纳米表面工程与摩擦学

利用表面工程技术解决摩擦磨损问题具有高效、实用等特点。随着科学技术的迅速发展，纳米材料和纳米技术在表面工程中得到了广泛应用，由此出现了“纳米表面工程”。利用纳米表面工程技术制备的涂层和镀层有着非常优异的摩擦学性能。本文叙述了作者近年来的有关工作，包括热喷涂纳米陶瓷涂层、热喷涂纳米自润滑涂层、纳米陶瓷／聚合物复合涂层、纳米复合电镀层以及纳米电泳沉积层的摩擦磨损特性和机制。     

纳米涂层的几种制备方法

介绍了纳米涂层和纳米薄膜制备方法的研究进展及其特性。着重对热喷涂制备纳米涂层进行了探讨，认为用热喷涂方法制备纳米涂层具有独特的优越性，具有广泛的应用前景。     

AZ91D热化学反应热喷涂陶瓷涂层耐磨性研究

在镁合金AZ91D表面使用火焰喷涂制备Al2O3 TiO2 SiO2 ZnO Al陶瓷涂层,在喷涂制备涂层过程中伴随热化学反应的发生,涂层X射线分析发现,涂层内有MgSiO4、MgAl2O4等新相生成.磨损试验表明,热化学反应热喷涂陶瓷涂层耐磨性优于常用热喷涂陶瓷涂层.     

哈尔滨工业大学成功研制纳米陶瓷涂层技术

哈尔滨工业大学王铀教授课题组承担的省自然科学基金项目“纳米结构热喷涂强韧耐磨抗蚀陶瓷涂层”课题通过验收,以中国工程院院士张立同为主任的专家组认为,该课题成功研制出的纳米耐磨抗蚀陶瓷涂层技术达到世界先进水平。     

火焰喷涂法制备纳米改性陶瓷涂层

研究了纳米改性陶瓷粉的配制。对所制备的纳米改性陶瓷涂层的结合强度、孔隙率、耐磨性、耐蚀性、微观形貌进行了试验研究。结果表明;火粉喷涂法制备的纳米改性陶瓷涂层与等离子喷涂陶瓷涂层性能相近。     

等离子弧喷涂纳微米结构陶瓷涂层相变及显微分析

本文采用两种不同的工艺手段，分别制备了可用于热喷涂的Al2O3-13％TiO2纳米结构喂料，并采用等离子喷涂工艺制备了涂层。采用X-Ray衍射和TEM等分析手段对喂料和涂层进行了分析测试。结果表明，不同的造粒工艺获得的喂料和涂层具有不同的相组成，同时显微结构也有所不同。1300℃下热处理的喂料制备的涂层中包含纳米尺度的晶粒。     

激光熔覆制备纳米陶瓷涂层的研究进展

介绍了激光熔覆工艺纳米陶瓷粉末的供给方式、工艺参数的选择;对比分析了激光熔覆和其他主要的纳米陶瓷涂层制备方法的优缺点;着重分析介绍了激光熔覆制备的几种主要纳米陶瓷涂层的组织和性能特征,尤其是纳米抗裂的最新研究成果以及抗裂机理,分析表明,增加纳米颗粒将明显地改善陶瓷涂层的抗裂性能。另外,涂层的强度、致密度、耐磨性也随着纳米颗粒的增加而相应增加。阐述了激光熔覆制备纳米陶瓷涂层存在的主要问题,并对该技术发展前景和应用进行了展望。     

第一讲 装备再制造技术（七）

（3）超音速等离子喷涂技术制备微米、纳米结构涂层 装备再制造技术国防科技重点实验室采用自行研制的高效能超音速等离子喷涂系统喷涂Al2O3/TiO2和WC／Co纳米结构喂料,制备了纳米结构热喷涂涂层。表9为其超音速等离子喷涂工艺参数。     

等离子喷涂纳米Al_2O_3-13%TiO_2陶瓷涂层的组织结构与抗冲蚀性能

采用等离子喷涂方法分别制备了常规和纳米Al2O3-13%TiO2陶瓷涂层,用扫描电子显微镜分析了涂层的显微结构,并对涂层进行了抗冲蚀试验。结果表明:常规陶瓷涂层具有典型的片层状结构,但纳米陶瓷涂层片层状结构并不十分明显,且涂层裂纹数量明显减少;纳米陶瓷涂层中的显微结构的变化改善了涂层的韧性和结合性能;在冲蚀过程中,常规陶瓷涂层表面剥落严重,而纳米陶瓷涂层的冲蚀质量损失较小,抗冲蚀性能比常规陶瓷涂层提高了30%左右。     

混粉工艺对纳米Al2O3复合涂层组织和性能的影响

首次将纳米Al2O3作为弥散增强相应用于热喷涂领域中，先将其与Ni基自由熔性合金粉制成复合粉末，然后用氧－乙炔焰热喷焊工艺制备出复合涂层。研究了不同分散剂、液体介质、混合方式等对涂层耐磨性能的影响。结果表明，最佳工艺得到的复合涂层其耐磨性为单纯涂层的2倍。     

纳米陶瓷涂层磨削表面残余应力的研究进展

纳米陶瓷涂层材料具有高硬度和高耐磨性,采用超硬磨料的金刚石砂轮磨削是其最主要的加工方法,在磨削时容易出现表面残余应力而导致表面裂纹.目前,国外在纳米结构陶瓷涂层磨削表面残余应力的研究很少,我国正在对纳米陶瓷涂层材料超精密磨削后表面残余应力方面进行研究.介绍了纳米结构陶瓷涂层的研究背景,阐述了纳米结构陶瓷喷涂材料性能特点,分析了纳米结构陶瓷涂层的磨削研究动态和磨削表面残余应力的研究现状.分析研究表明,纳米结构陶瓷涂层的开发与研究将会受到越来越广泛的重视,其后续研究将是下一步的工作重点.     

纳米结构陶瓷涂层磨削表面残余应力的实验设计

以近年来新出现的纳米结构碳化钨/钴(n-WC/12Co)陶瓷涂层材料为磨削对象,巧妙选择磨削实验用磨床和三种砂轮,利用X射线衍射仪等设备,通过设计磨削参数,为纳米结构陶瓷涂层的磨削实验和表面残余应力的测量及后续研究"磨削参数对磨削表面残余应力的影响规律"提供依据。     

Tribological behavior of plasma sprayed Cr2O3-3%TiO2 coatings

Tribological behaviors of plasma-sprayed conventional and nanostructured Cr₂O₃-3%TiO₂ ceramic coatings (i.e., CC3T and NC3T, respectively) using pin on disc type dry sliding and pot type slurry erosion test were investigated in the present work. The experimental results indicated that there were two main wear mechanisms, plastic smearing and adhesive tearing, in the worn coatings under dry sliding. Plastic smearing corresponded to a lower average friction coefficient and wear rate, while adhesive tearing corresponded to higher values. The erosive environment selected for the slurry erosion experiments include 10, 20 and 30% of SiO₂ slurry concentrations in water with particle size 75-106 μm. The main damage mechanism observed in all the coatings submitted to slurry erosion were the formation and propagation of brittle cracks resulting in the detachment of coating surface material. Microstructural investigation was also carried to investigate the wear and erosion mechanism of the coatings using FE-SEM and EDS analysis. Properties like microhardness and porosity were also investigated for these coatings. Tribological performance of NC3T was better as compared to CC3T as observed in the present work.     

Corrosion-wear behaviour of thermal sprayed nanostructured FeCu/WC-Co coatings

The corrosion and corrosion-wear behaviour of a thermal sprayed nanostructured FeCu/WC-Co coating were investigated in a Hank's solution and compared to stainless steel AISI 304 and nanostructured WC-Co coatings. Electrochemical noise and potentiodynamic polarization measurements were conducted along with an ex situ scanning electron microscopy to unfold the response of these materials under these corrosive and corrosion-wear test conditions. The multiphase structure of the FeCu/WC-Co coating induces a complex corrosion behaviour. Under corrosion-wear conditions, the nanostructured FeCu/WC-Co coating exhibits a depassivation/repassivation behaviour comparable to the behaviour of stainless steel AISI 304 and nanostructured WC-Co coatings.     

Corrosion-wear behaviour of PVD Cr/CrN multilayer coatings for gear applications

At present, one of the most important problems in automobile engines and transmission components is due to tribological processes (friction and wear) that in many cases come accompanied by corrosion processes due to the environmental conditions to which these materials are exposed during their lifetime. Both mechanisms can be minimized by means of the development and the application of adequate coatings that combine low friction with a high corrosion and wear resistance.The new tendencies in industrial PVD coatings to improve their properties are focused in the development of new multilayer and nanostructured coatings. These structures allow in a relatively simple way enhancing their tribological properties and the corrosion resistance that can not be reached by means of the traditional monolayer coatings. The background of this type of coatings consists of the stacking up of several layers with good individual tribological and mechanical properties, but every individual layer has a thickness that can be from hundreds of nanometres down to only 5-10 nm. The properties of these nanostructured coatings depend strongly on the thickness modulation of every individual layer.Concerning PVD coatings, the chrome nitride coatings have demonstrated to possess excellent wear resistance properties. In this work, multilayer Cr/CrN coatings with different individual layer thickness have been deposited on substrates of steel F1272 and silicon. The deposition has been carried out by means of the cathodic arc method alternating an atmosphere of pure Ar with a reactive mixture of N₂/Ar. The multilayers obtained have been analyzed by means of Glow Discharge Optical Emission Spectroscopy (GD-OES) and in some cases by means of FE-SEM obtaining bilayer (Cr/CrN) periods of the order of 220 and 45 nm. The coating characterization has been complemented with hardness and composition measurements as well as by the performance of several wear and corrosion-wear tests.     

超硬涂层材料滚动接触疲劳试验机的研制

在总结分析目前国内外表面超硬涂层零件接触疲劳失效行为评估技术的基础上，依据超硬涂层零件接触疲劳失效机制模型，自主研制了一种超硬涂层材料滚动接触疲劳试验机。介绍了该试验机的设计原理和特殊功能，采用该试验机对51306纳米超硬材料涂层轴承滚动接触疲劳失效行为进行了试验评定。试验证明所研制的超硬涂层材料滚动接触疲劳试验机智能检测控制系统能够动态探测诊断涂层轴承表面初始疲劳裂纹并实现急停，可捕捉试验轴承表面疲劳初始状态，为超硬涂层零件接触疲劳失效机制分析提供可靠的试验依据。     

超硬涂层零件滚动接触疲劳加速实验方法研究

提出了一种新的加速超硬涂层零件滚动接触疲劳失效的实验方法,并给出了机制模型及机制分析;采用该方法,在超硬涂层材料滚动接触疲劳实验机上,对纳米超硬材料涂层轴承滚动接触疲劳失效行为开展了加速疲劳实验和常规疲劳实验的对比实验研究。实验结果表明:该方法能取得与常规疲劳实验方法疲劳行为相同的实验结果;加速疲劳实验加速比约为3,加速疲劳实验方法十分有效地节省了疲劳实验中消耗的时间。该方法是一个适应于评价超硬涂层零件滚动接触疲劳性能及研究其失效机制的新方法。     

电沉积稀土改性陶瓷涂层磨损性能研究

探讨了在电火花加工机床上沉积碳化钛金属陶瓷涂层方法,利用TiC,WC,Mo,N i粉未添加不同比例稀土元素在高压下压制并烧结了试验电极,在45#钢表面沉积了不同稀土含量的TiC陶瓷涂层,并用扫描电镜(SEM)、X射线衍射仪(XRD)、显微硬度计、环块式磨损试验机对涂层组成、组织形态进行、硬度及摩擦学性能分别进行了研究,并结合试验结果进行了理论分析。试验结果表明:用电火花放电法可沉积TiC陶瓷涂层,涂层中加入质量分数为0.5%的氧化镧后,涂层的耐磨性能较未加稀土涂层提高了3倍,摩擦因数减少10%,而加入过多的稀土镧氧化物则不利于涂层组织性能及耐磨性能的改善。稀土氧化镧对涂层的组织有改善作用,加入适量的稀土元素使得涂层致密性提高,减少涂层中的缺陷,涂层表面呈多孔结构特性。