Cobalt Blue

Cobalt blue is mainly composed of CoO, Al2O3, or cobalt alumate [CoAl2O4]. According to the chemical formula theory, Al2O3 content is 57.63%, CoO content is 42.36%, or containing Co 33.31%. But the actual composition of cobalt blue pigment Al2O3 in 65% ~ 70%, CoO in 30% ~ 35%, some cobalt blue pigment cobalt oxide content is even lower than 10% or 10%, because there may be a small amount of other elements oxides, such as Ti, Li, Cr, Fe, Sn, Mg, Zn and so on. For example, the analysis of a cobalt blue pigment variety shows that CoO is 34%, Al2O3 is 62%, ZnO is 2% and P2O5 is 2%. In addition to the main composition, cobalt blue may contain a small amount of alumina, cobalt green (CoO·ZnO) and cobalt violet [Co2(PO4)2] to change the hue of cobalt blue pigment. These pigments belong to the spinel class, which is a cube with spinel crystals. The relative density is 3.8 ~ 4.54, the covering power is very weak, only 75 ~ 80g/m2, oil absorption is 31% ~ 37%, apparent specific capacity 630 ~ 740g/L, the quality of modern cobalt blue is essentially different from that of early products. Cobalt blue pigment has bright color, excellent weather resistance, alkali resistance, can withstand all kinds of solvents, heat resistance up to 1200℃. Its main weak color is not as good as phthalocyanine blue pigment, because it is calcined at high temperature, although after grinding, but the particles have a certain hardness.

Use:
(1) Cobalt blue bright color, excellent weather resistance, alkali resistance, can withstand all kinds of solvents, heat up to 1200℃.
(2) Cobalt blue is a kind of environmental protection non-toxic high temperature resistant inorganic pigment.
(3) Cobalt blue is mainly used for high temperature resistant coatings, ceramics, enamel, glass coloring.
(4) Cobalt blue is also used for high temperature resistant engineering plastics coloring, and as a fine art pigment.