Internationally used aluminium powder as foaming agent,Guest Posting China used to be dominated by using aluminum powder, now except for introducing a few to offline, most have switched to aluminum powder paste.
First, aluminum powder’s gas reaction
Aluminum powder’s specific gravity is only 2.7, under standard conditions, per 1g Al produce 1.241 hydrogen, thus using aluminum powder to conduct gas reaction has the advantages of less use, low cost and so on. In addition, aluminum production is larger, sources are more widely and for aerated concrete production were better control on the process, is the most commonly used material for gas release.
Alumina is stable in air and water, and aluminum products used in our everyday life has purified aluminium oxide protection film can prevent aluminum being further oxidized, alumina in acid or alkaline environments can react with acids or bases, generates new salt, causes the coating destroyed. The commonly used aluminium powder, its particle surface always has oxidized, produces alumina protective film, preventing the aluminium contact with water, only after eliminating the oxide film, aluminium powder can react, swapping out the hydrogen in the water. Therefore, we say that 7075 aluminum extrusions aluminium powder as foaming agent should be conducted the gas release reaction in an alkaline environment.
Second, aluminium powders production process and its main characteristics
Aluminum powder is forming by dissolved aluminum ingot, using compressed air sprayed into fine powder, and then after the election, gets granular powder joins in the closed ball to levigate. In order to prevent aluminum powder oxidized during the grinding process, and thus cause a fire explosion, except for the specially designed of ball mill system, ensure tight seal and pump into the ammonia protection, it also should be adding a certain amount of stearic acid in the aluminum powder, make aluminum powder pulverized and form of stearic acid protective layer on the particle surface in the pulverized process. Now, it usually uses gas former aluminium powder paste, in the grounding process does not add stearic acid, nor ammonia protection, but joined the media and various additives for grinding, the finely ground aluminium paste through centrifugalizing