Cobalt Aluminates

5 сентября, 2015

Pokraskin

Combinations of cobalt(II) oxide and aluminum oxide in the spinel stoichiometry give cobalt aluminate blue spinels, CoAl2O4, C. I. Pigment Blue 28. Variations of this pigment include modification by zinc (C. I. Pigment Blue 72), magnesium, titanium, and lithium oxides. If lithium and titanium modifiers are added, a turquoise blue pigment is obtained.

Cobalt aluminate blues are the most durable blue pigments commercially available. They have excellent chemical and heat stability, and can be used in chemically aggressive environments and exterior durable applications without color fade. One drawback is that these blues are poor UV absorbers when compared to other CICPs.

Table 5.3 Common aluminate-, chromite-, and ferrite-based CICPs.

Chemical type	C. I. Pigment	Color	Crystal Type
CoAl	Blue 28	Blue	Spinel
CoCrAl	Blue 36	Blue-green to teal green	Spinel
CoCr	Green 26	Dark green	Spinel
ZnFe	Yellow 119 Brown 31	Yellow-brown	Spinel
MgFe	Brown 11	Red-brown	Spinel
ZnCrFe	Brown 33	Brown	Spinel
FeCr	Green 17 Brown 29	Brown-black	Hematite/corundum
FeCr	Brown 35	Brown-black	Spinel
CuCrFe	Black 23	Black	Spinel
FeMn	Black 26	Black	Spinel
CoCrFe	Black 27	Black	Spinel
CuCr	Black 28	Black	Spinel
CoFe	Black 29	Black	Spinel
NiCrMn	Black 30	Black	Spinel