纳米硬质合金摩擦磨损与切削性能研究

摩擦磨损性能、磨削性能、切削性能对纳米硬质合金实用化具有极其重要意义。应用摩擦磨损试验机研究了纳米硬质合金WC-7Co和WC-10Co的摩擦磨损性能,利用在线电解修整（Electrolytic in Process Dressing, ELID）磨削技术对纳米硬质合金刀具进行了刃磨,并且对Al/SiCp复合材料进行了切削试验,研究了纳米硬质合金刀具的切削性能与刀具磨损机理。结果表明：纳米硬质合金整体摩擦系数低,耐磨性好,WC-10Co的磨损机理表现为鱼鳞状塑性流动;纳米硬质合金磨削加工性较好,磨削机理以塑性去除为主;纳米硬质合金刀具磨损机理为Al/SiCP复合材料中SiC颗粒对刃口断续冲击,其切削实质是断续切削,刀具磨损形式是刃口破损及晶粒脱落。纳米硬质合金刀具适于低速断续切削。     

表面微织构对WC-8Co在往复摩擦磨损中粘结-扩散磨损特性的影响

采用激光表面纹理化在WC-8Co上制备了微沟槽织构,通过往复式摩擦磨损试验对其与Ti6Al4V接触的耐磨性进行分析,并以无表面微沟槽织构的WC-8Co为对比样品,研究了表面微织构对WC-8Co粘结-扩散磨损特性的影响,揭示了摩擦过程中表面微织构的磨损机理. 结果表明:WC-8Co上的微沟槽对摩擦接触面具有抗粘结作用,在高接触载荷下,这种效应更为明显. 织构表面的抗粘结机制是由微沟槽包裹的碎屑产生的. 此外,与无表面微织构的WC-8Co不同,表面织构化的WC-8Co的磨损最初来源于微沟槽边缘的断裂,随后扩展到摩擦表面. 这种磨损特性归因于微沟槽边缘的高热载荷和机械应力集中,以及激光加工过程中WC晶粒长大与摩擦过程中粘结剂Co扩散的协同效应.      

等离子喷涂纳米WC-12％Co涂层与陶瓷和不锈钢配副时的摩擦磨损性能对比研究

利用大气等离子喷涂技术制备了纳米和微米WC-12%Co涂层,采用SRV摩擦磨损试验机考察了纳米和微米WC-12%Co涂层在干摩擦条件下分别与Si3N4陶瓷球和不锈钢球配副时的摩擦磨损性能.结果表明:在相同试验条件下,纳米和微米WC-12%Co涂层分别与Si3N4陶瓷球和不锈钢球配副时的摩擦系数相差不大,但纳米WC-12%Co涂层的抗磨件能明显优于微米WC-12%Co涂层;2种涂层的磨损机制差异亦较小,纳米涂层在低载荷下的主要磨损机制为微断裂和轻微磨粒磨损,而在较高载荷下的磨损机制为硬质相的剥落和磨粒磨损;微米涂层在较低载荷下的磨损机制为微断裂和磨粒磨损,在较高载荷下为疲劳磨损.在相同试验条件下,纳米WC-12%Co涂层的磨损表面损伤明显较轻微.     

HVOF制备的多峰WC-12Co涂层摩擦磨损特性

本文采用超音速火焰喷涂(HVOF)工艺制备了2种多峰结构和1种亚微米结构WC-12Co涂层,并采用SEM、XRD等方法对3种涂层进行了显微组织、孔隙率、相结构及显微硬度分析;在进行涂层球盘摩擦磨损试验的基础上,探讨了多峰WC-12Co涂层的磨损机理.研究结果表明:由含30% 纳米WC-12Co的粉末制备的多峰涂层WC氧化脱碳程度最低,显微硬度最高;采用含50%纳米WC-12Co的粉末制备的多峰涂层孔隙率最低、耐磨损性能最为优良.     

在氮气介质中WC-Co/Ti6Al4V摩擦副的摩擦磨损性能研究

在THT07-135型高温摩擦磨损试验机上采用销-盘式接触形式,研究了WC-Co硬质合金/Ti6Al4V钛合金摩擦副在氮气介质中的摩擦磨损性能,并与空气介质中的摩擦磨损性能进行对比.结果表明:与空气介质相比,在氮气介质中WC-Co/Ti6Al4V摩擦副的摩擦系数稍低;WC-Co硬质合金比Ti6Al4V钛合金的磨损量低得多,氮气介质具有一定的减磨作用;钛合金材料的主要磨损机理为摩擦副之间产生较强的犁沟与挤压撕裂,而硬质合金的主要磨损机理为磨粒磨损与粘结剥落.     

CVD金刚石薄膜在水润滑条件下的摩擦磨损性能研究

采用偏压辅助增强热丝CVD法在硬质合金衬底上制备常规金刚石薄膜和超细晶粒金刚石薄膜,在往复式球-盘摩擦磨损试验机上考察金刚石薄膜在干摩擦和水润滑条件下的摩擦磨损性能,分别采用扫描电子显微镜、拉曼光谱仪和能谱仪分析金刚石薄膜的表面形貌特性、结构特征及其摩擦表面残余物质的组成.结果表明,常规金刚石薄膜和超细晶粒金刚石薄膜在水润滑下的摩擦系数分别约为0.25和0.22,超细晶粒金刚石薄膜对偶件的磨损率仅为6.94×10-6 mm3/(Nm),显示出优异的减摩性能,可作为良好的水润滑摩擦副涂层材料.     

超音速火焰喷涂WC-Co层的高温氧化对摩擦磨损性能的影响

针对WC-12Co和WC-17Co超音速火焰喷涂层(HVOF),采用球/盘试验机研究其在大气环境下从室温至800℃的摩擦磨损性能,并结合涂层的氧化试验、氧化产物的XRD和Raman光谱分析、磨痕表面SEM观测,探索高温氧化对涂层摩擦磨损机制的影响.结果表明:WC-Co涂层在350 ～450℃时的摩擦磨损主要受Co氧化物的控制,体积流失小,为轻微氧化磨损;高于500℃时,WO3增多,虽有利于减摩却因消耗WC使涂层耐磨损性能下降;摩擦作用促进CoWQ的形成,这种钨钴双氧化物能够降低摩擦,减轻磨损,使涂层在600 ℃高温下仍维持良好的摩擦学性能;在更高温度条件下氧化剧烈,涂层性能迅速恶化而发生严重磨损,不宜作为耐磨涂层使用.Co含量较高的WC-Co涂层具有更好的高温耐磨性.     

纳米TiAlN涂层硬质合金刀具高速铣削AerMet100钢的磨损机理

采用纳米TiAlN结构涂层硬质合金刀具对新型难加工材料AerMet100钢进行高速铣削试验,并对实验获得的数据从刀具磨破损形态及其磨损机理两方面进行系统地分析和研究.研究表明纳米TiAlN结构涂层硬质合金刀具在高速面铣削AerMet100钢时磨损破损形式主要为前刀面磨损、后刀面磨损、涂层材料的破损、微崩刃、边界沟槽磨损和贝壳状崩落;磨损机理主要是磨粒磨损、粘结磨损、氧化磨损和扩散磨损.此外,研究发现,高速铣削AerMet100钢时,由于工件材料中的Co含量较高,刀具中的Co元素不但没有扩散流失,反而增加.     

高速干铣削钛合金时涂层硬质合金刀具磨损机理研究

采用CVD涂层硬质合金可转位立铣刀对钛合金(Ti-6Al-4V)进行了高速干铣削试验,采用扫描电子显微镜(SEM)观察刀具的磨损形貌,通过能谱分析(EDS)分析失效刀具表面的元素分布,并对刀具的主要磨损机理进行了分析.研究结果表明:使用涂层硬质合金刀具高速干铣削Ti-6Al-4V时,刀具的失效机理主要为磨粒磨损、粘结磨损、氧化磨损、扩散磨损和热-机械疲劳磨损的综合作用.刀具刚参与切削时,刀具后刀面会产生粘结和由于摩擦引起的擦伤,粘结层在断续冲击作用下的脱落过程还会造成后刀面涂层的剥落;随着刀具进一步的磨损,涂层剥落、粘结磨损及磨粒磨损伴随整个刀具失效过程,且还会出现氧化磨损、扩散磨损和疲劳裂纹等.切削速度越高,新产生的钛合金切屑就越容易燃烧,使刀具粘结、氧化和扩散以及热-机械疲劳等磨损加剧.     

Al_2O_3/TiCN涂层刀具的滑动磨损性能及切削性能研究

进行了滑动摩擦磨损和高速干切削试验,研究了Al_2O_3/TiCN涂层硬质合金刀具材料的磨损机理.结果表明:摩擦系数随着滑动速度的增加而减小,在FN=10 N时,摩擦系数最大.随着载荷和滑动速度的增加,磨损率有减小的趋势.受摩擦力和摩擦热的作用,在涂层刀具材料表面形成鱼鳞状的粘结层,随着速度和载荷增加,粘结的金属材料增多.在刀具前刀面靠近刀尖处形成了耐磨氧化物,提高刀具抗磨损性能,但在后刀面易形成少量的铁氧化物,加剧刀具磨损.其中,在刀具材料磨损表面形成的次生粘结层或氧化薄膜(如TiO_2、SiO_2),起到了润滑、减摩的作用,有利于刀具材料耐磨性能的提高.本文中的研究成果可望在指导高强度钢类材料的高效、高质量加工中发挥积极地作用.     

The 7th International Conference on Fluid Mechanics May 24-27,2015,Qingdao,China

正http://www.icfm7.org First Announcement and Call for PapersThe objective of International Conference on Fluid Mechanics(ICFM)is to provide a forum for researchers to exchange new ideas and recent advances in the fields of theoretical,experimental,computational Fluid Mechanics as well as interdisciplinary subjects.It was successfully convened by the Chinese Society of Theoretical and Applied Mechanics(CSTAM)in Beijing(1987,     

INFORMATION FOR CONTRIBUTORS

Contributions： The Journal, Acta Mechanica Solida Sinica, is pleased to receive papers from engineers and scientists working in various aspects of solid mechanics. All contributions are subject to critical review prior to acceptance and publication.     

Preface

This special issue of PARTICUOLOGY is devoted to the first UK-China Particle Technology Forum taking place in Leeds, UK, on 1-3 April 2007. The forum was initiated by a number of UK and Chinese leading academics and organised by the University of Leeds in collaboration with Chinese Society of Particuology, Particle Technology Subject Group （PTSG） of the Institution of Chemical Engineers （IChemE）, Particle Characterisation Interest Group （PCIG） of the Royal Society of Chemistry （RSC） and International Fine Particle Research Institute （IFPRI）. The forum was supported financially by the Engineering and Physics Sciences Research Council （EPSRC） of United Kingdom,     

基于鲁棒滤波的捷联导引头视线角速度估计方法

针对捷联导引头无法直接获取视线角速度等信息的问题,研究了鲁棒滤波在大气层外飞行器捷联导引头视线角速度估计中的应用。为了建立非线性滤波估计模型,考虑目标视线角速度的慢变特性,采用一阶马尔科夫模型建立了状态方程;推导了视线角速度的解耦模型,并建立了量测方程;考虑到实际应用中存在系统噪声统计特性失准的问题,基于Huber-Based鲁棒滤波方法,设计了视线角速度滤波器,并完成了基于Huber-Based滤波方法和扩展卡尔曼滤波方法的数学仿真。仿真结果表明Huber-Based滤波方法的视线角、视线角速度及视线角加速度估计精度分别达到0.1140'、0.1423'/s、0.0203'/s2,而扩展卡尔曼滤波方法的视线角、视线角速度及视线角加速度估计精度仅分别为0.6577'、0.6415'/s、0.0979'/s~2。仿真结果证明了该方法可以有效地估计出相对视线角速度等信息,并且在非高斯噪声的条件下,依然可获得较高的估计精度,具有一定的鲁棒性。     

Guide for authors

正Each of the sections below provides essential information for authors.We recommend that you take the time to read them before submitting a contribution to Acta Mechanica Sinica.We hope our guide to authors may help you navigate to the appropriate section.How to prepare a submission This document provides an outline of the editorial process involved in publishing a scientific paper in Acta Mechanica     

Use specification of multiscale materials for life spanned over macro-, micro-, nano-, and pico-scale

Multiscale material intends to enhance the strength and life of mechanical systems by matching the transmitted spatiotemporal energy distribution to the constituents at the different scale, say—macro, micro, nano, and pico,—, depending on the needs. Lower scale entities are, particularly, critical to small size systems. Large structures are less sensitive to microscopic effects. Scale shifting laws will be developed for relating test data from nano-, micro-, and macro-specimens. The benefit of reinforcement at the lower scale constituents needs to be justified at the macroscopic scale. Filling the void and space in regions of high energy density is considered.Material inhomogeneity interacts with specimen size. Their combined effect is non-equilibrium. Energy exchange between the environment and specimen becomes increasingly more significant as the specimen size is reduced. Perturbation of the operational conditions can further aggravate the situation. Scale transitional functions and/or f_j/j+1 are introduced to quantify these characteristics. They are represented, respectively, by , and (f_mi/ma,f_na/mi,f_pi/na). The abbreviations pi, na, mi, and ma refer to pico, nano, micro and macro.Local damage is assumed to initiate at a small scale, grows to a larger scale, and terminate at an even larger scale. The mechanism of energy absorption and dissipation will be introduced to develop a consistent book keeping system. Compaction of mass density for constituents of size 10⁻¹², 10⁻⁹, 10⁻⁶, 10⁻³ m, will be considered. Energy dissipation at all scales must be accounted for. Dissipations at the smaller scale must not only be included but they must abide by the same physical and mathematical interpretation, in order to avoid inconsistencies when making connections with those at the larger scale where dissipations are eminent.Three fundamental Problems I, II, and III are stated. They correspond to the commonly used service conditions. Reference is made to a Representative Tip (RT), the location where energy absorption and dissipation takes place. The RT can be a crack tip or a particle. At the larger size scales, RT can refer to a region. Scale shifting of results from the very small to the very large is needed to identify the benefit of using multiscale materials.