【摘要】：聚合物基復(fù)合材料在與金屬表面發(fā)生相對滑動的過程中,會在對偶件金屬表面形成一層轉(zhuǎn)移膜,轉(zhuǎn)移膜的質(zhì)量對于提高復(fù)合材料的摩擦學(xué)性能具有十分重要的意義。研究發(fā)現(xiàn)轉(zhuǎn)移膜的形成是一個伴隨著局部碎片脫落和再修復(fù)的動態(tài)過程,了解其動態(tài)變化過程對于研究轉(zhuǎn)移膜的形成機理及其對摩擦學(xué)性能的影響至關(guān)重要,但由于一般的實驗條件的限制,很難觀察到轉(zhuǎn)移膜的動態(tài)形成過程,這也在一定程度上制約了對聚合物材料摩擦學(xué)性能的研究。鑒于此,本文利用基于離散元法開發(fā)的二維顆粒流軟件(PFC2D)建立了PTFE復(fù)合材料/45#鋼摩擦副系統(tǒng)的摩擦磨損離散元計算模型,再現(xiàn)了PTFE與45#鋼的動態(tài)摩擦過程。在此基礎(chǔ)上,重點探究了復(fù)合材料中混合填料Cu、石墨的添加對PTFE復(fù)合材料磨損性能、轉(zhuǎn)移性能、轉(zhuǎn)移膜粘結(jié)強度、摩擦系數(shù)以及相關(guān)的力學(xué)性能(壓縮性能、剪切性能)的影響。并運用統(tǒng)計學(xué)中的相關(guān)性分析研究了PTFE復(fù)合材料的磨損性能、摩擦系數(shù)分別與轉(zhuǎn)移膜粘結(jié)強度、材料的壓縮強度、剪切強度之間的相關(guān)性�；谝陨涎芯�,本文主要得出如下創(chuàng)新性結(jié)論:(1)在PTFE與45#鋼滑動摩擦過程中,45#鋼粗糙表面會對PTFE產(chǎn)生剪切擠壓作用,使位于接觸表面的PTFE被拖拽下來形成PTFE碎片,部分脫落的碎片粘附于對偶件表面從而形成轉(zhuǎn)移膜。隨著摩擦的進行,轉(zhuǎn)移膜逐漸趨于穩(wěn)定,穩(wěn)定的轉(zhuǎn)移膜能夠有效地減小摩擦、降低磨損。且轉(zhuǎn)移膜的形成并不是一成不變的靜態(tài)過程,而是一個伴隨著轉(zhuǎn)移顆粒不斷脫落與再修復(fù)的動態(tài)過程。(2)復(fù)合材料中的混合填料Cu、石墨對其摩擦學(xué)性能具有顯著的影響,轉(zhuǎn)移顆粒數(shù)隨著混合填料中Cu質(zhì)量分數(shù)的增加而增加,輔助填料石墨的加入能夠在一定程度上增加轉(zhuǎn)移顆粒數(shù),混合填料對形成的轉(zhuǎn)移膜粘結(jié)強度具有類似的影響;混合填料的加入能夠有效地改善PTFE的磨損性能,磨損量隨Cu含量的增加而減小,而石墨對其的增強效果對載荷具有一定的敏感性;復(fù)合材料的宏觀摩擦系數(shù)隨著混合填料中Cu含量的增加而增大,石墨的加入能夠有效降低摩擦系數(shù)。(3)復(fù)合材料中的混合填料Cu、石墨對復(fù)合材料的壓縮性能、剪切性能影響明顯。兩種性能均隨著填料中Cu質(zhì)量分數(shù)的增加而增強。輔助填料石墨的加入能在一定程度上提高復(fù)合材料的壓縮性能,且這種增強效果隨著混合填料中Cu含量的增加而遞減。而石墨對復(fù)合材料剪切性能的影響較為復(fù)雜,其影響效果隨著混合填料中Cu含量的增加先增強后減弱。(4)通過對復(fù)合材料的摩擦學(xué)性能與力學(xué)性能的相關(guān)性分析發(fā)現(xiàn),材料的磨損性能與其轉(zhuǎn)移膜粘結(jié)強度、材料的壓縮強度之間的相關(guān)關(guān)系較強,而摩擦系數(shù)僅與材料的剪切強度之間存在較為顯著的相關(guān)關(guān)系。
[Abstract]:In the process of relative sliding between polymer matrix composite and metal surface, a transfer film will be formed on the metal surface of the dual part. The quality of the transfer film is very important for improving the tribological properties of the composite. It is found that the formation of the transfer film is a dynamic process accompanied by local shedding and rerepair. It is very important to understand the dynamic process of the film formation mechanism and its influence on the tribological properties. However, due to the limitation of general experimental conditions, it is difficult to observe the dynamic forming process of the transfer film, which to some extent restricts the study of the tribological properties of polymer materials. In this paper, the discrete element model of friction and wear of PTFE composite / 4steel friction pair system is established by using two-dimensional particle flow software (PFC2D) based on discrete element method, and the dynamic friction process between PTFE and 4steel is reproduced. On this basis, the wear properties, bond strength, friction coefficient and related mechanical properties of PTFE composites with the addition of Cu, graphite were investigated. Shear properties). The correlation between the friction coefficient and the adhesive strength of the transfer film, the compressive strength and the shear strength of the PTFE composite was studied by statistical correlation analysis. Based on the above research, the main conclusions are as follows: (1) in the process of sliding friction between PTFE and 4steel, the rough surface of 4steel will shearing and extruding PTFE, and the PTFE located on the contact surface will be dragged down to form PTFE fragments. Partially shedding debris adheres to the surface of the dual part to form a transfer film. With the development of friction, the transfer film tends to be stable, and the stable transfer film can effectively reduce friction and wear. Moreover, the formation of the transfer film is not a static process, but a dynamic process accompanied by the continuous shedding and rerepair of the transfer particles. (2) the Cu, graphite, a mixed filler in the composite, has a significant effect on the tribological properties of the composite. The number of transfer particles increases with the increase of Cu mass fraction in the mixed filler, and the number of transferred particles can be increased to a certain extent by the addition of the auxiliary filler graphite, and the bonding strength of the transfer film formed by the mixed filler has a similar effect. The addition of mixed filler can improve the wear performance of PTFE effectively, and the wear rate decreases with the increase of Cu content, while graphite has a certain sensitivity to the load. The macroscopic friction coefficient of the composite increases with the increase of Cu content in the mixed filler, and the addition of graphite can effectively reduce the friction coefficient. (3) Compression properties of Cu, graphite, the mixed filler in the composite, increase with the increase of the content of Cu, in the composite. The shear properties are obviously affected. Both properties were enhanced with the increase of mass fraction of Cu in filler. The compressive properties of the composites can be improved to a certain extent by the addition of auxiliary filler graphite, and the reinforcement effect decreases with the increase of Cu content in the mixed filler. However, the influence of graphite on the shear properties of composites is more complex, and the effect of graphite on the shear properties of composites increases firstly and then weakens with the increase of Cu content. (4) the correlation analysis of tribological properties and mechanical properties of composites is made. There is a strong correlation between the wear performance of the material and the bond strength of the transfer film and the compressive strength of the material, while the friction coefficient only has a significant correlation with the shear strength of the material.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB33

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