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ENVIRONMENTAL DURABILITY OF SILICON NITRIDE-BORON NITRIDE COMPOSITES

氮化硅-氮化硼复合材料的环境耐久性

基本信息

批准号：
06650972
负责人：
ODA Kohei
金额：
$ 0.32万
依托单位：
YONAGO NATIONAL COLLEGE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

It is well known that Si_3N_4-BN composite materials are attracting considerable interest for a range of diverse applications such as components for automobiles to refractory nozzles, tubes, sliding gates, and break rings for the horizontal continuous casting of steel. It is important to investigate the high-temperature oxidation and the high-temperature high-pressure water corrosion of these composites because these materials are subject to corrosive attack in severe environments such as chemical engineering. The purpose of this project is to investigate the corrosion behavior of pressureless-sintered and reaction-bonded Si_3N_4-BN composite in pure oxygen and pure water at elevated temperatures. The results are discussed with respect to the microstructure of these materials. The high-temperature oxidation tests were conducted in pure oxygen at 900-1200ﾟC.The hydrothermal corrosion tests were conducted in an autoclave at 120-300ﾟC.The following results were obtained.(1) The high-temperature oxidation resistance and the hydrothermal corrosion resistance were mainly dependent on BN content, and the material with higher amount of BN had more poor oxidation and corrosion resistance.(2) The depression of further oxidation and corrosion due to the stable passive film which were made from silica and additives such as Y_2O_3 and Al_2O_3 was recognized in pressureless-sintered Si_3N_4-BN composite.(3) The high-temperature oxidation resistance and the hydrothermal corrosion resistance for reaction-bonded Si_3N_4-BN composite were superior to those for pressureless-sintered Si_3N_4-BN composite.

众所周知，Si_3N_4-BN复合材料在一系列不同的应用中引起了相当大的兴趣，例如汽车部件，耐火喷嘴，管，滑动门和水平连铸钢的断裂环。由于这些材料在化学工程等恶劣环境中会受到腐蚀，因此研究这些复合材料的高温氧化和高温高压水腐蚀具有重要意义。本课题的目的是研究无压烧结反应键合Si_3N_4-BN复合材料在高温纯氧和纯水中的腐蚀行为。从微观结构的角度对结果进行了讨论。高温氧化试验在900 ~ 1200℃的纯氧环境下进行。在120-300℃的高压灭菌器中进行热液腐蚀试验。得到了以下结果：(1)材料的高温抗氧化性和水热腐蚀性能主要取决于BN含量，BN含量越高，材料的抗氧化性和耐腐蚀性越差。(2)在无压烧结Si_3N_4-BN复合材料中，由二氧化硅和Y_2O_3、Al_2O_3添加剂组成的稳定的钝化膜抑制了进一步的氧化和腐蚀。(3)反应键合Si_3N_4-BN复合材料的高温抗氧化性和水热耐蚀性优于无压烧结Si_3N_4-BN复合材料。