Qualifying Electrically Conductive Cold Embedding-Media for Scanning Electron Microscopy

Mineralogical information is becoming increasingly important for the interpretation and prediction of the long-term leaching behavior of mine waste rock and tailings, yet the collection of quantitative mineralogical data for these materials is complicated by biases introduced during sample preparation. Here, we present experiments with synthetic reference materials, soluble mineral (gypsum) and pulverized weathered waste rock samples to investigate potential artifacts that can be introduced during the preparation of granular sample specimen for quantitative mineralogical analysis. Our results show that, during epoxy-molding, particle segregation due to size is more important than that due to density, both of which can be effectively circumvented by cutting molds perpendicular to the orientation of settling. We also determine that sacrificing sample polish to avoid phase alteration need not impede phase attribution as long as surface roughness and slope are calibrated with sample-internal contrast references. Finally, bootstrapping analysis shows that variability in geometric and mineralogical particle parameters due to unresolved sample heterogeneity is small compared with other biases, even at particle numbers <25,000 at sizes >150 µm. Our results demonstrate the importance of quantifying potential sources of error during sample preparation in quantitative mineralogical studies on mine wastes.

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Conductive and Edge Retaining Embedding Compounds: Influence of Graphite Content in Compounds on Specimen’s SEM and EBSD Performance

Rojacz

Premauer

Nevosad

2021

Practical Metallography

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Since marginal sharpness is often an issue in metallographic samples preparation, various mounting compounds are commercially available which address these issues. Nevertheless, the conductivity of such products is not sufficient for electron backscatter diffraction measurements (EBSD) and products which are electrically conductive often result in a lack of marginal sharpness. Therefore, this study is focussed on the modification of commercially available embedding compounds (epoxy based and phenolic based hot embedding compounds) with graphite to increase their electrical conductivity. To verify the applicability of the modified embedding compounds, the austenitic steel grade 1.4301 was chosen for investigation via scanning electron microscopy and EBSD. Results indicate a good performance during SEM-investigations of the epoxy-based resins, even at 0 wt.-% graphite contents, whereas the phenolic resin-based embedding compound is only applicable for SEM-investigation > wt.-5 % of graphite. Best performance at EBSD measurements were achieved with phenolic resin based hot mounting compounds with glass fibres and an addition > 10 wt.-% graphite.

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Qualifying Electrically Conductive Cold Embedding-Media for Scanning Electron Microscopy

Cited by 3 publications

References 5 publications

Fatigue Behavior of Sheet-Bulk Metal Formed Components

Fatigue Behavior of Sheet-Bulk Metal Formed Components

Sample Preparation Biases in Automated Quantitative Mineralogical Analysis of Mine Wastes

Conductive and Edge Retaining Embedding Compounds: Influence of Graphite Content in Compounds on Specimen’s SEM and EBSD Performance

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