镀膜基板激光测温的自动化

描写了一种新型的ＣＣＤ摄像头一计算机系统，它可以在镀膜基板激光测温的过程中跟踪光斑中心，从而测出移过光斑中心的干涉条纹数，达到镀膜基板激光测温自动化的目的。     

矿用非接触式红外测温仪

为了满足煤矿井下测温需求,设计了一种基于红外技术的非接触式矿用温度测量仪.由于环境温度和距离对红外测温影响较大,系统采用DS18B20测温模块测量环境温度,超声波测距模块测量距离,通过数据分析得出环境温度和距离对红外测温的影响,并对测量结果进行修正.系统采用两级保护,温度超过第一级预设值发出报警信号,超过第二级预设值自动断电,以保证安全.同时,系统采用激光定位系统,方便测量和安装.     

旋转加热辊温度测量电路设计

针对工业用旋转加热辊温度测量系统存在精度低、可靠性差、系统复杂等问题,给出了一种针对旋转加热辊温度测量电路的设计方法。该方法首先对加热辊温度测量的原理进行了分析;然后设计了基于DSP和PWM技术的温度测量方案,测温电路被制作成圆环形PCB,直接安装在加热辊转轴上,随辊体一起旋转,实时采集温度信号,再利用温度信号和PWM信号占空比呈线性关系,通过PWM信号的占空比即可反知温度大小,整套电路均通过DSP控制;最后给出了关键的信号调理电路,并通过实验证明了该方案的正确性和可行性。研究结果表明,该设计方案能满足工业用旋转加热辊温度测量对高精度、高可靠性的需求,有利于提高测温性能,具有一定的实用参考价值。     

激光金属沉积成形基板预热温度的控制

为了降低激光金属沉积成形过程中试样和基板间的温度梯度,减小和抑制成形过程的热应力,提高试样的成形质量,提出并设计了一种用于激光金属沉积成形的基板预热系统.其中基板预热温度的控制由智能比例微分积分控制器以及计算机串口温度采集反馈控制来完成.利用自行研制的激光金属沉积成形设备和基板预热系统进行了成形实验,实验结果表明该基板预热系统温度控制良好,可以满足实际应用的需要.     

结构热试验中飞行器内部空间温度测量方法研究

热电偶测温系统是结构热试验中最常用的温度测量系统,热电偶的冷端温度补偿是热电偶测温系统准确性的重要体现。本文分析了热电偶冷端温度补偿的理论依据和方法,为结构热试验中测温时进行冷端补偿提供了依据。在此基础上,为更全面地测量飞行器内部温度数据,提出了一种温度测量的改进方案,并进行了理论分析和试验验证。试验结果表明,该方案完全满足试验委托方提出的温度测量要求。     

高精度铂电阻测温系统

普通四线制铂电阻测温系统受恒流源长短期漂移、导线热电动势影响,其测量准确度难以超过0.1℃量级。本文分析了一种改进型4线制高精度铂电阻测温方法的原理误差,并设计了相应的高精度铂电阻测温系统。采用温度系数小、阻值稳定性好的参考电阻作为铂电阻阻值测量基准,消除了恒流源长期漂移引起的铂电阻测温误差;分别在正、反向恒流激励条件下测量了铂电阻上的电压,利用导线热电势大小与方向的短期不变性,对得到的两电压量求差以消除导线热电势的影响;通过半导体致冷器（TEC）控制恒流源温度来减小恒流源的短期电流漂移,进而减小其对铂电阻测温精度的影响;设计了精度高、阶跃响应速度快的分时复用式电压信号采集单元用来高精度地测量铂电阻和参考电阻上电压量的比值。等效实验和校准实验结果表明,高精度铂电阻测温系统的测量稳定性优于0.005 ℃/10 day,测量分辨力优于0.005 ℃,测量准确度为0.02 ℃（k=2）,满足超精密激光干涉测量系统提出的高精度温度测量需求。     

高空间分辨率分布式光纤测温系统的设计及应用

分布式光纤测温系统是一种新型的线型感温探测器,以光纤作为传感器,可实现沿光纤分布的温度实时测量。理论分析了分布式光纤测温系统的原理以及影响空间分辨率指标的因素,并给出了0.5m高空间分辨率分布式光纤测温系统的设计以及测试情况。将高空间分辨率分布式光纤测温系统应用于电缆温度测量,测量结果表明0.5m空间分辨率下对小区域电缆过热点的探测更为显著,可及时发现潜在的火灾隐患。     

采用自然热电偶法测量铣削温度

开发了一种借助于刀—工自然热电偶在立式铣床上直接测量刀—工界面温度的水银集流器式测温系统。通过改制主轴拉杆并增设水银杯,将旋转铣刀的热电势信号引出到固接的外电路上。通过实验检测了机床运行中集流器的摩擦发热,结果表明这种集流器的附加摩擦电势很小,该测温系统具有较好的实用性。     

大型旋转工件直径在线检测系统及误差分析

激光三角法是一种光电检测技术,可以实现长度、距离以及三维形貌检测,测量系统结构简单、测量速度快、能够进行数据的实时处理。基于激光三角测距技术,提出了一种大型旋转工件直径在线测量方法及系统,给出了测量系统的组成结构,对测量系统中主要误差源进行了分类,重点针对系统误差,进行了影响测量精度的误差定量和定性分析,并进行了仿真分析,为以后研究一种大型旋转工件直径自主在线测量机器人奠定了理论基础。     

磁感应供电多路温度变送器的设计

介绍了一种针对旋转物体的多点温度测量方案.测温电路由旋转部分和静止部分构成,旋转部分采用无线磁感应供电,温度脉宽调制光脉冲发射送至静止部分光电接收器件,由单片机完成PWM脉宽至温度的转化,并通过串行通信实现与外界的通信.     

等离子熔射皮膜温度过程监控

提出一种红外测温仪结合机器人熔射路径进行在线温度检测的新方法,实现了对预热、熔射与冷却过程中基体与皮膜温度的在线监控。为保证监控系统的实时性,参考统计学方法采用周期温度均值与标准差等特征信息对温度变化趋势进行表征。结果表明:选取的特征量能够简单、直观地反映温度变化;能够对温度波动和皮膜破坏等现象做出及时响应;能够辅助熔射工艺分析与过程监控、诊断。同时也为等离子熔射过程控制提供了一种新途径。     

A numerical study on parameter control for remelted coating processes

A parametric finite element analysis was carried out to investigate the relation between processing parameters in remelted coating processes (e.g. remelting power, beam diameter, and scanning speed) and thermal behavior of the coating/substrate system such as dilution, melt pool, and heat affected zone. In the simulation, nickel-based alloys and alumina are studied as coatings deposited on AISI 1040 carbon steel substrate. A wide range of processing parameters are investigated. Scanning speed ranges from 5 to 100mm/s. Machining beam radius is taken from 0.5 to 3mm. It is found that the dilution is very sensitive to the re-melting power, scanning speed and machining beam radius. The role of the preheating temperature of the coating/substrate system is also considered. Significant reductions in remelting power of around 20%, 30% and 40% can be seen when the coating/substrate system is preheated at 250, 500 and 750°C, respectively. Numerical results provide useful suggestions for a re-melting process in practice.     

电热爆炸喷涂层温度场的数值模拟

涂层／基体的结合强度取决于涂层与基体间的热接触作用,尤其是第一层涂层与基体的相互作用。分析电热爆炸喷涂层的温度场特点,建立温度场模型,并对不锈钢基体上电热爆炸喷涂Al涂层进行了温度场的有限元数值模拟。给出了涂层和基体温度场随时间的变化规律。分析不同界面热阻对温度分布以及凝固过程的影响。结果表明涂层组织将在基体表面由于快速凝固而得到细化,仿真结果对于试验具有一定的指导意义。     

Interfacial Stress and Failure Analysis for Piston Ring Coatings under Dry Running Condition

A two-dimensional thermomechanical finite element model was developed to analyze the sliding process of a piston ring with coating sliding on cylinder liner under dry running condition. Thermal and mechanical effects were considered simultaneously in the model. The aim of the current work is to study the mechanisms of scuffing, failure, and seizure occurrence in a piston ring-liner system. It is shown that coating thickness plays an important role in the thermal and mechanical stress status at the contact area, coating bulk body, and interface of the coating and piston ring substrate. The coating thickness also exhibits a significant influence on the temperature rising at the contact area and interface of the ring coating and substrate, which could cause failure at the interface of the coating and substrate before it happens at the contact surface under some specific conditions. The results also show that thinner coating thickness in some specific range could have a higher possibility of cracking or failure. Furthermore, it is found that the thermal loading is the key cause of scuffing or failure of the piston ring coating.     

基于氮化铝HTCC基板的化学镀镍硼工艺研究

氮化铝(AlN)高温共烧陶瓷(High Temperature Co-fired Ceramic,HTCC)基板具有高的热导率以及与芯片匹配的热膨胀系数,是高功率多芯片组件首选的基板材料和封装材料。为了满足封装要求的良好钎焊性能,文中采用化学镀工艺在氮化铝HTCC基板钨导体表面沉积了化学镍钯金镀层。文中对化学镀镍溶液体系和高温热处理的工艺条件进行了研究,对化学镍层的厚度进行了优化。结果表明,高温热处理促使薄镍层向基板表面钨导体扩散,进而提高化学镀层与基底之间的附着力,镀层附着力良好,满足金丝键合和锡铅焊的要求,为微波高功率组件的研制提供了技术支撑。     

真空紫外Al/MgF_2反射镜

采用三步热舟蒸发制作法研制了真空紫外Al/MgF2反射镜,研究了改善制备工艺有效提升反射率的方法。在两层Al/MgF2反射镜制备过程中,第一步在室温石英基板上快速蒸发厚约70nm的铝膜;第二步在铝膜表面迅速蒸发厚约10nm的MgF2;第三步先对基板加热到一定温度后,再在Al+MgF2的表面上蒸发15~20nm厚的MgF2。通过调整基板温度(室温、100℃、200℃和300℃),研究了基板温度对Al/MgF2反射率的影响。真空紫外反射率计测试结果表明:第二步蒸镀MgF2之后增加基板温度有利于提高反射镜的反射率;MgF2薄膜的厚度对反射镜的反射率起到一定的调制作用,MgF2厚为26.7nm的反射镜在122nm处的反射率达85%。在实验室环境下存放1个月和5个月后,反射镜的反射率没有变化。研究结果为真空紫外光学系统需求的高性能光学元件的研制提供了技术基础。     

Mechanical analysis of the blistering of a thin film deposited on a glassy polymer

In most cases, scratching of the surface of a polymeric glass elicits brittle behavior. A common way to improve the scratch resistance of a sensitive surface is to coat it with a thin film. Further work is required to explain the improvement in scratch resistance due to coating technique and predict the cracking in anti-scratch coatings. Moreover, the substrate/thin film adhesion must be well controlled and measurable. The present study contributes to these aims. Using a single-asperity scratching device allowing in situ observation of the scratch, the fracturing of a thin nano-composite coating deposited on a polycarbonate substrate was investigated under different conditions of temperature and scratching speed. Four types of fracture mechanisms were observed, depending on these two variables. A global energy balance model of the blistering process which is obtained for some experimental conditions permits one to determine the adhesion of the system. The adhesion can be measured by following the delaminated area (quantified by image analysis) as a function of the scratching distance during blistering. The particular case of an experimental stable blistering process was studied and the corresponding substrate/thin film adhesion was derived using the global energy balance model.     

Residual stress analysis of the thermal barrier coating system by considering the plasma spraying process

The residual stress is the key factor causing the reliability problem of thermal barrier coating (TBC). The failure of plasma spray coatings due to residual stresses is a serious and recurring problem of TBC. The difference of thermal expansion coefficient between the substrate and each coating combined with temperature evolution and temperature gradients during deposition process determine the residual stress for the whole TBC system. The magnitudes and distributions of the residual stresses are affected by deposition process and deposition characteristics. Most of FEA (finite element analysis) has been performed under the assumption that the multilayer coating system is stacked at once without considering the deposition process during plasma spraying. In this research, FEA for a coupled heat transfer and elastic-plastic thermal stress was performed to obtain the more detailed and reliable result of residual stress of the TBC system using the element activation/deactivation technique. The residual stress variation from the start of plasma spraying to cooling stage with room temperature was obtained systematically considering the deposition process. It can be used as reference data to improve the performance of TBC. In addition, the relationship between residual stress and coating conditions such as cooling rate and time is also examined thoroughly.     

在钢基体上进行碳化钛气相沉积（CVD）

具有一定厚度（10～15μ）的碳化钛覆层具有某些优异性能。例如：高熔点、高硬度、低滑动摩擦系数和一定的耐腐蚀性。因此它可用于制造某些特殊要求的工件。如要求高耐磨性,和在高真空或高温下工作的无法润滑的摩擦付（如球轴承或柱塞付）等等。但目前使用的碳化钛CVD工艺存在着下列一些问题,因而限制了它的应用范围。（1）CVD过程温度过高（≥1100℃）,在这一温度下将使钢的晶粒粗化、并使其性能恶化。（2）由于碳化钛复层和钢基本间的热膨胀系数差别较大,因此使TiC复层的基体间的结合强度不够理想。（3）工件经过CVD之后,必需设法提高基体的强度,以免硬度很高的复层承载时因基体硬度不足而崩落。本文通过对CVD过程中某些化学反应的热力学分析,提出在反应室中加入海绵钛、并采用四氯化碳代替碳氢化合物作TiC的CVD过程中的供碳剂,使沉积温度降低到≤900℃。作者采取工件在进行CVD之前进行碳氮共渗处理,这样在沉积后、在TiC复层和基体之间形成一过渡层,它减少了TiC复层和基体间热膨胀系数差别,因此使结合强度提高了30%。把已沉积好的工件在充分脱氧的盐浴中重新加热后,在碱浴中淬火,可有效地强化工作基体。但沉积层厚度要烧损30%。目前,这一工艺已成功地用于电瓷行业中的修坯刀,机动丝锥和一些要求耐磨的零件上,并使其使用寿命大为提高。     

Hardness properties and high-temperature wear behavior of nitrided AISI D2 tool steel, prior and after PAPVD coating

Wear experiments in the range of 25–600 °C have been conducted on samples of D2 tool steel in different conditions involving unnitrided, nitrided and nitrided and coated with Balinit^® A (TiN) and Balinit^® Futura (TiAlN) deposited industrially at Balzers (Amherst, NY, USA), by means of PAPVD. The results indicate that coating the nitrided D2 tool steel substrate with these two films gives rise to an improvement of 97% (TiN) and 99% (TiAlN) in the wear behavior at the test temperature of 300 °C, in comparison with the uncoated substrate. However, at a temperature of 600 °C, besides oxidation of the coatings, the mechanical strength of the substrate decreases giving rise to fracture and delamination of the films. At this temperature the uncoated substrate exhibited the highest resistance to sliding wear, presumably due to the formation of a well bonded surface glazed layer which gives rise to a significant reduction in the friction coefficient. The indentation experiments that were conducted with the nitrided steel substrate and the coated systems indicates that the nitriding process applied to the D2 steel prior to PAPVD coating provides a satisfactory load support which contributes to the improvement of the coated systems capability to withstand indentation loads at room temperature. In this regard, the coated system with a TiAlN coating displayed a better behavior than that shown by the system with a TiN coating. An experimental procedure is proposed in order to predict the hardness profile of the nitrided tool steel, along the cross section of the material, just from hardness measurements taken on the surface of the sample, employing different indentation loads.