用超声波技术测量螺栓轴向紧固应力

超声波速度会因材料中加载应力而产生微小的变化，这一现象特别适用于测量螺栓的轴向应力。根据螺栓的轴向应力与超声波传播时间变化率的关系，作者研究了一种可直接测量螺栓轴同应力的仪器。实验结果显示，本项技术十分适合现场的实际应用。     

西气东输管道工程《管道对接环焊缝全自动超声波检测》标准及与国外先进标准的对比

介绍了西气东输管道工程《管道对接环焊缝全自动超声波检测》标准的技术特点、主要内容,并对本标准与国外先进标准、国外先进企业标准进行了较详细的对比分析。本标准在检测工艺方面与ASTM E1961-98相近。验收部分是从缺欠的位置、缺欠自身高度和长度来加以限制,较为合理,具有科学性,与EN25817-92和ISO5817-92标准相当,比API1104-99标准偏严,与西气东输工程射线检测企业标准也基本相当。     

射孔孔眼中散射超声脉冲波的FEM模拟

采用有限元素法 ,分别数值计算了平底孔道、台阶式孔道和尖劈状孔道等 3种孔眼模型中不同中心频率 (10 0 k Hz、5 0 0 k Hz、1MHz)的散射超声脉冲波。计算结果表明 ,无论选用哪一种孔底模型 ,均可以得到较为明显的对应于孔底的声波信号。但是 ,孔道越不规则 ,使用的超声信号的主频越高 ,则孔底信号越差。为了兼顾孔底信号质量和信号采集、传输的代价 ,在未来的检测仪器中应采用尽可能低的测量频率 (低于 5 0 0 k Hz)     

利用CFD获取超声流量计截面速度分布

 通过CFD技术在超声波流量计设计过程中的引入,为流量系数的获取提供了新的途径.通过对特定管道的理论计算表明,采用CFD技术获取的管道内部流型完全可以与试验数据吻合,有助于超声波流量计应用场合流量系数曲线的获取及其精度的保证.     

复合材料超声波直线电机的运动控制

针对复合材料超声直线电机振动体具有两个固有频率的特点，设计了具有频率跟踪特性的超声直线电机驱动器，利用激励信号频率变化改变电机运动方向，实现了超声直线电机的运动控制。     

45钢表面超音速电弧喷涂Ti-Al涂层的组织与性能研究

采用自行开发研制的超音速电弧喷设备，在45钢表面制成了钛铝合金复合涂层。并利用金相显微镜、X射线衍射仪、扫描电镜、电子探针，对涂层的成分、相结构、显微组织及其结合强度、显微硬度进行了研究。结果表明，利用超音速电弧喷涂设备，可以在45钢表面形成 度高、孔隙率低，结合强度较好和硬度高的Ti-Al合金涂层。     

超声波流量计计量系统性能的主要影响因素

随着我国天然气工业的发展，已有大量超声波流量计用于高压、大流量的天然气计量。尽管我国已于2001年颁布并实施了气体超声波流量计使用方面的国家标准GB/T18604-2001，但是随着超声波流量计越来越广泛的使用，国内外对超声波流量计计量性能的影响因素已有了进一步的研究；而且，目前我国超声波流量计在天然气计量中的应用效果也还需要进一步改善。因此，根据目前国、内外最新研究成果，对噪声、脏污、压力及温度测量对超声波流量计计量系统性能的主要影响因素以及控制对策进行了分析探讨，以期改变虽经实验室检定合格、但用于现场却不能达到预期计量性能效果的情况，使超声波流量计在现场能够得到更好的应用。     

Investigation of Centreline Segregation and Centreline Porosity in CC ‐ Slabs

Improvements of solidification processing in conventional or near net shape casting depend on sophisticated methods of macroscopic examination of central unsoundness and inhomogeneity of the cast material. As long as remarkable deviations referring to the quality features exist between the slab centre and the bulk material such methods should be looked after. Two semi‐macroscopic methods of segregation analysis are discussed in this paper: firstly, the potential of the emission spectral analysis combined with sectioning of a sample and secondly, the computer aided micro‐probe analysis. Both methods are restricted to small local areas. The proneness of elements and steel grades with respect to micro‐ and macrosegregation as well as distribution‐ and segregation coefficients are determined. The effect of a diffusion anneal on homogenisation of segregation is studied. Last not least the precipitation of sulphides, phosphides or carbonitrides is estimated. Ultrasonic detection of the central unsoundness of conventional slabs or thin slabs is a new approach towards a quantitative macroscopic examination. The sample size is 400 mm x 300 mm x 30 mm. To achieve a low ultrasonic noise using a 5 MHz‐transducer the samples are heat treated for grain refinement. “Dog bone porosity”, macroscopic topographical misfit between the upper and lower solidifying shells, periodical corner cracks or systematic transverse centre cracks are detected. Obviously, segregations do not reflect the ultrasonic beam. However, it can be presumed that an interrelation exists between porosity and segregation, although these might be locally apart from each other. This new ultrasonic test of the central unsoundness of continuous cast (c.c.) slabs gives valuable arguments to machine builders and maintenance people to decide on the right concepts for strand guidance, support rollers and secondary cooling. Soft reduction can be optimized and variations in casting speed counteracted by dynamic means. R&D service of this kind can help steelmakers when decisions are impending to build new casting machines or revamp old ones.     

Plasma Sprayed Hydroxyapatite Coatings with Nano-hydroxyapatite Prepared by Ultrasonic Precipitation Process

Nano-particle hydroxyapatite （ HA ） was prepared with a novel ultrasonic precipitation process and the as-prepared nanopowder was used to produce hydroxyapatite （ HA ） coatings on titanium substrate via plasma spraying. The phase and the microstructare of the coating were characterized by X- ray diffraction （XRD） and scanning electron microscopy （SEM）. Results showed that spherical particles could be prepared by ultrasonic precipitation process; and a corresponding dense HA coating with molten surface and low-porosity cross-section structure was acquired. During the plasma spraying process, new phases of Ca3 （ PO4 ）2 and Ca2 P2O7 were generated. After heat-treating at 800℃ for 1 h, the contents of Ca3 （ PO4 ）2 and Ca2 P2O7 decreased while HA content increased. Tensile adhesion tests showed that the plasma sprayed coating prepared with the spherical nanoparticles exhibited high tensile bond strength.     

C2 用于声化学研究的大功率超声系统的研制

根据声化学反应的特殊要求，我们研制了上前用于声化学研究的大功率超声系统，由参数可调节的超声发生器配合不同频率的换能器工作，并用它组合成杯式幅杆结构声化学反应器，解决了有关声化学设备的一些技术问题。为声化学技术从实验室规模向工业应用过渡做了必要的准备。