坩埚对高温合金中氧氮及氢分析结果的影响

Influence of crucible on the analysis results of oxygen,nitrogen and hydrogen in superalloy

应用4台仪器考察坩埚对高温合金中氧、氮及氢分析的影响,首先从空白实验开始,进口和国产石墨坩埚氧空白稳定在0.0Xμg/g,氮空白稳定在0.Xμg/g,可以满足高温合金中氧和氮的分析需求。国产石墨坩埚达到国际同类坩埚水平,可以满足实验针对坩埚应用研究的基本要求。实验表明:石墨套坩埚氧空白值最低,石墨套坩埚与单坩埚氮空白值相同,石英坩埚氢空白值最低。借助于钢中氧氮氢联测标样(502-863),比较石墨套坩埚和单坩埚在3台仪器上氧氮分析的差异,结果显示:用同一条内置标线进行计算,套坩埚对氧和氮分析结果比单坩埚低;按套坩埚和单坩埚自行建立的两条对应标线进行计算,两种坩埚对氧和氮分析结果基本一致。而对氢的分析检测,石墨单坩埚数据严重偏离而被禁用,套坩埚可以应用于较高含量氢(不小于0.6μg/g),钢标样中超低氢分析仅石英坩埚数据最佳。应用现有标钢已建立的标线和方法,3种坩埚、4台仪器实测高温合金样品中氧氮及氢含量,每组45点以上数据显示:高温合金实际样品中氧含量数据最分散,氮的测定值相对集中,不同坩埚之间氢的分析结果差别非常大。自带的高温合金内控样分析数据显示:石墨单坩埚氧氮测定值略高于套坩埚氧氮测定值,而3仪器间的差别很小。对高温合金中氢进行测定时,石墨坩埚与样品相互作用产生干扰,比石英坩埚数值虚高,特别是石墨单坩埚产生的干扰比石墨套坩埚更大,不建议使用。石英坩埚成为高温合金中超低氢分析的最佳选择。由于坩埚损坏和鼓泡导致的异常数据可以通过观察用后坩埚及时发现和剔除,不失为降低坩埚不良影响的有效手段之一。

The influence of crucible on analysis results of oxygen,nitrogen and hydrogen in superalloy was investigated using four instruments.The experiments firstly started from the blank test.The oxygen blank of imported and domestic graphite crucible was stabilized at 0.0 Xμg/g,while the nitrogen blank was stabilized at 0.Xμg/g,which could meet the analysis requirements of oxygen and nitrogen in superalloy.The quality of domestic graphite crucible reached the level of international crucible with similar type,and it could meet the basic requirements in the study.The results showed that the oxygen blank of graphite duplex crucible was lowest.The blank value of nitrogen was the same for graphite duplex crucible and single crucible.The blank value of hydrogen was lowest for quartz crucible.With the help of certified reference material(CRM,502-863)for simultaneous determination of oxygen and nitrogen,the analysis difference of oxygen and nitrogen in three instruments was compared between graphite duplex crucible and single crucible.The results indicated that the analysis results of oxygen and nitrogen was lower for the duplex crucible compared to the single crucible when same internal calibration curve was used for calculation.If two corresponding calibration curves prepared separately for duplex crucible and single crucible were used for calculation,the analysis results of oxygen and nitrogen were basically consistent.In terms of analysis and detection for hydrogen,the graphite single crucible had serious data deviation,and it could not be used.The duplex crucible was applicable for the analysis of sample with high hydrogen content(not less than 0.6μg/g).For the analysis of ultralow hydrogen in steel CRM,only the result of quartz crucible was best.Based on the calibration curves and methods established using the existing steel CRMs,three types of crucible,and four instruments,the content of oxygen,nitrogen and hydrogen in superalloy sample was determined.There were more than 45 data points in each group.The results showed that the data of oxygen content in actual superalloy sample were most dispersed,while the determination results of nitrogen were relatively concentrated.The analysis results of hydrogen had great difference among different crucibles.The analysis data of build-in internal control sample of superalloy indicated that the determination results of oxygen and nitrogen by graphite single crucible were slightly higher than those obtained by graphite duplex crucible.Meanwhile,the difference among three instruments was very little.During the determination of hydrogen in superalloy,the interaction between graphite crucible and sample cause interference,so the determination results were higher than those obtained by quartz crucible.Particularly,the interference caused by graphite single crucible was higher than that of graphite duplex crucible,and was not suggested for use.The quartz crucible was the best choice for the analysis of ultralow hydrogen in superalloy.The abnormal data caused by crucible damage and bubbling could be timely discovered and removed by observation of crucible after use.And it was one of effective approaches to reduced the adverse effect of crucible.