板波检测冷轧高强度钢薄板分层的研究

介绍了航天用冷轧高强度钢薄板分层的产生原因、检测方法。着重阐述了应用超声波板波检测分层的方法和检测参数选择;结合实际分析了不同类别分层的超声波波形及区别,并使用纵波和测厚仪等检测方法进行判定。实现了薄板中分层缺陷的高效检出,解决了分层缺陷定量、定性、定位、定深等难题,从而有效确保了薄板产品质量。     

铝合金薄板的超声透射法检测

分析了铝合金薄板内部缺陷以及分层缺陷产生的原因及其分布形态,讨论了常用的金属薄板无损检测方法的优缺点,选择超声透射法对不同厚度的铝合金薄板进行检测。在薄板上制作不同孔径的人工缺陷以模拟分层缺陷,测试在不同人工缺陷区域超声透射信号的幅度变化,并制作了对应的缺陷标定曲线。该方法检测铝合金薄板缺陷时,克服了超声探头的盲区,声束垂直于分层缺陷面,灵敏度高,不易产生漏检。     

线切割加工质量的分析及改善措施

线切割加工在模具制造业中常用于加工精密、微细的模具零件。通过介绍线切割的加工原理,研究了线切割加工过程容易产生的加工质量缺陷,分析了加工面变形与开裂、变质层及表面粗糙度产生的原因,提出了进一步提高工件表面质量的改善措施和方法。实践中可以通过合理选材、优化电参数、选择正确的加工路线等方面综合分析和控制线切割加工,在保证生产率的前提下,改善和提高线切割加工质量。     

模具零件在线切割加工中变形和开裂的分析与控制

在电火花线切割加工过程中,模具零件易产生变形和开裂.为了避免浪费,减少成本,对线切割加工中模具零件的变形和开裂进行了分析,找出其原因,并提出了控制变形和开裂的方法.     

线切割淬火后模具的变形及解决办法

我厂一直采用钱切割来加工淬火后的冷冲模零件(凸模、凹模、卸料板、固定板、托料芯、侧刃等)。线切割机床是一种比较先进的模具加工设备。线切割加工不仅解决了过去除磨削及电火花外无法用其他机械和手工方法加工的复杂模具加工问题,而且还大大提高了模具加工精度和生产效率。在我厂广泛采用线切割加工过程中也产生了一些具体问题,如线切割后模具变形,甚至产生开裂现象。对此,我们进行了试验研究,以求找到解决的办法。现将我们的一些分析和体会介绍如下。一、变形和开裂的原因原以为,采用线切割加工淬火后的冷冲压     

快走丝线切割加工过程中短路的原因与对策

在数控加工中,线切割加工是一种应用较广泛的加工方法.分析线切割加工过程中可能出现的短路的原因并给出相应的对策,为实际加工提供参考.     

薄板焊缝检测的超声相控阵楔块设计

针对薄板检测的特殊性,运用Snell公式等分析计算设计了一种超声相控阵斜探头楔块,并采用声场模拟以及实际检测方法验证了设计的楔块对于薄板搅拌摩擦焊缺陷的检测效果。结果表明,采用上述方法可以优化楔块设计,减少盲目性。按照设计结果加工的楔块对薄板具有良好的检测效果,可检测出3mm板中距离上表面1mm直径为0.3mm的侧孔。     

线切割加工模具的工艺要点分析

针对电火花线切割的工艺特征，分析加工过程中电极丝偏移量产生的原因。介绍了线切割数控编程中电极丝中心线实际走丝轨迹的计算原则和方法，提出穿丝孔的确定与切割路线的优化方面的工艺优点。并就线切割加工中模具零件的特殊工艺情况，提出相应的工艺措施，以改善模具的加工精度和制造质量，及提高生产效率。     

钛合金薄板的涡流阵列检测

制作了钛合金人工缺陷试板(薄板),通过工艺试验研究了涡流阵列检测的技术特点,并使用渗透检测方法对含有自然缺陷的成型钛板进行了对比验证试验。结果表明,涡流阵列能有效地检测出钛板的表面、近表面缺陷,为钛合金薄板涡流阵列检测的大范围应用奠定了基础。     

电火花放电点均匀性的一种评价方法

在电火花线切割加工过程中,会产生逐个的放电点,而放电点位置分布的均匀程度会对加工表面质量产生比较明显的影响。本文通过理论分析验证电位差法检测的合理性,并选定最优的标定函数,根据理论分析搭建电火花线切割放电点位置检测系统。对采集得到的数据研究直接导致对放电点位置检测以及评价的好坏。通过采用小波变换原理,对采集的原始放电点数据进行了去除噪点处理,探究电火花线切割加工过程中在25 ml/min蒸汽水雾介质中、在15 ml/min蒸汽水雾介质中他们的放电点位置均匀性是如何进行变化的,采用该系统采集了水雾中线切割精加工的放电点,验证了系统的实用性。     

On the extension of CP models to address cathodic protection under a delaminated coating

Cathodic protection models for pipeline and other metallic structures developed to address the presence of coating flaws or holidays do not account explicitly for the presence of a delaminated region surrounding a holiday. The potential drop in the delaminated region was obtained by solving the coupled, non-linear, partial differential, governing equations that describe transport and electrochemical reactions within the delaminated region. The results were used to develop an analytic expression for the potential drop across the delaminated region as a function of delaminated region length and the resistivity of the bulk environment exterior to the holiday. Expressions developed using this approach can be utilized by existing cathodic protection models to deliver improved potential distributions along protected metallic surfaces. The simulations were used to test the commonly employed assumption that transport by diffusion can be neglected in the delaminated region. The influence of diffusion on current was shown to be significant.     

5A06薄壁球壳件涡流检测技术

针对壁厚约为1.5mm的5A06锻轧薄壁球壳工件的加工工艺和内部可能的缺陷形貌,分析了该薄壁件质量的无损检测技术现状和检测难点。设计了含有不同尺寸的模拟裂纹和分层缺陷的对比试样,研制和改进了专用的高灵敏度探头。通过采用优化的涡流检测参数,实现了有效检出5A06薄壁壳体表面5mm×0.05mm(长度×深度)的裂纹类缺陷,具备了检出在1mm渗透深度下的5mm长线形刻槽和0.8mm深度左右的0.5mm面型缺陷的高灵敏度检测能力,并提出了100%检测工件质量的方法。     

用常规设备加工精密级进模的一些措施

介绍了在缺乏坐标磨床及线切割机床精度不足的条件下，加工制造一副精度较高的多工位级进冲模。借助于在模具结构设计中及制造加工工艺中采取的一系列措施，最终克服加工设备条件不足的困难，完成了该级进模的制造，取得了较好的效果。     

发动机波纹管破裂原因分析

发动机波纹管在工作中发生破裂失效。采用金相显微镜、三维视频、扫描电镜及能谱仪对波纹管的原材料、生产工艺及使用环境进行检验分析,以确定其破裂原因及性质。结果表明:由于波纹管内腔防腐蚀的聚酰亚胺漆膜脱落,裸露出的基体被管体内沉积物中的硫化物介质侵蚀,使管体发生晶间腐蚀。另外,对比了GH4169与PH15-7Mo、17-7PH的耐蚀性,发现固溶加调整状态下GH4169的耐蚀性优于PH15-7Mo、17-7PH。最后提出了更换材料的解决措施。     

Formation of Lamellar Pores for Splats via Interfacial or Sub-interfacial Delamination at Chemically Bonded Region

To comprehensively understand the formation mechanism of lamellar pores in splats, the delamination morphologies and crack patterns of yttria-stabilized zirconia (YSZ) and lanthanum zirconia splats were examined. Results showed that both types of splats grew epitaxially on well-polished YSZ substrates, evidently confirming the formation of chemical bonding between splats and substrate. However, the interfacial or sub-interfacial delamination was observed in all kinds of splats in this study. Residual vertical cracks passing through delaminated domains (on bare substrate) were also observed, which clearly indicated that transverse delamination followed vertical cracking. Mechanical analysis about delamination was addressed, and the results were consistent with the experimental data.     

用Kelvin探头技术研究铝合金的大气腐蚀

选择航空工业广泛使用的铝、铝合金及其涂层的试样，利用自行研制的Kelvin探头大气腐蚀测定仪、扫描电镜等设备，研究了纯铝试样随温、湿度变化，其表面电位的变化规律，测定了铝合金及涂层试样大气曝晒试验和周浸试验前后的表面电位、形貌,对铝、铝合金以及涂层的腐蚀规律进行了初步的探讨.结果表明，纯铝试样表面无可见液膜时，腐蚀电位随相对湿度增加逐渐下降；表面有可见液膜时，随着液层蒸发逐渐减薄，电位逐渐正移.铝合金裸材在北京大气环境下电位变化较小，且各个位置的电位基本相同.带涂层的试样优先在缺陷处发生腐蚀，并不断向周围扩展，涂层的剥离面积不断增大.涂层的铝合金，划痕处在腐蚀发生的初期腐蚀电位向负方向变化很快，但是随着时间的延长，腐蚀电位变化的速率减慢，并有向正方向移动的趋势.      

Delaminated areas beneath organic coating: A local electrochemical impedance approach

Local electrochemical impedance mapping was used to investigate delamination phenomena at the steel/epoxy-vinyl primer interface. The delamination occurred from an artificial defect (cutter scribing) and from ageing in a salt spray chamber. The samples were taken from the salt spray chamber after 20, 30 and 50 days of exposure. To observe delamination after ageing, the corrosion product layers were removed by a cathodic polarization at −1.5 V/SCE for 4 h. A non-aged reference sample was tested for comparison. Mapping was performed at 5 kHz. Initiation and propagation of the delamination were clearly observed. The delaminated surface areas measured by visual observations after the removal of the coating were lower than those determined by local electrochemical impedance mapping. The delamination mechanisms were discussed with reference to literature data.     

Influence of the specific surface area of a porous nickel to the intermetallic compound generated by reaction of a porous nickel and aluminum

A new process is proposed to fabricate an intermetallic compound reinforced aluminum alloy matrix composite by using the reaction between porous nickel and molten aluminum alloy. The intermetallic compound reinforced aluminum alloy composite was manufactured with the low-pressure infiltration process method. The amounts of the intermetallic compounds under 3 different specific surface area of porous nickel and the porosity inside composites were investigated. Porous nickel reacted with molten aluminum alloy at 973 K, and the intermetallic compound of Al₃Ni was generated on the surface of the porous nickel. The generated intermetallic compound Al3Ni, was delaminated according to the difference of thermal expiation coefficient with nickel. And the intermetallic compounds moves in the direction of aluminum matrix. The area fraction of the intermetallic compounds increased with the increasing specific surface area of porous nickel. In addition, the defect inside the composite decreased by the increasing specific surface area of porous nickel.     

金刚石膜剥落后硬质合金基体的表面形态

采用ＳＥＭ,ＦＴ－Ｒａｍａｎ,ＸＲＤ和ＥＤＸＡ对ＣＶＤ金刚石膜自发剥落后的ＹＧ８硬质合金基体表面的形貌、相结构和微区化学成分进行了表征,结果表明,该表面上存在石墨碳相,呈针片状;沉积金刚石膜后基体表面的ＷＣ颗粒显著细化,表层Ｃｏ含量仍很低。