【摘要】 1.用称重、化学分析、X射线相分析等方法研究六硼化镧于800及1000°在空气中的氧化作用。 2.在试验中采用酸洗除氧化膜方法求得真实氧化量、结果表明以原试样单位表面积计的氧化量(μ)随温度、时间的增加而增加。 3.生成物之一氧化硼在试验条件下将部分挥发。由于氧化硼挥发速度的差(己廾)导致800°与1000°时生成的氧化膜之组成有所不同,而试样在各温度下不同的重量变化系氧化增重和氧化硼挥发而减重两因素加合的结果。更多还原

【Abstract】 The oxidation of lanthanum hexaboride in air at 800 and 1000℃ has been studied by the thermogravimetric method, chemical analysis and X-ray diffraction. The reaction in air at our experimental conditions may be expressed by:4LAB₆+21O₂→4LaBO₃+10B₂O₃The rate of oxidation of lanthanum hexaboride has been investigated by finding the extent of oxidation of different specimens at definite time intervals after dissolving the oxidation layers formed on their surfaces by dilute hydrochloric acid. The experimental results may be summarized by the following relation: μ=a t^k, where μ is the extent of oxidation （=the amount of LaB₆ oxidized per unit surface area of the original specimen）, t is the time of oxidation, and a and k are constants at given temperature. It is found that k=0.75 and 0.95 at 800 and 1000° respectively.Under the experimental conditions, part of the boron oxide formed volatilizes, hence it is impossible to measure the extent of oxidation of the specimen directly from the weight increase. The changes in weight of specimens at different temperatures and at different time intervals are the results of summation of two factors: the weight gained due to oxidation and the weight lost due to volatilization of the boron oxide formed.更多还原