ON HIGH-TEMPERATURE OXIDATION OF CHROMIUM .2. PROPERTIES OF CR2O3 AND THE OXIDATION MECHANISM OF CHROMIUM
ON HIGH-TEMPERATURE OXIDATION OF CHROMIUM .2. PROPERTIES OF CR2O3 AND THE OXIDATION MECHANISM OF CHROMIUM
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DOI：
10.1149/1.2129481
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发表时间：
1980-01-01
影响因子：
3.9
通讯作者：
LILLERUD, KP
中科院分区：
文献类型：
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作者：
KOFSTAD, P;LILLERUD, KP
在1000~ 176 ℃和不同氧压（10 J-7、9、10-2 Pa 02）下对铬进行了高真空处理，作为氧化的直接延续。在高真空处理期间，所有试样均失重。在最初的一段时间内，体重减轻的速度缓慢下降，但经过较长的时间后，损失率基本上变成线性的。结果表明，铬的挥发是由于铬通过晶格扩散和沿着易扩散路径和微裂纹路径在氧化皮中迁移所致。根据Cr2 O3氧化皮的性质和Cr2 O3的缺陷相关性质的文献数据，提出了Cr2 O3氧化物的缺陷结构模型。有人提出，间隙铬离子是占主导地位的点缺陷在分压的Cr/Cr2 O3相界附近的氧。在接近大气压的压力下，氧化物是本征的电子导体。从扩散数据和建议的缺陷结构mocte~计算的抛物线速率常数与实验值进行了比较。讨论了铬的氧化机理。重要的因素是晶格扩散，运输沿着路径的容易扩散和微裂纹通过规模，生长应力的规模，能力的规模变形，和蒸汽运输从金属基板分离scales.Part的这项工作介绍了研究的氧化退火，在800~ 176 ℃温度范围内，在105 ~ 7.9 × 10 ~（-2）Pa（1）的不同氧压下，对铬进行了热腐蚀。本文第二部分介绍了铬氧化试样的高真空处理结果，并讨论了Cr_2O_3的性质和缺陷结构，作为全面考虑铬高温氧化机理的基础。第一部分（1）中给出了铬氧化的文献综述以及材料和方法的描述。
Chromium specimens oxidized at 1000~ 176 and at different oxygen pressures~ 10J-7 9 10-2 Pa 02) have been treated in high vacuum at temperature as a direct continuation of the oxidation runs. All specimens lost weight during the high vacuum treatment. During an initial period the rate of weight loss slowly decreased, but after longer time the loss rate became essentially linear. It is concluded that the weight loss is due to chromium evaporation due to chromium transport through the scales by lattice diffusion and transport along paths of easy diffusion and microcracks. On the basis of the properties of Cr203 scales and available literature data on defect-dependent properties of Cr2Os, a defect structure model has been proposed for the oxide. It is proposed that interstitial chromium ions are the predominating point defects at partial pressures of oxygen near the Cr/Cr203 phase boundary. At near-atmospheric pressures the oxide is an intrinsic electronic conductor. Parabolic rate constants calculated from the diffusion data and the proposed defect structure mocte~ are compared with experimental values. The oxidation mechanism of chromium is discussed. Important factors are lattice diffusion, transport along paths of easy diffusion and microcracks through the scale, growth stresses in the scale, the ability of the scale to deform, and vapor transport from the metal substrate to detached scales.Part I of this work describes studies of oxidation of annealed, thermally-etched chromium in the temperature range 800~ 176 at different oxygen pressures ranging from 105 to 7 9 10-2 Pa (1). This paper, Part II, presents results on high vacuum treatment of oxidized chromium specimens and discusses the properties and defect structure of Cr2Os as a basis for an overall consideration of the high temperature oxidation mechanism of chromium. A literature survey of oxidation of chromium and a description of materials and methods have been given in Part I (1).