本文選題：微波工藝 + 熱解炭��； 參考：《深圳大學(xué)》2017年碩士論文

【摘要】：熱解炭(PyC)材料具有優(yōu)良的機(jī)械、物理性能和良好的生物特性,廣泛用于核能、航天航空、電能和生物醫(yī)學(xué)工程等領(lǐng)域。本課題組研究了不同維度的炭炭復(fù)合材料的熱電性質(zhì),發(fā)現(xiàn)基體PyC結(jié)構(gòu)是影響其熱電性質(zhì)的關(guān)鍵。因此研究PyC的微觀織構(gòu)及其與熱電性質(zhì)之間的相互聯(lián)系具有重要意義。論文在課題組前期關(guān)于微波化學(xué)氣相滲透工藝研究的基礎(chǔ)上,提出了使用微波恒溫恒壓化學(xué)氣相沉積法(MICVD)制備PyC工藝;采用自行設(shè)計的微波加熱沉積裝置,研究了在不同工藝條件下制備的多種微觀結(jié)構(gòu)PyC及其電學(xué)性質(zhì),進(jìn)一步探討了PyC的微觀結(jié)構(gòu)、電輸運性質(zhì)、熱解炭生長機(jī)理和工藝參數(shù)之間的相互關(guān)系。本論文主要研究內(nèi)容如下:研究了MICVD工藝制備不同形貌和微觀織構(gòu)的PyC。通過控制工藝參數(shù),如沉積溫度、碳源分壓比、腔體總壓以及滯留時間,可以實現(xiàn)多種微觀織構(gòu)PyC的制備。通過偏光顯微鏡(PLM)、X射線衍射(XRD)、掃描電鏡(SEM)等手段表征PyC的結(jié)構(gòu)。結(jié)果表明,當(dāng)PyC微觀織構(gòu)有序性逐漸降低(即從高織構(gòu)到中織構(gòu),再到低織構(gòu)和無定型碳)時,PyC的石墨微晶尺寸La、Lc在逐漸減小,層間距d002在逐漸增大,取向性變差。研究了沉積時間對PyC結(jié)構(gòu)的影響,結(jié)果表明沉積時間對PyC結(jié)構(gòu)基本沒有影響。通過對PyC微觀結(jié)構(gòu)及形貌的分析,探討了MICVD工藝制備PyC的生長過程,提出了PyC的島狀-層狀生長模式。在沉積溫度1200℃,腔體總壓50KPa條件下,得到了高織構(gòu)PyC,且最高沉積速率可達(dá)到108μm/h。采用熱電性能測試儀(ZEM)和綜合物性測量系統(tǒng)(PPMS)等研究了不同結(jié)構(gòu)PyC的電輸運性質(zhì)。結(jié)果表明,PyC均表現(xiàn)出以空穴為主要載流子的導(dǎo)電特性。隨著PyC有序度的提高,其載流子濃度、載流子遷移率及電導(dǎo)率都在逐漸增大,磁電阻及霍爾系數(shù)在逐漸減小,Seebeck系數(shù)先減小后增大,高織構(gòu)PyC具有最好的電輸運性能。采用MICVD工藝,以碳化硅多孔陶瓷為基體,可制備出炭微米管,其直徑約5μm,壁厚約500nm,微觀組織結(jié)構(gòu)為高織構(gòu)PyC,比表面為1.5483 m2/g,比容量為40 F/g,表現(xiàn)出了一定的電容特性。
[Abstract]:Pyrolytic carbon (PyC) has excellent mechanical, physical properties and good biological properties. It is widely used in nuclear energy, aerospace, electrical energy and biomedical engineering. The research group has studied the thermoelectric properties of carbon carbon composites in different dimensions, and found that the structure of the matrix PyC is the key to influence the thermoelectric properties of the carbon carbon composites. Therefore, the microstructure of PyC is studied. The relationship between texture and its thermoelectric properties is of great significance. On the basis of the research on the microwave chemical vapor infiltration process in the earlier period of the project, the paper proposed the preparation of PyC by microwave constant temperature constant pressure chemical vapor deposition (MICVD), and the self designed micro wave heating and deposition device was used to study the different process conditions. A variety of microstructure PyC and its electrical properties were prepared. The microstructure, electrical transport properties, growth mechanism and technological parameters of PyC were further discussed. The main contents of this paper are as follows: the study of the process parameters for the preparation of different morphologies and microstructure of PyC. by MICVD process, such as deposition temperature, is studied. The carbon source pressure ratio, the total pressure of the cavity and the retention time can be used to prepare a variety of microtextured PyC. The structure of PyC is characterized by polarizing microscope (PLM), X ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that when the microstructure of the PyC microstructure is gradually reduced (from high texture to medium texture, then to low texture and amorphous carbon), Py The size of the graphite microcrystal of C is La, the Lc is gradually reduced, the spacing of D002 is gradually increasing and the orientation is worse. The effect of deposition time on the structure of PyC has been studied. The results show that the deposition time has no effect on the structure of PyC. By analyzing the microstructure and morphology of PyC, the growth process of PyC in MICVD process is discussed, and the island layer of PyC is proposed. Under the condition of the deposition temperature of 1200 and the total pressure of 50KPa, the high texture PyC is obtained, and the highest deposition rate can reach 108 m/h.. The electrical transport properties of the different structure PyC are studied by the thermoelectric performance tester (ZEM) and the comprehensive physical measurement system (PPMS). The results show that the PyC shows the conductance of the main carrier as the hole. With the increase of the order of PyC, the carrier concentration, carrier mobility and electrical conductivity are increasing gradually, the magnetoresistance and Holzer coefficient gradually decrease, the Seebeck coefficient decreases first and then increases, and the high texture PyC has the best electrical transport properties. The carbon microtubules can be prepared by MICVD process. Its diameter is about 5 m, the wall thickness is about 500nm, the microstructure is high texture PyC, the specific surface is 1.5483 m2/g, the specific capacity is 40 F/g, showing a certain capacitance characteristic.

【學(xué)位授予單位】：深圳大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ127.11

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