本文選題：化學(xué)氣相沉積 + 熱力學(xué)　； 參考：《西北工業(yè)大學(xué)》2015年博士論文

【摘要】：連續(xù)纖維增韌非氧化物陶瓷基復(fù)合材料具有密度低、耐高溫、優(yōu)異力學(xué)、抗腐蝕和抗氧化性能,在航空航天領(lǐng)域獲得廣泛應(yīng)用。Si-B-C-N系陶瓷備受關(guān)注,化學(xué)氣相沉積(CVD)是制備陶瓷基復(fù)合材料界面、基體和涂層組元的有效方法。本文擬選擇該體系有代表性的SiC、Si3N4、BN、SiBx和SiCN等作為陶瓷基復(fù)合材料界面、基體和涂層的候選材料。通過量子化學(xué)結(jié)合統(tǒng)計(jì)及經(jīng)典熱力學(xué)對(duì)相關(guān)體系進(jìn)行熱力學(xué)研究,充分理解CVD法制備上述材料的化學(xué)反應(yīng)過程及其機(jī)理,對(duì)CVD Si-B-C-N系高溫陶瓷材料制備工藝發(fā)展具有重要指導(dǎo)意義。本文對(duì)Si3N4、BN、SiBx、SiCN及SiBCN陶瓷的CVD先軀體體系涉及的熱力學(xué)問題進(jìn)行了系統(tǒng)計(jì)算,建立了相關(guān)產(chǎn)物的熱力學(xué)數(shù)據(jù)庫(kù),包括分子在298.15K-2000 K的標(biāo)準(zhǔn)摩爾熱容(Cθp,m),標(biāo)準(zhǔn)摩爾熵(Sθm)、標(biāo)準(zhǔn)摩爾生成焓(△fHmθ)和標(biāo)準(zhǔn)摩爾生成吉布斯自由能(△fGmθ)等。利用所得基本熱化學(xué)數(shù)據(jù),根據(jù)化學(xué)平衡(即系統(tǒng)的總化學(xué)勢(shì)最小)原理,對(duì)相關(guān)各體系進(jìn)行了熱力學(xué)產(chǎn)物平衡濃度分布研究,計(jì)算得到CVD工藝參數(shù)與固相產(chǎn)物生成量之間的關(guān)系,并對(duì)部分結(jié)果進(jìn)行了實(shí)驗(yàn)對(duì)比驗(yàn)證。主要研究?jī)?nèi)容和結(jié)果如下：(1)以BCl3-NH3-H2體系為先驅(qū)體制備氮化硼,確定了該體系可能存在的中間產(chǎn)物共144個(gè),其中87個(gè)為新產(chǎn)物。通過計(jì)算獲得其完整的熱力學(xué)數(shù)據(jù),包括分子結(jié)構(gòu),標(biāo)準(zhǔn)摩爾熱容(Cθp, m),標(biāo)準(zhǔn)摩爾熵(Sθm)、標(biāo)準(zhǔn)摩爾生成焓(△fHmθ)和標(biāo)準(zhǔn)摩爾生成吉布斯自由能(AfGme)。利用所得基本熱化學(xué)數(shù)據(jù),根據(jù)化學(xué)平衡(即系統(tǒng)的總化學(xué)勢(shì)最小)原理,計(jì)算了該體系在CVD典型工藝參數(shù)(1000 Pa總壓,進(jìn)氣比BC13:NH3:H2=1:3:6)和溫度范圍為300 K-2000 K的產(chǎn)物平衡濃度圖。結(jié)果表明,BCl3和NH3在300 K即可發(fā)生反應(yīng),高于2160 K可生成固相硼(B),1800K以下生成立方氮化硼(c-BN),1800 K以上生成六方氮化硼(h-BN)。而纖鋅礦氮化硼(w-BN)在此工藝參數(shù)下則無(wú)法穩(wěn)定存在。本文同樣計(jì)算了體系相關(guān)固相產(chǎn)物(B, c-BN和h-BN)生成量與溫度和先驅(qū)體進(jìn)氣比r= BCl3/(BCl3+NH3)的關(guān)系,熱力學(xué)計(jì)算結(jié)果表明,生成固相產(chǎn)物BN的最佳進(jìn)氣比r=0.5。(2)同樣計(jì)算獲得SiCl4-NH3-H2體系在CVD過程可能涉及的118個(gè)(總共161個(gè))新產(chǎn)物的熱力學(xué)數(shù)據(jù)。基于所獲數(shù)據(jù),計(jì)算了該體系在CVD典型工藝參數(shù)(1000 Pa,總壓,進(jìn)氣比SiCl4:NH3:H2=1:3:5和溫度范圍300 K-2000 K)的產(chǎn)物平衡濃度圖。結(jié)果表明產(chǎn)生固相產(chǎn)物Si3N4的熱力學(xué)溫度為300 K-1560 K。同樣計(jì)算了體系相關(guān)固相產(chǎn)物(Si和Si3N4)生成量與溫度和先驅(qū)體進(jìn)氣比r=SiCl4/(SiCl4+NH3)的關(guān)系。熱力學(xué)計(jì)算結(jié)果表明,生成固相產(chǎn)物Si3N4的最佳進(jìn)氣比r=0.5。(3)對(duì)于BCl3-SiCl4-H2-Ar體系,共涉及220個(gè)可能的中間產(chǎn)物。本文計(jì)算了其中128個(gè)新產(chǎn)物的熱力學(xué)數(shù)據(jù),以及該體系在CVD典型工藝參數(shù)(總壓1atm,進(jìn)氣比BCl3:SiCl4:H2:Ar=4:1:5:5)和300 K-2000 K的產(chǎn)物平衡濃度圖。同樣還有固相產(chǎn)物(B, SiB6和SiB14)生成量與溫度和先驅(qū)體進(jìn)氣比r= BCl4/(SiCl4+ BC13)的關(guān)系,熱力學(xué)計(jì)算結(jié)果表明：固相B生成條件為進(jìn)氣比r0.8,SiB6的產(chǎn)生條件為0.1 r0.8,700 K T1550 K, SiB1i4的產(chǎn)生條件為r0.7且溫度T1，，400 K。(4)對(duì)于SiCl3CH3-NH3-H2體系,總共涉及443個(gè)可能的中間產(chǎn)物。本文計(jì)算了其中99個(gè)新產(chǎn)物的熱力學(xué)數(shù)據(jù),以及該體系在CVD典型工藝參數(shù)(1000Pa總壓,進(jìn)氣比SiCl3CH3:NH3:H2=1:3:5)和300 K-2000 K的產(chǎn)物平衡濃度圖和固相產(chǎn)物(C, Si3N4和p-SiC)生成量與溫度和先驅(qū)體進(jìn)氣比r= SiCl3CH3/(SiCl3CH3 +NH3)的關(guān)系。熱力學(xué)計(jì)算結(jié)果表明,Si3N4可在300 K-1200 K生成,β-SiC生成條件為1200 K以上(5)計(jì)算了SiCl3CH3-BCl3-NH3-H2體系在氣壓1000 Pa,溫度300-2000 K,先驅(qū)體進(jìn)氣比SiCl3CH3:BC13:NH3:H2= 5:1:4:50條件下的產(chǎn)物平衡濃度分布。熱力學(xué)計(jì)算結(jié)果表明,在950-1100 K可實(shí)現(xiàn)C+SiC+Si3N4+BN的多相共沉積；高于1100 K可實(shí)現(xiàn)C+SiC+BN三相共沉積；在700 K-950 K則可實(shí)現(xiàn)C+Si3N4+BN的三相共沉積。(6)最后根據(jù)各體系的熱力學(xué)計(jì)算結(jié)果,在熱力學(xué)研究條件范圍內(nèi),與動(dòng)力學(xué)工藝參數(shù)的實(shí)驗(yàn)結(jié)果進(jìn)行比對(duì),結(jié)果表明兩者基本相符。本文建立了Si-B-C-N-H-Cl體系所有可能的氣相產(chǎn)物熱力學(xué)數(shù)據(jù)庫(kù),利用該氣相產(chǎn)物熱力學(xué)數(shù)據(jù)庫(kù),結(jié)合相關(guān)體系的固相產(chǎn)物實(shí)驗(yàn)數(shù)據(jù),即可計(jì)算得到任意工藝參數(shù)下的產(chǎn)物平衡濃度分布,這對(duì)指導(dǎo)相關(guān)材料體系的CVI工藝研究有重要意義。
[Abstract]:Continuous fiber reinforced non oxide ceramic matrix composites with low density, high temperature resistance, excellent mechanical, corrosion resistance and oxidation resistance, has been widely used to obtain.Si-B-C-N ceramics attention in the field of aerospace, chemical vapor deposition (CVD) was prepared by interfacial ceramic matrix composites, the matrix and the effective method of coating components in this paper. This system intends to select the representative of the SiC, Si3N4, BN, SiBx and SiCN as the interface of ceramic matrix composites, the candidate materials of substrate and coating. Through combining the statistical and quantum chemistry of classical thermodynamics thermodynamic study on the related system, fully understand the chemical reaction process and the mechanism of preparation of these materials by CVD, CVD Si-B-C-N the Department has an important guiding significance for high temperature ceramics preparation technology development. Based on Si3N4, BN, SiBx, SiCN and SiBCN thermodynamic problems involving CVD ceramic precursor system for the Department of The calculation, a thermodynamic database related products, including molecular in the standard molar heat capacity of K 298.15K-2000 (C 0 p m), the standard molar entropy (S theta m), the standard enthalpy of formation (fHm 0) and the standard molar Gibbs free energy (fGm 0). The use of the basic thermochemical data, according to the chemical equilibrium (total chemical potential is the minimum principle of the system), the thermodynamic equilibrium concentration distribution of the product, the calculated relationship between CVD production process parameters and solid products, and some of the results of the comparison test. The main research contents and results are as follows: (1) preparation of boron nitride precursor in the BCl3-NH3-H2 system, the intermediate product of the system may have a total of 144, including 87 new products obtained by calculating its complete thermodynamic data, including molecular structure, standard molar heat capacity (C 0 p m), Standard molar entropy (S - M), the standard enthalpy of formation (fHm 0) and the standard molar Gibbs free energy (AfGme). By using the basic data, according to the chemical equilibrium (total chemical potential is the minimum) principle, typical process parameters in the CVD system the calculation (1000 Pa total pressure. The inlet temperature range than the BC13:NH3:H2=1:3:6) and the product of the equilibrium concentration of figure 300 K-2000 K. The results showed that BCl3 and NH3 reacted at 300 K to above 2160 K can be produced by solid boron (B), 1800K generation of cubic boron nitride (c-BN), more than 1800 K to generate six boron nitride (h-BN). Wurtzite boron nitride (w-BN) on these parameters are not stable. This paper also calculated the relative solid system (B, c-BN and h-BN products) generation and the temperature and precursor intake than r= BCl3/ (BCl3+NH3) the relationship between the thermodynamic calculation results show that the formation of solid products and the best BN Intake than r=0.5. (2) also obtained 118 SiCl4-NH3-H2 system in the CVD process may involve (161 in total). The thermodynamic data of new products based on the data obtained in the CVD, the typical process parameters of this system were calculated (1000 Pa, total pressure, inlet temperature range than SiCl4:NH3:H2=1:3:5 and 300 K-2000 K) product the equilibrium concentration diagram. The results show that the thermodynamic temperature of solid products of 300 Si3N4 K-1560 K. also calculated the related product solid system (Si and Si3N4) generation and the temperature and precursor intake than r=SiCl4/ (SiCl4+NH3). The relationship between the thermodynamic calculation results show that the ratio of r=0.5. optimal intake produced by solid products of Si3N4 (3) for BCl3-SiCl4-H2-Ar system, involving a total of 220 possible intermediates. This paper calculated the thermodynamic data among the 128 new products, as well as the CVD system in the typical process parameters (inlet total pressure 1atm, BCl3:SiCl4:H2:Ar =4:1:5:5) and the product of the equilibrium concentration of figure 300 K-2000 K. There is also solid products (B, SiB6 and SiB14) generation and the temperature and precursor intake than r= BCl4/ (SiCl4+ BC13) the relationship between the thermodynamic calculation results show that the solid B formation conditions for the intake than r0.8, producing conditions for 0.1 r0.8700 K T1550 SiB6 K, SiB1i4 and r0.7 for generating conditions of temperature T1400 K. (4) for the SiCl3CH3-NH3-H2 system, involving a total of 443 possible intermediates. This paper calculated the thermodynamic data among the 99 new products, as well as the CVD system in the typical process parameters (1000Pa total pressure, inlet ratio SiCl3CH3:NH3:H2=1:3:5) and 300 K-2000 K product balance the concentration maps and solid phase products (C, Si3N4 and p-SiC) generation and the temperature and precursor intake than r= SiCl3CH3/ (SiCl3CH3 +NH3). The relationship between the thermodynamic calculation results show that the Si3N4 can be generated at 300 K-1200 K, beta -SiC generated a For more than 1200 K (5) SiCl3CH3-BCl3-NH3-H2 system in the 1000 Pa pressure calculation, temperature 300-2000 K, precursor concentration distribution of SiCl3CH3:BC13:NH3:H2= intake than the product balance under the condition of 5:1:4:50. The thermodynamic calculation results show that in the 950-1100 K C+SiC+Si3N4+BN can realize multi phase co deposition; above 1100 K can achieve C+SiC+BN phase co deposition in 700; K-950 K can achieve C+Si3N4+BN phase co deposition. (6) the final results according to the thermodynamics of each system, in the range of thermodynamic research conditions, and the dynamic parameters of the experimental results were compared, the results showed that both the basic line. This paper establishes a Si-B-C-N-H-Cl system of all possible gas phase thermodynamic database, product thermodynamic database by using the experimental data of gas, solid products combined with the related system, calculation of product balance parameters can be arbitrary The concentration distribution, it is important to study the CVI process to guide the related material system.

【學(xué)位授予單位】：西北工業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TQ174.758.2


本文編號(hào)：1758137