CLARIFICATION AND SUPPRESSION OF ACCELERATED OXIDATION IN MoSi_2 AS A ULTRA-HIGH TEMPERATURE MATERIAL.

超高温材料 MoSi_2 加速氧化的澄清和抑制。

• 批准号: 09450263
• 负责人: KUROKAWA Kazuya
• 金额: $ 4.61万
• 依托单位: HOKKAIDO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09450263/
• 关键词: MOLYBDENUM DISILICIDE; ACCELERATED OXIDATION PHENOMENA; SUPPRESSION OF ACCELERATED OXIDATION; H_2O VAPOR; DEFECTS; PEST; 環境側因子; 材料側因子

MoSi_2 has been known for a promising material for ultra-high temperature applications. Although MoSi2 has outstanding oxidation resistance, it also shows accelerated oxidation behavior, resulting in pesting, especially at low temperatures. The accelerated oxidation and posting are based on simultaneous oxidation of Mo and Si. However, the mechanism of the simultaneous oxidation has not been clear. Aims of the present research are to clarify the mechanism and the method of the suppression. The main results are as follows.(1) The accelerated oxidation is most severe at temperatures ranging from 673 to 773 K and became much milder as temperature increases.(2) The accelerated oxidation and pesting are liable to occur under a combination of defects on surface of MoSi2 and H2O vapor in atmospheres.(3) As the atomic ratio of Mo/Si increases, the oxidation resistance decreases. However, the effect is appreciably small.(4) Defects such as pores and cracks are responsible for the accelerated oxidation and pesting. Conversely, the accelerated oxidation and pesting are completely suppressed by using fully dense MoSi2.(5) The initiation sites of the simultaneous oxidation are deffects.The accelerated oxidation and pesting, after all, are most strongly affected by preexisting defects located on the surface of MoSi2. Thermodynamical consideration also shows that the simultaneous oxidation is not an intrinsic property of MoSi2.

MoSi_2是一种非常有前途的超高温材料。虽然MoSi2具有优异的抗氧化性，但它也表现出加速氧化行为，导致害虫，特别是在低温下。加速氧化和post是基于Mo和Si的同时氧化。然而，同时氧化的机理尚不清楚。本研究的目的是阐明这种抑制的机制和方法。主要结果如下：(1)在673 ~ 773 K的温度范围内，加速氧化最为严重，随着温度的升高，加速氧化的程度逐渐缓和。(2)在MoSi2表面缺陷与大气中H2O蒸气共同作用下，容易发生加速氧化和害虫。(3)随着Mo/Si原子比的增大，抗氧化性降低。然而，这种影响是相当小的。(4)气孔和裂纹等缺陷是加速氧化和害虫的原因。相反，使用全致密的MoSi2完全抑制了加速氧化和害虫。(5)同时氧化的起始部位为缺陷。毕竟，MoSi2表面存在的缺陷对加速氧化和害虫的影响最大。热力学的考虑也表明同时氧化不是MoSi2的固有性质。

项目成果

K.Kurokawa: "High Temperature Oxidation of Refractory Metal Disilicides." J.of High Temp.Soc.24 (No.5). 161-166 (1998)

K.Kurokawa：“难熔金属二硅化物的高温氧化”。

K.Kurokawa: "Low Temperature Oxidation of Fully Dense and Porous MoSi_2" Materials Sci.and Eng.A261. 292-299 (1999)

K.Kurokawa：“全致密多孔 MoSi_2 的低温氧化”材料科学与工程 A261。

黒川一哉: "金属間化合物の耐酸化性" 材料と環境. 48・3(印刷中). (1999)

Kazuya Kurokawa：“金属间化合物的抗氧化性”材料与环境48・3（出版中）。

K.Kurokawa: "In-Situ Synthesis of Fully Dense MoSi_2-SiC Composites by Spark Plasma Sintering." Proc.of International Sympo.on Applied Plasma Sci.129-134 (1997)

K.Kurokawa：“通过火花等离子烧结原位合成全致密 MoSi_2-SiC 复合材料。”

K.Kurokawa: "In-Situ Synthesis of Fully Dense MoSi_2-SiC Composites by Spark Plasma Sintering" Proc.of inter'l Sympo.on Applied Plasma Sci.129-134 (1997)

K.Kurokawa：“通过火花等离子烧结原位合成全致密 MoSi_2-SiC 复合材料”Proc.of interl Sympo.on Applied Plasma Sci.129-134 (1997)