共查询到19条相似文献,搜索用时 187 毫秒
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采用单颗金刚石压头作为磨粒对玻璃进行磨削实验,采集了磨削过程中的声发射信号,分析了磨削参数变化对声发射信号参数特征值的影响。结果表明:磨削过程中产生的声发射信号特征参量值振铃计数值、信号均方根值RMS随着磨削深度和磨削速度的增大而增大;随着工作台移动速度的增大而减小。在本实验条件下得到的声发射信号频率峰值主要在15.53 kHz以及18.65 kHz两个部分,且实验时主要研究玻璃材料脆性方式去除过程,说明了玻璃脆性断裂时产生的声发射信号频率峰值集中在15.53kHz和18.65 kHz。 相似文献
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文中以P92钢与Ni基焊材焊接热影响区为研究对象,通过采集紧凑拉伸试验过程中异种钢接头热影响区启裂及裂纹扩展的声发射特性信号,分析裂纹扩展的声发射信号幅值、频率分布、能量及振铃计数等特征参数,同时分析声发射特征信号与断口形貌之间的对应关系。结果表明:裂纹扩展声发射信号均为突发型信号,频率主要集中在50~200 kHz;裂纹稳定扩展的声发射信号具有平均幅值较低、总能量和振铃计数率参数变化平缓的特点;裂纹失稳扩展的声发射信号具有平均幅值较高、总能量和振铃计数率参数呈瞬时增加的特点;裂纹稳定扩展阶段的声发射特征信号与韧性断口特征相对应;裂纹失稳扩展阶段的声发射特征信号与准解理断裂或解理断裂特征相对应。 相似文献
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C/SiC复合材料拉伸过程的声发射研究 总被引:1,自引:0,他引:1
利用声发射(AE)技术对C/SiC复合材料试样拉伸试验过程进行动态监测。通过声发射多参数分析法对拉伸过程中的声发射累计能量和平均持续时间随载荷或时间的变化进行了综合分析;同时对拉伸过程中典型AE信号的频率特征进行了分析,揭示了C/SiC复合材料拉伸损伤的演化过程及规律,给出了材料拉伸损伤发展的不同阶段以及各阶段损伤类型。通过声发射累计能量随载荷变化的斜率突变定义了材料临界损伤强度。 相似文献
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金属板材在塑性加工中不可避免产生摩擦。利用声发射技术检测塑性加工的摩擦状况。以SPCC钢在单向拉伸与相对运动速度为100mm/min、正压力为7.5 kg的动态摩擦过程产生的声发射信号为研究对象,采用参数关联分析方法对两种信号进行了对比分析。试验结果表明,在相同采集的条件下有①摩擦声发射幅度与拉伸声发射幅度相差不大。②幅度相同时的摩擦声发射能量值比拉伸过程产生的声发射能量值要大得多;而摩擦声发射振铃计数值却小于拉伸声发射振铃计数值。③动态摩擦过程产生的声发射信号的持续时间在从很低到8 000μs这一范围;而拉仲过程声发射信号的持续时间一般低于5 800μs,仅当出现裂纹或断裂时才出现更高的持续时间的声发射信号。 相似文献
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基于声发射(AE)信号和计算机断层扫描(CT)成像技术,开展了高温复合材料的内部损伤状态分析。通过声发射技术获得复合材料损伤时的宏观应力波信号,分析得到声发射信号的频率等波形特征参数;通过计算机断层扫描得到复合材料结构内部微细观三维损伤图像,判断存在的损伤类型。结果表明,不同工艺陶瓷基高温复合材料在拉伸载荷下,内部会产生不同类型的损伤,纤维束与基体之间的脱黏开裂所对应的声发射信号特征频率为44 kHz,基体失效的特征频率为150 kHz,纤维束断裂损伤的特征频率为250 kHz。 相似文献
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电参数对锆材微弧氧化膜层厚度的影响 总被引:1,自引:0,他引:1
利用微弧氧化技术在锆材表面原位生成微弧氧化膜层。研究电压、占空比、频率和电流密度对锆材微弧氧化膜层厚度的影响,并利用单因素方差分析法,分析各电参数对膜厚影响的显著性。结果表明:在试验范围内,随着电压的升高、占空比的增大、频率的减小或电流密度的增大,锆材微弧氧化膜层厚度增加;各电参数对微弧氧化膜层厚度影响的主次顺序为:电压和电流密度>占空比>频率,其中频率对膜层厚度无明显影响。 相似文献
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M. V. Koteneva S. A. Nikulin A. B. Rozhnov S. O. Rogachev 《Protection of Metals and Physical Chemistry of Surfaces》2014,50(1):64-68
The structure and mechanical properties, as well as the mechanism and kinetics of the destruction of oxide films formed on tube specimens of E110 zirconium alloy based on electrolytic or sponge zirconium upon corrosion testing in an autoclave and high-temperature oxidation in steam (LOCA conditions), were studied with the use of transmission and scanning electron microscopy, microhardness measurements, acoustic emission, and fractography. Oxide films on specimens made of electrolytic zirconium upon testing in an autoclave are found to be composed of extended grains with a thickness of 100 nm, while those on sponge specimens are composed chiefly of equiaxial grains with a diameter of 30 nm. After high-temperature oxidation, the structure of oxide films consists of extended grains of a variable thickness, which increases from the surface to the film-metal boundary from 600 nm to 2.5 μm on specimens made of electrolytic zirconium and from 250 nm to 2 μm on sponge-zirconium specimens. The microhardness of films after testing in an autoclave is 1200 ± 50 HV on electrolytic zirconium and 2000 ± 50 HV on sponge zirconium. The hardness of films on sponge-zirconium specimens upon high-temperature oxidation is 1600 ± 50 HV. The combined analysis of deformation diagrams, fractures, and acoustic emission data showed that the destruction of thin oxide films after testing in an autoclave and that of thick films after high-temperature oxidation begins with the formation of transverse brittle ruptures at the same load of 12–15 MPa. The number of cracks in the films on specimens that underwent high-temperature oxidation increases under loading especially rapidly on electrolytic zirconium. 相似文献
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基于实验设计研究了应变参数对锆合金动载下塑性变形机制的影响。通过控制应变速率,采用应变限位环的方法实现了锆合金高应变速率下应变参数的单一分离,应变速率为2300 s~(-1)时,获得了4个不同的应变水平:0.11、0.21、0.30、0.33。基于锆合金高应变速率不同应变下微观组织的表征,预测了应变参数对锆合金动载下塑性变形过程的影响。结果表明:形变带和转变带是锆合金不同应变阶段塑性变形的重要方式,形变带内部由严重变形的晶粒组成,而转变带内部主要由100~300 nm的细小等轴晶粒组成。在变形初始阶段,锆合金变形以柱面滑移和锥面滑移为主,以孪生为辅;随着应变的增加,位错持续增殖,位错的塞积导致应力增加,直至最大抗压强度;当应变达到一个临界值时,形成形变带;随应变继续增加,形变带发生动态再结晶,演化为转变带;应变继续增加,便会在剪切带内部诱发微空洞、微裂纹,直至材料断裂。 相似文献
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声发射技术在三维编织复合材料测试中的应用研究 总被引:8,自引:0,他引:8
论述了声发射技术在三维编织复合材料拉伸过程损伤测试中的应用,结果表明,通过采集声发射参数可以描述复合材料在载荷情况下的内部变形的损伤机制。系统采用小波分析方法对声发射信号进行噪声处理,用频谱图描述复合材料的内部损伤变形特征,为复合材料的力学性能分析和材料复合工艺的改善提供理论基础。 相似文献
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锆及锆合金是重要的核结构材料和有潜力的生物医用材料,但在实际应用中,腐蚀、磨损易造成其失效,而适当的表面改性是提高它们服役性能的有效手段。重点介绍了锆及锆合金微弧氧化(MAO)表面处理技术的研究现状,讨论微弧氧化过程中电压电流特征及微弧放电机理,总结电解液体系及电参数对锆微弧氧化膜生长及膜层性能的影响规律,最后指出目前存在的问题和后续的研究方向。锆微弧氧化膜硬度高,致密性好,能大幅度提升基材的抗磨损和抗腐蚀性能。因此,锆微弧氧化技术在核电及生物医学领域有着很好的应用前景。此外,电解液中铝、硅元素进入微弧氧化膜后可以稳定膜层中高温氧化锆相(t-ZrO2),避免膜层中应力集中和微裂纹的产生。用P和Ca元素修饰后的锆微弧氧化膜具有较好的生物活性、抗体液腐蚀和抗菌性能。 相似文献
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H. Hattendorf 《工业材料与腐蚀》2011,62(6):481-489
Chromium aluminum yttrium (FeCrAlY) alloys owe their low oxidation rate to the formation of a slow growing α‐alumina scale. For material used for heating elements not only the life time and the behavior of the resistance during the life time is of relevance, but also the emission coefficient of the oxide scale. The power density JS produced by resistance heating of strip with 50 µm thickness and about 5–6 mm width at 1050 °C is approximately equal to the radiant flux density, which is according to Stefan–Boltzmann's law proportional to the total emission coefficient εg. Resistance heating tests were performed on samples made from FeCrAlY alloys with different zirconium and carbon content. The “high zirconium” containing FeCrAlY alloys (zirconium > about 0.10%) have a higher power density/emissivity than the “low zirconium” alloys. In parallel with this, all samples with higher power density/emissivity have internal oxidation and therefore a “rough” metal–oxide interface. Thus, one cause for the increase of the emissivity of the scale could be this rough metal–oxide interface; other causes could be a higher amount of zirconium incorporated into the scale, more pores and/or different grain structure in the scale. Additionally the carbon content influences the appearance of a higher emissivity and the internal oxidation. 相似文献
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《腐蚀工程科学与技术》2013,48(7):533-537
Zirconia nanotubes were prepared in glycerol electrolytes containing fluoride ion and water via anodisation. The systematic study of the influence of anodising parameters (applied voltage and electrolyte temperature) on the zirconia nanotube diameter and their corrosion resistance in the artificial saliva solution as biological medium at 37±1°C have been demonstrated. Nanotubes were characterised by field emission scanning electron microscopy (FE-SEM). The FE-SEM results show that zirconia nanotubes have an outer diameter of 40–120 nm and inner diameter of 10–60 nm. The corrosion properties of samples were examined by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation tests. The results indicate that zirconium oxide nanotubes that were prepared at 50 V and 5°C demonstrate the best corrosion resistance. 相似文献