本文選題：Bi相 + 石墨　； 參考：《合肥工業(yè)大學》2012年碩士論文

【摘要】：鉛是一種有毒有害元素，隨著環(huán)�；陌l(fā)展趨勢，產品無鉛化勢在必行。本文主要以無毒低熔點金元素鉍作為軟質相、石墨作為輔助固體潤滑劑，利用石墨的減摩特性與鉍的抗粘著特性的協(xié)同作用取代銅鉛軸承材料中的鉛，實現(xiàn)銅基軸承材料無鉛化。采用常規(guī)的粉末冶金方法制備了無鉛銅鉍、銅鉍石墨滑動軸承材料，并開展了相關力學性能及不同工況條件下的摩擦學特性研究，利用掃描電子顯微鏡、光學顯微鏡、表面形貌輪廓儀等微觀分析手段對材料的顯微組織結構、斷口與磨痕表面形貌、表面輪廓以及磨痕表面的化學組分進行了系統(tǒng)的分析，探討了無鉛銅鉍軸承材料的摩擦磨損機理。 研究表明，鉍含量對無鉛銅鉍軸承材料力學性能有較大的影響。由于鉍為脆性相，且呈薄片網帶狀分布于銅合金基體晶界處，割裂了銅合金基體的連續(xù)性，使得含Bi銅基軸承材料硬度、壓潰強度和沖擊韌性隨Bi含量的增加而明顯減小，含Bi銅基軸承材料斷口以脆性沿晶斷裂為主。當Bi含量大于4wt%后，銅合金基體晶界處富Bi相的薄片網帶狀分布已較完整，Bi含量的進一步增大，其對銅合金基體的割裂作用不再明顯增加，所以材料力學性能的降低趨勢減緩。 由于摩擦熱的作用，摩擦磨損過程中銅鉍軸承材料中的低熔點組元鉍會在摩擦副表面直接接觸區(qū)域熔融、析出，降低接觸區(qū)域的剪切強度，穩(wěn)定摩擦副的運行，含鉍銅基軸承材料體現(xiàn)出較好的減摩、抗粘著特性。但是鉍的含量對銅基軸承材料的摩擦學性能影響較大，適宜鉍含量的銅鉍軸承材料有利于提高其減摩、耐磨、抗粘著性能；添加適宜含量石墨可以進一步改善無鉛銅鉍軸承材料的減摩、抗粘著性能，提高耐磨性，，由于鍍銅石墨和鍍鎳石墨與銅合金基體結合較好，添加鍍銅石墨或者鍍鎳石墨的銅鉍軸承材料的減摩、抗粘著特性更優(yōu)，鉍與石墨在減摩、抗粘著方面有較好的協(xié)同作用。
[Abstract]:Lead is a toxic and harmful element. With the development of environmental protection, lead-free products are imperative. In this paper, the non-toxic low melting point gold element bismuth is used as soft phase and graphite as auxiliary solid lubricant. The synergistic effect of anti-friction property of graphite and anti-adhesion property of bismuth is used to replace lead in copper-lead bearing material. Copper-based bearing materials are lead-free. The lead-free copper-bismuth and copper-bismuth graphite plain bearing materials were prepared by conventional powder metallurgy method. The related mechanical properties and tribological properties under different working conditions were studied. The scanning electron microscope and optical microscope were used to study the mechanical properties of lead-free copper-bismuth and copper-bismuth graphite plain bearings. The microstructure of the material, the surface morphology of fracture and wear mark, the profile of the surface and the chemical composition of the worn surface were systematically analyzed by means of surface topography profilometer and other microanalysis methods. The friction and wear mechanism of lead-free copper-bismuth bearing materials is discussed. The results show that the content of bismuth has great influence on the mechanical properties of lead-free copper-bismuth bearing materials. Because bismuth is a brittle phase and distributes along the grain boundary of the copper alloy matrix as a thin mesh, the continuity of the copper alloy matrix is severed, which makes the hardness, crushing strength and impact toughness of the bearing material containing Bi obviously decrease with the increase of Bi content. The fracture surface of bearing material containing Bi copper is mainly brittle intergranular fracture. When the Bi content is more than 4wt%, the distribution of Bi-rich thin strip at the grain boundary of the copper alloy matrix increases further, and the cleavage effect on the copper alloy matrix is no longer significantly increased, so the decreasing trend of the mechanical properties of the material is slowed down. Due to the effect of friction heat, the low melting point component bismuth in the copper-bismuth bearing material will melt and precipitate directly in the contact area of the friction pair during friction and wear, thus reducing the shear strength of the contact area and stabilizing the operation of the friction pair. Bismuth-containing copper-based bearing materials show good anti-friction and anti-adhesion properties. However, the content of bismuth has a great influence on the tribological properties of copper-based bearing materials. The Cu-Bi bearing materials with suitable bismuth content can improve their friction reduction, wear resistance and adhesion resistance. The addition of graphite with proper content can further improve the friction reduction, adhesion resistance and wear resistance of lead-free copper-bismuth bearing materials. The anti-adhesion property of copper-bismuth bearing materials with copper-bismuth coating or nickel-coated graphite is better than that of copper-bismuth bearing materials. Bismuth and graphite have good synergistic effect on antifriction and adhesion resistance.
【學位授予單位】：合肥工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：TH117;TH133.31

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