本文關(guān)鍵詞： 高速高溫工況 接觸式密封 PTFE復(fù)合材料 摩擦磨損 密封性能　出處：《哈爾濱工業(yè)大學(xué)》2014年博士論文　論文類型：學(xué)位論文

【摘要】：航空發(fā)動機(jī)中的密封、軸承等典型摩擦學(xué)部件的滑動摩擦副需要工作在高速、高溫、低溫和高低溫交變等趨近當(dāng)前材料使用極限的苛刻工作條件下，密封等摩擦副常因表面接觸應(yīng)力過高、摩擦生熱加劇及潤滑失效而發(fā)生磨損加劇現(xiàn)象，從而導(dǎo)致密封失效。為了滿足航空發(fā)動機(jī)向著大推重比、高可靠性和長壽命的趨勢發(fā)展的需要，密封等零部件的材料特性及其結(jié)構(gòu)需要不斷的改進(jìn)。因此，開展高速高溫復(fù)合材料摩擦學(xué)特性的研究，揭示苛刻工況下復(fù)合材料的增強(qiáng)規(guī)律和失效機(jī)理，以指導(dǎo)新材料的設(shè)計和評價，發(fā)展航空摩擦學(xué)設(shè)計規(guī)范體系，對推動航空發(fā)動機(jī)密封技術(shù)的發(fā)展有重要理論和實際應(yīng)用價值。 本文以小型高速發(fā)動機(jī)泵用接觸式動密封的高速高溫工況為背景，結(jié)合發(fā)動機(jī)封嚴(yán)密封介質(zhì)，完成密封材料配方設(shè)計，對密封材料在苛刻環(huán)境下的磨損行為進(jìn)行試驗研究，研究填料、溫度、速度對密封材料的影響規(guī)律，優(yōu)化耐高溫高速密封材料配方；建立密封材料磨損模型，研究密封在不同潤滑狀態(tài)下唇口結(jié)構(gòu)、接觸特性的變化關(guān)系；建立密封泄漏模型，分析結(jié)構(gòu)參數(shù)、材料特性對泄漏的影響，研究密封失效原因。 利用M-200摩擦磨損試驗機(jī)測試了復(fù)合材料在常溫低速干摩擦條件下的摩擦學(xué)性能，利用沖擊強(qiáng)度測量儀、邵氏D硬度計、拉伸試驗機(jī)測試了復(fù)合材料力學(xué)性能，通過對基本摩擦學(xué)和力學(xué)性能分析，初步確定了含有碳纖維、球形石墨和鱗片石墨的動密封材料配方及其成型工藝；研制了高速高溫滑動磨損試驗裝置，，利用該試驗裝置，研究了線速度、溫度及增強(qiáng)體含量對復(fù)合材料磨損率的影響規(guī)律，發(fā)現(xiàn)速度、溫度和鱗片石墨對磨損率有顯著影響。 利用掃描電子顯微鏡分析了常溫低速、高速、高溫高速復(fù)合材料磨損表面形貌及斷口形貌，在此基礎(chǔ)上研究了增強(qiáng)體的增強(qiáng)機(jī)理，發(fā)現(xiàn)碳纖維提高了復(fù)合材料的強(qiáng)度和韌性，同時在高溫的條件下，能夠起到骨架、阻止基體軟化后流動的作用；球形石墨降低了復(fù)合材料的摩擦系數(shù)；鱗片石墨提高了復(fù)合材料的導(dǎo)熱性能，增強(qiáng)了復(fù)合材料的熱穩(wěn)定性，同時降低了材料基體之間的結(jié)合強(qiáng)度。 通過對Archard粘著磨損公式和基于分形理論的W-M磨損公式的分析，建立了密封材料磨損數(shù)學(xué)模型，模擬了開關(guān)機(jī)、加壓、穩(wěn)定運行階段在不同潤滑狀態(tài)下磨損過程，分析了唇口結(jié)構(gòu)及其接觸特性隨磨損時間的變化規(guī)律。結(jié)果表明由結(jié)構(gòu)帶來的接觸應(yīng)力不均勻現(xiàn)象消失，高速密封穩(wěn)定運行階段處于流體潤滑狀態(tài)。 通過對“表面效應(yīng)及泵吸作用”唇形密封機(jī)理的研究，建立了密封泄漏及回油的數(shù)學(xué)模型，分析穩(wěn)定運行階段密封泄漏量及回油量隨磨損時間的變化規(guī)律。同時進(jìn)行了發(fā)動機(jī)工況適應(yīng)性試驗研究，在給定的運行時間內(nèi)，密封未出現(xiàn)明顯泄漏。
[Abstract]:The sliding friction pairs of typical tribological components such as seals and bearings in an aeroengine need to work under harsh working conditions such as high speed, high temperature, low temperature and high and low temperature alternating to the current limit of material use. Due to the high surface contact stress, the friction heat generation and the lubrication failure, the sealing and equal friction pairs often cause wear and tear, which leads to the seal failure. In order to satisfy the large ratio of thrust and weight of the aero-engine, Due to the trend of high reliability and long life, the material characteristics and structure of sealing and other parts need to be improved continuously. Therefore, the tribological properties of high speed and high temperature composite materials are studied. It is of great theoretical and practical value to reveal the reinforcement law and failure mechanism of composite materials under harsh working conditions, to guide the design and evaluation of new materials and to develop the aviation tribology design code system, which is of great theoretical and practical value in promoting the development of aero-engine sealing technology. In this paper, based on the high temperature working condition of contact dynamic seal for small high-speed engine pump, combined with the sealing medium of engine seal, the formula of sealing material is designed, and the wear behavior of sealing material under harsh environment is studied experimentally. The effects of packing, temperature and speed on sealing materials were studied, and the formula of high temperature and high speed sealing materials was optimized, and the wear model of sealing materials was established to study the change of lip structure and contact characteristics under different lubricating conditions. The leakage model of seal is established, the influence of structural parameters and material characteristics on leakage is analyzed, and the reason of seal failure is studied. The tribological properties of composites under normal temperature and low speed dry friction were tested by M-200 friction and wear tester. The mechanical properties of composites were tested by impact strength tester, Shao's D hardness tester and tensile tester. Based on the analysis of basic tribological and mechanical properties, the formula and forming process of dynamic sealing materials containing carbon fiber, spherical graphite and flake graphite were preliminarily determined, and a high speed and high temperature sliding wear test device was developed. The effects of linear velocity, temperature and reinforcement content on the wear rate of composites were studied. It was found that velocity, temperature and flake graphite had significant effects on the wear rate of composites. The wear surface morphology and fracture surface morphology of composites at room temperature and low speed, high speed and high temperature were analyzed by scanning electron microscope (SEM). On the basis of this, the reinforcement mechanism of composites was studied. It was found that carbon fiber enhanced the strength and toughness of composites. At the same time, at high temperature, it can play the role of skeleton to prevent the flow of matrix after softening; spherical graphite reduces the friction coefficient of composites; flake graphite improves the thermal conductivity of composites and enhances the thermal stability of composites. At the same time, the bonding strength between the matrix is reduced. Based on the analysis of Archard adhesive wear formula and W-M wear formula based on fractal theory, a mathematical model of sealing material wear is established, and the wear process of switch machine, pressurized machine and stable running stage under different lubrication states is simulated. The changes of lip structure and its contact characteristics with wear time are analyzed. The results show that the non-uniform contact stress caused by the structure disappears and the high speed seal is in the state of fluid lubrication at the stable operation stage. Based on the study of the mechanism of "surface effect and pump suction" lip seal, a mathematical model of seal leakage and oil recovery is established. The variation law of seal leakage and oil return with wear time in stable operation phase is analyzed. At the same time, the experimental study on engine operating condition adaptability is carried out, and no obvious leakage appears in the seal under given operating time.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TB42

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