火箭发动机包覆层测厚时间延迟估计算法研究

用超声测量火箭发动机包覆层厚度时,当包覆层较薄时检测回波信号会出现时域混叠。为此提出一种时间延迟估计的新方法。该方法能对修正的检测信号能量谱的对数微商求逆傅里叶变换。实验结果表明,该方法能准确估计出时域混叠信号的延迟时间。提高了火箭发动机包覆层厚度测量精度。     

Deformation behavior ofA6063 tube with initial thickness deviation in free hydraulic bulging

Experiment on seamless tubes of aluminum alloy A6063 with initial thickness deviation of 0-20% was conducted through a free hydraulic bulging with tube ends free. The influence of initial thickness deviation on the cross-section profile, thickness distribution, maximum internal pressure and maximum radial expansion was investigated. FEM simulation was also performed in order to examine and help explaining the experimental results. The results indicate that the internal pressure and maximum internal pressure appear to be little influenced by the initial thickness deviation, and that the cross-section profile of the bulged tube changes diversely and can not be a perfect circle. The results also suggest that the increase in initial thickness deviation may lead to a remarkable decrease in maximum radial expansion, and a rapid increase in thickness deviation and the center eccentricity of the inner and outer profiles.     

水压轴向柱塞泵配流盘最小水膜厚度的理论分析——结构参数的影响

最小水膜厚度是保证配流盘静压支承工作的基本条件，本文提出了最小水膜厚度应满足的基本要求，在两种不同的运动副表面粗糙度下，分别讨论了配流盘静压支承的主要结构参数对最小水膜厚度的影响，另一方面，分析结果又为结构参数的设计提供了参考依据。     

Diffusion bonding/superplastic forming of Ti-6Al-6V-2Sn/SUS 304 stainless steel/Ti-6Al-6V-2Sn

The superplasticity of the Ti- 6Al- 6V- 2Sn alloy for different temperatures was evaluated by single-sheet free blowing. The optimal superplastic temperature for the Ti- 6Al- 6V- 2Sn alloy was found to be 850 °C. Diffusion bonding of Ti- 6Al- 6V- 2Sn and 304 stainless steel was carried out in a vacuum. The interface of both bonded alloys was examined by EPMA. The concentration profile of Ni exhibited a peak at the interlayer and a valley adjacent it, whereas that of Cr exhibited a peak where Ni showed the valley. X- ray diffraction (XRD) analyses showed that the Fe ₂ Ti, NiTi, and CrMn Intermetallic compounds and the Cr element formed at the interface. The thickness profiles of the blown specimens were measured and compared with theoretical calculations.     

Evaluation of hydrogen absorption properties of Ti–0.2 mass% Pd alloy in fluoride solutions

The hydrogen absorption properties of Ti–0.2 mass% Pd (Ti–0.2Pd) alloy in 2.0% and 0.2% acidulated phosphate fluoride (APF) and neutral 2.0% NaF solutions (25 °C) has been evaluated by hydrogen thermal desorption analysis. During the early stage of immersion (120 h) in the 2.0% APF solution, the amount of absorbed hydrogen was lower than 500 mass ppm. A thermal desorption of hydrogen primary appearing with a peak at 500–600 °C and a broad desorption ranging from 100 to 400 °C were observed. In the 0.2% APF solution, the amount of absorbed hydrogen saturated at 100–200 mass ppm; the thermal desorption of hydrogen appeared with a single peak at 550 °C. In the 2.0% NaF solution, hydrogen absorption was negligible even after 1000 h of immersion, although corrosion pits were observed. The results of the present study suggest that the hydrogen absorption of Ti–0.2Pd alloy, as compared with commercial pure titanium, is suppressed in fluoride solutions.     

Application of auger electron spectroscopy and inert metal marker techniques to determine metal and oxygen transport in oxide films on metals

Auger electron spectroscopy in combination with depth profiling by Ar ion sputtering was employed as a surface analytical technique to determine the positions of thin (3–5 nm) inert Pd markers during growth of oxide films on Al, Ni, and -NiAl. Alumina films 35 and 120 nm thick formed on Al and -NiAl, respectively, grew by inward diffusion of oxygen. Metal migration accounted predominantly for the growth of a NiO film 150 nm thick on the (111) crystal face of Ni. However, an assessment could not be made with respect to oxygen diffusion, if any, in this film due to the limitations imposed on precise depth profiling of the marker position caused by uneven sputtering of the oxide and metal phases.     

Co/Cr/Pd多层膜的磁性及其准确性

研究了测量程序对不同Cr层厚度的Co／Cr／Pd多层膜磁性的影响，分析了反磁化机理在不同测量程序中对磁性准确性的影响。     

冷连轧机末机架AGC控制方式分析

介绍了冷连轧机末机架AGC控制3种方式的特点和适用范围，得出控制方式的选取须同时考虑轧制产品、轧机能力的发挥、板形、轧辊和后道工序的要求等多方面因素。     

一种智能纸张厚度计设计

根据纸张厚度测量控制系统的功能要求,应用β射线吸收原理,完成了一种智能纸张厚度计设计。它以MSP430FG479为微处理器,具有CAN和RS—485通信接口,具有自检测和自标定功能。给出了系统硬件实现方法,软件设计流程。经实验验证,检测精度达到0.1%以上。该设计方案,换用不同的放射源,可对各种纸和纸板的厚度进行检测,易于操作,工作稳定。     

电磁超声检测钢板厚度实验的参数优化

为提高电磁超声检测信号的信噪比,研究激励信号频率、脉宽及换能器提离距离对厚度测量结果的影响,搭建了电磁超声实验系统。该系统利用RITEC-SNAP 5000产生高能正弦波激励电磁超声换能器EMAT ( Electromagnetic Acoustic Trans-ducer),通过调节激励信号的频率、脉宽,改变提离距离来观测超声回波幅度的变化。实验结果表明：当激励频率和EMAT固有频率相同时其换能效率最高,采用6个周期的脉冲串时前后波包之间分界明显,为获得较大的回波幅度应尽可能减小提离距离。