本文關(guān)鍵詞：金剛石增強鋁基復(fù)合材料界面形成機理及導(dǎo)熱性能　出處：《北京科技大學(xué)》2017年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 鋁基復(fù)合材料 金剛石 熱物理性能 界面結(jié)構(gòu)

【摘要】：隨著電子信息技術(shù)的不斷發(fā)展,電子器件的單位面積發(fā)熱量不斷提高,電子器件的安全、高效運行受到嚴(yán)重影響。因此,急需開發(fā)新一代的電子封裝散熱材料來保證電子元器件的有效散熱。金剛石具有優(yōu)異的熱物理性能,其熱導(dǎo)率為600-2000 W/mK,是自然界中熱導(dǎo)率最高的材料。金剛石顆粒增強金屬基(metal/diamond)復(fù)合材料具備優(yōu)異的熱物理性能,成為新一代電子封裝散熱材料的代表。采用高壓氣體輔助熔滲法制備的Al/diamond復(fù)合材料有效結(jié)合金剛石優(yōu)異的熱物理性能和A1基體較低的密度以及優(yōu)良的加工成形性,是新一代電子封裝散熱材料的研究熱點。金剛石和A1之間的界面結(jié)合狀態(tài)直接決定了 Al/diamond復(fù)合材料的整體性能,對復(fù)合材料界面結(jié)構(gòu)的調(diào)控可實現(xiàn)對復(fù)合材料熱物理性能的優(yōu)化,是提升復(fù)合材料性能的有效方式。然而,目前針對復(fù)合材料界面結(jié)構(gòu)的表征并不完善,對于A1基體和金剛石之間的界面反應(yīng)機理缺乏深入研究,無法從理論上指導(dǎo)復(fù)合材料界面結(jié)構(gòu)和導(dǎo)熱性能的優(yōu)化。本文通過高壓氣體輔助熔滲法制備Al/diamond復(fù)合材料,通過聚焦離子束刻蝕系統(tǒng)(FIB)和透射電子顯微鏡(TEM)等先進表征手段來研究不同制備工藝下復(fù)合材料的界面結(jié)構(gòu),深入理解界面形成機制,建立復(fù)合材料制備工藝、界面結(jié)構(gòu)和導(dǎo)熱性能之間的有效聯(lián)系,進而實現(xiàn)Al/diamond復(fù)合材料熱物理性能的提升。本文采用高壓氣體輔助熔滲法制備Al/diamond復(fù)合材料,通過改變復(fù)合材料制備工藝,控制A1基體和金剛石顆粒之間界面反應(yīng)程度,系統(tǒng)研究了界面反應(yīng)產(chǎn)物的形核和長大機制。結(jié)果表明,界面反應(yīng)產(chǎn)物A14C3的形成是非均勻形核過程,其形核和長大受到金剛石表面狀態(tài)影響。碳化物在金剛石表面臺階處形核并長大,金剛石(100)面上的碳化物與金剛石表面呈55°夾角,顆粒密度較高,尺寸較小;金剛石(111)面的碳化物顆粒平行金剛石表面,碳化物密度較小,尺寸較大。對比不同反應(yīng)階段碳化物顆粒的形貌以及復(fù)合材料熱導(dǎo)率發(fā)現(xiàn),當(dāng)界面A14C3呈現(xiàn)細小彌散分布時,復(fù)合材料具有最高熱導(dǎo)率。這是由于細小彌散分布的碳化物顆粒顯著改善復(fù)合材料的界面結(jié)合,同時由于A14C3具有較低的熱導(dǎo)率,細小的碳化物顆粒不顯著增加界面熱阻。在此基礎(chǔ)上對金剛石顆粒進行預(yù)處理來促進金剛石表面碳結(jié)構(gòu)轉(zhuǎn)變,進而調(diào)整界面A14C3的形成過程。研究發(fā)現(xiàn),通過預(yù)加熱處理可在金剛石表面產(chǎn)生sp2碳結(jié)構(gòu),進而促進細小彌散的界面碳化物的形成,起到優(yōu)化復(fù)合材料界面結(jié)構(gòu)和熱導(dǎo)率的作用。所制備的Al/diamond復(fù)合材料熱導(dǎo)率從540 W/mK提高至 710W/mK。Al/diamond復(fù)合材料界面產(chǎn)物A14C3的水解性限制了復(fù)合材料的應(yīng)用范圍。通過在金剛石表面鍍覆合金元素引入新的界面反應(yīng)層,是優(yōu)化Al/diamond復(fù)合材料界面結(jié)構(gòu)的重要手段。然而,界面反應(yīng)層的引入必然會影響復(fù)合材料熱導(dǎo)率,因此需要在抑制A1基體和金剛石發(fā)生界面反應(yīng)形成A14C3的前提下,對復(fù)合材料界面反應(yīng)層的微觀結(jié)構(gòu)進行調(diào)控和優(yōu)化。本文系統(tǒng)研究了金剛石表面Ti和W鍍層在制備Al/diamond復(fù)合材料過程中的演化行為,從而獲得最佳的鍍層厚度和復(fù)合材料制備參數(shù)。研究表明,Ti鍍層與金剛石發(fā)生化學(xué)反應(yīng)生成TiC界面層,并在熔滲階段保持穩(wěn)定。隨著Ti鍍層厚度的增加,復(fù)合材料熱導(dǎo)率呈現(xiàn)先增高后降低的趨勢,當(dāng)鍍層厚度為200 nm時,復(fù)合材料熱導(dǎo)率最高值為650 W/mK。對于上述現(xiàn)象的解釋是,為降低復(fù)合材料界面熱阻,應(yīng)盡量減小TiC層的厚度,然而較薄的鍍層無法有效改善復(fù)合材料界面結(jié)合,導(dǎo)致熱導(dǎo)率下降。在低溫加熱過程中,TiC界面層與A1基體發(fā)生反應(yīng)生成少量的A14C3相。W鍍層在復(fù)合材料制備過程中與A1基體發(fā)生反應(yīng),在界面位置生成Al5W反應(yīng)層。研究表明,這一界面反應(yīng)較慢,可通過調(diào)控復(fù)合材料的制備工藝參數(shù)來控制界面反應(yīng)層厚度,從而優(yōu)化復(fù)合材料界面結(jié)構(gòu)和熱物理性能。當(dāng)復(fù)合材料熔滲時間從10 min延長至60 min時,復(fù)合材料的熱導(dǎo)率從520 W/mK上升至630 W/mK。雖然鍍W金剛石顆粒增強鋁基復(fù)合材料的熱導(dǎo)率相對較低,但所形成的A15W界面反應(yīng)層可以有效抑制復(fù)合材料中A14C3界面相的生成,擴大了復(fù)合材料的應(yīng)用范圍。綜上所述,本文系統(tǒng)研究了金剛石顆粒增強鋁基復(fù)合材料的界面形成機理,建立了復(fù)合材料制備工藝參數(shù)、界面結(jié)構(gòu)和導(dǎo)熱性能之間的有效聯(lián)系。通過研究金剛石顆粒增強鋁基復(fù)合材料的界面結(jié)構(gòu)以及相應(yīng)的界面結(jié)構(gòu)優(yōu)化手段,為復(fù)合材料的優(yōu)化設(shè)計和可控制備提供了理論參考。研究結(jié)果進一步提升了金剛石顆粒增強金屬基復(fù)合材料的熱物理性能,可以更好地應(yīng)用于電子器件散熱。
[Abstract]:With the continuous development of electronic information technology, electronic device unit area heat rising, the safety of electronic devices, seriously affect the efficient operation. Therefore, electronic packaging materials are in urgent need of the development of a new generation of heat dissipation to ensure effective cooling of electronic components. Diamond has good thermal physical properties, the thermal conductivity of 600-2000 W/mK. Is the highest thermal conductivity in nature. The diamond particles reinforced metal matrix composites (metal/diamond) possess good thermal physical properties, become the representative of a new generation of electronic packaging materials. The heat assisted infiltration of Al/diamond composite materials prepared by the combination of diamond excellent thermal physical properties and A1 matrix of low density and excellent the formability of the high-pressure gas, is the research focus of a new generation of electronic packaging material for cooling. Between diamond and A1 interface directly Determines the overall performance of the Al/diamond composite material, can realize the optimization of the thermal physical properties of composite materials on the regulation of the interface structure of composite materials is an effective way to improve the properties of the composite materials. However, the characterization of the interface structure of composite materials is not perfect, for further study the mechanism of interface reaction between A1 matrix and diamond lack of optimization to guide the structure and thermal performance of composite material interface in theory. This paper through the high-pressure gas assisted infiltration of Al/diamond composite was prepared, by focused ion beam etching system (FIB) and transmission electron microscopy (TEM) and other advanced characterization methods to study the different preparation of the interface structure of composite process, in-depth understanding of the interface formation the establishment of mechanism, composite material preparation process, the effective connection between structure and thermal conductivity of the interface, and then realize the Al/diamond composite heat Physical performance. This paper uses the high pressure gas Al/diamond composites were fabricated by molten infiltration, by changing the composite material preparation process, control interface between A1 matrix and diamond particles reaction, studied interfacial reaction mechanism of nucleation and growth. The results show that the formation of interfacial reaction of A14C3 is heterogeneous nucleation the process of nucleation and growth of diamond surface is affected by the state. On the steps at the surface of Carbide Diamond Nucleation and growth of diamond (100) surface of the carbide and diamond surface at a 55 degree angle, particle density is high, small size; diamond (111) surface of carbide particles parallel to the surface of the diamond, carbide density smaller size comparison of different reaction stages. Larger morphology of carbide particles and the thermal conductivity of the composites was found, when the interface A14C3 exhibits fine dispersed, composite material has the most High thermal conductivity. This is because the fine carbide particles dispersed significantly improve the composite interface, at the same time, because A14C3 has low thermal conductivity, fine carbide particles do not significantly increase the interfacial thermal resistance. Based on the pretreatment of diamond particles to promote the carbon structure of diamond surface change, and then adjust the interface forming process A14C3. The study found that SP2 can produce carbon structure on the diamond surface by pre heating treatment, and promote the formation of interface carbide dispersed, play a role in optimization of composite interface structure and thermal conductivity. The prepared Al/diamond composite thermal conductivity limits the scope of application of composite materials from the hydrolysis product of interface 540 W/mK increased to 710W/mK.Al/diamond A14C3 composites. The interfacial reaction layer by introducing new alloy plating on diamond surface elements, is optimized for Al/d An important means of interface structure of iamond composites. However, the introduction of the interface reaction layer will affect the thermal conductivity of composite materials, so in the inhibition of A1 matrix and diamond react to form A14C3 under the premise of control and optimize the microstructure of the interfacial reaction layer. This paper studies the diamond surface Ti and W the coating in the preparation process of Al/diamond evolution behavior of composite material, so as to obtain the optimum coating thickness and composite material preparation parameters. The results show that Ti coating and diamond chemical reaction between TiC interface layer, and the infiltration stage remained stable in the melt. With the increase of Ti coating thickness, thermal conductivity of the composites is increased after the first decreased, when the coating thickness is 200 nm, the thermal conductivity of the composites is the highest value 650 W/mK. explanation for this phenomenon is, in order to reduce the interfacial thermal resistance of composite materials , should try to reduce the thickness of the TiC layer, however thin coating can not effectively improve the composite interface, resulting in decrease of thermal conductivity at low temperature. The heating process, the TiC interface layer and A1 substrate reacted to generate a small amount of A14C3 phase.W coating during the preparation of composites with A1 substrate reaction at the interface the position of formation of Al5W layer. The results show that the interface reaction is slow, can be controlled by regulating the thickness of interfacial reaction layer composite material preparation process parameters, so as to optimize the structure and thermal physical properties of composites interface. When composite infiltration time is extended from 10 min to 60 min, the thermal conductivity of composite materials increased from 520 W/mK to 630 W/mK. while W plated diamond particles reinforced aluminum matrix composites thermal conductivity rate is relatively low, but the A15W interfacial reaction layer formed can effectively inhibit the formation of A14C3 interphase in composites, expand The application of composite material. In summary, this paper studies the formation mechanism of diamond particles of aluminum matrix composites interface enhanced established composite material preparation process parameters, the effective connection between structure and thermal conductivity of the interface. The interface structure of reinforced aluminum matrix composites and the corresponding interface structure optimization by means of diamond particles in order to optimize the design of composite materials and controllable preparation. The results provide a theoretical reference to further enhance the thermal physical properties of diamond particles reinforced metal matrix composites, can be better used for heat dissipation of electronic devices.

【學(xué)位授予單位】：北京科技大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TB333

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