Peculiarities of Granulation of the PAP-2 Aluminum Powder in the Technology of the Al–Al2O3 Powder Composite with a Layered Structure

Аннотация

An analysis of modern scientific-and-technical information evidences great prospects for using composite materials (CMs) based on the Al–Al₂O₃ system. It is shown in works of the Materials Science Department of the Moscow Aviation Institute that one promising method of fabricating aluminum-based CMs is the reaction sintering in air of blanks made of highly dispersed powders of the PAP-2 brand. However, to implement the proposed method in practice, it is necessary to solve a series of problems, in particular, associated with their low manufacturing properties, such as a lack of fluidity and extremely low apparent density. To granulate the PAP-2 aluminum powder, various process approaches are applied. They are based on process operations such as powder heating in air with subsequent isothermal holding at 350°C, introducing water-diluted sodium silicate glass into its composition, mechanical processing of the powder in a high-energy planetary mill, its heat treatment in vacuum at 650°C, and initiating the stearin saponification reaction on the surface of the PAP-2 flaked particles with the formation of the organic plasticizer component. It is found that the proposed granulation methods of the industrial PAP-2 powder make it possible to improve and vary the process characteristics of the initial powder, as well as modifying its composition and structure. The highest apparent density (up to 1.25 g/cm³) is attained when using the mechanical treatment of the initial powder in a high-energy planetary mill with the formation of rounded granules 50–150 μm in size. The most producible and cost-effective method is based on the initiation of the chemical reaction of stearin saponification on the surface of powder particles (the apparent density is ~0.4 g/cm³).