铝合金-丁腈橡胶复合密封件的界面结合性能

硫化粘合成型金属-橡胶复合密封件存在环境污染、效率低、难以形成复杂构件的缺点。提出一种利用阳极氧化和硅烷偶联剂处理铝合金表面,再通过控制注塑工艺参数直接成型铝合金-丁腈橡胶(Aluminum alloy-nitrile butadiene rubber,Al-NBR)复合密封构件的方法。研究了阳极氧化电解液温度、偶联剂浓度和注塑成型时模具温度与成型构件界面力学性能的对应关系。利用扫描电子显微镜(Scanning electron microscope,SEM)和傅里叶变换红外光谱(Fourier transform infrared spectrometry,FTIR)对不同条件处理的铝合金基材表面形貌和成分进行表征,探讨了铝合金表面结构形态和成分对铝合金-丁腈橡胶界面结合强度的影响规律以及铝合金-丁腈橡胶密封构件的失效原因和机理。试验结果表明,在优化后的成形参数下制得的复合构件其界面结合强度高于橡胶基体强度,研究所取得的结果对拓展金属-橡胶复合密封构件的成型方法和应用领域具有重要作用。     

界面微构对注射成型铝塑复合件性能的影响研究

铝塑复合构件具有强度高、质量小、易成型复杂结构等优点,在航天、能源、汽车、通信等领域的应用逐渐广泛。提出采用注射方法直接成型铝-塑复合构件的方法,采用阳极氧化对铝合金表面进行处理,获取金属表面的纳米级微结构形态。为提高金属与聚合物之间的界面作用,将阳极氧化的金属表面进行活化处理,X射线能谱分析仪(X-ray photoelectron spectroscopy,XPS)对处理后的表面微结构进行形态和成分表征,探讨活化处理后铝合金表面组织成分的变化,并优化获得了最佳的处理时间。对表面处理完成的铝合金试样置入高温模具中进行注塑成型,成功获得了铝-塑复合构件。采用激光共焦扫描显微镜(Laser scanning confocal microscopy,LSCM)和扫描电子显微镜(Scanning electron microscope,SEM)分析拉伸剪切断裂后金属表面的界面形态,讨论了铝塑复合件的失效原因和机理,为金-塑复合产品的生产成型提供了理论基础。     

铝合金表面阳极氧化及光整加工工艺

为了提高铝合金的表面硬度、耐磨性和装饰性及其它的功能要求,可对铝合金零件进行表面处理,本文结合笔者的工作实践,对铝合金的光整加工及其与阳极氧化的关系作一介绍。　　一、铝合金阳极氧化膜的分类及影响氧化膜质量的主要参数　　铝合金阳极氧化膜的性能随工艺不同而...     

钢-聚氨酯柔性复合构件一体化注塑成型及界面强度研究

金属-聚合物异质复合构件具有强度高、轻质和减振等优点，在航空航天、汽车制造、能源等领域得到广泛应用。探索成形便利、界面结合强度高、且可形成复杂特征的成形工艺是工业领域共同追求的目标。提出了一种利用注塑工艺一体化成型钢-热塑性聚氨酯(TPU)复合构件的方法。首先，对钢表面进行喷砂、氧化和硅烷化处理，改变钢材表面的微结构形态和成分；然后，将处理后的试样放入模具型腔中，在其表面直接注塑TPU熔体一体化成型钢-TPU复合构件；最后，对成型的复合构件进行退火处理，既消除了成型构件的残余应力，又促使金属表面硅烷化后氨基类官能团与TPU中官能团产生作用，进一步提高其界面强度。拉剪测试表明，当复合构件界面结合强度达到17.8MPa时，TPU材料自身发生破坏，而其结合界面并未产生脱落。利用提出的方法成功制得了钢-TPU柔性可变形夹具，可用于对不同直径的工件施加径向力以实现夹紧的作用，提高了夹具的通用性。     

铝合金材质硬质阳极氧化工艺方法的应用分析

以硬质阳极氧化工艺方法改善铝合金材料表面性能为目的,首先概述了硬质阳极氧化工艺的发展概况,然后比较详细地分析了铝合金硬质阳极氧化膜的结构成分、特点、封闭后处理;最后研究了铝合金材质在硬质阳极氧化时的需考虑的影响因素、工艺要求和性能要求,并以铝合金液压阀岛的零件为例对其进行硬质阳极氧化的工艺分析,得出了具体的硬质阳极氧化的工艺流程,这对铝合金材质的其它零件应用硬质阳极氧化工艺方法提供了有意义的参考价值。     

精密仪表用铝合金瓷质阳极氧化表面粘接性能研究

铝合金瓷质阳极氧化工艺是精密仪表制造中的一种特殊且关键的技术应用，但该氧化表面的胶粘连接常常出现脱粘、泄漏等失效问题。为此，通过探究瓷质阳极氧化表面的微纳形貌与润湿性特征以及高低温下的胶接强度与失效模式，并与自然氧化表面及磷酸阳极氧化表面进行对比分析，阐明瓷质阳极氧化表面胶接失效的影响机理。结果表明，磷酸阳极氧化虽未在微米尺度上显著改变表面粗糙度，但其纳米级多孔氧化膜结构，可显著提高表面润湿性与界面粘接作用力；而瓷质阳极氧化膜在50 000×的SEM形貌下较为致密、平滑，显示出不利于胶粘剂润湿与吸附的物理特征；在-30～80℃下，温度与氧化方法均对胶接强度影响显著，胶接强度随着温度的升高而降低；磷酸阳极氧化表面的强度最高(36.75～20.54 MPa)，其次为自然氧化，最差为瓷质阳极氧化(24.79～17.10 MPa)。热红外与能谱分析表明，瓷质阳极氧化表面的粘附强度低于胶粘剂的内聚强度，失效模式为粘附失效，而磷酸阳极氧化表面的失效模式为胶粘剂的内聚失效。因此，瓷质阳极氧化表面由于氧化膜的致密性，缺少类似磷酸阳极氧化膜的纳米级多孔结构，不利于表面润湿吸附，降低了胶粘剂与基底表面的机...     

聚苯酯/MoS2填充聚四氟乙烯复合材料对铝合金的摩擦学性能

采用冷压-烧结成型工艺制备聚苯酯/MoS2填充聚四氟乙烯复合材料,考察聚苯酯含量对复合材料力学性能的影响,考察聚苯酯和MoS2含量对复合材料与铝合金及表面阳极氧化铝合金对摩时摩擦学性能的影响;用扫描电子显微镜观察复合材料和铝合金磨损后的表面形貌。结果表明：填充聚苯酯降低了复合材料的拉伸强度和断裂伸长率,提高了球压痕硬度;随着聚苯酯和MoS2含量的增加,复合材料对铝合金及表面阳极氧化铝合金的摩擦因数逐步减小,磨损率降低;MoS2存在时,铝合金及阳极氧化铝合金表面可形成均匀连续的转移膜,表面光滑,从而降低了磨损;阳极氧化后铝合金表面有一层致密的氧化膜,改善了对复合材料对摩时的摩擦学性能。     

探讨表面处理工艺对铝合金防腐涂层性能的影响

本文主要针对铝合金防腐涂层所受表面处理工艺的影响展开研究。通过实验研究进一步发现对其表面采取钝化处理或者是打磨处理对提升铝合金的防腐性能和防污涂层性能都有着显著影响,但是采取阳极氧化处理技术会降低铝合金的涂层附着性能,因此我们在进行工艺选择时一定要根据实际过程而定,最终使其产生比较好的效果。     

电子束扫描对铝合金表面强化层的影响

电子束表面处理可以提高铝合金材料的表面硬度、增加耐磨性.利用电子束扫描对铝合金进行表面强化处理,讨论功率密度、扫描频率、下束时间等电子束工艺参数对铝合金表面强化层形态的影响;研究电子束扫描对铝合金强化层组织和性能的影响;探讨电子束表面处理过程中试样产生裂纹的原因.采用扫描电镜分析铝合金电子束表面强化层的显微组织,并进行EDS成分测试;用HMV-ZT洛氏硬度计进行硬度测试;用HT-500高温摩擦磨损试验机进行摩擦磨损试验,结果表明:强化层的深度和宽度随着功率密度和下束时间的增加而增大;但扫描频率的影响不显著;电子束扫描处理后,强化层组织的晶粒高度细化,表面强化层硬度是基体组织的1.39倍,耐磨性明显改善;凝固过程中产生的收缩应力是试样产生裂纹的主要原因.     

LY12CZ铝合金的双重处理表面摩擦学改性研究

本采用双重处理表面改性技术对LY12CZ铝合金进行了摩擦学表面改性处理,即首先对LY12CZ铝合金进行硫酸的阳极氧化处理,然后在其表面再沉积一层润滑薄膜,实验结果表明,双重处理可有效地降低铝合金在真空环境中的摩擦并用明显提高耐磨寿命,特别是采用低摩擦系数的MoS2-Au基复合薄膜,可在较高载荷下达到较长的耐磨寿命,对双重处理铝合金的摩擦失效机理也作了初步探讨。     

Investigating the effects of hard anodizing parameters on surface hardness of hard anodized aerospace AL7075-T6 alloy using fuzzy logic approach for fretting fatigue application

Aerospace applications and energy saving strategies in general raised the interest and study in the field of lightweight materials, especially on aluminum alloys. Aluminum alloy itself does not have suitable wear resistance. Therefore, improvements of surface properties are required in practical applications, especially surface hardness when aluminum is in contact with other parts. In this work, first Al7075-T6 was coated using hard anodizing technique in different parameters condition and the surfaces hardness of hard anodizing-coated specimens were measured using microhardness machine. Second, fretting fatigue life of AL7075-T6 was investigated for both uncoated and hard anodized specimens at the highest surface hardness obtained. Third, a fuzzy logic model was established to investigate the effect of hard anodizing parameters, voltage, temperature, solution concentration, and time on the anodized AL7075-T6. Four fuzzy membership functions are allocated to be connected with each input of the model. The results achieved via fuzzy logic model were verified and compared with the experimental result. The result demonstrated settlement between the fuzzy model and experimental results with 95.032 % accuracy. The hardness of hard anodizing-coated specimens was increased up to 360 HV, while the hardness of uncoated specimens was 170 HV. The result shows that hard anodizing improved the fretting fatigue life of AL7075-T6 alloy 44 % in low-cycle fatigue.     

Comparison of tribological characteristics between aluminum alloys and polytetrafluoroethylene composites journal bearings under mineral oil lubrication

This study examined the tribological behavior of journal bearings made from polytetrafluoroethylene (PTFE) composites and aluminum (Al) alloys. The PTFE composite journal bearings consisted of a steel backing with a thickness of 1.6 mm, a middle layer of sintered porous bronze with a thickness of 0.24～0.27 mm, and a surface layer of PTFE filled with fluorinated ethylene propylene (FEP) powder and carbon fibers with a thickness 0.06～0.14 mm. The other was an aluminum alloy journal bearing consisted of a steel backing with a thickness of 1.5 mm and a surface layer of an Al-6Sn-6Si alloy with a thickness 0.35～0.75 mm. A series of lubrication tests were performed using a journal bearing tester under various normal loads. The tribological properties for each journal bearing were evaluated by measuring the lubricant oil temperature and friction coefficient as a function of the applied normal load. In addition, the chemical compositions and microstructures of the journal bearing materials used in this study was analyzed by inductively coupled plasma (ICP), optical microscopy (OM), and scanning electron microscopy (SEM), respectively. The experimental results showed that the Al alloy journal bearings reduce the friction coefficient by 28 % compared to the PTFE composites bearings. In addition, the Al alloy journal bearing worked properly at the maximum load of ～ 8,000 N without adhesion. However, the PTFE composite journal bearings exhibited strong adhesion at the loads ranging from 6300 to 8000 N. This suggests that the Al alloy is a more promising material in journal bearings than PTFE composites.     

Influence of tool inclination on chip formation process and roughness response in ball-end milling of freeform surfaces on Ti-6Al-4V alloy

An experimental test part, which was made up of flat, concave, and convex surfaces of variable curvatures, was designed to be fabricated in a four-axis machining center. Aluminum alloy 7075 and titanium alloy Ti-6Al-4V were used for the fabrication. Within the finishing process, smeared/adhered material was found in some areas of the concave and convex surfaces of the titanium alloy. On the other hand, smeared/adhered material was not found in the aluminum alloy. To characterize the type of defects, the 3D roughness parameters of the surfaces were measured by confocal microscopy, and surface morphology was observed using optical microscopy and scanning electron microscopy. The kinematics of the ball-end milling process was modeled and it was found that the lead and tilt angles between the tool axis and surface normal vector vary continuously, producing transitions between oblique-plunge-push-up milling and oblique-reverse-push-up milling. This causes variation in the thickness behavior during the chip formation process. It was found that the lead angle has a moderate influence, while the tilt angle has a strong effect on the quality of the surfaces of the titanium alloy, with negative tilt angles producing the worst surfaces when there was the oblique-plunge-push-up milling process.     

Effect of pre-treatment polishing on fabrication of anodic aluminum oxide using commercial aluminum alloy

Aluminum anodizing is a process in which metal is oxidized with an electrochemical method to make a metallic oxide. Because it can be used to manufacture an Anodic aluminum oxide (AAO) with dozens to hundreds of nanoscale pores that are vertically and uniformly arranged, it is widely applied in a variety of fields. In particular, most of the pre-treatment methods in the anodic oxidation processes using a high-purity aluminum adopt surface treatment through electrolyte polishing. In this study, complex polishing was performed using an abrasive film and Magnetorheological (MR) fluid for a commercial aluminum alloy to produce a uniform porous oxidized aluminum. The surface roughness and surface integrity were analyzed after each process to investigate the production behavior of AAO in relation to the pre-treatment of the surface. In addition, a study was conducted on the nano-pore production by the anodizing process in accordance with the pre-treatment polishing, in terms of the work-hardening and residual stress. Thus, in the anodic oxidation process, it was possible to generate uniform nano-pores when surface integrity including surface roughness and residual stress distribution of the aluminum alloys are excellent. Test results showed that the polishing process using the MR fluid did not generate process scratches and pits, but could effectively remove the work-hardening and compressive residual stress, proving that MR fluid polishing method is a suitable pre-treatment process to produce nano-pores in the anodizing process.

     

阳极化处理对铝箔网与树脂基复合材料粘接性能的影响

采用磷酸阳极化工艺对铝箔网进行了表面处理,研究了阳极化工艺参数对其与树脂基复合材料粘接性能的影响,并对优化后工艺处理的铝箔网表面形貌及粘接性能进行了分析。结果表明:最佳工艺参数的去氧化时磷酸体积分数为16%,处理时间为6min,氧化时磷酸体积分数为16%,处理时间为23min;磷酸阳极化后,铝箔网表面生成一层疏松多孔的氧化膜,可以增大铝箔网表面与复合材料的粘接界面面积,并有良好的界面效应,有效地提高了粘接强度,与处理前的抗拉剪强度相比,提高了14.66%;同时铝箔网的耐蚀性也得到了较大提高。     

大型复杂型面铝合金翻边件电磁成形塑性流动行为研究

大型复杂型面铝合金翻边件电磁成形是一个电磁场和结构场耦合作用下的复杂塑性成形过程。由于大型复杂型面的影响,使得铝合金翻边件在电磁成形过程中的塑性流动行为与传统带凸模翻边成形不同。基于松散耦合法建立耦合电磁场和结构场的大型复杂型面铝合金翻边件电磁成形有限元模型,研究采用1层、2层和3层平板线圈电磁翻边下的板料塑性流动行为,并采用试验研究揭示了不同压边力控制下板料法兰部分塑性流动规律。结果表明,当采用3层平板线圈时,翻边件的复杂型面部分完全贴膜,法兰部分材料进入凹模腔的部分更多,促使板料发生更多的塑性流动;不同压边力控制下,法兰部分由塑性流动产生不同的工件形式,在压边力不足时,法兰部分产生明显的起皱现象;通过合理的压边力控制,可得到贴膜性良好的大型复杂型面铝合金翻边件。     

Effects of Loading and Sliding Speed on the Dry Sliding Wear Behavior of Mg-3Al-0.4Si Magnesium Alloy

The friction and wear properties of Mg-3Al-0.4Si alloy were investigated using a pin-on-disc tester. Morphologies and compositions of worn surfaces were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS) for identification of the wear mechanisms. Microstructural evolution and hardness change in subsurfaces were analyzed by confocal scanning laser microscopy and hardness testing. The results revealed that the wear behavior of Mg-3Al-0.4Si alloy was classified into two types of wear regimes; that is, mild and severe. In the mild wear regime, wear rates increased at a low slope with increasing load; the corresponding wear mechanisms were oxidation, abrasion, and delamination. In the severe wear regime, wear rates increased rapidly at a high slope with load; the wear mechanisms were severe plastic deformation and surface melting. Analysis of microstructural evolution on the subsurface identified the reason for the transition from mild to severe wear; that is, the realization of dynamic recrystallization (DRX) in the surface layer material. A contact surface DRX temperature criterion for the mild to severe wear transition was proposed, and the critical DRX temperatures for the mild to severe wear transition were calculated using DRX kinetics.     

氮碳共渗-渗硫复合层的摩擦学行为

采用离子氮碳共渗-离子渗硫复合处理技术在CrMoCu合金铸铁表面制备了氮碳共渗-渗硫复合层,并对未渗及复合渗表面在含硫添加剂液体石蜡润滑下的摩擦学行为及其磨损表面形貌和成分进行了测试.结果表明,在含硫添加剂润滑下,复合层与含硫添加剂产生协同作用,生成钼的化合物、磷酸盐和硫化物等化学反应膜使复合渗表面的摩擦系数较未渗表面降低了25%,耐磨性较未渗表面提高了50.1%.     

等离子熔积高温合金件表面激光气化光整研究

针对高温合金零件机械加工周期长、刀具损耗大的难点,开发采用高功率调Q激光对高温合金零件进行表面光整的方法.通过系统研究分析激光表面去除加工的激光功率、调Q频率、扫描速度、保护气体气压等主要工艺参数对高温合金零件表面光整加工质量的影响,获得适于高温合金件的表面光整条件,采用此条件光整加工得到表面质量好的高温合金零件,为等离子熔积成形快速直接制造高温合金零件提供技术基础.     

Wear Behavior of Ceramic Powder and Solid Lubricant Cladding on Carbon Steel Surface

Thick composite coatings of carbides on a metal matrix are ideal for use in components that are subjected to severe abrasive wear. It is a metal matrix composite (MMC) that is reinforced by an appropriate ceramic phase, a solid lubricant coating to reduce friction and to protect the opposing surface. This study tested the wear behavior of a carbon steel surface after cladding by a gas tungsten arc welding (GTAW) method to enhance wear resistance. The microstructures, chemical compositions, and wear characteristics of the cladded surfaces were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The coating was uniform, continuous, and almost defect-free, and particles were evenly distributed throughout the cladding layer. The results of wear tests indicate that the friction coefficient of the TiC coating is lower than that of AISI 1020 carbon steel. Thus, the wear depth of the TiC coating is only one tenth of that exhibited by the AISI 1020 carbon steel. The experiments confirm that the cladding surfaces of TiC particles reduce the wear rate and friction.