惰气熔融-红外吸收光谱法测定镧铈稀土钢中氧含量

高品质稀土钢要求进行精确低氧含量控制，而依据现有GB/T11261-2006标准进行氧含量测定，检测结果具有较大的不准确性。本研究以具有不同镧、铈稀土元素含量的稀土钢为对象，以其氧含量精确测定为目标，基于惰气熔融-红外吸收法，开展了分析功率、助熔剂和称样量对镧铈稀土钢中氧含量分析结果的影响研究。结果表明，对于不同镧、铈元素含量的稀土钢，需要采用不同的分析方法：当稀土钢中的镧、铈含量较低时，通过降低分析功率即可较为精确的测定稀土钢中的氧含量；对于镧、铈含量较高的稀土钢，在调控分析功率（分析功率在4000W～4500W）的基础上，需同时采用锡作为助熔剂，并将助熔剂与样品比例设定为1:1（称样量为0.3g～0.6g），即可实现氧含量的精确测定。精密度验证实验结果显示，采用本研究所建立的方法，氧含量测试结果相对标准偏差（RSD）小于8.0%；采用钢标样进行回收率实验，回收率值在97%～108%，而加标回收率略有升高的原因在于助熔剂Sn降低了合金熔点，使少量难熔氧化物中的氧得到更充分释放。本研究所建立的分析方法可准确测定不同镧、铈元素含量稀土钢中的氧含量。

Determination of oxygen in the rare earth steel by inert gas fusion infrared absorption method

High quality rare earth steel requires precise control of low oxygen content, and testing results based on existing GB/T11261-2006 standards have significant inaccuracies. This study focuses on rare earth steel with different levels of lanthanum and cerium rare earth elements, with the goal of accurately measuring its oxygen content. Based on inert gas melting infrared absorption technique, an approach for determining oxygen content in La-Ce rare earth steel was explored. According to different contents of La and Ce in the rare earth steel, a special analysis method was established, and the effect of analysis power, flux and sample mass on the analysis results was investigated. Experimental results showed that a moderately low analysis power was helpful for accurate determination of oxygen content in the rare earth steel. For the steel with high content of rare earth, the oxygen analysis needed the aid of tin flux with a mass ratio of 1:1 to the sample. The best result was obtained while the analysis power was set between 4000W and 4500W with the sample weight ranging from 0.3g to 0.6g. Experiment for precision showed that the relative standard deviation (RSD) was less than 8.0%, and rates of recovery from 97% to 108% were confirmed by employing certified reference material. These results prove that this method can be used for accurate determination of oxygen in rare earth steel.