【作者】 敬承斌；

【导师】 赵修建；

【作者基本信息】 武汉理工大学 ， 材料学， 2004， 博士

【摘要】 全反射型CO₂激光空芯波导材料的合成技术是CO₂激光应用领域的关键性课题之一。本研究工作探索了溶胶—凝胶法合成Al₂O₃和GeO₂基CO₂激光空芯波导反射膜材料的工艺路线，为制备全反射型CO₂激光空芯波导材料开辟了新的途径。 针对传统浸渍提拉法不适合于在细长的毛细管内表面等异型件上镀膜，自行组装了浸渍降液法镀膜设备，并提出了能够预测溶胶—凝胶薄膜厚度、密实性以及均一性的新方法。 通过对异丙醇铝、硝酸铝和二级丁醇铝（ASB）为前驱物的各种Al₂O₃溶胶的合成工艺和溶胶性质进行预测，将由ASB通过分散法合成的溶胶确定为制备Al₂O₃反射膜的基本溶胶分散系。在多次镀膜中，采用100℃左右的温度进行中间热处理，Al₂O₃溶胶—凝胶薄膜会出现厚度“零增长”现象。以260℃左右的温度进行中间热处理不仅可以有效消除“零增长”现象，同时能防止多层膜开裂、减少界面污染的几率。 ASB：H₂O高于1：100的Al₂O₃溶胶中固液相间较大的界面差异以及胶体颗粒双电层较薄、胶体颗粒有效直径较大、Zeta电位不高，导致溶胶在热力学、动力学和DLVO位能等方面的显著不稳定性。乙酰乙酸乙酯（EAcAc）能够与Al₂O₃胶体颗粒表面的-Al-OH基团发生螯合作用从而降低Al₂O₃胶体颗粒的反应活性，并显著缩小固液相之间的界面差异，使体系的Gibbs焓变下降。通过EAcAc的改性作用可以获得ASB：H₂O为1：30的高固含量、高稳定性铝溶胶。 向EAcAc改性Al₂O₃溶胶中引入聚乙烯吡咯烷酮（PVP）分子，可获得ASB：H₂O为1：25的更高固含量的铝溶胶。PVP分子的空间稳定效应是使该溶胶胶体颗粒的势垒高于15kT的重要原因。PVP分子中-CH₂-CH₂-主链和内酰胺侧基结构可以延缓Al₂O₃胶体颗粒间的密实化反应、增强Al₂O₃凝胶强度，以及其松弛性质和当它处于橡胶弹性时模量随温度的升高而升高的性质是它能阻止凝胶开裂的可能原因。使用EAcAc和PVP双改性的Al₂O₃溶胶可以获得厚度达到4μm而且具有高度密实性和平整性的Al₂O₃薄膜材料。 以3-三氯锗丙酸，钛酸丁酯和正硅酸乙酯（TEOS）为前驱物可武汉理工大学博士学位论文以制得了钦硅锗溶胶。山该溶胶可以获得非品态的5102一TioZ一Go02薄膜材料。该合成工艺较为繁琐而且材料具有裂纹。使用二甲基二乙氧基硅烷代替正硅酸乙醋能够合成出稳定的5102一GeOZ溶胶。由该溶胶可以制得膜厚近4抖m而且密实平整的薄膜材料。 通过引入lhJ断点附近无限小偏差量A不f!polynomia一、oaussian、Lorentzian拟合等多个拟合函数模型，可以对材料的红外反射谱相位角进行精确计算。计算结果表明5102一TioZ一GeO:和5102一GeO:以及A朽03溶胶一凝胶薄膜材料在940cln一’处的光学常数分别为0.53一0.961、0.62一0.slitrlo.69一0.171。芯径为1000于‘m的5102一TIOZ一Ge02涂层材料空芯光纤在94ocm一’处的总损耗a，l为o.69dB/m。5102一oeoZ涂层材料空芯光纤的附加损耗as在10“3至10一ZdB/m数量级。芯径为1000林m、750林m和500卜Lm的5102一GeO:涂层空芯光纤的a::值分别为0.064 dB/m、0.15 dB/nl不“0.52dB/m。由于a:很低，A12O3涂层材料空芯光纤的损耗主要由a。决定，芯径为100饵:m、750“m和500卜m的A12O3涂层光纤的al，值分别为0.045 dB/m、0.11 dB/m和0.36dB/m。更多还原

【Abstract】 The synthesis of materials for total reflection type of hollow waveguide has been a key point of applications in CO2 laser delivery. In this work the synthesis of sol-gel Al2O3 and GeO2 based films for hollow waveguide delivery of CO2 laser was studied. This research will develop a new route to fabricate materials for hollow waveguide delivery of CO2 laser.In the question of the traditional dip-coating method that is not suitable for the inner coating of capillary and coatings on other irregular surfaces, a drop coating device was particularly designed and equipped. A new method for predicting qualities of sol-gel optical films such as the thickness, compactness and uniformity was proposed.Based on researches of the processes and properties of various alumina sols derived from aluminum iso-propoxide, aluminum nitrate and aluminum sec-butoxide(ASB) through polymerization and peptization technical routes, the alumina sol synthesized from ASB according to peptization route was chosen as the basic sol system for the preparation of alumina reflective films. Using a temperature within 240~260 in stead of 100 as the temperature of temporally heating alumina sol-gel films in multi-time coating can not only eliminate the phenomenon of "zero-growth" in thickness, but also prevent the crack formation and decrease the probability of interfacial pollutions. The surface difference exists in the sol with a mol ratio of ASB/H2O more than 1:100 between the colloidal particle and solvent, combined with the large colloidal particle, small thickness in electrical double layer and lower zeta potential, resulting in its very poor stability in thermodynamics, kinetics and DLVO energy barrier. It was indicted that ethylacetoacetate(EAcAc) can chelated with -Al-OH groups on the surface of the colloidal particles, depressing the activity of the colloidal particles, reducing the interphase distinction between the solid and liquid phase remarkably, lowering the change of Gibbs enthalpy. Therefore, the stable alumina sols with high solidity contents, namely the ratio 1/30 of ASD/H2O can be obtained by introducing EAcAc into the original sol.Sol with higher alumina content with a ratio 1/25 of ASB/H2O can be prepared by adding polyvinylpyrrolidone(PVP) with EAcAc. The stericstabilization of PVP plays an important role to keep the energy barrier above 15kT. The effect of -CH2-CH2-chains and the lateral lactam groups in PVP to retard the condensation of gels, reinforce the gel, and its structural relaxation and its modulus increases with the increase of temperature when the temperature is beyond Tg and PVP acting as an elastomer are all the possible reasons for the anticrack effect of PVP. Compact and homogenous alumina films thicker than 4m can be obtained by using this double modified alumina sol.SiO2-TiO2-GeO2 sol was synthesized from Si(OC2H5)4, Ti(OC4H9)4 and CI3GeCH2CH2COOH. SiO2-TiO2-GeO2 gel glass films were obtained from this sol. The sol derived from (CH3)2Si(OC2H5)2 and Ge(OC2H5)4 was much more stable than that prepared by Si(OC2H5)4 and Ge(OC2H5)4. Compact and smooth sol-gel films thicker than 4m or so can be obtained by using this sol.The phase angle integral of the infrared reflection spectra of materials can be accurately calculated by introduced a infinitesimal parameter A adjacent to the disconnected point and various fitting functions including Polynomial, Gaussian and Lorentzian etc. It was verified that the complex refractive indices at 940 cm-1 for SiO2-TiO2-GeO2, SiO2-GeO2 and A12O3 sol-gel films are 0.53-0.96i, 0.62-0.8 liand 0.69-0.17i, respectively. The total loss an of SiO2-TiO2- GeO2 films coated hollow fiber with diameter of 1000m is 0.69dB/m. The additional loss of SiO2-GeO2 films coated hollow waveguide at 940 cm-1 reaches the magnitude of 10-3 to 10-2 dB/m. As for hollow fibers with diameters of 1000m, 750m and 500m, the total loss an are 0.064dB/m, 0.15dB/m and 0.52dB/m, respectively. The additional loss of A12O3 films coated hollow waveguide at 940 cm is so small that the total loss of hollow fiber is更多还原