钢芯铝绞线微动损伤机理及防护措施的研究进展

微动损伤普遍存在于钢芯铝绞线输电线路中,钢芯铝绞线在长期的使用过程中,微动磨损及腐蚀加速了其失效过程,给输电线路造成巨大的隐患。本文综述了国内外钢芯铝绞线微动损伤的研究现状,论述了其损伤机理,探讨了导线微动损伤的合理防护方法,并提出了一些尚待研究与探索的问题。     

5083铝合金/35CrMo钢线接触切向微动磨损行为

研究钢/铝配副的线接触微动磨损具有重要的理论意义和工程价值,过去对其报道不够。在电磁激振微动磨损试验机上,采用自调节式线接触夹具,对5083铝合金/35Cr Mo钢摩擦副进行线接触式切向微动磨损,研究了其在线接触条件下的切向微动磨损行为。结果表明:在线接触条件下,5083铝合金/35Cr Mo钢的微动运行区域存在部分滑移区、混合区和滑移区;部分滑移区摩擦系数较小,混合区摩擦系数峰值最大;部分滑移区损伤轻微,接触呈不连续特征,混合区和滑移区磨损严重;5083铝合金的磨损体积随着位移幅值的增加而增加,磨痕表层有微裂纹;5083铝合金/35Cr Mo合金钢的磨损机制主要为磨粒磨损和疲劳磨损。     

防松散型疏绕扩径导线的制造

本文主要介绍一种可以防止安装过程中出现导线松散的疏绕型扩径钢芯铝绞线的制造工艺，与普通的扩径导线相比防松散型疏绕扩径钢芯铝绞线的钢芯与外层紧密绞合的铝线层之间的疏绕扩径铝线层，采用了微紧压技术，保障导线在不出现影响导线正常的传输性能的情况下，使疏绕层进行轻微变形，从而使导线的疏绕层可以轻微的咬合在一起，层与层之间更好的接触，从而提高导线的抗松散能力。     

某铝包复合材料芯软铝型线绞线断裂原因分析

某输电线路用铝包复合材料芯软铝型线绞线在架线后不久即发生断裂。通过宏观分析、力学性能试验、机电性能试验、断口分析、金相检验等方法对导线的断裂原因进行了分析。结果表明:该断裂导线的复合材料芯棒在包覆铝管前已多处受损及断裂,复合材料芯棒断裂的导线在架线后,所有张力都由软铝层和铝管承担。因夜间温度降低,且风载荷作用引发线路舞动,使得导线所受张力超过软铝层和铝管的强度极限,最终导致导线断裂。     

saline溶液中钛合金扭动微动运行区域研究

在自制的已获专利的恒温扭动磨损腐蚀试验装置上,对TC4钛合金在saline溶液中的扭动微动磨损行为进行了研究,通过扭动三维图、磨损形貌等特征对扭动微动运行区域进行了重点讨论。结果表明,与切向微动类似,在介质中的扭动过程中也出现了微动的3个运行区域,3个区域的摩擦扭矩曲线、扭动三维图、磨斑形貌及损伤机理表现出不同的特征;扭动微动的混合区磨损形貌与切向微动不同,在扭动初期,磨斑表现为典型的微动环特征,随循环次数增加,损伤区域逐渐向心部扩展,并有完全覆盖接触区域,使整个接触区域都发生磨损的趋势。滑移区的Tf-θ曲线受频率影响明显,在低频率时为典型的平行四边形,随频率升高,逐渐变成椭圆形。     

植酸封闭对钢芯铝绞线表面Ni-P镀层耐蚀性的影响

在钢芯铝绞线中的铝股线表面化学镀镍磷可以改善其在沿海工业大气中的耐蚀性,但工艺流程较复杂。在铝股线表面不经过二次浸锌工艺直接化学镀Ni-P后再进行植酸封闭改性,通过红外光谱(FTIR)、扫描电镜(SEM)和能谱(EDS)对镀层进行形貌和成分分析,通过在1 mol/L H_2SO_4+3%Na Cl混合溶液中的浸蚀试验和Tafel极化曲线比较镀层的耐蚀性。结果表明:经植酸封闭后,铝股线表面的Ni-P镀层更均匀,外层由于植酸与镀层相互作用,局部出现细小孔洞,但腐蚀介质不易渗入基体;腐蚀电位正移,腐蚀电流变小,腐蚀前后形貌变化不大,结合力仍很好,植酸封闭后镀层的耐蚀性更好。     

新型特强钢芯软铝绞线在实际工程中的应用

新型特强钢芯软铝绞线的广泛使用,可有效提高输电线路输送能力,具有推广应用的价值和前景。本文以东莞500k V沙广甲乙线迁改工程为案例,分析特强钢芯软铝导线的应用特点。     

TA1钛合金单搭自冲铆接头微动磨损机理

对TA1钛合金单搭自冲铆接头进行疲劳实验研究接头失效形式;用扫描电子显微镜和X射线能谱线扫描研究铆钉各部位微动磨损程度的差异和接头微动磨损机理;采用威布尔分布验证数据有效性。结果表明:接头疲劳失效形式主要为上板断裂,高周疲劳均为上板断裂,低周疲劳为上下板混合断裂;微动磨屑包含氧、钛、锌和锡元素,铆钉头部微动磨损程度高于铆钉腿部。微动磨损区出现严重脱层、微动磨屑堆积和微裂纹萌生等现象,随着微动磨损及剪切力共同作用导致接头断口部位出现大量微裂纹并逐步沿深度和宽度方向扩展为宏观裂纹,最终导致接头疲劳失效。     

铝基SiOx膜层滑动磨损及其机理研究

本文采用低温常压CVD方法制备铝基SiOx陶瓷膜层.以黄铜为对磨材料,使用销-盘式磨损试验机对比研究纯铝表面与SiOx膜层的滑动磨损性能,通过SEM分析磨损的表面形貌并分析其磨损机理.结果表明纯铝表面发生粘着磨损,存在大量塑性变形和折叠,导致片状脱落,磨损率高;SiOx薄膜硬度较高,存在孔隙,表面发生塑性变形、崩塌和磨粒磨损;因薄膜孔隙具有储存润滑剂(水)的作用,磨损率明显低于对比纯铝样品;随沉积时间增加,SiOx膜层变厚,承载能力提高,磨损量减小.     

TA1钛合金单搭自冲铆接头微动磨损机理

对TA1钛合金单搭自冲铆接头进行疲劳实验研究接头失效形式;用扫描电子显微镜和X射线能谱线扫描研究铆钉各部位微动磨损程度的差异和接头微动磨损机理;采用威布尔分布验证数据有效性.结果表明:接头疲劳失效形式主要为上板断裂,高周疲劳均为上板断裂,低周疲劳为上下板混合断裂;微动磨屑包含氧、钛、锌和锡元素,铆钉头部微动磨损程度高于铆钉腿部.微动磨损区出现严重脱层、微动磨屑堆积和微裂纹萌生等现象,随着微动磨损及剪切力共同作用导致接头断口部位出现大量微裂纹并逐步沿深度和宽度方向扩展为宏观裂纹,最终导致接头疲劳失效.     

Failure analysis of aluminum cable steel reinforced (ACSR) conductor of the transmission line crossing the Paraná River

The failure of the conductor of the 460 kV overhead transmission line located along the crossing of the Paraná River was investigated. As a result of this failure, a blackout took place in the southern states of Brazil in January of 2002, reaching approximately 67 million inhabitants. Investigation of the external aluminium layer of the ACSR conductor near the fracture showed typical static deformation marks and dynamic fretting wear tangential marks, both associated with the presence of Al₂O₃ debris. Additionally, encrusted silicon particles were observed on the external surface of the strands. The internal Al layer showed elliptical deformation marks also associated with Al₂O₃ debris. Both Al₂O₃ and Si particles are efficient abrasive material, which associated with slight relative motion of metallic surfaces (clamp/strand and strand/strand) can promote fretting wear. Two types of fracture surface of the Al strands were identified: 45° and quasi-normal surfaces, the former being the predominant type. Delamination and particle detachment were the mechanisms of superficial degradation observed on the Al strands, indicating that the rupture of the strands occurred under a gross slip fretting regime induced by sub-conductor oscillation. Inspection of the internal surface of as-cast Al–10%Si spacer clamps revealed different stages of intense circumferential wear caused by the preferential cracking and particle detachment of the eutectic constituent of the as-cast microstructure. This intense wear reduces the clamping contact pressure, which allows higher displacement amplitude and leads to the critical fretting regime. Finally, a few suggestions are discussed to minimise the occurrence of future failures.     

Effect of high mean tensile stress on the fretting fatigue life of an Ibis steel reinforced aluminium conductor

The aim of this work is to evaluate the effect of a high mean tensile pre-load on the fatigue life of an Ibis type of steel reinforced aluminium conductor (ACSR) mounted on a monoarticulated cast aluminium suspension clamp. To carry out the tests a new and enhanced version of a fretting fatigue rig for overhead conductors was built. Based on the obtained S–N curves for this assembly it was shown that an increase of the Everyday stress (EDS) from 20% to 30% of the cable rated tensile strength (RTS) caused an average reduction of 50% in life. Failure analysis revealed that cracks always initiated at contact interfaces within the cable/clamp assembly, at the fretting marks.     

Determination of early failure sources and mechanisms for Al 99.7% and Al–Mg–Si alloy bare conductors used in aerial transmission lines

In this article, early failure reasons and their sources for the bare aerial transmission line conductors have been presented with a combination of measuring data on wear tendency of their components and analyzing of collected samples due to processing damages and continue cast defects onto wires produced by 99.7% EC grade Al and Al–Mg–Si alloys. Nominal service life of aerial conductors is 30 years. However most of them are failed early. Essential source of the failure depends on environmental conditions and manufacturing process. After installation of conductors to trusses, the fretting phenomenon between strands under greased and non-greased applications is triggered due to fluctuation of bending, tension and torsional stresses by wind and dead loads of conductors. Environmental forcing functions cause working of surfaces of defected and processing damaged wires each other with small displacements and create grinding of small particles and finally fretting. Samples collected from the aerial conductor plant including processing defects and damages were illustrated and interpreted in the article deeply. Additionally, tribological behaviors of conductor wires were also investigated with different parameters under grease lubrication and dry friction conditions. Results were presented in graphics and figures in details to indicate the early failure reasons which were mainly related to manufacturing process and tooling used in processing of them.     

高压架空钢绞Al导线的腐蚀与防护

钢绞Al导线（Aluminium Conductor Steel Reinforced,ACSR）是我国高压输电线路主要的导体材料。在工业污染或沿海区,ACSR导线发生较严重腐蚀,导致强度降低,甚至断线,影响输电安全,提高运行成本。本文基于Al及Zn的溶液及大气腐蚀腐蚀机理,综述了国内外有关ACSR导线的腐蚀机理、影响腐蚀的因素、腐蚀对ACSR导线性能的影响及ACSR导线的防护的研究成果,并就今后如何在实验室内开展工业污染环境下的ACSR导线腐蚀研究提出自己的观点。     

A note on the behind armour effects from perforated alumina/aluminium targets

A thin, ceramic-faced armour, separated from a thick metal block, has been subjected to high-velocity impact by a 6.35 mm diameter steel sphere. Experimental work was carried out which compared firings into ceramic-faced aluminium armour, separated from thick aluminium “witness” blocks, with firings into the thick aluminium blocks alone. The depth of penetration and the area of damage were measured and an estimated percentage weight saving due to the inclusion of the ceramic-faced armour was calculated at varying velocity. This note yields useful information for the design and application of ceramic appliqué systems.     

Ti6Al4V合金在血清溶液中的扭动微动腐蚀行为研究

在新型恒温扭动微动腐蚀实验装置上,通过改变角位移幅值,在恒温37℃的25%血清溶液中对Ti6Al4V合金的扭动微动腐蚀行为进行了研究。实验结果表明,角位移幅值对扭动微动的运行区域及腐蚀行为有重要的影响,摩擦扭矩-角位移幅值(T-θ)曲线分别呈直线型、椭圆型和平行四边形型,Ti6Al4V合金的扭动微动运行区分别呈现部分滑移区、混合区及滑移区等3个微动运行区。当角位移幅值较小时,扭动磨损发生在接触边缘,损伤轻微;扭动微动对腐蚀几乎不产生影响,腐蚀电流和腐蚀电位随时间的曲线波动不大;随着角位移幅值的增大,接触表面产生强烈的塑性变形,损伤严重。腐蚀电流和腐蚀电位随时间的变化曲线表明,扭动微动对腐蚀的影响较大,呈磨损加速腐蚀的特征。     

A study on the combined effect of notch and fretting on the fatigue life behaviour of Al 7075-T6

In this study, an investigation was conducted on the fatigue performance of Al 7075-T6 plates in the presence of stress raisers (notch, fretting, and a combination of notch and fretting). Fretting situation was induced on the surface of the aluminium plate through steel contacting pads under two different clamping forces of 2 kN and 5.6 kN. The fatigue tests revealed a more dominant effect from stress concentrators originating from geometrical discontinuities such as the tested notch compared to the fretting wear conditions. Therefore, no noticeable differences were found between the fatigue lives of the notched specimens and the combined notch and fretting condition. A finite element stress analyses of the notched model under the contacting fretting pads agreed with the experimental results. The stress distribution at the clamped area introduced tensile stresses at the edge of the contact region, however, the stress at the notch tip was observed to be higher when an axial tensile load was applied to the end of the plate. Fractographic analyses confirmed the presence of cracks initiating from the fretting damaged surface for most of the combined notch and fretting fatigue test specimens particularly at the high cycle fatigue (HCF) zone.     

Multi‐axial fretting fatigue behaviour of 35CrMoA steel

The fretting fatigue behaviours in 35CrMoA steel were investigated under conditions of the various contact pressure and the same maximum equivalent stress of cyclic multi‐axial loading. The specimens were characterized by optical microscopy and scanning electron microscopy. Results showed that the fretting fatigue life has complex variation with the increase of contact pressure. The different contact pressure also played very important role in fretting wear model and various wear scars were formed. The influence of them at the fretting surface on the fretting fatigue life was finally discussed by the comparison of the experimental and numerical analysis results.     

Torsional wear behaviours of TiO2/PMMA film against Ti6Al4V alloy and alumina femoral head ball in dry condition

The torsional fretting wear tests of Ti₆Al₄V alloy flat against alumina femoral ball in dry condition were carried out on a new high-precision torsional fretting-wear tester. The TiO₂/P-methoxymethamphetamine (PMMA)/Ti₆Al₄V pair showed higher contact stiffness, friction torque, wear damage and material transfer than that of the presentation of TiO₂/PMMA/Al₂O₃ pairs. The mechanisms of torsional wear under different counterbodies were discussed in detail. The mechanisms of torsional fretting wear of aluminium alloy are mainly oxidative wear, abrasive wear and delamination in the three fretting regimes. The torsional fretting running regimes transferred from partial slip regime (PSR) to SR were analysed; however, the mixed fretting regime was never appeared in this test. In PSR (lower angular displacement amplitudes), only a dint was found after the tests. The kinetics behaviours and damage mechanism of Ti₆Al₄V alloy under different angular displacement amplitudes with friction torque and dissipation energy, which are strongly dependent upon the imposed angular displacement amplitudes and presented in three stages, were discussed in detail.