提出了在压片法X射线荧光光谱分析中存在包覆效应.用粉末压片X射线荧光光谱法测定刚玉镁砂浇注料的成分时,氧化镁的测定结果偏高,氧化铝的测定结果偏低,且偏低量、偏高量相近.用玛瑙研钵将样品不断研磨至更小的粒径时,上述现象没有明显的改变,表明此现象不属于粒度效应.用分别研磨至0.096 mm的刚玉和镁砂粉末,按氧化铝和氧化镁含量与浇注料相近的比例混合均匀后,分别用压片法和熔片法测定,发现两种制片方法测定结果相近,表明上述现象也不是矿物效应.因此,提出了包覆效应的概念.用已有的报道证实了包覆效应,并指出了粒度效应、矿物效应和包覆效应的区别.

Coating effect in XRFS analysis with pressing discs was proposed. It was discovered that the measured results of MgO was lower,while Al2O3 was higher in castable alumina and magnesia by XRFS,and the degree of the discrepancy was equal. This phenomenon could not be significantly changed by grinding sample to lower size with agate mortar. Thus,it was not affected by the particle size of the sample. When alumina and magnesia were grinded to 0.087 mm,and then mixed in according to the amounts of MgO and Al2O3 in the castable alumina and magnesia,the difference of the results between the pressing discs and melted discs was very small. Thus,the phenomenon could not be explained by mineral effect either. Therefore,the idea of coating effect was proposed. The coating effect in original research literature could be found. And the difference between the coating effect,the particle size effect,and the mineral effect was given.