基于多层硅模具的Zr基非晶合金双层微小齿轮制备工艺研究

应用分层设计与制备工艺得到了具有微小多层型腔的复杂硅模具,采用坯料直径为3mm的Zr41.2Ti13.8Cu12.5Ni10Be22.5非晶合金为实验材料,使用自行设计的实验平台,对双层微小齿轮（大齿轮模数0.05mm,齿数36,厚度150μm;小齿轮模数0.05mm,齿数30,厚度150μm;中心轴孔直径0.8mm)进行了超塑性成形工艺研究,优化了零件成形、腐蚀脱模、飞边去除及质量分析的工艺流程。结果表明,该工艺流程合理可靠,制备出的Zr基双层微小齿轮保持了非晶态结构、形状完整、充型率高、表面质量良好。     

非晶合金微小零件制造技术研究进展及展望

非晶合金因其特殊的非晶态微观结构而具有优异的性能,在产品微小型化、精密化方面已经展现出极具诱惑力的应用前景。但是,非晶合金在热力学上为亚稳态,极易因热作用而发生不可逆的晶化,导致其优越性能丢失,而且,大部分非晶合金在室温下硬度高、脆性大且表面极易钝化成膜,这严重限制了它的广泛应用。通过综合国内外文献资料,介绍了非晶合金微小零件超塑性成形、精密/超精密切削、微纳尺度3D打印、激光/微细电火花加工以及微细电解加工的最新研究进展,分析了现有制造技术的优缺点及非晶合金微成形与加工的难点,并指出非晶合金微小零件制造技术未来发展的重要方向。     

塑料模具超塑性材料及成形研究

本文研究、制造了四种铝基耐磨、耐蚀塑料模具超塑性合金-Al-13Si、Al-10Si-1Mg、Al-7 Si-1.5 Cu-0.7 Mg 和Al-8.2 Mg-4.7 Si。通过超塑性拉伸试验证明,四种合金均显示出超塑性能。研究了四种合金的超塑化工艺并给出了合金的最佳超塑工艺参数。模具超塑成形试验解决了铝基超塑合金高温成形时的脱模、润滑及成形后的清洗问题。试验结果表明,四种合金都具有良好的超塑成形性能、光洁度高、复制性能好,是较为理想的塑料模具超塑性成形材料。     

块体非晶合金超塑性微成形

非晶合金超塑性微成形技术随着微细产品的兴起而诞生,由于非晶合金在常温下微尺度时具有极高的力学性能且在过冷液态区具有显著的超塑成形能力,在制备高性能微型零件方面具有广泛的应用前景。本文论述了几种典型非晶合金的玻璃转变温度和过冷液态区宽度及其在过冷液态区的力学行为,并在此基础上,分析了不同温度和应变速率对块体非晶合金成形结果的影响;同时,概述了块体非晶合金成形工艺,指出了存在的问题并进行了发展展望。     

Zr基非晶合金过冷液态区的微反挤压实验研究

利用微反挤压实验,研究了Zr55Cu30Ni5Al10大块非晶合金在过冷液态区域内的超塑性微成形工艺。选取不同的温度(705～735K,5K一个间隔)和不同的冲头速度(2μm/s～8μm/s,递增1μm/s)进行交叉实验,并对挤压成形过程以及影响成形的工艺因素进行了分析。结果表明,非晶合金的微反挤压过程可以分为四个阶段,且零件的挤压深度随成形温度的升高或冲头速度的降低而增大,在710～725K的温度范围内,零件的挤压深度对温度更敏感。低速或高温成形容易使坯料晶化,因此较为理想的挤压工艺条件为725K左右和6μm/s的冲头速度,在此条件下成功地挤压出了壁厚为0.1mm和0.05mm的微型杯零件,SEM显示该成形件杯口整齐,与模具尺寸的符合性较好。     

纳米Si2N2O-Sialon陶瓷齿轮超塑性锻造研究

采用Deform有限元软件对纳米Si2N2O-Sialon陶瓷超塑性锻造成形过程进行模拟,较直观地预测了齿轮成形过程中齿形充填情况。在1550℃,纳米Si2N2O-Sialon陶瓷显示出良好的超塑性成形性能,通过试验,超塑性锻造成形出了质量良好的齿轮零件。在模拟与试验的基础上,通过与金属齿轮的齿形充填情况进行对比,建立了陶瓷齿轮齿形充填模型,得到了纳米陶瓷齿轮超塑性锻造成形的基本规律:陶瓷齿轮锻造过程中齿形充填过程分为5个基本阶段,与金属齿轮锻造成形充填过程相比,齿形前端的鼓形量和齿形侧面的鼓形量明显较小。     

薄板件台阶孔冲压冷锻组合工艺的数值模拟

针对构想的一种薄板件台阶孔冲压冷锻组合工艺,应用金属塑性加工有限元模拟的关键技术,包括几何模型、材料断裂破坏、网格划分等,用DEFORM-3D软件对此种薄板件台阶孔的冲压冷锻组合变形进行数值模拟。得到了工件材料的等效应力、应变分布,速度场和力—行程曲线。提出细观变形过程可分为冲头小直径处冲孔、冲头大直径处压凹和闭式模锻三个阶段的认识,分析组合工艺特点和材料成形性能。用料厚为2.35 mm的AL-1100铝板材料进行工艺试验,获得了清晰的台阶孔形状,验证了数值模拟的认识。     

TiAl合金研究进展

Ti Al合金密度低且具有优异的高温性能、良好的阻燃能力以及抗氧化性,是未来航空航天领域重要的高温结构材料之一。文中分析了PIGA、EIGA、VIGA、PREP、PA等方法制备Ti Al合金粉末的工艺特点,阐述了热等静压、放电等离子烧结、反应烧结、粉末注射成形技术制备Ti Al合金的工艺,分析了制备Ti Al合金工艺所存在的问题对于TIAl合金实际应用的影响,讨论了提高Ti Al合金的高温抗氧化性及室温塑性的方法。     

高精度陶瓷镀金极杆的制造技术

陶瓷镀金极杆是高端四极质量分析器的核心零件,其精度与表面质量要求高,制造难度大,目前国内尚无研制报道。提出了一种陶瓷镀金极杆的精密制造工艺方法,采用"陶瓷基体精密磨削-化学镀镍磷合金-金刚石超精密切削镍磷合金层-电镀金"的工艺路线,攻克了陶瓷基杆上化学镀镍磷合金及镍磷合金层的金刚石超精密切削两项关键工艺,成功制造出了高精度镀金极杆(φ12mm×150mm规格),其整杆圆度(0.1~0.4)μm,圆柱度小于1μm,表面粗糙度Ra小于0.02μm,完全满足高精度四极质量分析器对极杆的制造精度要求。采用制造的陶瓷镀金极杆,研制出了国内首套高精度陶瓷镀金四极质量分析器,经检测其综合几何精度达到了2.25μm。     

微型齿轮精密微塑性成形工艺研究

为了进行微塑性成形工艺研究,设计了一套精密微塑性成形系统.系统采用宏动/微动相结合的驱动模式,既可获得高的位移精度又可以实现较大的冲头行程,在成形过程中对工艺参数进行实时采集和记录.使用该系统进行了微型齿轮的微塑性成形工艺试验,结果表明,微成形件的表面质量好,轮廓清晰,证明采用微塑性成形技术可以成形出质量良好的微型零件.     

HRTEM analysis of nanocrystallization during uniaxial compression of a bulk metallic glass at room temperature

Nanocrystallization during deformation of metallic glass at room temperature has significant implications to understand its deformation mechanism. We present here direct high-resolution transmission electron microscopy (HRTEM) observations of nanocrystallization in a Zr(55)AI(10)Ni(5)Cu(30) bulk metallic glass (BMG) fractured by uniaxial compression at room temperature. The formed nanocrystallites are Zr(2)Cu, with the average diameter of less than 10nm, and are distributed within the round-like regions of localized plastic deformation. We also show direct evidence of atomic neighbor distance increases associated with the shrinkage and broadening of diffused ring pattern from local deformed areas, which may enhance atomic mobility so that nanocrystallization occurred. Our results demonstrate that the origin of the room-temperature deformation of BMG can be attributed to the local atomic spacing increases induced by localization of plastic flow under uniaxial compression test.     

非晶态合金塑性加工的可行性研究

为防止非晶合金加工时产生晶化现象,采取在一定温度范围内,对Zr41.2TiCu13.8Ni10Be22.5非晶合金进行静液挤压,按不同挤压比截取试样,进行x-射线衍射分析得出,未发现晶态物质,从而确定加工方法的可行性.     

Zr55Cu30Al10Ni5块体非晶合金在超声振动场下的流变成形能力

将超声振动场引入到非晶过冷液流变成形中,设计了一套超声振动辅助金属热塑成形实验装置,进行了Zr55Cu30Al10Ni5块体非晶合金高温单轴压缩实验,研究了非晶合金在超声振动辅助下过冷液相区内的流变行为。实验结果表明,超声振动能减小非晶合金的流动应力与黏度,且输入功率越大,越有利于非晶合金的变形。分析了超声振动场提高非晶合金流变成形能力的机理：振动导致变形过程中内应力和摩擦力周期性消失,宏观上则表现为变形抗力的降低和摩擦条件的改善。     

Structure studies of ball-milled ZrCuAl, NiTiZrCu and melt-spun ZrNiTiCuAl alloys

ZrNiTiCu and ZrNiTiCuAl alloys were amorphized using either a melt‐spinning or ball‐milling process in a high‐energy planetary mill. The elemental powders were initially blended to the desired composition (in at.%) of Zr, 65; Cu, 27.5; Al, 7.5 and of Ti, 25; Zr, 17; Cu, 29; Ni, 29, respectively. The composition of alloys was chosen to be the same as for the bulk amorphous ZrCuAl and easy glass‐forming ZrNiTiCu alloys. An almost fully amorphous structure was obtained after 80 h of milling in the case of both compositions. Transmission electron microscopy studies of ball‐milled powders revealed the presence of nano‐crystallites [2–5 nm for ZrCuAl and smaller (1–3 nm) for the ZrTiNiCu alloy]. High‐resolution transmission electron microscopy of melt‐spun ZrNiTiCuAl ribbons provided evidence of the amorphous structure.     

A combined arc-melting and tilt-casting furnace for the manufacture of high-purity bulk metallic glass materials

An arc-melting furnace which includes a tilt-casting facility was designed and built, for the purpose of producing bulk metallic glass specimens. Tilt-casting was chosen because reportedly, in combination with high-purity processing, it produces the best fatigue endurance in Zr-based bulk metallic glasses. Incorporating the alloying and casting facilities in a single piece of equipment reduces the amount of laboratory space and capital investment needed. Eliminating the sample transfer step from the production process also saves time and reduces sample contamination. This is important because the glass forming ability in many alloy systems, such as Zr-based glass-forming alloys, deteriorates rapidly with increasing oxygen content of the specimen. The challenge was to create a versatile instrument, in which high purity conditions can be maintained throughout the process, even when melting alloys with high affinity for oxygen. Therefore, the design provides a high-vacuum chamber to be filled with a low-oxygen inert atmosphere, and takes special care to keep the system hermetically sealed throughout the process. In particular, movements of the arc-melting electrode and sample manipulator arm are accommodated by deformable metal bellows, rather than sliding O-ring seals, and the whole furnace is tilted for tilt-casting. This performance of the furnace is demonstrated by alloying and casting Zr(55)Cu(30)Al(10)Ni(5) directly into rods up to ? 10 mm which are verified to be amorphous by x-ray diffraction and differential scanning calorimetry, and to exhibit locally ductile fracture at liquid nitrogen temperature.     

Sliding wear behavior of Fe-based bulk metallic glass at high temperature

In the past decade Fe-based bulk metallic glasses (BMGs) have attracted increasing attention due to their beneficial properties, including high glass forming ability (GFA), high strength and hardness and high fracture toughness in both fundamental science and engineering application. Most research using these materials has been conducted at room temperature environment, and research that assesses their behavior especially at high temperature has been scarce. We present the results of high temperature effect on the friction and wear behavior of Fe-based bulk metallic glass (BMG), and we tested that this material may satisfy wear and oxidation resistance at high temperature as well as to explore the high temperature wear mechanism of the Fe-based BMG. The dry sliding tribological behaviors of Febased BMG against Si₃N₄ ceramic were conducted with a pin-on-disc friction and wear tribometer. The morphology of the worn surfaces of Fe-based BMG was examined by scanning electron microscopy (SEM) and the chemical composition characterized with energy dispersive spectroscopy (EDS) to observe the wear characteristics and investigate the wear mechanisms. The overall average friction coefficient value generally decreased with increasing temperature, and the glass transition and the formation of protective oxide film played an important role in the tribological behavior of BMG. The wear resistance of Fe-based BMG was not only from their hardness but also from the formation protective oxide layer. Analysis of the worn surface revealed abrasion, plastic deformation and oxidation during sliding test.     

Effect of Flash Temperature on Tribological Properties of Bulk Metallic Glasses

The tribological properties of Cu-based and Zr-based bulk metallic glasses (BMGs) sliding against Si₃N₄ under dry and water lubrication were studied on a pin-on-disc tribometer. The wear mechanisms of bulk metallic glasses were investigated based on the calculated flash temperature. The friction coefficients if fully amorphous alloy are about 0.7, while those of BMGs with nanocrytalline are a little higher. The wear rates of Cu-based BMG (V101) are about one order of magnitude lower than those of Zr-based BMG (Vit1) under dry friction, even two orders of magnitude lower under water lubrication. The wear resistance of bulk metallic glasses was influenced by the flash temperature. The calculated flash temperature (3,337 K) on the friction surface of Zr-based amorphous alloy exceeds its glass transition temperature, even its melting temperature. The high flash temperature leads to glass transition accompanied with viscous flow and material transfer, which is responsible for the poor wear resistance of Zr-based BMGs.     

Al_2O_3Cu-Ti-Zr/Nb钎焊研究

使用Cu Ti Zr钎料对Al2 O3 Nb进行了钎焊试验。通过扫描电镜、能谱、X射线衍射分析了界面形貌、元素分布 ,并对反应相进行了判定。Cu70 Ti2 5 Zr5 钎料在 12 93K、10min条件下界面产生了 3种新相 :Cu2 Ti4O、Ti固溶体、CuTi,界面结构为Al2 O3 Cu2 Ti4O Ti固溶体 CuTi Cu固溶体 +CuTi。采用拉剪试验评定了强度 ,结果证实12 93K、10min ,使用Cu70 Ti2 5 Zr5 钎料的接头强度最高达到 16 2MPa ,增加或减少Ti的质量分数以及改变保温时间都会使接头抗剪强度下降。     

Rolling Friction in a Micro Tribosystem

Pin-on-disc apparatus was used to investigate the effect of temperature on the dry sliding friction characteristics of a Zr-based bulk metallic glass (BMG) near its glass transition temperature (T _g = 625 K) (an analogous phenomenon in crystalline metals called the ductile-brittle transition). Unexpected variation in frictional behavior was observed in the temperature range of 603–643 K, suggesting that the glass transition and formation of protective oxide layers played roles in the tribological properties of BMG. An explanation of the behavior is given based on Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) analysis.