本文選題：鎂合金 + 摩擦磨損�。� 參考：《吉林大學(xué)》2017年碩士論文

【摘要】：鎂合金在室溫下具有優(yōu)良的綜合性能,隨著我國(guó)航空航天和汽車工業(yè)的迅速發(fā)展壯大,對(duì)鎂合金的綜合性能和應(yīng)用范圍提出了更高的要求。傳統(tǒng)的商用鎂合金(AZ系等)已經(jīng)在汽車工業(yè)中用于制造壓鑄件和車身成形組件,然而較差的耐磨性和抗高溫性能成為該類鎂合金在摩擦學(xué)領(lǐng)域應(yīng)用的一個(gè)重要障礙,不能如鋁合金那樣用于制造較高工況要求的活塞、滑動(dòng)軸承、缸套等磨損部件。因此,發(fā)展具有優(yōu)良耐磨性能的耐熱鎂合金及其復(fù)合材料是解決限制鎂合金在摩擦學(xué)領(lǐng)域應(yīng)用的一條重要途徑。本論文在室溫干滑動(dòng)磨損狀態(tài)下采用銷-盤式磨損裝置對(duì)Mg97Zn1Y2耐熱鎂合金進(jìn)行研究,在滑動(dòng)速度0.2-4.0m/s、加載載荷20-380N的范圍內(nèi)對(duì)合金的磨損形貌、表面氧含量和磨損率進(jìn)行分析測(cè)量,繪制了不同滑動(dòng)速度下的轉(zhuǎn)變載荷圖和磨損轉(zhuǎn)變圖,深入研究了表層及亞表層組織的演變過程。結(jié)合硬度的變化情況,詳細(xì)分析了輕微-嚴(yán)重磨損轉(zhuǎn)變過程中的組織演變,揭示了磨損過程中引起轉(zhuǎn)變的本質(zhì)原因,得出了如下結(jié)論:Mg97Zn1Y2合金在摩擦磨損的過程中存在輕微磨損和嚴(yán)重磨損兩種行為,輕微磨損區(qū)包括氧化磨損+磨粒磨損機(jī)制、嚴(yán)重氧化的剝層磨損機(jī)制和剝層磨損機(jī)制,嚴(yán)重磨損區(qū)包括嚴(yán)重塑性變形機(jī)制、伴有氧化層剝落的嚴(yán)重塑性變形機(jī)制和表面熔化磨損機(jī)制。輕微磨損時(shí)氧化層和機(jī)械混合層的出現(xiàn)抑制了磨損率的快速上升,進(jìn)入嚴(yán)重磨損階段之后,摩擦熱的累積使得近表層的溫度超過動(dòng)態(tài)再結(jié)晶的溫度,導(dǎo)致磨損表面發(fā)生嚴(yán)重塑性變形或者熔化,表層硬度迅速降低,磨損率快速上升,表面動(dòng)態(tài)再結(jié)晶的出現(xiàn)是造成輕微-嚴(yán)重磨損轉(zhuǎn)變的根本原因。近表層組織隨著輕微磨損向嚴(yán)重磨損過渡的過程中也逐漸發(fā)生變化,在加載載荷20N時(shí)即發(fā)生了塑性變形,在輕微磨損階段載荷的逐漸增加使得變形區(qū)域深度進(jìn)一步增大,過渡到嚴(yán)重磨損階段時(shí),摩擦熱引起的高溫對(duì)近表層材料的影響更為嚴(yán)重,從塑性變形轉(zhuǎn)變到動(dòng)態(tài)再結(jié)晶軟化,進(jìn)一步增大載荷和滑動(dòng)速度使材料表面發(fā)生熔化,近表層區(qū)域的組織演變順序?yàn)?塑性變形-動(dòng)態(tài)再結(jié)晶-表面熔化再凝固。輕微-嚴(yán)重磨損轉(zhuǎn)變之前,磨損試樣近表層發(fā)生塑性變形,加工硬化產(chǎn)生的效果使得磨損表面硬度在較低的載荷范圍內(nèi)即上升到較高的區(qū)間并隨著載荷的增加而逐漸增大,亞表層區(qū)域的硬度值也整體隨著加載載荷的增加而增大,同時(shí)硬度的增加也阻止了磨損率的快速上升。輕微-嚴(yán)重磨損轉(zhuǎn)變之后,摩擦熱的累積超過了材料的動(dòng)態(tài)再結(jié)晶溫度(TDRX),磨損表面發(fā)生軟化,抵消了塑性變形帶來的加工硬化效果,因此硬度下降,磨損率上升,發(fā)生了嚴(yán)重磨損,亞表層材料的整體硬度值也逐漸下降。
[Abstract]:Magnesium alloys have excellent comprehensive properties at room temperature. With the rapid development of aerospace and automobile industry in China, the comprehensive properties and application scope of magnesium alloys are required to be higher. Traditional commercial magnesium alloys, such as AZ series, have been used in the automobile industry to manufacture die castings and body forming components. However, poor wear resistance and high temperature resistance have become an important obstacle in the application of this kind of magnesium alloys in the field of tribology. It can not be used to manufacture wear parts such as piston, sliding bearing, cylinder liner and so on. Therefore, the development of heat-resistant magnesium alloys with excellent wear resistance and their composites is an important way to limit the application of magnesium alloys in the field of tribology. In this paper, Mg97Zn1Y2 heat-resistant magnesium alloy was studied by pin-disc wear device under dry sliding wear condition at room temperature. The wear morphology, surface oxygen content and wear rate of the alloy were measured in the range of sliding speed of 0.2-4.0 m / s and loading load of 20-380 N. The transition load diagram and wear transition diagram at different sliding velocities were plotted, and the evolution process of surface and subsurface microstructure was studied. Combined with the change of hardness, the microstructure evolution in the process of mild to severe wear transition is analyzed in detail, and the essential cause of transformation in wear process is revealed. It is concluded that there are two behaviors of slight wear and serious wear in the friction and wear process of Mg97Zn1Y2 alloy. The slight wear zone includes the wear mechanism of oxidized abrasive wear, the mechanism of serious oxidation delamination and the mechanism of delamination wear. Serious wear zone includes serious plastic deformation mechanism, serious plastic deformation mechanism with oxide layer flaking and surface melting wear mechanism. The appearance of oxidized layer and mechanical mixed layer inhibited the rapid increase of wear rate. After entering the serious wear stage, the accumulation of friction heat caused the temperature of near surface layer to exceed the temperature of dynamic recrystallization. As a result of serious plastic deformation or melting of the worn surface, the hardness of the surface decreases rapidly, the wear rate increases rapidly, and the appearance of dynamic recrystallization of the surface is the root cause of the slight to severe wear transition. In the process of transition from slight wear to severe wear, the near surface microstructure changes gradually, and plastic deformation occurs at loading load of 20N, and the depth of deformation area increases further with the increasing of load at slight wear stage. During the transition to the serious wear stage, the high temperature caused by friction heat has a more serious effect on the near surface material, which changes from plastic deformation to dynamic recrystallization softening, and further increases the load and sliding speed to make the material surface melt. The order of microstructure evolution near the surface is: plastic deformation, dynamic recrystallization, surface melting and solidification. Before the mild to severe wear transition, plastic deformation occurs near the surface of the wear specimen, and the effect of work hardening causes the hardness of the worn surface to rise to a higher range in the lower load range and increase gradually with the increase of the load. The hardness of the subsurface area also increases with the increase of loading load, and the increase of hardness also prevents the wear rate from rising rapidly. After the mild to severe wear transition, the accumulated heat of friction exceeds the dynamic recrystallization temperature of the material TDRX, and the worn surface softens, which counteracts the work hardening effect caused by plastic deformation, so the hardness decreases and the wear rate increases. Serious wear occurs and the hardness of the subsurface material decreases gradually.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG146.22

【相似文獻(xiàn)】

相關(guān)碩士學(xué)位論文 前1條

1 軒習(xí)華;Mg97Zn1Y2鎂合金摩擦磨損行為研究[D];吉林大學(xué);2017年

，

本文編號(hào)：1929914