Determination of High-Temperature Properties Relevant to Laser Materials Processing

摘要-- CTS-9312325 PI -- Michael F.谦虚 虽然激光加工（钻孔，切割，焊接）正在以极快的速度获得工业上的重要性，但基本工艺仍然知之甚少，主要是因为缺乏高温性能数据（被加工材料及其上方形成的激光羽流）的知识。 存在复杂的模型，可以准确地预测钻速、孔直径、锥度、切割速率等，如果不是因为缺乏财产数据。 该建议提出了三组实验，将进行测量所有相关的高温性能的CO2和Nd：YAG激光加工陶瓷：（1）的吸收率的几个陶瓷试样（在激光波长，作为温度的函数），烧蚀温度，和烧蚀材料所需的能量将在积分球装置中测量。 (2)将通过高速摄影和红外测温对激光相互作用区进行成像，以捕捉清除机制（烧蚀、分解、熔化或微爆炸清除），并确定碎片清除和再沉积。 (3)将使用透射和发射光谱法在激光波长（以确定光束阻挡量）和中红外（以确定来自羽流的再发射）下测量激光羽流的吸收系数。 这项调查的结果将允许对陶瓷的激光加工进行定量预测，并将提供实验设计来测量其他材料（包括金属）的相关性能。

ABSTRACT -- CTS-9312325 PI -- Michael F. Modest While laser processing (drilling, cutting, welding) is gaining industrial importance at an extremely rapid pace, the basic process remains poorly understood, largely because of a dearth of knowledge of high-temperature property data (of the material being processed, and of the laser plume forming above it). Sophisticated models exist that could accurately predict drilling rates, hole diameter, taper, cutting rates, etc., were it not for this lack of property data. This proposal addresses three groups of experiments, which will be carried out to measure all relevant high-temperature properties for CO2 and Nd:YAG laser processing of ceramics: (1) The absorptivity of several ceramic specimens (at the laser wavelengths, as a function of temperature), the ablation temperature, and the energy required to ablate material will be measured in an integrating sphere apparatus. (2) The laser interaction zone will be imaged through high-speed photography and infrared thermometry to capture the removal mechanism (ablation, decomposition, melting, or micro-explosive removal) and to identify debris removal and redeposition. (3) Absorption coefficients of the laser plume will be measured at the laser wavelengths (to determine amount of beam blockage) and in the mid-infrared (to determine re-emission from the plume) using transmission and emission spectroscopy. Results from this investigation will allow quantitative predictions for laser processing of ceramics, and will provide experimental designs to measure the relevant properties for other materials, including metals.