展以及相关标准,缺乏对减速机油轴温的温升曲线研究,文章设计一套减速机油轴温实时监测的测温仪,其关键技术是通过ds18b20和MLX系列红外传感器对油温和轴温参数的监测,具有系统报警及数据存储的功能.通过实验对比不同故障机与合格机的温升变化,最终实现通过减速机的温升曲线诊断其故障类型.该研究可以解决现有减速机行业标准在油轴温度曲线的空白,为减速机的故障类型诊断提供技术指标.     

超声作用下的电铸铜微观结构与机械性能

为了改善电铸微细部件的机械性能,通过改变电铸工艺参数以及在电铸铜过程中引入超声场,得到具有不同微观结构特征的电铸铜材料.采用金相显微镜、扫描电子显微镜观察电铸铜层微观形貌,用X射线衍射分析铸层晶面择优取向,并用维氏硬度计和拉伸试验机分别测试电铸铜层机械性能.实验结果表明,超声作用下电铸和普通电铸得到的铜层表面均为(220)晶面择优取向,并且超声电铸铜层的择优取向程度更强.超声电铸铜层晶粒为细小柱状晶结构,与普通电铸铜相比,其抗拉强度和显微硬度均提高约30%.在电铸溶液中氯离子(Cl-)质量浓度为60mg/L时,铸铜层晶粒比其他Cl-质量浓度时晶粒更细小,抗拉强度和塑性也更高.在电铸过程中引入超声场能改善电铸铜层的微观结构,并提高电铸铜的机械性能.     

高能电脉冲-超声滚压耦合技术对淬火态GCr15钢表面强化研究

采用高能电脉冲辅助超声滚压技术对高频淬火态GCrl5轴承钢进行了表面强化处理,并对表层硬度梯度、表面粗糙度以及摩擦磨损性能进行了表征.与普通超声滚压技术相比,声电耦合处理后样品在提高表面硬度的同时强化层深度提高约100μm,表面粗糙度Ra由1.4μm降低至0.23μm,并且在电脉冲作用下位错运动与越过能垒的能力都得到增强,从而促进表面微裂纹得到愈合,表面质量显著提高,摩擦磨损性能提高约50％.对高频淬火态GCr15轴承钢而言,脉冲电流的电致塑性效应能够促进位错运动,提高材料表面塑性变形能力,从而使超声滚压产生的塑性变形向次表层发展,显著提高强化效果.     

M2高速钢插齿刀激光熔凝强化层与刀刃显微硬度关系的调控研究

研究了M2（W6Mo5Cr4V2）高速钢经激光熔凝淬火和570℃一次回火处理前后的强化层硬度变化和表面粗糙度,并对M2高速钢插齿刀的激光熔凝淬火加工部位进行了分析优化,讨论了刀具经激光强化及精加工后刀刃部位的显微硬度变化规律。试验研究表明：经过不同工艺参数组合的激光熔凝淬火后,试样得到不同的表面硬度,再经过一次回火后,试样表面具有明显的二次强化效应,且粗糙度值较稳定;插齿刀前刀面刀刃部位显微硬度变化规律具有工程适用性,为优选出最佳激光工艺参数及工艺方法提供了实验依据。     

汽车转向节淬火过程温度场数值模拟、淬硬层深度预测与验证

本文采用ANSYS对某汽车40Cr转向节的淬火冷却过程温度场进行了数值模拟、温度场的求解,并考虑了材料热物性参数随温度的变化,得到瞬态温度场,进而对照40Cr的CCT推导组织转变,利用临界冷却速度预测了某些位置的淬硬层深度,并通过金相组织分析和硬度测试进行了验证。模拟结果和实验结果基本吻合。实测淬硬层与预测淬硬层深度相比,其值偏大;实测硬度值与预测硬度值相比,其值偏小。     

B7螺杆上的螺纹剥落原因分析

应用光学显微镜、洛氏硬度计、显微硬度仪和光电直读光谱仪,对表面开裂并严重剥落的B7螺杆及同批经退火、拉拔后原材料的金相组织、洛氏硬度、显微硬度和化学成分进行了分析。结果表明,原材料中存在的夹杂物及带状偏析是引起螺杆纵向开裂的主要原因;原材料退火时引起表面脱碳,使螺杆在进行中频感应淬火时出现了层裂纹,最终因螺杆表面严重剥落而失效。     

NdFeB表面镀镍层不同脉冲参数时的形貌及性能

与直流电镀相比,脉冲电镀具有许多优点;而目前有关脉冲参数对NdFeB表面镀镍层耐蚀性影响的研究少有报道.以NdFeB为基体材料,以不同的电流密度和占空比脉冲电镀镍,利用扫描电镜(SEM)观察镀层表面形貌,在3.5％ NaCl溶液中进行极化曲线和交流阻抗谱测试考察镀层的耐蚀性能,并测量镀层硬度以及结合强度,以获得最佳脉冲电镀工艺.结果表明:NdFeB表面脉冲电镀镍层较直流电镀层晶粒更细,表面更光滑平整;电流密度为2 A/dm2,占空比为0.4时,镀层表面晶粒均匀致密,表现出良好的耐腐蚀性能;脉冲电镀层的硬度大于直流电镀层,且在电流密度2 A/dm2,占空比0.4时硬度最大,达497.5 HV0.98N,热震20次表现出良好的结合性能.     

Numerical study on an application of subwavelength dielectric gratings for high-sensitivity plasmonic detection

Although subwavelength dielectric gratings can be employed to achieve a high sensitivity of the surface plasmon resonance (SPR) biosensor, the plasmonic interpretation verifying the resulting sensitivity improvement remains unclear. The aim of this study is to elucidate the effects of the grating's geometric parameters on the amplification of SPR responses and to understand the physical mechanisms associated with the enhancement. Our numerical results show that the proposed SPR substrate with a dielectric grating can provide a better sensitivity due to the combined effects of surface reaction area and field distribution at the binding region. An influence of adhesion layer on the sensor performance is also discussed. The obtained results will be promising in high-sensitivity plasmonic biosensing applications.     

Numerical Study of Nonlinear Structures of Locally Excited Marangoni Convection in the Long-Wave Approximation

We investigate stationary and non-stationary solutions of nonlinear equations of the long-wave approximation for the Marangoni convection caused by a localized source of heat or a surface active impurity (surfactant) in a thin horizontal layer of a viscous incompressible fluid with a free surface. The distribution of heat or concentration flux is determined by the uniform vertical gradient of temperature or impurity concentration, distorted by the imposition of a slightly inhomogeneous heating or of surfactant, localized in the horizontal plane. The lower boundary of the layer is considered thermally insulated or impermeable, whereas the upper boundary is free and deformable. The equations obtained in the long-wave approximation are formulated in terms of the amplitudes of the temperature distribution or impurity concentration, deformation of the surface, and vorticity. For a simplification of the problem, a sequence of nonlinear equations is obtained, which in the simplest form leads to a nonlinear Schrödinger equation with a localized potential. The basic state of the system, its dependence on the parameters and stability are investigated. For stationary solutions localized in the region of the surface tension inhomogeneity, domains of parameters corresponding to different spatial patterns are delineated.     

Temperature gradient distribution in permafrost active layer,using a prototype of the ground temperature sensor (REMS-MSL) on deception island (Antarctica)

Deception Island, an active volcano on South Shetland Archipelago of Antarctica (62°43′S, 60°57′W), is a cold region with harsh, remote and hostile environmental conditions, what could be considered in most aspects such an analog of the Martian surface. The volcanic materials on the surface, the permafrost and active layer existence, and the cold-climate conditions made this region of the Earth a perfect site to test instruments for the future missions to Mars. This is the case of the Ground Temperature Sensor (GTS), based on an infrared radiation (IR) sensor, included into the Rover Environmental Monitoring Station (REMS) instrument on board of the Mars Science Laboratory (MSL) mission of NASA, with that it will measure the Mars surface temperature.We conducted a summer Antarctic scientific campaign in 2009 on Deception Island in order to test the GTS instrument in the field. That device was placed near other already installed instruments and used to monitor permafrost and active layer thermal evolutions: air, surface and ground temperatures, as well as short and long wave radiation were registered. In brief the main objectives are (1) test in the field and improve the GTS device prototype, and (2) develop a methodology to derive soil gradient temperature in the active layer zone; which could be applied in the MSL mission.With the obtained data during 2009 campaign, we (a) compared temperatures from GTS versus our Pt100 contact temperature sensors to analyze GTS response accuracy; (b) calculated the active layer thickness using the sinusoidal heat transfer conduction model from soil surface temperature records; and (c) calculated the unfrozen active layer thermal diffusivity.The main results show that the degree of adjustment between the temperature measurements by to Pt100 contact temperature sensors and the CGT-REMS instrument is high, with a mean error value of below ± 0.6 °C although it could reach values of ± 5.0 °C due to the heating of the instrument case due to the sun. On the other hand, the calculated active layer thickness was consistent with the direct measures from both; our temperature probes placed in shallow boreholes and mechanical probing. Then, using soil surface temperature data from GTS instrument will be able to establish indirectly the active layer thickness and its thermal structure, what will have important applications for the MSL mission to Mars.     

In situ evaluation of density, viscosity, and thickness of adsorbed soft layers by combined surface acoustic wave and surface plasmon resonance

We show the theoretical and experimental combination of acoustic and optical methods for the in situ quantitative evaluation of the density, the viscosity, and the thickness of soft layers adsorbed on chemically tailored metal surfaces. For the highest sensitivity and an operation in liquids, a Love mode surface acoustic wave (SAW) sensor with a hydrophobized gold-coated sensing area is the acoustic method, while surface plasmon resonance (SPR) on the same gold surface as the optical method is monitored simultaneously in a single setup for the real-time and label-free measurement of the parameters of adsorbed soft layers, which means for layers with a predominant viscous behavior. A general mathematical modeling in equivalent viscoelastic transmission lines is presented to determine the correlation between experimental SAW signal shifts and the waveguide structure including the presence of the adsorbed layer and the supporting liquid from which it segregates. A methodology is presented to identify from SAW and SPR simulations the parameters representatives of the soft layer. During the absorption of a soft layer, thickness or viscosity changes are observed in the experimental ratio of the SAW signal attenuation to the SAW signal phase and are correlated with the theoretical model. As application example, the simulation method is applied to study the thermal behavior of physisorbed PNIPAAm, a polymer whose conformation is sensitive to temperature, under a cycling variation of temperature between 20 and 40 degrees C. Under the assumption of the bulk density and the bulk refractive index of PNIPAAm, thickness and viscosity of the film are obtained from simulations; the viscosity is correlated to the solvent content of the physisorbed layer.     

Microsensor based on low temperature cofired ceramics and gas-sensitive thin film

A novel design of gas sensor using low temperature cofired ceramics (LTCC) and thin film technologies is presented. The LTCC structure is composed essentially of two ceramic layers with interlayer thick film Pt heater, interdigitated electrodes on top, contact pads and metallic connections realised by vias. The thin films of both SnO₂ and In₂O₃, intentionally doped and activated, were deposited on top of the structure. With some modifications of the lamination process and heat treatment parameters, the authors obtained the upper ceramic layer with the roughness not exceeding 250 nm, what was suitable for thin film technology. The films deposited onto such LTCC structure revealed the sensing properties very similar to the reference films deposited onto glass. The gas-sensitive films were tested with changing concentrations of reducing and oxidising gases in air. The necessary sensor working temperature was obtained and stabilised using a custom-built digital controller. The low heat capacity of the sensor structure enabled also a sinusoidal temperature control. The satisfactory results obtained by the authors indicate that the connection of LTCC and thin film technologies can lead to the fabrication of good quality gas sensors.     

Simulation of the spectra and determination of the optical constants of online low-emission glass from visible to mid-infrared region

Online low emissivity glass (Low-E glass) is a promising glass product. Simulation of the spectra and determination of the optical constants of online Low-E glass are of practical interest for many applications such as product design, adjustment of coating process and comparison of samples produced using different methods. The online Low-E glass investigated here has two layers of films on 6 mm thick float glass substrate, which include the functional layer (the upper layer) and the transition layer (the lower layer). In this paper, the relation between transmittance and the parameters used in the model in the visible and near-infrared region was derived, so was the relation between reflectance and the parameters used in the model in the infrared region. The parameters used in the model were obtained by fitting the measured and simulated spectra. From the obtained parameters, the optical constants of the functional layer of online Low-E glass in the visible region and the infrared region were obtained, respectively. The sheet resistance and the infrared reflectance of Low-E glass were also calculated from the obtained fitting parameters. The simulated results are well consistent with the experimental ones.     

Influence of nanosecond laser irradiation on optical properties of surface layers of CdTe crystals

The effect of surface laser processing on the optical properties and structure of the surface region of (111) oriented CdTe single crystals have been studied by multiple-angle-of-incidence single-wavelength ellipsometry. The measurements were performed both on Cd and Te surfaces of CdTe(111) crystals and morphology was monitored by AFM. CdTe crystals were subjected to various treatments including chemical and laser etching. The ellipsometric parameters Δ and Ψ were obtained at several light incidence angles and data were interpreted based on the model of an absorbing surface layer located on an absorbing substrate. Surface roughness was taken into account and the surface layer was considered as an equivalent film with flat boundaries and effective optical parameters. The refraction n and absorption k indexes, and thickness d of the modified surface layer were calculated and features of nanosecond laser irradiation on CdTe(111) polar surfaces were discussed.     

Determining the parameters of electron traps in inhomogeneous layers by method of thermionic emission

Quasi-stationary nonlinear variation of the density of filled electron traps in the course of thermionic emission from the surface oxide layer on a metal cathode is theoretically described. Expressions for the electron affinity, energy, and density of electron traps in this dielectric layer are obtained. Numerical estimates of the electron trap parameters are obtained based on the results of measurements of the temperature dependence of thermionic emission from the porous surface oxide layer of an iron-nickel alloy.     

高灵敏Love波传感器及其关键材料

Love波传感器是声表面波传感器的一种,其灵敏度最高.对Love波生物、化学传感器的研究现状进行了综述,着重分析了波导材料及其厚度、基板材料及其切向对传感器的灵敏度及温度稳定性的影响关系.指出采用高频谐振型的器件结构并结合聚合物波导的方案可进一步提高Love波传感器的灵敏度.     

A New Multifunctional Sensor Using Piezoelectric Ceramic Transducers for Simultaneous Measurements of Propagation Time and Electrical Conductance

The aim of this paper is to develop a system for reconstructing an image of two parameters, e.g., temperature and body composition, in the same region of a living body. In this paper, a new multifunctional sensor for simultaneous measurements of the ultrasonic and electrical properties of an object is proposed. The proposed sensor, which uses a pair of piezoelectric ceramic transducers, measures not only the ultrasonic property of the object but also its electrical property by using the surface electrodes of each piezoelectric ceramic transducer. In the experiment, the propagation time and conductance of a simple cell model for the living body are simultaneously measured by the proposed sensor. The sodium chloride (NaCl) concentration, which is the composition that determines the conductivity of the model, and temperature are estimated from the measurements. It was found that the ultrasonic and electrical properties could simultaneously be measured. In addition, two parameters of the model could be estimated from these measured values. Therefore, it is suggested that the proposed sensor has the potential for application, although there are some problems that must be solved.