电弧熔敷用高熵合金粉芯丝材熔敷层的摩擦磨损行为

通过研究电弧熔敷不锈钢高熵合金粉芯丝材在不同摩擦条件下的摩擦磨损行为,为实现电弧现场快速修复和成形在耐磨性能方面提供可靠的保证.将高熵合金组成的Fe、Co、Ni、Cu四种金属元素以粉末按等原子比制成不锈钢高熵合金粉芯丝材,通过电弧熔敷方式熔敷在不锈钢表面.采用Nanovea Tribometer摩擦磨损仪和Nanove...     

20钢电弧熔覆制造成形与性能研究

低碳钢在装备制造中应用广泛,但其零部件易损坏,以20钢为研究对象,采用电弧熔覆修复技术,对其废旧零部件再制造技术进行研究.采用ER49-1低碳钢焊丝,在20钢基板上进行TIG焊电弧熔覆修复试验.通过光学显微镜、扫描电镜、显微硬度仪和拉伸试验机分析熔覆层微观结构及其性能.试验结果表明,电弧熔覆修复试样件焊缝出现细针状铁素...     

搭接中心距对电弧增材熔池流动及熔积层形貌影响的数值模拟

搭接中心距对电弧增材搭接熔积的熔池流动及熔积层形貌有重要影响,为探究其影响机理,建立了钨极气体保护焊(Tungsten inert gas welding, TIG)电弧增材成形过程的三维数值模型,研究了不同搭接中心距对熔池流动及熔积层形貌的影响。结果表明：不同搭接中心距下熔池表面温度峰值相近,约为1900 K,表面流速呈非对称的双峰式分布。当搭接中心距小时,由于第一道焊道的支撑作用,使得第二道焊道横截面熔池流动和形貌不对称,熔池深而窄,熔池流动为单向的顺时针环流,左侧流速普遍大于右侧;随着搭接中心距的增大,第一道焊道的支撑作用逐步减弱,使得搭接焊道横截面熔池流动逐渐变为以第二道焊枪中心线为对称轴,左侧顺时针、右侧逆时针的两个环流,两侧流动逐渐对称,搭接熔池宽度逐渐增大、深度逐渐减小,两焊道逐渐分离并出现波谷,当搭接中心距为6 mm时熔积层形貌最平整。模拟与试验结果基本吻合,本研究结果可为电弧增材工艺参数调控提供理论支撑。     

2219铝合金CMT电弧增材熔滴过渡行为

在冷金属过渡(cold metal transfer,CMT)电弧增材制造过程中,熔池的流动行为极易受到电弧和熔滴的影响,从而严重影响堆积层的稳定性和成形件质量.该文利用高速摄影结果及电信号参数波形图,引入热输入量计算公式,从特征电信号、熔滴过渡特征量、热输入量等方面定量分析了CMT+P模式下送丝速度及脉冲修正系数对熔滴过渡过程及单道成形形貌的影响,同时分析了脉冲变极性冷金属过渡(Advanced CMT,CMT+PA)模式下送丝速度及控制面板上的EP/EN修正系数η对熔滴过渡过程及单道成形形貌的影响,为后续工艺优化提供参考和指导.     

激光熔覆各向异性对Fe60合金磨损腐蚀性能的影响

The laser cladding technique has been widely used to improve the tribo-corrosion performance of metal productions. However, the microstructure of materials prepared by laser cladding can present an anisotropy due to the differences of temperature gradient along different directions during solidification. As a result, the performance of tool materials maybe fluctuate greatly with the selection of different working surfaces. Herein, in this paper, the effects of anisotropy on the tribo-corrosion performance were primarily focused on. For that, Fe60 alloy powders manufactured by laser cladding on a stainless steel substrate were selected as the research object. And then three working surfaces, i.e. parallel, incline 45° and vertical to the building direction, were respectively taken for the tribo-corrosion test. Most of efforts were mainly made to analyze the friction coefficient, open circuit potential (OCP), and wear as a function of working surfaces. In order to explore the corresponding reasons, the microstructure, mechanical properties, and worn surfaces morphologies of different testing samples were characterized as well. The results showed that the OCP decreased as wear began at the initial stage. It was ascribed to the destruction of passive film outside the testing surface. Simultaneously, the re-passive behavior also existed, which would reach a balance with the destruction when the friction tended to be stable. The wear rate became slower with the continuous friction. On one hand, it was attributed to the lower contact stress between friction pairs after a running-in stage, which could reduce the complicate mechanical interactions. On the other hand, it was closely related with the re-generated passive film. As compared with other surfaces, the 45° one had the best friction stability, corrosion resistance, and wear resistance. It was resulted from the differences of microstructure. Firstly, the higher density of grain boundaries enhanced the deformation resistance, which was beneficial to the stable contact. Secondly, the corresponding crystal orientation with lower atomic density was also responsible for the deformation resistance. In addition, the selection of 45° sample was compared with an as-casted sample under different loads. It was found that samples prepared by laser cladding had better tribo-corrosion resistance. It was closely related with the refinement of organizations caused by the rapid cooling rate. For instance, the generation of sub-grains could improve the surface hardness, and could reduce the surface activity, so that the materials resistance to mechanical damage and corrosion could be obviously improved. The tribo-corrosion performance was deeply influenced by loads. The increasing load could result in the lower friction coefficient, which was attributed to the disproportionate increase of contact area at tribology interface. Besides, the laser cladding sample had the lower sensitivity to the various load. After test, the worn surfaces of different samples were observed. It was suggested that the load and microstructure could lead to the change of physical mechanisms. Under lower load, the materials damage was dominated by corrosion and abrasive wear. As the load increased, the adhesive mechanism began to play significant roles. The research results could provide reference value in practice. © 2023 Chongqing Wujiu Periodicals Press. All rights reserved.     

激光熔覆TiZrHfCrMoW涂层在大气和模拟体液环境下的摩擦磨损行为

目的 提高钛合金表面耐磨性。方法 采用激光熔覆技术在TC4基体表面制备TiZrHfCrMoW涂层,采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)等分析涂层的相组成和显微组织结构。联合电化学工作站和摩擦磨损试验仪,分别在大气和37 ℃的0.9%NaCl模拟体液环境条件下,研究TiZrHfCrMoW高熵合金(HEA)涂层与TC4合金的摩擦磨损行为。结果 激光熔覆HEA涂层均匀致密,无明显缺陷,主要由2种BCC相及1种未知相组成,涂层平均硬度为584.6HV0.2,约为TC4基材硬度的1.6倍。在空气中滑动时,HEA涂层在0.3、0.5、1 N下的磨损率均比TC4基体低,且涂层的磨损率随载荷的增加而增加,TC4的磨损率则相反。在(37±0.5) ℃的0.9%NaCl溶液中,0.5 N载荷下TC4的磨损率是HEA涂层的6倍。HEA涂层与TC4钛合金基体相比,具有更高的自腐蚀电位和更低的腐蚀电流密度。模拟体液环境下HEA涂层的主要磨损机制为逐层剥落和腐蚀磨损。结论 激光熔覆HEA涂层可以有效提高TC4合金的耐磨损及耐腐蚀性能。     

液氮辅助激光熔覆温度场仿真及熔覆层摩擦磨损性能分析

针对液氮辅助激光熔覆制备高熵合金涂层过程,综合使用有限元分析与试验验证等方法,分析不同液氮施加方式下的熔覆层温度梯度与冷却速率,揭示施加液氮对熔覆层温度梯度和冷却速率影响的理论依据。有限元仿真结果表明,在激光功率相同时,液氮辅助技术的添加会使熔覆层冷却速率加快,温度梯度增大,残余应力减小,最高冷却速率为8900℃/s,是空冷状态下的1.505倍;在液氮施加方式相同时,激光功率的增加会使熔覆层温度梯度增大,冷却速率加快。试验结果表明,液氮辅助激光熔覆过程中液氮的加入会提高熔覆层的硬度,在激光功率为1500 W时硬度提升最明显,是空冷状态下的1.3倍;降低熔覆层的摩擦因数,在1100～1900 W时熔覆层平均摩擦因数为0.146、0.256、0.375、0.351、0.382,均低于空冷状态下的平均摩擦因数;减少熔覆层的磨损体积,在1700 W时磨损体积较空冷状态下的磨损体积减少量最多,可达55.4%,提高了熔覆层的摩擦磨损性能。     

热锻模具电弧增材再制造技术研究进展

热锻模具是制造业中的基础工艺装备,是大规模生产的基础.由于其复杂的工作环境,热锻模具内部易产生疲劳裂纹、磨损、塑性变形等失效.将电弧增材技术引入热锻模具修复与再制造可提高模具基体材料的利用率,降低制造成本,提高锻造生产连续性.本文总结了热锻模具的主要失效形式及成因,并通过对现有修复技术比较,得出了电弧增材技术的适用性范围.分析了焊材、工序及工艺因素等对热锻模具再制造质量的影响,结合该技术已取得的进展及面临的技术瓶颈,对热锻模具电弧增材再制造技术的未来研究方向进行了展望:如研究热锻模具再制造专用焊材、匹配低热输入量增材制造工艺、建立电弧增材制造多金属层热锻模具剩余服役寿命预测模型、研发增减材净成形修复设备等.     

电弧增材制造中两种特殊位置熔积的电弧仿真

为了研究电弧增材制造过程中两种特殊熔积位置即每一层的第一道熔积和最后一道熔积位置电弧的传热传质特性,建立了电弧的数值模型,模拟并对比分析了这两种特殊情况下电弧形态、压强以及等离子和保护气流动状态,并在仿真区域取竖直和水平两条路径,详细对比分析了路径上电弧的温度、电流密度、电磁力、压强、速度、电势的分布.结果 表明:受熔...     

搅拌摩擦焊与氩弧焊接接头摩擦磨损性能研究

分别试验了LF2铝合金搅拌摩擦焊焊接接头与氩弧焊接接头的摩擦磨损行为，试验分为3个阶段进行，转数分别为480，1200，2400转。结果表明在相同的实验条件下，搅拌摩擦焊接头的摩擦磨损性能明显优于氩弧焊接接头，其中第一阶段磨损失质量差别不大，后两个阶段搅拌氩弧焊接接头的磨损失质量是搅拌摩擦焊接头的4~6倍。氩弧焊接接头磨损表面呈现明显的塑性变形和表层剥落开裂迹象。搅拌摩擦焊接头磨损表面呈现轻微的疲劳磨损特征。     

Tribological behavior and wear mechanism of resin-matrix contact strip against copper with electrical current

The resin-matrix pantograph contact strip （RMPCS）, which has excellent abrasion resistance with electrical current and friction-reducing function, was developed in view of the traditional contact strips with high maintenance cost, high wear rate with electrical current and severe damage to the copper conducting wire. The characteristics of worn surfaces, cross-section and typical elemental distributions of RMPCS were studied by scanning electron microscopy （SEM） and energy dispersion spectrometry （EDS）. The wear behavior and arc discharge of RMPCS against copper were investigated with self-made electrical wear tester. The results show that the electrical current plays a critical role in determining the wear behavior, and the wear rate of the RMPCS against copper with electrical current is 2.7-5.8 times higher than the value without electrical current. The wear rate of the contact strip increases with the increase of the sliding speed and electrical current density. The main wear mechanism of RMPCS against copper without electrical current is low stress grain abrasive and slightly adhesive wear, while arc erosion wear and oxidation wear are the dominate mechanism with electrical current, which is accompanied by adhesive wear during the process of wear.     

LF2铝合金搅拌摩擦焊接接头磨损性能研究

试验了LF2铝合金搅拌摩擦焊接接头的摩擦磨损行为，通过观察接头磨损表面形貌没有发现明显的大块剥落开裂迹象。表面呈现疲劳磨损特征。这是由于搅拌摩擦焊接头形成的细小等轴晶粒导致裂纹扩展困难所造成的。     

新型离子液体作为甘油润滑添加剂的摩擦性能

目的 改善甘油作为润滑剂的摩擦学性能。方法 合成一种含脲基新型无卤素的功能化咪唑离子液体(M-16-DOSS)并作为甘油的润滑添加剂。通过核磁共振和高分辨四级杆飞行时间质谱对M-16-DOSS的结构进行表征。采用同步热分析仪测试甘油润滑体系的热稳定性。采用SRV-IV微动摩擦磨损试验机评价了甘油润滑体系的摩擦磨损性能,通过三维轮廓仪对磨损体积和磨斑形貌进行了表征。采用EDS和XPS分析了磨斑表面元素和元素化学形态。结果 合成的功能化咪唑盐离子液体结构正确、纯度合格。M-16-DOSS与甘油具有良好的相容性且能够提高甘油的热稳定性。M-16-DOSS作为甘油的润滑添加剂可显著改善甘油的摩擦学性能,添加量达到1.5%时,摩擦系数下降到0.1,磨损体积下降80%。结论 在摩擦过程中发生了摩擦化学反应,通过硫氮的协同作用与铁和氧等元素形成了化学反应保护膜,有效地阻止了摩擦副之间的直接接触和碰撞,提高了甘油的减摩抗磨性能。     

Cr3C2/WC的添加对Stellite 12熔覆层耐磨耐蚀性的影响

目的 提高Stellite 12熔覆层的耐磨耐蚀性能。方法 将Stellite 12合金粉末与碳化物(Cr3C2、WC)混合,采用激光熔覆技术在H13钢板上制备复合熔覆层。通过超景深显微镜和XRD分析其显微组织和物相,通过显微硬度测试、摩擦磨损试验和电化学腐蚀试验,分别评价熔覆层的硬度、耐磨性和耐蚀性,并通过超景深显微镜对磨痕形貌进行分析。结果 添加碳化物后,熔覆层的微观组织以柱状晶和树枝晶为主,物相主要由γ-Co固溶体和碳化物(M23C6、M7C3)组成;Cr3C2的添加使得熔覆层的硬度降低,由610HV0.2降至530HV0.2,但耐磨性得到提高,磨损量由0.45 mm³降至0.33 mm³,下降了28%,耐蚀性得到提高,腐蚀电位由−0.385 V增加到−0.264 V,腐蚀电流密度由9.269×10⁻¹⁰ A/cm²降至1.496×10⁻¹⁰ A/cm²,极化电阻由3.982×10⁷ Ω.cm²提升至2.424×10⁸ Ω.cm²,提高了1个数量级;WC的添加使其硬度由610HV0.2提高至750HV0.2,磨损深度变浅,磨损量由0.45 mm³降至0.19 mm³,下降了43%,但耐腐蚀性有所降低。3种熔覆层的磨损机制主要为磨粒磨损和黏着磨损。结论 WC的添加可以有效提高熔覆层的硬度和耐磨性,但耐腐蚀性有所降低;添加Cr3C2后,耐蚀性得到显著提高,耐磨性略微提升,但硬度降低。     

65Mn钢表面熔敷硬质合金及其耐磨性能

以65Mn钢为研究对象,使用电弧熔敷由WC、Ti C和Co组成的硬质合金粉末,在材料表面形成电弧熔敷层。使用光学显微镜,X射线衍射分析仪和扫描电镜观察和分析了电弧熔敷层的组织与结构,并通过显微硬度计和磨粒磨损试验机研究了熔敷层的硬度和耐磨性能。结果表明,电弧熔敷硬质合金可在65Mn钢表面形成与基体结合紧密的耐磨涂层,当涂层中Co、Ti C和WC含量分别为45%,20%和35%时,硬质合金涂层表面的平均磨损量仅为未处理65Mn旋耕刀的27%。电弧熔敷可显著提高表层显微硬度,改善表面耐磨性能,提高耕作部件的使用寿命。     

钛合金摩擦磨损性能及减磨方法研究进展

钛合金具有比强度高、抗腐蚀性强、耐高温以及生物相容性好等优点,在汽车制造、生物医疗等众多领域具有重要应用.但钛合金的摩擦磨损性能较差,会影响机械系统的使用寿命和可靠性.首先论述了摩擦磨损过程中摩擦层的形成过程以及摩擦层对钛合金磨损机理的作用,分析了润滑条件、环境温度、滑动速度、载荷等工况条件对钛合金摩擦磨损性能的影响规律.其次,对比总结了钛合金减磨的常见工艺方法及优缺点,指出了当前钛合金磨损机理研究和性能改善方面存在的问题.最后,对今后的研究工作进行了展望:将实验与仿真相结合,阐明钛合金摩擦层和磨损机理的动态变化规律;考虑各种环境因素对钛合金磨损机理的影响,完善钛合金磨损机制图;通过对多种技术协同配合时的工艺参数进行优化,促进钛合金表面强化复合技术的发展,从而提升钛合金的耐磨减摩性能.     

STUDY ON THE TRANSPORT MECHANISM IN THE ANODE BOUNDARY LAYER OF WELDING ARGON ARC

1. IntroductionThere exists a very thin transition domain between the arc plasma and the workpiecein TIG welding (D.C., workpiece-positive). This domain is called as the anode boundary layer within which there are very steep temperature gradient and various transportphenomena, such as energy, momentum and mass t.ansfe.11]. The complicated physicalprocesses occurred in the anode boundary layer directly dominate the values and distribution of current density and heat flux on the workpiece surf…     

石英与长石对搪瓷涂层组织和摩擦磨损性能的影响

目的 通过等比例添加石英与长石,提高低碳钢搪瓷涂层的摩擦磨损性能.方法 采用一次浸搪法在Q235低碳钢表面制备等比例添加石英与长石的搪瓷涂层.采用SEM、HSR-2M型高速往复摩擦试验机,研究了不同石英与长石添加量的搪瓷涂层的组织形貌及摩擦磨损性能.结果 未添加石英与长石的搪瓷涂层硬度高、韧性差,且大气孔对裂纹形核扩展阻力小,摩擦时气孔边缘易脆性断裂.随着石英与长石添加量的增加,致使烧结体系的熔点和黏度降低,气孔形核位点增多,促进熔体扩散和气体排出,表层韧性和塑性提高,且小尺寸气孔阻碍裂纹扩展,磨屑填充气孔形成转移膜,显著降低了涂层脆性断裂倾向,发生轻微磨粒磨损和粘着磨损.然而当长石添加量过多(6％)时,Na2O的断网作用明显,致使更多Si─O键断裂,降低小气孔对裂纹扩展的阻力,因而导致涂层的耐磨性变差.结论 等比例添加石英与长石可降低涂层气孔率、提高涂层韧性,进而提高涂层的摩擦磨损性能.     

陶瓷润滑油添加剂对钢/钢摩擦副摩擦学性能的影响

研究了金属陶瓷润滑油添加剂在球（销）盘磨损试验机上对钢/钢摩擦副摩擦学性能的影响及其作用机理,采用扫描电镜,原子力显微镜,纳米压痕仪,X光衍射仪等仪器对摩擦表面形成的金属陶瓷修复层进行了分析.结果表明,该添加剂对钢/钢摩擦副具有很好的抗磨作用,试验中反复出现的负磨损现象体现了其显著的动态自修复功能;在钢/钢摩擦副表面形成的金属陶瓷修复层,粗糙度可低至十几个纳米,硬度高达16GPa,对改善摩擦学性能发挥了重要作用;但XRD广角衍射和小角掠射的分析都只发现基体α-Fe相,没有发现其它新相.陶瓷润滑油添加剂代表当前添加剂领域中一种最新发展趋势,其作用机理有待进一步深入系统的研究.