Conclusions
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1.
An analysis is made of the effects of external friction upon the rates of densification of Newtonian and non-Newtonian porous solids in hot pressing. It is shown that external (die-wall) friction brings about uneven flow of a porous solid being pressed.
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2.
It has been established that the rate of densification of a Newtonian porous solid is directly proportional to the applied pressure and inversely proportional to the shear viscosity of its solid phase, the initial relative density, the coefficient of external friction, and the height-to-diameter ratio. For a non-Newtonian porous solid, the influence of all these factors except viscosity grows to a degree corresponding to the exponent of the nonlinear flow equation.
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3.
Decreasing the coefficient of external friction accelerates the densification process, enabling higher and more uniform density and physicomechanical properties to be obtained in hot-pressed blanks and components.
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4.
The effects of external friction are reduced in double-ended pressing and eliminated in isosatic pressing.
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Translated from Poroshkovaya Metallurgiya, No. 7 (151), pp. 22–26, July, 1975.
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Koval'chenko, M.S. Effects of external friction upon the rate of densification of a viscous porous solid in hot pressing. Powder Metall Met Ceram 14, 534–537 (1975). https://doi.org/10.1007/BF00810985
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DOI: https://doi.org/10.1007/BF00810985