Boron Nitride Coated Ceramic Crucible With a Hole in the Bottom—a New Device Replacing Expensive Crucibles for the Preparation of Fusion Bead Samples for X-ray Fluorescence Analysis

Abstract

A new method of casting a melt of a borate fusion bead glass is proposed. After reaching a suitable low viscosity, the melting glassbody will flow through a hole in the bottom of a BN coated ceramic crucible into a mould of platinum or a mould made from pressed BN powder. The formed glass disks are intended for X-ray elemental analysis. The crucible is an inexpensive item intended for once-only use, and it is produced from a mixture of ordinary refractory castable materials. The crucible has a conic shape and is coated with a thin layer of mainly fine-grained BN powder that contains some additives.

The performance characteristics of the BN coated crucible have been compared with those of standard Pt–Au crucibles and different kinds of dense BN crucibles. Reproducibility tests carried out for a wide variety of samples showed the general usefulness of the new crucible. Selected samples were analyzed. Special attention was paid to the analysis of a copper and an arsenic concentrate, since both contained volatiles that had a strong tendency to escape when the sample was fused as glass. Element losses attributable to other causes and chemical interactions were included in the study.

Advantages and disadvantages of the new BN coated crucible are discussed. One notable advantage is the substantial cost saving that can be achieved using BN coated ceramic crucibles to prepare samples for analysis.