金屬Ag，Cu及其與石墨烯復(fù)合界面摩擦的第一性原理研究
發(fā)布時(shí)間：2018-08-29 16:06
【摘要】：摩擦現(xiàn)象對(duì)人類的生產(chǎn)和生活有著不可忽視的影響。世界上有大約1/3-1/2的一次性能源消耗在摩擦過程中,世界上工業(yè)發(fā)達(dá)國家由于摩擦和磨損引起的損失占了國民生產(chǎn)總值(GDP)的5%-7%。所以對(duì)摩擦的研究至關(guān)重要,從四世紀(jì)開始,人們已經(jīng)開始對(duì)摩擦進(jìn)行研究,最基本的摩擦學(xué)規(guī)律是阿蒙頓定律。隨著科學(xué)技術(shù)的發(fā)展,現(xiàn)代精密器件的尺寸越來越小,比表面積越來越大,摩擦對(duì)微電子機(jī)械器件的正常運(yùn)行和使用壽命有著決定性的影響�？茖W(xué)家在對(duì)一些材料研究中發(fā)現(xiàn)了超潤滑現(xiàn)象,超潤滑指摩擦因數(shù)為0或無限接近于0,超潤滑的發(fā)現(xiàn)為現(xiàn)代微納機(jī)械系統(tǒng)設(shè)計(jì)和制造帶來了希望。理論研究表明最有可能產(chǎn)生超潤滑現(xiàn)象的材料就是二維材料,如石墨烯,二硫化鉬,六方氮化硼等。這些二維材料由于晶面原子間有極強(qiáng)的化學(xué)鍵,晶面間不易發(fā)生形變,同時(shí)層間有很弱的范德華力,界面間滑動(dòng)時(shí)的摩擦力更易接近零。隨后在實(shí)驗(yàn)中也證實(shí)了超潤滑現(xiàn)象驗(yàn)證了理論預(yù)測(cè)。軟金屬Ag,Cu的優(yōu)良潤滑性能使它們被應(yīng)用于精密儀器的制造。但是隨著科學(xué)技術(shù)的飛速發(fā)展,在超高精密儀器或微電子機(jī)械系統(tǒng)的滑動(dòng)界面需要非常低的摩擦甚至沒有摩擦。這就對(duì)潤滑材料有了更苛刻的要求,傳統(tǒng)的軟金屬Ag,Cu的潤滑性能已不能滿足需要,超潤滑(Superlubricity)(指發(fā)生相對(duì)運(yùn)動(dòng)的物體間的摩擦力幾乎為零甚至完全消失的現(xiàn)象)性能的發(fā)現(xiàn)和研究為更高摩擦學(xué)性能需求的器件和微電子機(jī)械系統(tǒng)帶來了希望。二維材料(石墨烯,MoS2,WO2等)在特定的實(shí)驗(yàn)條件下摩擦力消失摩擦因數(shù)為零出現(xiàn)超潤滑現(xiàn)象,但是,都有不足之處,就拿石墨烯來說,承受一定載荷后滑動(dòng)會(huì)引起邊緣起皺,這種面內(nèi)形變會(huì)引起摩擦因數(shù)升高導(dǎo)致超潤滑失效。于是,我們希望把石墨烯附著在軟金屬表面上作為潤滑層,一方面保護(hù)金屬層,另一方面改善表面的潤滑性能,滿足機(jī)械系統(tǒng)所需要的超低摩擦要求。本文中運(yùn)用第一性原理密度泛函理論(DFT)系統(tǒng)地研究了在微納尺度下金屬與金屬界面,金屬與石墨烯界面和通過石墨修飾的金屬界面的摩擦性能研究。我們的研究發(fā)現(xiàn)了金屬與金屬界面在微尺度下仍遵守阿蒙頓定律;金屬與石墨烯界面有著極低的摩擦因數(shù)是由界面間較弱的物理吸附引起的;石墨修飾的金屬界面產(chǎn)生了超潤滑現(xiàn)象,比單獨(dú)的石墨烯界面更易實(shí)現(xiàn)超潤滑。
[Abstract]:Friction phenomenon has an important influence on the production and life of human beings. About 1 / 3-1 / 2 of the world's disposable energy is consumed in the friction process. The losses caused by friction and wear in the developed countries in the world account for 5- 7% of the gross national product (GDP). Therefore, the study of friction is very important. Since the fourth century, people have begun to study friction, the most basic law of tribology is Amonton's law. With the development of science and technology, the size and specific surface area of modern precision devices are becoming smaller and larger. Friction has a decisive effect on the normal operation and service life of microelectro-mechanical devices. In the study of some materials, scientists have found the phenomenon of superlubrication, which means that the friction coefficient is zero or infinitely close to zero. The discovery of superlubrication brings hope to the design and manufacture of modern micro-nano mechanical system. Theoretical studies show that the most likely superlubricating materials are two-dimensional materials, such as graphene, molybdenum disulfide, hexagonal boron nitride and so on. Due to the strong chemical bond between the atoms in the crystal plane, the deformation between the two planes is not easy, and there is a very weak van der Waals force in the interlayer, so the friction force between the interfacial sliding is closer to zero. Then the theoretical prediction was verified in the experiment. The excellent lubricating properties of soft metal Ag,Cu make them used in the manufacture of precision instruments. However, with the rapid development of science and technology, very low friction or no friction is required in the sliding interface of ultra-high precision instruments or microelectromechanical systems. This has more stringent requirements for lubricating materials. The lubricating performance of traditional soft metal Ag,Cu can no longer meet the needs. Superlubricating (Superlubricity) (refers to the phenomenon that the friction between objects in relative motion is almost zero or even completely disappeared) the discovery and study of the properties bring hope to the devices and microelectromechanical systems with higher tribological properties. Two dimensional materials (graphene, MoS2WO2, etc.) have superlubricating phenomena when the friction coefficient is zero, but there are some shortcomings. For graphene, sliding under certain load will cause edge wrinkle. This in-plane deformation can cause the friction coefficient to increase and lead to overlubrication failure. Therefore, we hope to attach graphene to the soft metal surface as a lubricating layer, on the one hand to protect the metal layer, on the other hand to improve the lubricating performance of the surface, to meet the requirements of the mechanical system for ultra-low friction. In this paper, the friction properties of metal-metal interface, metal-graphene interface and graphite-modified metal interface are systematically studied by using first-principles density functional theory (DFT). It is found that the metal to metal interface obeys Amonton's law at the microscale, and the very low friction coefficient between the metal and graphene interface is caused by the weak physical adsorption between the metal and the graphene interface. The metal interface modified by graphite produces superlubrication, which is easier to realize than the single graphene interface.
【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TH117.1
本文編號(hào)：2211710
[Abstract]:Friction phenomenon has an important influence on the production and life of human beings. About 1 / 3-1 / 2 of the world's disposable energy is consumed in the friction process. The losses caused by friction and wear in the developed countries in the world account for 5- 7% of the gross national product (GDP). Therefore, the study of friction is very important. Since the fourth century, people have begun to study friction, the most basic law of tribology is Amonton's law. With the development of science and technology, the size and specific surface area of modern precision devices are becoming smaller and larger. Friction has a decisive effect on the normal operation and service life of microelectro-mechanical devices. In the study of some materials, scientists have found the phenomenon of superlubrication, which means that the friction coefficient is zero or infinitely close to zero. The discovery of superlubrication brings hope to the design and manufacture of modern micro-nano mechanical system. Theoretical studies show that the most likely superlubricating materials are two-dimensional materials, such as graphene, molybdenum disulfide, hexagonal boron nitride and so on. Due to the strong chemical bond between the atoms in the crystal plane, the deformation between the two planes is not easy, and there is a very weak van der Waals force in the interlayer, so the friction force between the interfacial sliding is closer to zero. Then the theoretical prediction was verified in the experiment. The excellent lubricating properties of soft metal Ag,Cu make them used in the manufacture of precision instruments. However, with the rapid development of science and technology, very low friction or no friction is required in the sliding interface of ultra-high precision instruments or microelectromechanical systems. This has more stringent requirements for lubricating materials. The lubricating performance of traditional soft metal Ag,Cu can no longer meet the needs. Superlubricating (Superlubricity) (refers to the phenomenon that the friction between objects in relative motion is almost zero or even completely disappeared) the discovery and study of the properties bring hope to the devices and microelectromechanical systems with higher tribological properties. Two dimensional materials (graphene, MoS2WO2, etc.) have superlubricating phenomena when the friction coefficient is zero, but there are some shortcomings. For graphene, sliding under certain load will cause edge wrinkle. This in-plane deformation can cause the friction coefficient to increase and lead to overlubrication failure. Therefore, we hope to attach graphene to the soft metal surface as a lubricating layer, on the one hand to protect the metal layer, on the other hand to improve the lubricating performance of the surface, to meet the requirements of the mechanical system for ultra-low friction. In this paper, the friction properties of metal-metal interface, metal-graphene interface and graphite-modified metal interface are systematically studied by using first-principles density functional theory (DFT). It is found that the metal to metal interface obeys Amonton's law at the microscale, and the very low friction coefficient between the metal and graphene interface is caused by the weak physical adsorption between the metal and the graphene interface. The metal interface modified by graphite produces superlubrication, which is easier to realize than the single graphene interface.
【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TH117.1
【參考文獻(xiàn)】
相關(guān)期刊論文 前1條
1 鄭泉水;歐陽穩(wěn)根;馬明;張首沫;趙治華;董華來;林立;;超潤滑:“零”摩擦的世界[J];科技導(dǎo)報(bào);2016年09期
，本文編號(hào)：2211710
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