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

A new method of casting a melt of a berate fusion bead glass is propos ed, After reaching a suitable low viscosity, the melting glassbody wil l now through a hole in the bottom of a BN coated ceramic crucible int o a mould of platinum or a mould made from pressed BN powder, The form ed glass disks are intended for S-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 crucibl e has a conic shape and is coated with a thin layer of mainly fine-gra ined BN powder that contains some additives, The performance character istics of the BN coated crucible hale been compared with those of stan dard Pt-Au crucibles and different kinds of dense BN crucibles, Reprod ucibility tests carried out for a wide variety of samples showed the g eneral 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 tendenc y to escape when the sample was fused as glass, Element losses attribu table to other causes and chemical interactions were included in the s tudy, Advantages and disadvantages of the new BN coated crucible are d iscussed, One notable advantage is the substantial cost saving that ca n be achieved using BN coated ceramic crucibles to prepare samples for analysis.