Lei Jincheng, Chen Jie, Hong Yuzhe, Zhang Qi, Chen Qiushi, Tong Jianhua, Xiao Hai, Peng Fei, Bordia Rajendra K
Department of Electrical and Computer Engineering, Clemson University, Clemson, South Carolina.
Center for Optical Materials Science and Engineering Technologies (COMSET), Clemson University, Anderson, South Carolina.
J Am Ceram Soc. 2020 Jan;103(1):70-81. doi: 10.1111/jace.16640. Epub 2019 Jun 13.
Combining sol-gel processing and laser sintering is a promising way for fabricating functional ceramic deposition with high dimensional resolution. In this work, crack-free silica tracks on a silica substrate with a thickness from ~360 nm to ~950 nm, have been obtained by direct exposure to a CO laser beam. At a fixed scanning speed, the density and microstructures of the silica deposition can be precisely controlled by varying the laser output power. The porosity of the laser-sintered silica tracks ranged from close to 0% to ~60%. When the thickness of the silica deposition exceeded the critical thickness (eg, ~2.2 μm before firing), cracks occurred in both laser-sintered and furnace-sintered samples. Cracks propagated along the edge of the laser-sintered track, resulting in the crack-free track. However, for the furnace heat-treated counterpart, the cracks spread randomly. To understand the laser sintering effect, we established a finite element model (FEM) to calculate the temperature profile of the substrate during laser scanning, which agreed well with the one-dimensional analytical model. The FEM model confirmed that laser sintering was the main thermal effect and the calculated temperature profile can be used to predict the microstructure of the laser-sintered tracks. Combining these results, we were able to fabricate, predesigned patterned (Clemson tiger paw) silica films with high density using a galvo scanner.
将溶胶-凝胶工艺与激光烧结相结合是制造具有高尺寸分辨率的功能陶瓷沉积物的一种很有前景的方法。在这项工作中，通过直接暴露于CO激光束，在厚度约为360纳米至950纳米的二氧化硅衬底上获得了无裂纹的二氧化硅轨迹。在固定扫描速度下，通过改变激光输出功率可以精确控制二氧化硅沉积物的密度和微观结构。激光烧结的二氧化硅轨迹的孔隙率范围从接近0%到约60%。当二氧化硅沉积物的厚度超过临界厚度时（例如，烧制前约2.2微米），激光烧结和炉烧样品中都会出现裂纹。裂纹沿着激光烧结轨迹的边缘扩展，从而形成无裂纹轨迹。然而，对于炉热处理的对应物，裂纹随机扩展。为了理解激光烧结效果，我们建立了一个有限元模型（FEM）来计算激光扫描过程中衬底的温度分布，该模型与一维解析模型吻合良好。有限元模型证实激光烧结是主要的热效应，计算出的温度分布可用于预测激光烧结轨迹的微观结构。综合这些结果，我们能够使用振镜扫描仪制造出高密度的预先设计图案（克莱姆森老虎爪）二氧化硅薄膜。
