Aluminum powder, commonly known as "silver powder", that is, silver metal pigment, pure aluminum foil with a small amount of lubricant, after pounding crushed into a scaly powder, and then polished.
Aluminum powder is light in weight, high in buoyancy, strong in covering, good in light and heat reflection.
After treatment, it can also become non - leafing aluminum powder.
Aluminum powder is a kind of metallic pigment because of its wide use, large demand and variety.
Aluminum is a silver-gray metal with a relative molecular weight of 26.98, relative density of 2.55, purity of 99.5%, melting point of 685 degrees, boiling point of 2065 degrees, melting heat absorption of 323kj/g, aluminum has reducibility, easy oxidation, heat release in the oxidation process.
When oxidized rapidly, the heat released per gram is 15.5kj /g. Aluminum is ductile and easy to be processed.
The oxide film on the surface of metal aluminum is transparent and has good chemical stability.
The main features
1. Characteristics of scaly covering
Aluminium powder particles are scaly, its diameter and thickness of scale is about (40:1) - (100:1), aluminum powder scattered to the carrier has the characteristics of parallel to the substrate, and after numerous aluminium connected to each other, mutual size particles fill the form a continuous metal film, covering the substrate, and outside light reflection film, this is aluminium covering power.
The covering power of aluminum powder depends on the surface area, which is the diameter to thickness ratio.
Aluminum is extended in the grinding process, the diameter to thickness ratio increases continuously, and the covering power also increases accordingly.
2. Shielding characteristics of aluminum powder
The aluminum powder dispersed in the carrier always floats, and the result of the motion always makes itself parallel to the substrate coated by the carrier, forming a continuous aluminum powder layer, and this aluminum powder layer is arranged in parallel in multiple layers within the carrier film.
The pores of each layer of aluminum powder stagger with each other, cutting off the capillary holes of the carrier film. The outer water and gas cannot reach the substrate through the capillary holes, which is the good physical shielding property of aluminum powder.
3. Optical properties of aluminum powder
Aluminum powder by light color, high metallic luster of aluminum, its surface is smooth, can reflect visible light, ULTRAVIOLET light and infrared light of 60%-90%, with the coating containing aluminum powder coating object, its surface silver white bright, this is the characteristics of aluminum powder reflected light.
4. "Two-color effect" characteristics of aluminum powder
Aluminum powder has the characteristic of metallic luster and parallel to the coated substance. In the carrier containing transparent pigment, the brightness and color of aluminum powder change with the change of incident Angle and Angle of view, which is called "two-color effect".
Aluminum powder is arranged in different layers in the coating film. When the incident light hits each layer of aluminum flake, it will be weakened by passing through different thickness of the coating film, and the reflected light will obviously have different brightness.
When light hits including transparent pigment and aluminum film, incident light through the paint particles become light, reflected by different levels of aluminum powder, can change colors and light metal, incident light and the Angle from the vertical occur gradually angular displacement, the light is through different quantity of pigment particles and different particle size of aluminum powder, of the light reflected from its tone and light metal and endless changes.
This characteristic of aluminum powder, has been widely used in coatings, as hammer paint or metal paint.
5. leafing characteristics of aluminum powder
One of the major grades of aluminum powder and paste used for pigments is the leafing grade, which is characterized by the scale-like leafing on the surface of the coating film.