本文選題：炭纖維 + 電熱法　； 參考：《華東交通大學》2015年碩士論文

【摘要】：炭/炭復(fù)合材料（C/C復(fù)合材料）作為新一代高性能的復(fù)合材料有著無限廣闊的應(yīng)用前景，隨著C/C復(fù)合材料應(yīng)用領(lǐng)域的拓展，更加苛刻的使用環(huán)境對其性能及生產(chǎn)效率等的提高提出了更高的要求。 本文采用了一種新的C/C復(fù)合材料的制備方法即電熱法，即利用炭纖維自身的導電性對其直接通電加熱，再利用化學氣相沉積（CVD）的方法沉積熱解碳（PyC），研究了熱解碳的結(jié)構(gòu)、形成機理及其對炭纖維表面微晶結(jié)構(gòu)的影響，并通過催化化學氣相沉積（CCVD）的方法在炭纖維表面生長了納米碳，研究了不同電鍍工藝和CCVD工藝下納米碳的形態(tài)、生長機理及其影響因素。實驗結(jié)果表明： （1）較高的加熱功率下（50W），熱解碳有兩種沉積模式。沉積初期，熱解碳主要以小球狀分子沉積生成球狀微晶組織的生長方式生長，隨著沉積時間延長為60min，大片狀分子沉積的生長方式占主導地位。 （2）降低初始加熱功率（30W），即降低沉積溫度，熱解碳的沉積方式主要為大片狀的分子沉積生成層狀微晶，且沉積1h后形成了結(jié)構(gòu)致密的C/C復(fù)合材料。 （3）在大的氣流作用下，電熱法生成的熱解碳沿垂直于纖維軸向方向定向生長。 （4）CVD熱解碳會優(yōu)先在炭纖維表面的刻蝕點、孔洞等更大的活性點生長，，形成一些無序堆疊的細小碳原子團，使炭纖維表面微晶結(jié)構(gòu)的有序度降低，而碳原子團會組裝形成一些小的石墨微晶，故而使炭纖維表面的平均微晶尺寸降低。 （5）不同電鍍時間下生成的納米碳可能是顆粒狀、木耳狀、竹節(jié)狀、樹枝狀等，也可能是CNT/CNF。合適的電鍍時間下，電鍍鎳顆粒分布均勻，尺寸合適，有利于生長出CNT/CNF，電鍍時間過長，幾乎不能生成CNT/CNF�？梢酝ㄟ^控制電鍍時間來控制鎳顆粒的數(shù)量、形態(tài)和分布等，并進一步控制生成的納米碳的形態(tài)。單晶的鎳顆粒催化生長出較直的CNT/CNF或螺旋狀的CNT/CNF，多晶的鎳顆粒催化生成木耳狀、竹節(jié)狀、樹枝狀或顆粒狀的納米碳。本實驗最佳電鍍時間為3min。 （6）CCVD生長CNT/CNF后，炭纖維的晶化程度和表面平均微晶尺寸都增大。 （7）CCVD工藝3下生長的CNT/CNT晶粒尺寸更大，石墨化度更高。本實驗最佳氣體流量為：C2H2=80mL/min，N2=200mL/min。 （8）沉積時間對CNT/CNF的影響主要有兩個階段。第一階段為沉積初期，CNT/CNF和熱解碳（PyC）的沉積同時進行，前者速率大且CNT/CNF的形貌由鎳顆粒的大小和分布決定；第二階段為沉積后期，鎳顆粒失去活性，CNT/CNF幾乎停止生長，此時主要為PyC的沉積，另外，鎳催化劑和生長的CNT/CNF都能促進和加快PyC的沉積。
[Abstract]:Carbon / carbon composites (C / C composites) as a new generation of high performance composites have an unlimited application prospects, with the expansion of the field of application of C / C composites, The more demanding environment for its performance and production efficiency to raise higher requirements. In this paper, a new preparation method of C / C composite, electrothermal method, is used to deposit pyrolytic carbon PyCn by means of direct electric heating of carbon fiber itself and chemical vapor deposition (CVD) method, and the structure of pyrolytic carbon is studied. The formation mechanism of carbon fiber and its effect on the microcrystalline structure of carbon fiber surface were studied. The carbon nanocrystalline was grown on the carbon fiber surface by catalytic chemical vapor deposition (CVD) method. The morphology of nano-carbon was studied under different electroplating and CCVD processes. Growth mechanism and influencing factors. The experimental results show that: 1) at higher heating power, pyrolytic carbon has two deposition modes. In the early stage of deposition, pyrolytic carbon mainly grew in the form of globular microcrystalline structure formed by the deposition of small globular molecules. With the increase of deposition time to 60 min, the growth mode of large flake molecules was dominant. (2) to reduce the initial heating power by 30 W / W, that is to say, to reduce the deposition temperature, the deposition mode of pyrolytic carbon is mainly formed by large flake molecular deposition to form layered microcrystals, and a compact C / C composite is formed after 1 hour of deposition. 3) under the action of large airflow, the pyrolytic carbon generated by electrothermal method grows in a direction perpendicular to the axial direction of the fiber. Carbon pyrolytic carbon will be preferentially grown at larger active points such as etching points and pores on the surface of carbon fibers, forming some small carbon atoms which are stacked disorderly, thus reducing the order of microcrystalline structures on the surface of carbon fibers. The carbon cluster assembles some small graphite microcrystals, which reduces the average microcrystalline size of the carbon fiber surface. The nanocrystalline carbon produced under different electroplating time may be granular, auricular-shaped, bamboo-shaped, dendritic, or CNT / CNF. When the electroplating time is suitable, the distribution of nickel particles is uniform and the size is suitable, which is beneficial to the growth of CNT / CNF, and the electroplating time is too long to produce CNT / CNF. The amount, morphology and distribution of nickel particles can be controlled by controlling the electroplating time, and further controlling the morphology of the resulting carbon nanoparticles. Single crystal nickel particles catalyze the growth of straight CNT/CNF or spiral CNT / CNF, and polycrystalline nickel particles catalyze the formation of auricular-shaped, bamboo-shaped, dendritic or granular nano-carbon. The optimum electroplating time is 3 min. The degree of crystallization and the average surface microcrystalline size of carbon fibers increased after CNT/CNF growth. The grain size and graphitization degree of CNT/CNT grown under CCVD process 3 are larger and higher. The best gas flow rate in this experiment is 80 mL / min N _ 2N _ 2 N _ 2N _ 2 / min. The influence of deposition time on CNT/CNF has two stages. The first stage is the deposition of CNT / CNF in the early stage of deposition and the deposition of pyrolytic carbon (PyC) at the same time. The former has a high rate and the morphology of CNT/CNF is determined by the size and distribution of nickel particles, the second stage is the late stage of deposition, when the nickel particles lose their activity, the CNT / CNF almost stops growing. In addition, both the nickel catalyst and the growing CNT/CNF can promote and accelerate the deposition of PyC.
【學位授予單位】：華東交通大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TQ127.11;TB383.1

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