ПОЛУЧЕНИЕ ВЫСОКОКАЧЕСТВЕННЫХ ПОРОШКОВЫХ КОМПОЗИЦИОННЫХ МАТЕРИАЛОВ МЕТОДАМИ ПОРОШКОВОЙ МЕТАЛЛУРГИИ

МАТЕРИАЛОВЕДЕНИЕ

Аннотация

In difficult operating conditions, the use of powder can be achieved only when its absolute density is achieved in the case of elimination of all types of porosity. Isostatic concentration and hot isostatic molding are partially the most promising methods for condensation of irregularly stretched powders or cold-pressed particles. In the case of simultaneous exposure to temperature and pressure for almost all solid materials, 100% or similar density can be achieved. Another method of obtaining absolute density provides hot or cold pressing after intermediate preparation of the powder. The possibility of using hot extrusion of the synthesis of powder composite materials on a metal basis is substantiated. Extrusion provides a non-porous structure and combines the processes of extrusion and clumping, and the high velocities of molding completely eliminate the negative interaction of the matrix and the hardening phase. The mechanisms and kinetics of compaction, as well as the processes of structure formation of composite materials and high mechanical properties are revealed. The creation of materials and products with a non-porous structure is a fundamental direction in the field of powder metallurgy. Porosity is a discontinuity, i.e. structural defect, which not only significantly reduces the strength properties of the composite material, but also accelerates corrosion and ageing. At hot extrusion, maximum degrees of deformation are achieved ( =60...90%), whereas with static and dynamic pressing, they do not exceed 15 ... 20%. In addition, the extrusion process is characterized by shear plastic deformations caused by the action of deviator stresses.