B5后桥A356铝合金支承座早期断裂失效分析

针对某B5后桥A356铝合金支承座台架试验早期断裂的问题,采用宏观分析、化学成分分析和扫描电镜断口观察等方法对支承座的断裂原因进行了分析.结果表明:由于该支承座受到意外挤压而造成其在加强筋处表面产生一较小的凹坑,由此形成的应力集中使零件在随后的台架试验中很快在此处萌生裂纹源;同时由于该支承座在裂纹源附近存在大面积的疏松...     

机车车钩断裂分析

某机车在运行中其车钩发生断裂。对断裂车钩进行了断口观察、化学成分复验、力学性能测试和夹杂物及显微组织检验。结果表明，该车钩退火处理前已存在的铸造裂纹成为疲劳源，退火处理时的过热又造成钩体表面氧化和严重脱碳，尤其钩腕处的晶粒度达到2～3级，大大降低了车钩的力学性能，在综合因素作用下导致车钩疲劳断裂。     

汽车发动机盖锁扣断裂原因及改进措施

某种车型的发动机盖锁扣在总装过程中发生断裂失效。通过化学成分分析、金相检验和力学性能测试等方法对锁扣断裂的原因进行了分析。结果表明:所用的SCM435钢为未球化退火状态,材料硬度过大,以及镀锌过程中可能引起氢脆等原因导致锁扣断裂。通过改变材料球化退火状态,以及改进加工工艺,解决了锁扣断裂问题。     

退火气氛与扩散阻挡层对Cu膜表面完整性的影响

用反应磁控溅射和离子束辅助沉积(IBAD)方法分别在(111)单晶硅基体上沉积了Cu／ZrSiN与Cu／ZrN膜系，制得的试样在800℃下分别在真空和N2、H2混合气体两种气氛中退火lh。结果表明，在真空中退火的Cu／ZrSiN膜由于ZrSiN膜裂纹导致Cu膜裂纹的产生：ZrSiN和ZrN扩散阻挡层上的Cu膜还有很多由晶界迁移导致的孔洞。在氮氢混合气体中退火时ZrSiN扩散阻挡层上的Cu膜由于具有高的应力而发生断裂，ZrN扩散阻挡层上的Cu膜则没有这一现象。在N2、H2混合气体中退火时Cu由于还原性气氛抑制了晶界迁移而使Cu膜的孔洞变小、减小。     

大型支承辊置裂原因分析

大型支承辊在放置时自然断裂，采用化学分析、金相检验和扫描电镜等手段对断裂支承辊进行了套料取样分析，结果表明．辊身心部较高的内应力和在带状碳化物中存在严重的网状碳化物是造成大型支承辊置裂的主要原因。     

电站稳压器支承裙座锚固螺栓断裂失效分析

某电站稳压器支承裙座锚固螺栓在安装一段时间后发生断裂,从力学和材料角度对该螺栓断裂原因进行了分析。对断裂螺栓进行了金相组织观察、化学成分分析、力学性能试验以及断口的宏观及微观形貌观察,发现螺栓断口附近组织异常,外部环状带晶粒粗大,硬度和抗拉强度偏低导致裂纹启裂,裂纹逐渐扩展引起螺栓整体失稳断裂;螺栓局部出现组织异常的原因为螺栓热处理过程中控温不当导致局部过热。     

高氮奥氏体钢低温脆断中的三种断裂刻面

用扫描电镜对18Cr-18Mn-0.7N高氮奥氏体钢低温脆断中裂纹的形成、扩展及断面进行了分析.结果表明,低温脆断中,首先沿退火孪晶界及晶界形成微裂纹,微裂纹穿晶连接使裂纹扩展,其结果导致断口上形成三种断裂刻面,即光滑平面状退火孪晶界断裂刻面、光滑曲面状沿晶断裂刻面及粗糙不平的穿晶断裂刻面.     

α+β相区高温退火对Ti80合金板材组织与性能的影响

研究了Ti80合金板材在α+β相区较高温度退火时,退火温度与冷却方式对其组织及性能的影响。结果表明,两相区高温退火时,初生α相对温度极为敏感,随着退火温度的升高,其含量急剧下降,而次生α相含量则明显增加。随着退火温度的升高,室温强度逐渐降低,伸长率变化不明显,而冲击功则随着退火温度的升高明显增加。两种冷却方式下,Ti80合金板材冲击断裂方式均为穿晶断裂。两者相比,980℃/60 min,水冷获得了较小的初生α相,以及较薄的次生α相片层,从而导致板材强度明显升高,伸长率略有降低,而冲击功则大幅下降。     

铜母线冷弯断裂原因分析

汽轮发电机用铜母线在冷弯过程中发生断裂,对未断和断裂铜母线进行了检验并作对比分析,结果表明,预变形度不够,导致铜母线在退火中晶粒显著长大,造成冷弯断裂。     

风机联轴器断裂原因分析

某风机在试运行过程中其膜片联轴器发生断裂失效,采用宏观分析、金相检验、化学成分分析和力学性能测试等方法对联轴器的断裂原因进行了分析。结果表明:该联轴器发生断裂主要是由于联轴器锻造后热处理不当,形成过热组织缺陷,从而导致其韧性极差;另一方面是由于联轴器锻造后未进行退火处理,内应力未及时消除,最终导致其在使用过程中的应力作用下发生早期脆性断裂失效。对断裂的联轴器进行退火+调质处理,可使其韧性大幅度提高,得到优良的综合力学性能。     

椭圆轴承与圆轴承动力特性CFD数值分析

滑动轴承动力特性对旋转机械转子稳定性有着重要影响。将CFD动网格技术应用于椭圆轴承与圆轴承动力特性求解。在验证滑动轴承CFD动力特性求解模型准确性的基础上,建立基于CFD动网格技术的椭圆轴承动力特性求解模型,分析椭圆度、偏心率以及转速等因素对滑动轴承动力特性影响,比较分析椭圆轴承与圆轴承动力特性之间的差异。研究表明,椭圆轴承与圆轴承的承载力与刚度阻尼系数随着偏心率、转速的增加而增大;与圆轴承相比,椭圆轴承两个油楔形成两个流体动压区有效的增大轴承的阻尼,滑动轴承增加椭圆度可提高转子稳定性。     

变频驱动电机轴承电气损伤原因及对策

随着变频调速技术在电机系统节能领域的广泛应用,如何最大程度降低轴电压对轴承的损伤是目前面临的一个问题。本文在对比分析现有的一些技术和方案的基础上,介绍一项全新的低成本、高性能的轴电压解决方案。     

连杆衬套的开裂分析

机车280型柴油机连杆衬套在使用过程中发生开裂,采用宏观观察、扫描电镜分析、组装工艺分析、受力分析以及金相检验等方法对开裂的连杆衬套进行了综合分析。结果表明,连杆衬套的装配工艺不合理,造成衬套与活塞销高点接触而产生应力集中,这是导致连杆衬套开裂的原因。定位销位置设计不合理以及衬套基体存在严重的疏松,是促使连杆衬套开裂的主要因素。     

An examination of tellurium ion-implanted GaAs by transmission electron microscopy

The effect of implanting high energy tellurium ions into single crystal GaAs has been investigated by transmission electron microscopy. Results from annealing experiments on specimens implanted at room temperature show that two anneal stages centred near 200 and 600° C occur, the actual anneal temperature being dose dependent. Non-crystalline surface layers were formed after implanting doses in the range 5×10¹³ to 5×10¹⁵ ions cm^?2 at room temperature. However, implanting similar doses at 180° C caused no change in crystallinity. Thus the low temperature anneal stage which is the epitaxial recrystallization of the non-crystalline material, does not occur for the higher implant temperature. The high temperature anneal stage is associated with the annealing out of tiny defects such as twins and/or stacking faults leaving a single crystal containing only dislocation loops. The anneal stages observed by electron microscopy correlate with changes in sheet resistivity and Rutherford backscattering measurements on similar material. It is suggested that changes in dislocation loop size and density at high temperatures are coincident with the attainment of electrical activity.     

Angular dependence of magnetic annealing effects in permalloy base films

Attempts have been made to interpret magnetic annealing effects by assuming that the uniaxial anisotropy is caused by a directional order of local atomic configurations. By studying both evaporated and electroplated films, it is found that during an anneal the number of such elementary anisotropy sources is conserved. The angular dependence of magnetic annealing effects can be described by assuming a reorder of elementary anisotropy sources parallel to the magnetization at a rate independent of the magnetization direction. In the absence of a physical model describing the kinetics of reorder, it is shown how experimental values of the anisotropy field measured during hard-axis anneals can be used to predict for any annealing direction, the changes in anisotropy field, skew, and coercivity. Changes in angular dispersion were also studied but could not be explained satisfactorily. The variations of all main film parameters are found to be reversible during subsequent easy-axis anneals, and the recovery of the anisotropy field during such an anneal can be used to predict the recovery of all other parameters.     

45钢厚板断裂原因分析

在使用４５钢厚板制造大高炉自动装料机的轨道过程中，板材发生多处开裂和断裂。采用金相，扫描电镜和化学成分分析等方法对断裂进行了分析，结果表明，厚板气割后产生较大的内应力和退火时加热不均匀而使局出现粗大的魏氏组织是致断的主要原因。     

Study on failure mechanism of roadway with soft rock in deep coal mine and confined concrete support system

Surrounding rock control is a tough issue in roadway with soft rock in deep underground. To solve this problem, the original supporting scheme is monitored and analyzed on site with Liangjia coal mine of China as engineering background. Located in Longkou seashore mining area, Liangjia coal mine is a typical deep mine with soft rock in China. The analysis shows that roadway deformation is large with a big damage range; anchor bolts are generally in seriously broken surrounding rock; the support potential fails to be played; the support strength of arch is insufficient and the post bearing capacity is low. All of these mainly lead to the failure of the roadway bearing capacity. Numerical test is conducted with the consideration of arch strength, geostress, mechanical parameters of surrounding rock and other factors; it is to comparatively analyze the deformation of surrounding rock, the range of plastic zone and the mechanical properties of support components under different factors; therefore, the failure and control mechanism are defined on deep roadway with soft rock; and a concept of “high-strength, integrity, and pressure-relief” is proposed. Meanwhile, a confined concrete (CC) support system is developed; and a laboratory comparative test for full-size arch is carried out on its core component - CC arch and the conventional U36 arch as well. The research shows that the instability and failure of the entire U36 arch is caused by partially bending and buckling of the arch, and its bearing capacity is drastically reduced. The bearing capacity of CC arch is 2.03 times compared with that of U36 arch, and also has a good post bearing capacity. On the basis of these numerical and laboratory tests, a comparative test is carried out on-site. The monitoring results in the test show the rock deformation in CC support testing section is only 22.4% of that in U36 arch support; and no yield and failure phenomenon occurs in CC support test section, which proved the effectiveness of CC support system on surrounding rock control.     

基于试验设计与有限元仿真的辐射井水平钻机承载部件优化设计

为了提升辐射井水平钻机承载部件的安全性与稳定性，运用试验设计（design of experiment，DOE）与有限元仿真技术对承载部件进行优化设计。通过正交试验法结合ANSYS Workbench有限元静力学仿真对由回转平台、立支架及横支架组成的承载系统的加强筋板布置形式进行优化设计，获得承载系统加强筋板的最优布局类型。在此基础上，运用基于试验设计的响应面优化法对回转平台的台面厚度、筋板高度及筋板厚度进行优化设计，进一步减小回转平台的最大等效应力、最大变形及质量，提升承载系统的安全性与稳定性。结果表明承载系统加强筋板的最优布局类型为：回转平台采用纵横筋板，立支架采用X形筋板，横支架采用V形筋板；回转平台的最优参数组合为：台面厚度为11.2 mm，筋板高度为31.9 mm，筋板厚度为12.3 mm。集成运用试验设计与有限元仿真技术对水平钻机承载部件进行优化设计的方法可为水平钻机实体样机设计提供一定的参考。     

Dopant diffusion and activation induced by sub-melt laser anneal within the co-implanted p+ polycrystalline silicon gate used in CMOS technologies

Due to the continuous CMOS transistor scaling requirements, highly doped shallow junctions with improved activation have been widely investigated in recent CMOS technologies. In this scope, sub-melt millisecond laser annealing has been introduced in the integration flows to enhance dopant activation, without any additional detrimental diffusion. This MSA step impacts not only the transistor junction properties, but also the polysilicon gate depletion. This paper is devoted to the study of the MSA influence on boron and germanium co-implanted polysilicon films. A sensitive boron diffusion occurring during the laser anneal step, with or without an initial spike annealing step, has been observed. The activation energy of the boron diffusivity extracted from SIMS profiles in the laser only sequence has been found equal to 4.05 eV. In addition, it was shown that either a high temperature laser anneal sequence or a spike anneal followed by a laser anneal sequence can reach the same activation levels.