等离子体CVD法制备氮化碳涂层的理论与实验研究

发布时间：2018-06-22 05:06

本文选题：氮化碳 + 第一性原理　；参考：《南京航空航天大学》2015年硕士论文

【摘要】：晶体氮化碳材料是一种在自然界未被发现的新型超硬材料,α、β、立方和准立方相氮化碳的体弹性模量都能够媲美甚至超过金刚石。另外,优异的化学惰性和耐磨性也使得晶体氮化碳有望在刀具涂层方面有突出的表现。本文开展了等离子体CVD法制备氮化碳材料的理论与实验研究,主要内容包括计算仿真、机理分析和实验验证三个部分。本文主要研究及结论如下:(1)利用Material Studio软件进行了第一性原理化学吸附仿真研究。研究表明:N2分子在金刚石过渡层和硬质合金表面不产生化学吸附,N原子在其表面上产生化学吸附;N原子在硬质合金表面吸附能比在金刚石过渡层上有更大的值;N原子在硬质合金表面比在金刚石过渡层上更易于与基底成键,氮化碳更易于在其上直接形核和生长;若采用直流电弧等离子体喷射法制备晶体氮化碳膜,可以通过增大反应气体配比中N2分子量和提高电弧功率密度,产生更多活性N原子,以便提高氮化碳膜形核和生长效率。(2)对等离子体CVD法制备晶体氮化碳涂层的机理进行了研究。有别于王季陶提出的CVD法制备金刚石膜的“化学泵”理论,提出了应用于氮化碳涂层制备过程的新型“化学泵”模型;在金刚石过渡层上沉积氮化碳涂层时,基底温度对金刚石相和氮化碳相的刻蚀与沉积产生显著影响,并提出了在适当温度下金刚石相刻蚀和氮化碳相沉积同时进行的假设模型;当氮源/碳源配比在100:1~10:1时,氮化碳膜才易于成核和生长,并且碳源浓度增长对氮化碳的晶形和晶粒大小影响很大;沉积气压与碳源浓度有交互作用,共同对氮化碳材料的形貌有显著影响。(3)采用直流电弧等离子体喷射法分别在金刚石过渡层和硬质合金上开展制备氮化碳实验,并对实验结果与仿真结论和理论分析进行对比研究。对在不同基底温度下金刚石过渡层沉积的氮化碳涂层进行SEM,XRD等测试,研究表明基底温度对金刚石过渡层上制备的氮化碳涂层的晶形和晶粒大小产生显著影响;首次在硬质合金基底上直接制备出了晶形较为完好的氮化碳晶体涂层,并对在不同碳源浓度条件下于硬质合金上沉积氮化碳涂层进行SEM,XRD等测试,碳源浓度和基底选择等对氮化碳制备的影响与机理分析、仿真结果相一致。
[Abstract]:Crystalline carbon nitride is a new superhard material that has not been found in nature. The bulk elastic modulus of 伪, 尾, cubic and quasi cubic carbon nitride is comparable to or even higher than that of diamond. In addition, the excellent chemical inertia and wear resistance also make the crystal carbon nitride has a promising performance in tool coating. In this paper, the theoretical and experimental studies on the preparation of carbon nitride materials by plasma CVD are carried out. The main contents include computer simulation, mechanism analysis and experimental verification. The main research and conclusions are as follows: (1) First-principle chemisorption simulation is carried out using material Studio software. The results show that no chemisorbed N atom is produced on diamond transition layer and cemented carbide surface by N 2 molecule. The adsorption energy of N atom on cemented carbide surface is higher than that on diamond transition layer. Atoms bond to the substrate more easily on the surface of the cemented carbide than on the diamond transition layer. It is easier for carbon nitride to nucleate and grow directly on it. If carbon nitride films are prepared by DC arc plasma jet method, more active N atoms can be produced by increasing the molecular weight of N 2 in the reaction gas ratio and increasing the arc power density. In order to improve the nucleation and growth efficiency of carbon nitride film. (2) the mechanism of preparing crystal carbon nitride coating by plasma CVD was studied. Different from the "chemical pump" theory proposed by Wang Jitao for the preparation of diamond films by CVD, a new "chemical pump" model applied to the preparation process of carbon nitride coatings was put forward, and the carbon nitride coating was deposited on the transition layer of diamond. The substrate temperature has a significant effect on the etching and deposition of diamond and carbon nitride phase, and a hypothetical model of diamond phase etching and carbon nitride deposition at appropriate temperature is proposed, when the ratio of nitrogen source to carbon source is 100: 1 / 10: 1, Nitride carbon film is easy to nucleate and grow, and the increase of carbon source concentration has a great influence on the crystal shape and grain size of carbon nitride, and the deposition pressure has interaction with carbon source concentration. (3) carbon nitride was prepared on diamond transition layer and cemented carbide by DC arc plasma jet method. The experimental results are compared with the simulation results and theoretical analysis. The carbon nitride coatings deposited at different substrate temperatures were tested by SEM XRD. The results show that the substrate temperature has a significant effect on the crystal shape and grain size of the carbon nitride coatings prepared on the diamond transition layer. For the first time, the crystalline carbon nitride crystal coating was prepared on cemented carbide substrate for the first time, and the carbon nitride coating deposited on cemented carbide with different carbon source concentration was tested by SEM XRD and so on. The effects of carbon source concentration and substrate selection on the preparation of carbon nitride were analyzed and the simulation results were consistent.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB306

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