基于四极质谱计质量歧视效应修正的材料CxHy放气率测试方法研究

Research on Measurement Method of Material CxHy Outgassing Rate Based on the Correction of Mass Discrimination Effect of Quadrupole Mass Spectrometer

材料的碳氢化合物分放气率直接关系到精密仪器的稳定性、可靠性及寿命,分放气率的测量通过四极质谱计(QMS)测量的真空分压力计算得到。然而,QMS存在的质量歧视效应导致了大质量数离子的测量灵敏度降低,从而影响碳氢化合物分放气率的测量准确度。针对该问题,文章对小孔流导法分放气率测量装置进行了优化改进,并提出了一种利用十二烷修正QMS质量歧视效应的方法。为验证方法的有效性,对两台QMS的质量歧视效应进行了修正,并选取聚四氟乙烯(PTFE)、氟橡胶(FKM)样品,测试了不同时刻碳氢化合物的放气率,结果表明,文章所提方法可以有效地降低QMS的质量歧视效应,另外,通过质量歧视修正后的碳氢化合物放气率较未修正时有明显上升,其中PTFE样品CxHy-1、CxHy-2放气率分别上升19.78%、123.83%,FKM样品CxHy-1、CxHy-2放气率分别上升31.91%、155.22%。

The outgassing rate of carbon-hydrogen compounds from materials significantly impacts the stability,reliability,and lifespan of precision instruments.Measurement of partial outgassing rate is accomplished through vacuum partial pressure calculations using a quadrupole mass spectrometer(QMS).However,the mass discrimination effect of QMS reduces the measurement sensitivity of high-mass ions,which affects the measurement accuracy of hydrocarbon outgassing rates.Aiming at this problem,this study focused on optimizing and enhancing the apparatus for outgassing rate measurement by orifice conductance method.Additionally,a method utilizing dodecane as a calibration substance for the QMS was proposed to rectify the mass discrimination effect.To verify the effectiveness,the mass discrimination effect of two QMSs was corrected,and samples of PTFE and FKM were selected to test the outgassing rate of hydrocarbons at different times.The results show the method proposed in this paper can effectively reduce the mass discrimination effect of QMS.In addition,the outgassing rate of hydrocarbons in the sample corrected by the mass discrimination effect is significantly higher than that without correction.Among them,the outgassing rates of CxHy-1 and CxHy-2 of PTFE samples increased by 19.78%and 123.83%,respectively,and the outgassing rates of CxHy-1 and CxHy-2 of FKM samples increased by 31.91%and 155.22%,respectively.