Certification of a Boron Carbide Powder Reference Material for Chemical Analysis

Abstract

The certification of a boron carbide reference material for chemical composition is described. The mass fractions of 16 elements and two boron species are certified in an international interlaboratory comparison with 35 participating laboratories from six different countries. Beside chemical characterization the certification process includes homogeneity and stability testing of the candidate material boron carbide (type F360, 305M422). Details of the analytical methods used for chemical characterization and of the calculation of the uncertainties of the certified mass fractions are given. The new reference material ERM®‐ED102 with certified mass fractions of 18 parameters (elements and species) and of the amount fraction of the isotope 10B is a valuable tool for laboratories working in the field of advanced ceramic materials analysis to improve their analytical results.

Comparison of sample preparation methods for determination of free carbon in boron carbide by X-ray powder diffraction

“…The curve crosses the horizontal axis at a value of −1.14 to the left of the origin, indicating that the free carbon content of the original B 4 C powder was 1.14 wt%. This value is far from the mass fraction of free carbon (0.51 ± 0.12 wt%) given as an indicative value for the B 4 C powder (ERM-ED 102) [26]. The significant difference between these values was assumed to be due to substantial amorphization of graphite during the grinding process [43].…”

“…It should also be mentioned that although Matschat et al [26] (from BAM Federal Institute for Materials Research and Testing) in their attempt to certify the chemical composition of B 4 C reference material by international interlaboratory comparison with 35 participating laboratories from six different countries, were able to certify the mass fractions of 19 elements and species in B 4 C, but in the case of free carbon as well as Mg and W, the data were not good enough to certify their mass fractions because of the high spreading among the laboratory mean values. For free carbon, which had to be determined by all the laboratories using the wet chemical oxidation method, proposed originally by Schwetz and Hassler [16], the reported mass fractions were between 0.39 and 0.66 wt%, i.e., the lowest result was ~40 % different from the highest value [26].…”

“…For free carbon, which had to be determined by all the laboratories using the wet chemical oxidation method, proposed originally by Schwetz and Hassler [16], the reported mass fractions were between 0.39 and 0.66 wt%, i.e., the lowest result was ~40 % different from the highest value [26]. Therefore, the mass fraction of free carbon in BAM ERM ® -ED 102 (type 305F422) B 4 C powder was given as an indicative and not a certified value (0.51 ± 0.12).…”

“…The resulting carbon dioxide is measured by manometry, gravimetry, infrared absorption or coulometry [16,23,26,27]. Generally, the wet chemical method is also unreliable and does not provide sufficient accuracy and precision [24,28] unless the partial oxidation of the combined carbon is accounted for by performing necessary corrections [23,25,26].…”

“…In the wet chemical oxidation method, which is based on oxidation of carbon to carbon dioxide using chromic-sulfuric acid [21][22][23] or nitric acidpotassium chlorate mixture [24], also the combined carbon is oxidized to some extent [22,25]. The resulting carbon dioxide is measured by manometry, gravimetry, infrared absorption or coulometry [16,23,26,27]. Generally, the wet chemical method is also unreliable and does not provide sufficient accuracy and precision [24,28] unless the partial oxidation of the combined carbon is accounted for by performing necessary corrections [23,25,26].…”