Cutting and Shaping of Hard Ceramics with a CO2-Laser

使用 CO2 激光切割和成型硬质陶瓷

• 批准号: 8915027
• 负责人: Michael Modest
• 金额: $ 21万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-09-15 至 1993-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8915027&HistoricalAwards=false
• 关键词: Cutting; Shaping; Hard; Ceramics; CO2

Extremely hard ceramics such as silicon nitride and silicon carbide have generated considerable interest in recent years as potential materials for many high-temperature engineering applications. In their dense high-strength forms, these materials are being proposed for use as structural materials in power-generating gas turbines to increase their efficiency by allowing gas inlet temperatures to about 1400oC. These materials are also being considered for automotive gas turbines, small thermal reactors, roller bearings, and advanced combustion chambers. An important drawback to silicon compound ceramics is their extreme hardness, which makes their processing and shaping an extremely difficult, tedious and expensive procedure. Preliminary work has already shown that vastly higher removal rates are possible with a CO2 laser as compared to the conventional diamond grinding. To demonstrate the feasibility of laser shaping of hard-to-machine materials, a multi- disciplinary research effort has been undertaken to study the basic mechanisms governing the interaction between a high- powered CO2-laser beam and silicon compound ceramics. The research program is looking at the heat transfer, material property and manufacturing aspects of the laser-shaping process. A heat transfer model is being established to predict shape and depth of single, multiple-pass and overlapping grooves, material removal rates, surface roughness, etc. Material properties relevant for the model are being measured, including surface reflectivity (as function of temperature, angle and beam polarization), surface temperatures and ejected material properties (particle size and number density). Material characteristics of the ceramics before and after laser treatment are being investigated, such as microstructure, chemical composition of elements on the surface, flexure strength an thermal shock resistance. Laser machining is being carried out with variable operating conditions, and measurements are being made to determine quality, uniformity, reproducibility and predictability of the process. Machining results from single and overlapping grooves are being used to validate the heat transfer model.

近年来，氮化硅和碳化硅等极硬陶瓷作为许多高温工程应用的潜在材料引起了人们极大的兴趣。 这些材料的致密高强度形式被提议用作发电燃气轮机的结构材料，通过允许气体入口温度达到约 1400oC 来提高其效率。 这些材料也被考虑用于汽车燃气轮机、小型热反应堆、滚子轴承和先进的燃烧室。 硅化合物陶瓷的一个重要缺点是其极高的硬度，这使得其加工和成型成为极其困难、繁琐且昂贵的过程。 初步工作已经表明，与传统的金刚石磨削相比，CO2 激光器可以实现更高的去除率。 为了证明难加工材料激光成形的可行性，我们进行了多学科研究，以研究高功率 CO2 激光束与硅化合物陶瓷之间相互作用的基本机制。 该研究项目着眼于激光成形过程的传热、材料特性和制造方面。 正在建立传热模型来预测单通道、多通道和重叠凹槽的形状和深度、材料去除率、表面粗糙度等。正在测量与模型相关的材料特性，包括表面反射率（作为温度、角度和光束偏振的函数）、表面温度和喷射材料特性（颗粒尺寸和数量密度）。 正在研究激光处理前后陶瓷的材料特性，例如微观结构、表面元素的化学成分、弯曲强度和耐热冲击性。 激光加工是在可变的操作条件下进行的，并进行测量以确定过程的质量、均匀性、再现性和可预测性。 单个和重叠凹槽的加工结果用于验证传热模型。