Abstract
A rapid and sensitive infrared spectrometric method is described for the determination of microgram quantities of boron nitride in steel. An infrared absorption spectrum of boron nitride (BN) is characteristic and sensitive as reported by Ohiko Kammori and others, by whom a very successful method for the determination of BN in steel has been proposed.
In this study further improvements were made by employing the procedure of the incineration of the residues, that is, the recovery of BN on filter became complete and very little effects of other chemical compounds (carbides, filter, etc.) were observed.
0.5 to 1.0g of sample is dissolved with 50ml of H2SO4 (1+6) in a 200ml beaker, then the solution is filtered with fine pore size filter as used for BaSO4 filtration. The residues on filter paper in a crucible is heated very gently with small flame of burner until all the paper is reduced to carbon without taking fire, then incinerated in electric furnace at 500°C for 20 minutes.The resulting residues mixed with 300 mg of KBr for about 15 minutes in agate motor is prepared into a pellet of 13 mm in diameter. Absorbance measurements of the characteristic BN band at 1380-1 cm are made by the base line method. The minimum detectable content of BN in steel was 0.0001% and the calculated values as B agreed to the acid insoluble B content.
