People commonly used iron oxide pigments are divided into many colors, including blue iron oxide blue, brown iron oxide brown, red iron oxide red, yellow iron oxide yellow, etc. Since they are all called iron oxide pigments, why are so many colors present? Where are their color advantages? Let's understand the mysterious world of iron oxide.
The color of iron oxide pigment is not only related to its chemical composition, but also its crystal configuration and particle size, such as iron oxide red is α -fe2o3, iron oxide yellow is α -fe2o · H2O, and iron oxide black is Fe3O4.
The small difference of grain size and shape has a very important influence on the properties of pigment when the chemical composition is the same as crystal configuration. For the wet synthesis of iron oxide red, its particles are nearly globular. When the particle size increases from 0.15 μ m to 0.5 μ m, its color gradually changes from light orange (yellow) to dark red and dark brown red (purple red). The color saturation (c* value) increases first, then decreases gradually after the maximum value, and the brightness (l* value) changes generally. For dry process iron red, its c* value and l* value of alum forging *The results show that the color of the particles is needle rod, and their color is not only determined by the size of the particle's axial ratio, but also closely related to the diameter of the short axis. With the increase of iron oxide yellow particles, the color of the pigment changes from light lemon yellow to orange yellow, and the color saturation c* value and brightness l* value increase to the maximum value first and then decrease gradually. The shape and integrity of the particles also have a significant influence on the optical properties.
The color of pigment is the most characteristic property of pigment performance, especially the pigment. The color essence of pigment is closely related to its chemical composition. Different chemical composition pigments have their own color, but the color still has some range of changes. Although the chemical composition is the same, the difference in particle size, particle size distribution, impurity content and so on will cause the difference of color light. Moreover, the color is extremely sensitive to these factors, and it is also the sensitive of human eyes to color, which is also the reason why the color light of pigment is difficult to control absolutely consistent.