超声测厚仪及测厚

本文介绍了超声波测厚仪的原理和种类,超声波测厚在压力容器、管道、复合材料中的应用以及影响超声测厚的因素。     

容器壁厚的超声监测

超声波在同一均匀介质中传播时,声速为一常数;在不同介质的界面上则具有反射特性。超声波测厚仪就是利用这一特性,采用脉冲反射法进行测厚的。 当探头接触被测件表面时,探头上发生的超声脉冲波即从接触面向被测件传播,在到达被测件的另一面时,遇到不同介质的界面,又反射回来被探头接收。这样,只要测出从发射一脉冲到接收反射脉冲所需时间,乘上被测件的声速常数,就是超声脉冲所经历的来回距离。据此即可算出被测件的厚度。 容器壁厚,尤其是盛装酸、碱或其它腐蚀性介质的容器壁厚,在使用一定年限后必然会减薄。当壁厚减薄到一定程度时,就会给安全生产造成威胁;如果是压力容器,其危险性就更大。因此,定期对容器壁厚进行监测,及时掌握壁厚减薄量,是保证安全生产、防止恶性事故发生的重要措施。     

高精度手持式电磁超声测厚仪

研制了高精度手持式电磁超声测厚仪。根据电磁超声回波峰值出现时刻不规律的特点,采用了基于首个周波检测的电磁超声测厚方法。设计了基于FPGA的大功率发射电路和低噪声接收电路,实现了超声波发射和低噪声接收;设计了基于ARM处理器的嵌入式Linux软件,实现了厚度计算、波形显示、参数设置、厚度-距离曲线等功能。利用该测厚仪对不同厚度的铝合金标准试块和钢板进行测厚实验。实验结果表明,该测厚仪分辨力达到0.01 mm,测量厚度可精确到0.001 mm。     

昆山市超声仪器有限公司

<正>昆山市超声仪器有限公司是国内专业研发、制造超声波清洗设备的企业。注册"舒美"商标,系国内知名的超声清洗产品专业制造商,公司主要产品包括:各类超声波清洗设备、超声波细胞粉碎机、检测仪器、恒温仪器、磁力搅拌仪器、测厚仪器、超声波塑焊机、水流压力喷洗设备及水质处理设备等,主要产品有9个大类、60多个品种、480余种规格。     

微波非金属厚度测量仪

迄今,测厚仪有射线、超声、涡流和同位素等各种类型,新近发展了微波测厚仪,它既有测量金属片材、带材的厚度仪,又有测量非金属材料的厚度仪。根据非金属材料微波测厚法基本原理〔1〕研制的微波测厚仪补充了超声波测厚仪之不足,为非金属材料厚度的测量提供了新方法。利用微波测厚具有设备简单、测量速度快,对样品能进行非破坏性相对测量,不需要耦合剂等优点。经过仪器校正和在标准试件上标定后,可以用于绝对厚度的测量。     

基于虚拟仪器技术的超声波探伤

在描述超声波脉冲反射法探伤的工作原理的基础上,以数据采集卡PCI-9812为核心,设计了超声波收发电路、放大、检波、滤波等电路,利用LabVIEW开发了相应的软件程序,实现了超声探伤从传统仪器向虚拟仪器的转化,为大规模自动化探伤奠定了基础.     

湿法超声机械镀锌设备的研发

提出了一种机械镀锌工艺,阐述了其工艺原理。开发了湿法超声机械镀锌设备。该设备包括超声波发生器、超声换能器和超声变幅杆,并叙述了该设备的设计原理和设计方法。利用上述设备进行了镀锌试验,用涂层测厚仪测量镀锌层的厚度,用划格法测试了镀层与基体的结合强度。结果表明:湿法超声机械镀锌设备运行良好、操作方便,可在工件表面获得一定厚度的镀锌层,镀层结合强度较好。通过调整超声波发生器的功率进而改变镀层的表面质量及厚度。     

上海超声波仪器厂举办产品现场表演会

为了进一步做好用户服务工作和推广超声波应用技术,上海超声波仪器厂召开了超声波清洗器、超声波测厚仪、超声波塑料焊接机、超声波探伤仪、超声波检漏仪等产品的操作展示会,并结合技术咨询。历     

超声测厚仪在材料检测中的应用

文章介绍了超声测厚仪的结构，以及超声测厚仪检测材质的原理，此外文章还介绍了超声测厚仪在检测应力，蠕变，氢损伤和氢脆方面的应用。     

橡胶摩擦材料粘弹性的超声评价

基于复数域超声波传播理论和Moore理论,提出了一种新的橡胶摩擦材料动态粘弹性的超声评价法。该方法考虑超声波在轮胎用橡胶摩擦材料中的传播特性,论述了橡胶摩擦材料的摩擦与衰减的相关性,引入衰减系数与损耗角正切参数建立了超声波底面反射法的数学模型,计算结果和已成熟的DMA方法非常吻合。建立了适于橡胶摩擦材料动态粘弹性的超声无损评价系统,为轮胎橡胶摩擦特性的研究及在线无损评价提供了新的方法。     

Design and construct of a new detector for gas chromatography based on continuous negative corona discharge

In this work, a new detector was designed and constructed based on negative corona discharge. This detector can be used separately or as a detector in gas chromatography. The detector and chromatographic variables including cell temperature, gas flow rates, voltage between the two electrodes, and column temperature were optimized. Chloroform was used as a test compound to evaluate the performance of the detector. The detection limit of chloroform was obtained 0.78 ng∕ml and its dynamic range was over the range of 2-840 ng∕ml. The relative standard detection was about 6% for the limit of quantification. This detector is able to be used as an alternative for analysis of compounds containing electronegative elements.     

A detector for the pulsed nuclear quadrupole resonance spectrometer

An increase in the sensitivity of a pulse-type detector for the nuclear quadrupole resonance spectrometer has been attained by optimizing the delay time for switching on the receiver after termination of an excitation pulse and by using an original circuit of the synchronous detector with a high dynamic range of 100 dB. The sensitivity of the nuclear quadrupole resonance spectrometer improved by using the developed detector is about twice as great as the spectrometer sensitivity before its upgrading. The spectrometer is capable of detecting 0.5 g of sodium nitrite.     

调幅式电容位移传感器的峰值检波电路设计

针对调幅式电容位移传感器解调过程中由系统不确定相移导致的信号解调不准确问题,提出了一种基于改进的峰值保持电路的调幅式电容位移传感测量方法。首先,分析了调幅式电容位移传感器及其检测电路的工作原理,在研究调幅信号附加相移产生机理的基础上,提出了延迟反馈式峰值保持电路,用以去除附加相移对峰值解调的影响。然后,设计并制作了调幅式电容位移传感器,并对其各个性能指标进行了测试。最后,对实验结果和误差进行了分析。实验显示,提出的峰值保持电路的输出线性度优于0.05%,制作的传感器在0～25μm内数据测量稳定性优于10nm/30min,传感器测量偏差最大值为36nm。结果表明,采用延迟反馈型峰值保持电路有效地解决了系统不确定相移带来的峰值检波不准确的问题,所制作的电容传感器满足了高精度测量的要求。     

Radon/thoron detection properties of a CR-39 plastic track detector

We have performed a series of experiments in order to develop a personnel dosimeter, employing a plastic track detector and having a high sensitivity for the detection of alpha particles emitted in the decay of radon and thoron gases. The paper describes our work on a new type of plastic track detector known as CR-39. This new type of detector has been calibrated and the optimum operating conditions have been established for its use as a radon/thoron dosimeter. The results obtained so far strongly suggest that CR-39 is not only the most sensitive track detector existing today for the detection of alpha particles from radon and thoron, but that it also has some unique properties which make it an ideal track detector for radon/thoron measurements.     

Down-scattered neutron imaging detector for areal density measurement of inertial confinement fusion

A custom developed (6)Li glass scintillator (APLF80+3Pr) for down-scattered neutron diagnostics in inertial confinement fusion experiments is presented. (6)Li provides an enhanced sensitivity for down-scattered neutrons in DD fusion and its experimentally observed 5-6 ns response time fulfills the requirement for down-scattered neutron detectors. A time-of-flight detector operating in the current mode using the APLF80+3Pr was designed and its feasibility observing down-scattered neutrons was demonstrated. Furthermore, a prototype design for a down-scattered neutron imaging detector was also demonstrated. This material promises viability as a future down-scattered neutron detector for the National Ignition Facility.     

The time characteristics of a single module of the neutron detector

The time characteristics of the scintillation plate that is an element of the neutron detector designed for measuring the energy of a neutron by its time of flight and determining the coordinate of the point of its interaction with the detector have been investigated on cosmic rays. The time resolutions of the neutron detector element measured with P9814B and FEU-63 photomultiplier tubes are σ ≈ 0.14 and 0.29 ns, respectively.     

Detection efficiency vs. cathode and anode separation in cylindrical vacuum photodiodes used for measuring x-rays from plasma focus device

A qualitative study on the performance of cylindrical vacuum photodiodes (VPDs) for x-ray detection in plasma focus device has been carried out. Various parameters of VPD such as electrode's diameter, electrode's separation, and its sensitivity are experimentally tested in plasma focus environment. For the first time it is found experimentally that the electrode-separation in the lateral direction of the two coaxial electrodes of cylindrical VPD also plays an important role to increase the efficiency of the detector. The efficiency is found to be highest for the detector with smaller cathode-anode lateral gap (1.5 mm) with smaller photo cathode diameter (10 mm). A comparison between our VPD with PIN (BPX-65) diode as an x-ray detector has also been made.     

自动超声探伤的抗干扰研究

在自动超声探伤领域中，传统的多通道超声波探伤仪的抗干扰性能不甚理想的主要原因是其相关报警电路的抑制干扰性能较差。本文介绍了设计新颖的干扰抑制电路——符合式缺陷脉冲鉴别电路的构成与工作原理，并进一步叙述了采用该电路的ＣＴＳ－４６型六通道超声波探伤仪的抗干扰性能实验及现场测试实验。结论表明符合式缺陷脉冲鉴别电路的抗干扰性能很强，对自动探伤用多通道超声探伤仪而言，是一个很好的相关报警电路。     

A neutron detector that is insensitive to attendant γ rays

A neutron detector is described, whose operating principle is based on detecting charge-transfer effects of secondary recoil protons produced in hydrogen-containing materials under exposure to primary neutrons. The physical mechanism of the operation of this detector is presented and its sensitivity is determined as a function of the neutron energy. The design of a detector that is insensitive to attendant γ rays is proposed. The serviceability of the detector has been confirmed experimentally. The detector may find application to tests in mixed fields of γ rays and neutrons.     

检测技术及其在生命科学中的应用进展

本文对检测技术及其在生命科学中的应用进展进行综述,阐述现代各种新的检测器,如二极管阵列紫外检测器、示差折光检测器、电化学检测器、红外检测器、核磁共振检测器、质谱检测器、蒸发光散射检测器、小角度激光散射检测器等在药物食品质量控制、快速分析、毒物毒剂、临床医学和环境检测等生命科学方面的应用。