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研究了1—76毫米汞柱氧压和350—500℃温度范围内钼的氧化过程。结果表明,钼的氧化是首先在表面生成MoO_2,MoO_2生长到某种厚度以后才出现MoO_3,这种厚度与温度和氧压有关。MoO_2的生长服从抛物线规律。MoO_3的出现虽使钼的氧化速率略为增大,但并不意味着MoO_2停止了生长。在MoO_3与MoO_2同时生长的情况下,钼的氧化仍然遵从抛物线规律。氧化后表面的MoO_3晶粒随氧化时间的延长而变大,长大到一定程度的晶粒往往容易从表面脱落,困而是氧化层出现疏松的象征。这种疏松可能使钼的氧化偏离抛物线开始向直线规律过渡。在450℃1—76毫米汞柱氧压范围内,钼的氧化速率与氧压的2/3次方成正比,即K∝P_(O_2)~(2/3)。因此有理由认为,在上述条件下表面吸附层中的氧分子浓度对钼的氧化速率起着控制作用。
Oxidation of molybdenum was studied at oxygen pressures between 1 and 76 mm Hg and temperatures between 350 and 500 ° C. The results show that the oxidation of molybdenum is the first to generate MoO_2 on the surface, MoO_3 appears only after the growth of MoO_2 to a certain thickness, which is related to temperature and oxygen pressure. The growth of MoO 2 obeys the parabolic law. Although MoO 3 appears to slightly increase the oxidation rate of molybdenum, it does not mean that MoO 2 stops growing. In the case of simultaneous growth of MoO_3 and MoO_2, the oxidation of molybdenum still obeys the parabolic law. Oxidation of the surface of the MoO_3 grains with the oxidation time becomes larger, up to a certain extent, the grain tends to easily fall off from the surface, sleepy and oxide is a symbol of porosity. This looseness may shift the oxidation of molybdenum from a parabola to a linear regularity. The rate of oxidation of molybdenum is proportional to 2/3 of the oxygen pressure, ie KαP_ (O_2) ~ (2/3), at a pressure of 1-76 mmHg at 450 ° C. Therefore, it is reasonable to assume that the concentration of oxygen molecules in the surface adsorption layer under the above conditions plays a controlling role in the oxidation rate of molybdenum.