Nd：YAG激光陶瓷特性及关键技术研究

发布时间：2018-05-15 19:39

本文选题：Nd:YAG透明陶瓷 + 烧结助剂　；参考：《西安电子科技大学》2015年博士论文

【摘要】：随着陶瓷制备技术的高速发展,Nd:YAG透明陶瓷作为固体激光材料,自出现以来,在工业、医疗、国防等领域得到了广泛的应用。本文采用固相反应真空烧结法,以高纯Al_2O_3、Y_2O_3和Nd_2O_3为原料,利用X射线衍射分析、扫描电镜、分光光度计和导热仪等仪器,分别对陶瓷样品的物相、显微结构和热性能进行了表征,研究了Nd:YAG激光陶瓷的关键技术、激光性能和热性能,为Nd:YAG激光陶瓷的国产化提供了实验依据。以高纯Al_2O_3、Y_2O_3和Nd_2O_3为原料,采用固相反应法,添加不同含量的TEOS制备Nd:YAG透明陶瓷。得到在1750℃烧结30h,添加0.3wt%TEOS的样品致密化程度较高,有个别气孔分布在晶粒内部,晶界上无杂质相生成,平均晶粒尺寸为30μm左右,在1064nm处的透过率为72.32%。在添加TEOS的基础上添加不同质量分数的MgO作为复合烧结助剂制备陶瓷,得到添加0.3wt%TEOS+0.3wt%MgO的陶瓷样品,在1730℃烧结30h,致密化程度高,晶界上无杂质相生成,平均晶粒尺寸为25μm,晶粒均匀,在1064nm处的透过率为78.46%,高于仅添加TEOS的样品在1064nm处透过率值(72.32%)。这主要是因为MgO加入起到抑制晶粒生长,增加晶界密度,为气孔的排出提供更多通道,所以陶瓷的透过率得到提高。对于B_2O_3和SiO_2作为复合烧结助剂,在保持添加总量不变的情况下,通过改变B~(3+):Si4+比例(0.5,1.0,2.0),研究了其对样品显微结构及透过率的影响。得到当B~(3+):Si4+=0.5,在1700℃烧结30h的样品其致密度较高,在1064nm处的透过率为76.87%,晶界干净,晶粒均匀。这主要是因为B_2O_3通过降低液相的粘度来提高样品的致密化速率,使得陶瓷快速到达理论致密度值,所以添加B_2O_3能降低陶瓷的烧结温度。采用固相反应法、化学共沉淀法以及溶胶—凝胶法在不同烧结温度下合成了Nd:YAG粉体,进而使用Nd:YAG粉体制备陶瓷样品,通过对比陶瓷样品的显微形貌及测量其透过率值,选择固相反应法制备Nd:YAG透明陶瓷。通过对Y_2O_3粉体的预处理、改进素坯成型方式及改变烧结制度,制备厚尺寸Nd:YAG激光陶瓷。使用冷等静压成型的素坯相对密度为51.6%,高于双向轴压的素坯相对密度。以素坯成型为基础,设计模具,实现了Nd~(3+)浓度的梯度掺杂。由于粉体颗粒尺寸、烧结活性、比表面积值不同,使用不同处理方式的Y_2O_3粉体合成YAG相的温度不同。从化学沉淀法处理到1200℃热处理,合成YAG相的温度依次提高50℃。采用不同处理方法的Y_2O_3粉体,使用冷等静压法制备的素坯在1730℃烧结30h,得到的陶瓷样品显微结构差异明显。以1200℃热处理2h的Y_2O_3粉体为原料,得到的样品晶粒尺寸均匀,大小约为15μm,气孔含量少,在1064nm处透过率为78.46%。对1200℃热处理2h的Y_2O_3粉体为原料制备的样品,通过改变烧结制度,得到升温速率为1℃/min,保温时间为30h烧结成的陶瓷样品显微结构中晶粒内部的气孔基本排除完全,在1064nm和400nm处的透过率分别为83.59%、80.82%,达到了作为激光材料透明度的要求。选用平行平面谐振腔,端面泵浦的方式,成功实现了Nd:YAG透明陶瓷1064nm的激光输出,其中泵浦阈值为1.15w,最大输出功率为1.54w,相应的光—光转换效率为18.4%,斜效率为21.3%。同时采用LFA—447的Nanoflash导热仪来测量不同透过率及不同晶粒尺寸的陶瓷样品的热扩散系数、比热值,并计算出陶瓷样品的热导系数。得到陶瓷样品的热导率随着气孔率的增大(即透过率减小)而减小,并随着晶粒尺寸的增大(即晶界密度的减小)而增大,为制备高热导率的陶瓷样品提供参数指标。
[Abstract]:With the rapid development of ceramic preparation technology, Nd:YAG transparent ceramics, as solid laser materials, have been widely used in the fields of industry, medical treatment and national defense since they appeared. In this paper, the solid phase reaction vacuum sintering method was used, with high purity Al_2O_3, Y_2O_3 and Nd_2O_3 as raw materials, using X ray diffraction analysis, scanning electron microscope, spectrophotometer and guide. The phase, microstructure and thermal properties of the ceramic samples were characterized by heat instrument and other instruments. The key technologies, laser properties and thermal properties of Nd:YAG laser ceramics were studied. The experimental basis for the localization of Nd:YAG laser ceramics was provided. The high purity Al_2O_3, Y_2O_3 and Nd_2O_3 were used as raw materials, and the solid phase reaction was used to add different content of TEO. Nd:YAG transparent ceramics were prepared by S. The samples were sintered at 1750 C for 30h, and the densification degree of the samples added with 0.3wt%TEOS was high. There were some pores in the grain and no impurity phase on the grain boundary. The average grain size was about 30 m, and the transmittance at 1064nm was 72.32%. on the basis of adding TEOS. The ceramics were prepared by sintering aids, and the 0.3wt%TEOS+0.3wt%MgO ceramic samples were obtained. The densification degree was high at 1730 C for 30h. The densification degree was high and the grain boundary was not formed. The average grain size was 25 m, the grain was uniform and the transmittance at 1064nm was 78.46%, which was higher than that of the samples with TEOS only at 1064nm (72.32%). This is mainly due to MgO plus. In order to suppress the grain growth, increase the grain boundary density and provide more channels for the discharge of the pores, the transmittance of the ceramics is improved. For B_2O_3 and SiO_2 as a composite sintering additive, the microstructure and transmittance of the samples are studied by changing the amount of B~ (3+): Si4+ (0.5,1.0,2.0). When B~ (3+): Si4+=0.5, the density of the samples sintered at 1700 C for 30h is higher, the transmittance at 1064nm is 76.87%, the grain boundary is clean and the grain is uniform. This is mainly because B_2O_3 increases the densification rate of the sample by reducing the viscosity of the liquid phase and makes the ceramics reach the theoretical density value at a fast speed, so the addition of B_2O_3 can reduce the pottery. The sintering temperature of porcelain was prepared by solid phase reaction, chemical coprecipitation and sol-gel synthesis of Nd:YAG powders at different sintering temperatures. Then the ceramic samples were prepared by using Nd:YAG powder system. By comparing the microstructure of the ceramic samples and measuring the transmittance of the ceramics, the transparent Nd:YAG ceramics were prepared by the solid phase reaction method, and Y_2O_3 was prepared by the method of solid phase reaction. The thick size Nd:YAG laser ceramics are prepared by the pretreatment of the powder, improving the forming mode of the plain billet and changing the sintering system. The relative density of the plain blank with cold isostatic pressure is 51.6%, which is higher than the relative density of the billet. Based on the forming of the plain billet, the mold is designed to achieve the gradient doping of the concentration of Nd~ (3+). The temperature of YAG phase synthesized by Y_2O_3 powder with different treatment methods is different. The temperature of the synthetic YAG phase is increased by 50 degrees centigrade by the chemical precipitation process to 1200 C heat treatment. The ceramic samples prepared by the cold isostatic pressure method by cold isostatic pressure method are sintered at 1730 C for 30h. The microstructure difference is obvious. With the Y_2O_3 powder of heat treated 2H at 1200 C as raw material, the grain size of the sample is uniform, the size is about 15 mu m, the gas pore content is little, the transmittance at 1064nm is 78.46%. to the Y_2O_3 powder of 2H at 1200 C heat treatment 2h, and the heating rate is 1 C /min and the heat preservation time is obtained by changing the sintering system. The pores in the microstructures of the 30h sintered ceramic samples are basically eliminated completely, and the transmittance at 1064nm and 400nm is 83.59%, 80.82% respectively, reaching the requirement of the transparency of the laser materials. The laser output of the Nd:YAG transparent ceramic 1064nm is successfully realized by using the parallel plane resonant cavity and the end pump mode. The pump threshold is 1.15w, the maximum output power is 1.54w, the corresponding light to light conversion efficiency is 18.4%, the oblique efficiency is 21.3%. and the LFA 447 Nanoflash thermal conductivity meter is used to measure the thermal diffusivity of the ceramic samples with different transmittance and different grain sizes, the specific heat value and the thermal conductivity of the ceramic samples are calculated. The ceramic samples are obtained. The thermal conductivity decreases with the increase of the porosity (that is, the transmittance decrease), and increases with the increase of grain size (i.e. the decrease of grain boundary density), which provides parameters for the ceramic samples prepared with high thermal conductivity.

【学位授予单位】：西安电子科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ174.1

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