Minimisation of toxicity in nickel ferrite black pigment

Abstract

Black ceramic pigments are usually prepared from a mixture of transition metal oxides, including toxic and hazardous elements such as Ni, Co, Cr, and Mn. Spinel type black ceramic pigments based on Ni(Fe,Cr)₂O₄ prepared by a ceramic method have been optimised to reduce toxic and hazardous components. Ni (an A1 carcinogen as classified by ACGIH)has been partially substituted by inert elements such as Mg and Zn and the content of Cr (an A1 carcinogen in hexavalent form) has been minimised, to obtain a black ceramic pigment in which the important properties (colour and stability) are maintained. The black pigments obtained have been glazed and compared with commercial pigments. While maintaining adequate colouring properties, the concentration of toxic elements in the composition has been reduced.