纳米SiO2形态对铜基摩擦材料摩擦学性能的影响

采用粉末冶金法分别制备了添加0.75 wt%的纳米SiO2(n-SiO2)和0.75 wt%Cu包纳米SiO2(Cu/n-SiO2)复合粉体的新型铜基摩擦材料.采用惯性台架试验机,研究比较了2种材料与未添加纳米SiO2的材料的摩擦学性能.结果表明添加0.75 wt% Cu/n-SiO2的铜基摩擦材料,耐热性提高了32%,摩擦因数更稳定,耐磨性提高了2.02倍.经铜包覆处理后的n-SiO2对材料性能的影响优于未处理的n-SiO2.     

纳米SiC晶须增强铜基纳米复合材料摩擦学性能研究

采用粉末冶金法制备了添加纳米SiC晶须（n-SiCw）的铜基纳米复合材料（SiCw／Cu）。研究了复合材料的显微组织、密度、硬度与n-SiCw含量之间的关系，通过球／盘式摩擦磨损试验机研究了SiCw／Cu复合材料的摩擦磨损性能。结果表明：随n-SiCw含量增加，基体中孔隙增多，并出现n-SiCw的偏聚，复合材料的密度减小，硬度增加；当n-SiCw含量为0．3wt％时，材料的减摩、耐磨性能最好；SiCw／Cu复合材料的磨损机制为疲劳磨损和磨粒磨损，并以疲劳磨损为主。     

纳米SiO2颗粒增强铜基复合材料性能研究

以纳米SiO2颗粒为增强体,采用粉末冶金法制备铜基纳米复合材料.考察不同质量分数的纳米颗粒对复合材料密度、硬度以及摩擦磨损性能的影响.结果表明纳米SiO2颗粒的加入,使铜基体的硬度和摩擦磨损性能都得到了明显提高;但随着纳米SiO2质量分数的增加,复合材料的密度和硬度均呈下降趋势;当纳米SiO2质量分数为0.3 %时,复合材料的减摩耐磨性最好.     

纳米SiC在聚四氟乙烯复合材料中的性能

添加质量分数为3.0%的纳米碳化硅(n-SiC)的多元聚四氟乙烯(PTFE)复合材料具有优良的摩擦因数和耐磨性.研究了n-SiC对复合材料摩擦磨损过程中的转移膜、磨损形貌的影响.研究认为,n-SiC在多元PTFE复合材料中的主要作用是促进PTFE转移膜的形成,以获得低而稳定的摩擦因数;有效提高复合材料的耐热性、承载能力,减少粘着磨损量,提高复合材料的抗微切削能力;促进复合材料的磨损机制由粘着磨损为主向微切削磨损为主的转变.     

磁控溅射工艺对CrN基复合涂层微观结构及摩擦学性能的影响

采用闭合场非平衡磁控溅射技术在不锈钢基体上制备了不同质量分数Mo的CrMoN复合涂层。采用X射线衍射仪（XRD）、扫描电子显微镜（SEM）、能谱仪（EDX）和光电子能谱仪（XPS）,系统分析了CrMoN复合涂层的相结构、表面形貌、成分、原子化合价价态等,结果表明：添加Mo后,CrMoN涂层的择优取向由CrN涂层的（220）转变为（200）,CrMoN涂层中的Mo原子取代了CrN晶格中的Cr原子,形成（Cr,Mo）N置换固溶体。采用Nano Test 600硬度测试仪测定了CrMoN复合涂层的纳米硬度,结果表明：由于CrN相和MoN两种硬相的协同作用,使得CrMoN复合涂层的纳米硬度值增大。采用多功能摩擦磨损试验机测定了CrN涂层及CrMoN复合涂层的摩擦因数,结果表明：CrMoN复合涂层的摩擦因数低于CrN涂层,磨损过程中由于摩擦热反应生成大量MoO3,使得复合膜的摩擦因数降低,起到了一定的润滑效果,降低了磨损量。     

纳米SiO_2在润滑油中的高温摩擦学性能

采用多功能SRV试验机考察了纳米SiO2在菜籽油中的高温摩擦学性能,利用表面轮廓仪观察磨损表面形貌。结果表明,在恒定负荷试验中,纳米SiO2能明显改善菜籽油的高温减摩抗磨性能,在500℃时,摩擦因数仅为0.16,磨损量降低了80%以上。在连续加载的高温试验中,当试验温度为200℃时,纳米SiO2对菜籽油的减摩抗磨性能没有明显的改善;而当试验温度达到500℃时,纳米SiO2能明显地改善菜籽油的减摩抗磨性能,在大负荷(500N)的情况下更为突出。     

Si3N4和CCr15对巴氏合金摩擦副的摩擦磨损性能研究

在UMT-3摩擦磨损试验机上,将Si3N4、CCr15分别与巴氏合金进行了摩擦磨损试验,并利用扫描电镜和X射线能谱仪观察巴氏合金的磨损表面,探讨其磨损机理,为Si3N4-巴氏合金新型陶瓷轴承的实际应用提供理论依据.结果表明:载荷相同时,Si3N4-巴氏合金的平均摩擦因数和磨损率比CCr15-巴氏合金低;随着载荷的增加,Si3N4-巴氏合金的摩擦因数先升后降,波动幅度明显小于CCr15-巴氏合金;载荷为10N时,Si3N4-巴氏合金摩擦因数达到最大值0.13,在15N时达到最小值0.04;摩擦副整体磨损率较低,巴氏合金的磨损率随载荷增大而增大,平均为10-6 mm3/(N-m).在Si3N4-巴氏合金摩擦表面同时存在陶瓷氧化物润滑膜和金属磨屑,共同起到了润滑减摩的作用.Si3N4-巴氏合金作为陶瓷轴承的配合材料,具有比传统轴承更好的摩擦磨损性能,具有广阔的应用前景.     

球-盘摩擦磨损试验机的设计及其应用

提供一种制备球-盘摩擦磨损试验机(pin-on-disk wear tester)的方法,用以测试硬质薄膜的摩擦学性能.此试验机提供的数据有摩擦因数f, 磨损量Wv和比磨损率Wr.首先深入研究球-盘磨损试验机的工作原理,确定其工作原理是通过荷重传感器的A-D转换,将摩擦力的模拟信号转变为电压数字信号,输入计算机或者X-Y记录仪.然后与事先标定好的电压值对比,得到测试过程中的摩擦力.传感器的标定方法为用已知载荷(一定质量的砝码)对传感器施加拉力,传感器将其转变成电压值,绘出电压U-拉力F关系曲线,将其用直线拟合.同时提供了数据处理的方法,并利用此试验机测试了多弧离子镀TiN薄膜以及磁控溅射非晶碳膜的摩擦学性能,得到摩擦因数曲线和磨痕形貌.最后对此试验机的缺点进行了分析.     

梯度变化非晶碳涂层的摩擦学行为

采用多源磁控溅射物理气相沉积法在单晶硅片、20Cr和Cr12W表面制备了梯度变化非晶碳涂层,测试了非晶碳涂层的纳米硬度和弹性模量及摩擦磨损行为.结果表明涂层具有较高的硬度和弹性模量,分别达到15.3 GPa和184 GPa;涂层具有较好的摩擦性能,在干摩擦条件下摩擦因数基本保持在0.1～0.2,磨损率达到10-9 mm3/( N·m)数量级.     

CeO2对NiCrBSi合金激光熔覆层滑动摩擦磨损性能的影响

采用NdYAG激光器,在45CrNi钢表面制备了添加有0、0.4%、0.8%和1.2?O2的NiCrBSi合金熔覆层.在MM-200环块摩擦磨损试验机上分别检测了4种熔覆层的滑动摩擦磨损性能.测试结果表明 经CeO2强化后熔覆层的耐磨性提高,摩擦因数略有下降.利用SEM分析磨损表面形貌可知未加入CeO2的熔覆层对应的磨损机理是显微切削;加入1.2?O2熔覆层的磨损表面光滑,显微切削造成的沟槽明显减少.上述试验结果与熔覆层显微组织密切相关.     

环氧树脂/CTBN/无机颗粒高分子合金修补剂材料的制备与性能分析

通过端羧基丁腈液态橡胶(Carboxyl Terminated Butadiene Acrylonitrile,CTBN)协同纳米Al2O3、SiO2颗粒与微米MoS2颗粒共混改性环氧树脂,制备了双组分的耐磨高分子合金修补剂材料。采用拉伸、摩擦磨损等试验及SEM等方法测试和分析了该高分子合金修补剂的拉伸强度、显微硬度等基本性能及摩擦学性能,并对其耐磨减摩机理进行了分析。结果表明:该材料的拉伸强度为42.3MPa,拉伸剪切强度为13.8MPa,显微硬度为231.1MPa,摩擦因数为0.17,耐磨性比LY12铝合金提高了50%。     

Experimental investigations on wear properties of Palm kernel reinforced composites for brake pad applications

The use of asbestos material is being avoided to manufacture the brake pads as it is harmful and toxic in nature. Further it leads to various health issues like asbestosis, mesothelioma and lung cancers. These brake pads can be replaced by natural fibers like Palm kernel (0–50%), Nile roses (0–15%) and Wheat (0–10%) with additives like aluminum oxide (5%–20%) and graphite powder (10%–35%). Phenolic resin of 35% is utilized as a binder. Particulated Nile roses are used to increase the friction coefficient and wheat powder is used to reduce the wear rate. Aluminum oxide and graphite are abrasive in nature. This helps to make brake pads with high friction co-efficient and less wear rate with low noise pollution. The wear of the proposed composites have been investigated at different speeds. Various tests like wear on pin-on-disc apparatus, hardness on the Rockwell hardness apparatus and oil absorption test have been conducted. Phenolic resin produces good bonding nature to fiber. Thus, Fibers found to have performed palatably among all commercial brake pads. The objective of the research indicates that Palm kernal shell could be a conceivable alternative for asbestos in friction coating materials.     

磁流变液的摩擦与润滑

采用四球摩擦磨损试验机考察了羰基铁-矿物油体系磁流变液和基础油摩擦系数随时间的变化曲线、磨斑直径,用扫描电镜观察了磨痕表面形貌.结果表明,与基础油相比,磁流变液的摩擦加剧,润滑性能降低,磁性颗粒是导致其润滑性能下降的首要原因;摩擦磨损机理主要是磨粒磨损,表现为犁沟效应.     

Cu/C复合型润滑添加剂减摩抗磨性能研究

将纳米Cu和纳米金刚石复配成Cu/C复合添加剂,对其在500SN基础油中的减摩抗磨性能进行了研究.结果表明,加入了Cu/C复合添加剂的试油能明显改善500SN基础油的摩擦学性能:当纳米Cu添加量为4%,纳米C添加量为2%时,加入了Cu/C复合添加剂的试油减摩性能最好,同500SN空白试油相比,摩擦因数可降低94.8%;...     

润滑油纳米铜添加剂及其对不同粗糙度表面的减摩自修复行为

采用KBH4液相还原法制备了纳米铜添加剂,采用透射电子显微镜对纳米铜添加剂进行了表征,通过摩擦磨损试验机测试了纳米铜添加剂对4种不同粗糙度摩擦表面所表现的抗磨减摩性能,并对不同的磨损表面进行了光学显微镜和能谱分析。结果表明:纳米铜添加剂为分散性能稳定的20nm的球形颗粒;纳米铜添加剂具有良好的抗磨减摩性能,尤其是对于光滑的摩擦表面,与基础油相比,可使摩擦因数降低24%。纳米铜添加剂还具有良好的自修复性能,摩擦过程中,能够在摩擦表面形成一层高弹性低硬度的自修复膜,自修复效果对于光滑的摩擦表面更为显著。     

Friction stir surfacing of cast A356 aluminiumesilicon alloy with boron carbide and molybdenum disulphide powders

Good castability and high strength properties of Ale Si alloys are useful in defence applications like torpedoes,manufacture of Missile bodies,and parts of automobile such as engine cylinders and pistons.Poor wear resistance of the alloys is major limitation for their use.Friction stir processing(FSP) is a recognized surfacing technique as it overcomes the problems of fusion route surface modification methods.Keeping in view of the requirement of improving wear resistance of cast aluminiumesilicon alloy,friction stir processing was attempted for surface modification with boron carbide(B4C) and molybdenum disulfide(Mo S2) powders.Metallography,micro compositional analysis,hardness and pin-on-disc wear testing were used for characterizing the surface composite coating.Microscopic study revealed breaking of coarse silicon needles and uniformly distributed carbides in the A356 alloy matrix after FSP.Improvement and uniformity in hardness was obtained in surface composite layer.Higher wear resistance was achieved in friction stir processed coating with carbide powders.Addition of solid lubricant Mo S2 powder was found to improve wear resistance of the base metal significantly.     

Analysis of sliding electric contact characteristics in augmented railgun based on the combination of contact resistance and sliding friction coefficient

The contact resistance between the armature and rails is an important indicator of the contact characteristics in electromagnetic launches. As the contact resistance depends not only on the contact state but also on the contact stress and temperature, there are some limitations in analyzing the contact characteristics using only the contact resistance. In this paper, the contact characteristics of the augmented railgun are analyzed by the combination of contact resistance and sliding friction coefficient. Firstly, the theoretical calculation model of the contact resistance and friction coefficient of the augmented electromagnetic railgun is established. Then the contact resistance and friction coefficient are calculated by the measured values of the muzzle voltage, rail current and armature displacement. Finally, the contact characteristics are analyzed according to the features of the waveforms of the contact resistance and the friction coefficient, and the analysis conclusions are verified by experimental rail images. The results showed that: the aluminum melt film gradually formed on the contact surface reduces the contact resistance and the friction coefficient; the wear and erosion of the armature cause deterioration of the contact state; after the transition, the reliability of the sliding contact between the armature and rails decreases, resulting in an increase in contact resistance.