Bulk trace and distribution analysis in refractory and hard metals. examples from research and development and applications in quality assurance

Abstract

For the characterization of high purity materials with respect to trace impurities in the ng/g range it is state of the art to use high sensitive methods such as GDMS and SIMS. The low sample consumption of these methods is a significant drawback in the characterization of sintered materials due to the heterogeneous distribution of the trace impurities. TMS procedures with AAS, ICP-AES and ICP-MS end determination overcome these problems by the enrichment of the impurities in a small volume of diluted acid. In many cases of research work and quality assurance distribution analysis is more meaningful than bulk analysis. A few examples are given to demonstrate the respective potential of SIMS. Diffusion processes of K and Si in doped Mo are investigated. Depth profiling on single grains shows the effect of surface cleaning of high purity Cr-powder by etching with HF-acid. Quality control of Mo foils is achieved by high resolution depth profiling for O and S. Influences on CVD process parameters can be derived from high resolution S depth profiling in the Al2O3 layer of coated hard metals. Furthermore, outlooks are given on the applications of high resolution SNMS, 3D-SIMS and high resolution ICP-MS.