Quality standard of aerated aluminum powder
There are many classifications of aerated aluminum powder. Different types have different precision ranges, and their use and performance are very different. Aerated aluminum powder should be used for special purposes, so it has strict quality requirements. The activity rate of aerated aluminum powder is As well as the fineness of the product, the appearance and shape, as well as the overall physical and chemical reactions, they must meet the relevant standards. The following is a detailed introduction.
1. Active aluminum of aluminum powder: The amount of air generated by aluminum powder determines the amount of aluminum powder used in aerated concrete. The amount of gas generated by aluminum powder refers to the volume of hydrogen produced by a unit mass of aluminum powder that fully reacts with water in a standard state. 1g of metallic aluminum has a theoretical gaseous volume of 1.24L under standard conditions, while industrial aluminum powder contains a small amount of impurities, and some aluminum is oxidized into alumina, which makes the actual gaseous volume of aluminum powder lower than the theoretical value.
2. The fineness of aluminum powder: The fineness of aluminum powder does not affect the amount of gas generation, but it affects the rate of gas generation. The finer the aluminum powder, the larger the specific surface area, and the larger the surface area involved in the reaction, so the gas generation starts earlier. The speed is fast, and the end of the breath is also early. In the production process, aluminum powder needs to have stricter quality control, and its fineness is usually controlled within a certain range. Some manufacturers and production processes are different, and the actual fineness still fluctuates greatly, which will cause aerated concrete The stability of pouring becomes worse.
3. Particle shape of aluminum powder: The shape of aluminum powder has an important effect on the gas generating characteristics of aluminum powder. The shape of aerated concrete is required to be ground broad-leaved or irregular scaly. The ground aluminum powder particles, It forms a flat thin scaly shape with a larger new metal surface, thereby increasing the area of gassing reaction.
4. The gas evolution rate of aluminum powder: The above introduced the physical and chemical properties of aluminum powder quality standards. Whether the physical and chemical properties of aluminum powder meet the needs of the production of aerated concrete must be reflected in the gas expansion process of the slurry. Therefore, the determination of the gas evolution process of aluminum powder in the slurry can make a comprehensive evaluation of its performance.
5. Water dispersibility of aluminum powder: aerated aluminum powder is a hydrophilic metal aluminum powder, which is suspended in an aqueous solution in water. When aluminum powder is added to the slurry, the better the water dispersibility, the more soluble in water, and the gas reacts. It can be done as soon as possible. Some aluminum powder manufacturers use some aluminum products that contain oil or other water-insoluble impurities to produce aerated aluminum powder, which will cause water-insoluble substances on the surface of the aluminum powder, resulting in water dispersion of the aluminum powder It has poor performance, does not disperse in the slurry, and agglomerates, which eventually leads to unsmooth gassing and affects pouring quality.