Study on Hydro-thermal Processing of Cubic Boron Nitride by Laser Beam Irradiation

点击翻译按钮获取中文摘要

When solid materials are irradiated by laser beam in the presence of water, they are heated to high temperature, further chemical reaction between solid materials and radicals which are produced from water is expected. The aim of this research is to process cubic boron nitride or other ceramic materials by using these reactions.Firstly water and water which dissolving gases, such as methane, hydrogen and oxygen, were irradiated by an ArF excimer laser beam, an Ar ion laser beam and a YAG laser beam and the luminescences were examined by Spectrophotometry. As the results ArF excimer laser beam can excite water and radicals such as O2+, OH, H2, O2 and etc. are produced. While the other laser beams could not excite one but heat the solid materials. Secondly approximately 60 volume percent of a chamber was filled with water and the upper part was filled with methane. The pressure of the methane dissolved in water was 350kPa. The gas pressure of the upper part of the chamber was 100kPa. The … More n ArF excimer laser beam was focused just below the water surface. Consequently, film was deposited on the water around the beam-focus area. From a TEM image, small particles of about 30nm in diameter are connected with each other in the mesh.Thirdly Si3N4 ceramics were immersed in water and ArF excimer laser beam was irradiated. Although the amics were placed 1mm away from the laser beam, the color of ceramics adjacent to the laser beam changed. ArF excimer laser beam can excite water as mentioned above, on the other hand, Ar ion laser beam can not excite water but rather heats the ceramic material. The same Si3N4 ceramics were irradiated by an Ar ion laser in both water and air. On both cases holes are formed, however the formed features are different each other and one processed in water seems to be partly etched. This depends on the hydro-thermal reaction between water and heated ceramics. It is also expected to process cBN which react with water at high temperature. cBN single crystal was irradiated in water and water vapor environments. In both cases very clear shaped holes were formed. In particular one in water vapor showed high crystallinity on electron diffraction. Also crystal habits were observed around the holes. Less