Flake aluminum powder
Aluminum powder, commonly known as "silver powder", is a silver-colored metallic pigment. It is made by adding a small amount of lubricant to pure aluminum foil and crushing it into flaky powder through pounding. Then, it is polished to form. Aluminum powder is lightweight, has high buoyancy, strong covering power, and good reflective properties to light and heat. It can also be processed into non-floating aluminum powder. Aluminum powder can be used to identify fingerprints and can be used in fireworks. Due to its wide range of uses, large demand, and various varieties, it is a major category of metallic pigments.
Compared with other pigments, pigment-grade aluminum powder has more of its own characteristics in the following aspects:
1. The characteristic of flake-like covering
The aluminum powder particles are in the form of flakes, with the ratio of the particle diameter to thickness being approximately (40:1) - (100:1). After being dispersed into the carrier, the aluminum powder has the characteristic of being parallel to the substrate, with numerous aluminum powder particles connecting with each other and filling the continuous metal film to cover the substrate and reflect the light outside the coating. This is the unique covering power of aluminum powder. The size of the aluminum powder's covering power depends on the size of the surface area, that is, the ratio of diameter to thickness. During the grinding process, aluminum is elongated, and the ratio of diameter to thickness increases, resulting in an increase in covering power.
2. The shielding characteristic of aluminum powder
The aluminum powder dispersed in the carrier undergoes floating motion. The result of this motion is always to make itself parallel to the substrate being coated, forming a continuous layer of aluminum powder, and this aluminum powder layer is arranged in multiple layers parallelly within the carrier film. The pores between each layer of aluminum powder are offset, cutting off the capillary pores of the carrier film, preventing external moisture and gases from passing through the capillary pores to the substrate. This characteristic is the good physical shielding property of aluminum powder.
3. The optical properties of aluminum powder
Aluminum powder is made of aluminum with a light color and high metallic luster. Its surface is smooth and can reflect 60%-90% of visible light, ultraviolet light, and infrared light. When coated on an object with aluminum powder-containing paint, the surface becomes silver-white and shiny. This is the characteristic of aluminum powder reflecting light.
4. The "double-color effect" characteristic of aluminum powder
Due to its metallic luster and the characteristic of being parallel to the coated object, the gloss and color depth of aluminum powder in the carrier containing transparent pigments change with the incident angle and viewing angle of the incident light. This characteristic is called the "double-color effect". Aluminum powder is arranged in different layers within the coating, and when the incident light shines on each layer of aluminum flakes, due to the different weakening of the coating thickness, the reflected light has different brightness. When light enters the layer containing transparent pigments and aluminum powder, the incident light becomes colored light, and then passes through different layers of aluminum powder and is reflected, resulting in changes in hue and metallic light. The incident light and viewing angle gradually change from vertical to an angle, and the light passes through different numbers of pigment particles and particles of different diameters, resulting in infinite changes in the hue and metallic light of the reflected light. The characteristic of this property has been widely applied in coatings, as hammering paint or metallic paint.
5. The floating characteristic of aluminum powder
One type of pigment-grade aluminum powder and aluminum powder paste is floating type. Its characteristic is that the flake-like aluminum powder floats on the surface of the coating.