ISO/TR 7955:1982, Ferroniobium - Determination of niobium content - Gravimetric method

Specifies a photometric method for the determination of the titanium content (annex A), a gravimetric method for the determination of tantalum contents greater than 1 % (m/m) (annex B) and a photometric method for the determination of tantalum contents less than 1 % (m/m) (annex C). The methods are applicable to ferroniobium having niobium contents between 40 and 75 % (m/m), tantalum contents between 0,25 and 8,0 % (m/m) and titanium contents between 0,05 and 5,0 % (m/m). Interference may arise if bismuth or trivalent antimony are present.