基于纳秒激光的金属微流道成型及质量研究

发布时间：2018-04-16 23:20

本文选题：微流道 + 热效应　；参考：《广东工业大学》2017年硕士论文

【摘要】：微流控芯片技术是一种在微米甚至纳米尺度的低微通道结构中控制体积为皮升甚至纳升的流体进行流动并传质、传热的技术,是工程、物理、化学、生物、纳米技术等众多学科交叉的技术领域。目前,微流控芯片的制备主要使用光刻工艺来保证微米级的尺寸精度,而光刻工艺环节众多,操作和制备手段极其复杂且繁琐。本课题组提出了微流控芯片的快速批量化制造,而模具是工业中批量化制造的最佳方案,因此在金属材料上加工出形貌规则的微结构至关重要。材料微结构的制备主要使用了微细加工技术,包括精密机械加工、电火花加工、微细电解加工、LIGA技术和激光加工等多种加工方法。由于微流芯片多在一百微米尺度下,相比于上述其他加工方法,激光加工具有光斑尺寸小、无需制备电极和刀具、无需配置溶液等特点,所以对激光加工微流道进行实验和研究很有必要。本文以激光微加工技术和激光抛光技术为基础,以制备形貌规则、底部平滑的微流道为目标,提出了激光加工微流道和流道底部表面质量改善的复合工艺方案。主要研究方法和结论如下:(1)从激光微加工的机理出发,概述了激光与材料相互作用的机理,分析了本实验设备的合理性。介绍了激光加工的表面效应,并通过数值分析,计算Fe对波长为1064nm的红外激光的吸收率,求得吸收率理论值约为0.36。结合激光作为电磁波对电子和离子的影响,在激光材料产生的热效应方面分析了纳秒激光和飞秒激光的区别,得出纳秒激光必然存在明显热传导效应的结论。由材料的热物理性质出发,考虑金属材料发生相变时的熔化潜热和气化潜热,在不考虑脉宽影响的前提下,粗略估算了加工过程中使用的最小单脉冲能量。(2)对316L不锈钢进行激光微加工单因素实验,然后绘制流道宽度/深度趋势图,展示代表性的流道形貌,用以研究激光微加工中尺寸和形貌的规律。结果表明:扫描速度过低,流道出现过熔和加工表面两侧的烧蚀现象,速度过低,流道直线度下降;脉冲宽度越小,加工得到的形貌越规律;扫描次数越多,流道形貌越差,流道底部的波动越明显。(3)借助激光抛光技术,对单脉冲能量和扫描速度进行流道底部表面质量改善的单因素实验,然后测量流道底部表面粗糙度Rt的值,并绘制相应的曲线。结果表明:随着单脉冲能量的增大,流道底部表面粗糙度Rt值先下降后上升;随着扫描速度的逐渐增大,流道底部的表面粗糙度Rt值同样先下降后上升。(5)在COMSOL软件环境中使用固体热传导模块,将激光模拟为高斯热源,对单脉冲激光加工过程中材料表面的温度场分布、气化宽度和激光作用后的冷却过程进行仿真模拟。结果表明:相邻两个激光脉冲的时间间隔内,材料表面光斑中心温度在激光脉冲宽度内迅速以指数形式升高和下降,在5μs范围内迅速降低至材料的熔化温度以下,在下一个脉冲到来之前材料已经冷却,这表明脉冲激光加工具有瞬时性;单脉冲能量越高,材料表面最高温度越大,气化宽度越大;脉冲宽度越短,材料表面温度越高,气化宽度越大;与脉冲宽度变化相比,单脉冲能量的变化对气化宽度的影响更明显。
[Abstract]:Microfluidic chip technology is a fluid for skin or even nanoliter volume control a small channel structure in micro or nano scale in the flow and mass transfer, heat transfer technology, engineering, physics, chemistry, biology, nanotechnology and many other interdisciplinary technical field. At present, the main preparation of microfluidic chip the use of lithography process to ensure the accuracy of the size of micron, and the lithography process part number, operation and preparation methods are extremely complex and tedious. This paper puts forward the rapid mass production of microfluidic chip, and the mold is in the industrial batch manufacturing best scheme, so the processing micro structure plays an important role in metal morphology the micro structure of the material. The material preparation is mainly used microfabrication technology, including precision machining, EDM, micro machining, LIGA technology and laser processing and other processing methods. The microfluidic chip in one hundred micron scale, compared with the other processing methods, laser processing with a small spot size, without preparation of electrode and tool, without configuration solution, so it is necessary for laser processing of micro channel experiments and research. In this paper, laser micro processing technology and laser polishing technology based on the rules of morphology for the preparation, micro channel bottom smooth as the goal, put forward the composite process scheme of laser processing and surface quality of micro channel flow at the bottom of improvement. The main research methods and conclusions are as follows: (1) starting from the mechanism of laser micro machining, the mechanism of interaction between laser and material, analysis the rationality of experimental equipment. The effect of laser surface processing, and through the numerical analysis, the calculation of Fe wavelength of 1064nm infrared laser absorption rate, absorption rate obtained theoretical value is about 0.36. with shock As the optical effects of electromagnetic waves on electrons and ions, thermal effect in laser materials analysis of the difference between nanosecond laser and femtosecond laser, teller second laser must exist obvious heat conduction effects. Starting from the thermal physical properties of material, considering the metal material occurs when the phase transformation latent heat and latent heat of vaporization. Without considering the influence of pulse width, a rough estimate of the process used in the minimum pulse energy. (2) of 316L stainless steel by laser micro machining experiment of single factor, and then draw the channel width / depth trend chart show channel morphology representative, to study the size and morphology of laser micro processing in the law. The results show that the scanning speed is too low, the channel had ablation phenomenon, welding and machining surface on both sides of the low speed flow linearity decreased; pulse width is smaller, the more regular morphology processing; scanning The more the number of channel morphology is worse, at the bottom of the channel fluctuations are more obvious. (3) by means of laser polishing technology, experiments on the single factor to improve the surface quality of the channel at the bottom of the single pulse energy and scanning speed, and then measuring the channel bottom surface roughness value of Rt, and draw the corresponding curve. The results show that: with the increase of single pulse energy flow, the bottom surface roughness Rt value decreased first and then increased; with the increasing of scanning speed, the bottom of the channel surface roughness Rt value also decreased and then increased. (5) the use of solid heat conduction module in the COMSOL software environment, the simulation of laser Gauss heat source on the surface material of single pulse in the laser cutting process of temperature field simulation of cooling process of gasification width and after laser irradiation. The results showed that two adjacent laser pulses within a time interval, the surface temperature in the laser spot center materials The optical pulse width in the rapid rise and fall in exponential form, below the melting temperature decreased rapidly to the material in the 5 s range, in the next pulse before the arrival of material has been cooling, which indicates that the pulse laser processing is temporary; the single pulse energy is high, the high temperature of the material surface, the width of gasification big; the shorter the pulse width, the material surface temperature is higher, compared with the width of the gasification; the pulse width changes, changes of single pulse energy on the gasification width is more obvious.

【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH16

【参考文献】