The densification of fine-grained tungsten carbide-based cermet with 25 wt.% cobalt binder during impact sintering at 1150, 1200, 1250, and 1300°C with the initial impact velocity of 5.8 and 6.2 m/s, with the initial solid-phase state of the binder, is investigated. Based on the obtained experimental data and the calculated elastic properties of the samples and the impact machine, the simulation of densification dynamics using third-order dynamic system is carried out by hit-and-miss method and the value of the shear viscosity of cermet matrix determining the energy dissipation in the system and the irreversibility of the material densification are obtained. In addition, the data on the phase trajectory of the dynamic system motion, the duration of impact loading, the time variations of the force, compression, velocity, and acceleration of the system, densification work, and the mechanical-thermal effect resulting from the energy dissipation and causing a significant increase in the temperature of the porous cermet samples are obtained. At the starting temperature of the samples close to that of eutectic formation and low starting porosity of the samples, this temperature increase can cause the liquid phase squeezing from the sample volume into the porous graphite shell that protects the samples against adhesion to the metal die. The estimated activation energy of the viscous flow of the matrix forming the porous cermet is 1.1 eV or 103 kJ/mol.
Similar content being viewed by others
References
M. S. Kovalchenko and A. V. Laptev, “Dynamics of WC–Co hard alloy compaction with hot pulsed pressing,” Powder Metall. Met. Ceram., 43, Nos. 3–4, 117–126 (2004).
M. S. Kovalchenko and L. F. Ochkas, “Densification dynamics of copper and iron powder billets in hot shock compaction: Simulation and analysis,” Powder Metall. Met. Ceram., 47, Nos. 5–6, 273–283 (2008).
M. S. Kovalchenko, T. P. Hrebenok, and L. F. Ochkas, “Simulation of the compaction dynamics of Cu + Al2O3 powder mixture under impulse hot pressing,” Powder Metall. Met. Ceram., 49, Nos. 11–12, 637–646 (2010).
M. S. Kovalchenko, “The dynamics of mechanical actions on materials. V. Periodic and aperiodic movements of an autonomous dynamic system,” Powder Metall. Met. Ceram., 36, Nos. 3–4, 217–225 (1997).
M. S. Kovalchenko, “Pressure sintering of powder materials,” Powder Metall. Met. Ceram., 50, Nos. 1–2, 18–33 (2011).
M. S. Kovalchenko, “Rheological models of pressure sintering of powders,” Powder Metall. Met. Ceram., 52, Nos. 1–2, 7–19 (2013).
M. S. Kovalchenko, “Rheology and kinetics of pressure sintering,” Mater. Sci. Forum., 835, 76–105 (2016).
M. S. Kovalchenko, “Elasticity and viscosity of isotropic porous materials,” Powder Metall. Met. Ceram., 42, Nos. 1–2, 81–87 (2003).
M. S. Kovalchenko, “Strain hardening of a powder body in pressing,” Powder Metall. Met. Ceram., 48, Nos. 3–4, 133–144 (2009).
V. V. Skorokhod, Rheological Bases of Sintering Theory [in Russian], Nauk. Dumka, Kyiv (1972), p. 152.
R. B. Kotelnikov, S. N. Bashlykov, Z. G. Galiakbarov, and A. I. Kashtanov, Particularly Refractory Elements and Compounds: Handbook [in Russian], Metallurgiya, Moscow (1969), p. 376.
G. V. Samsonov (Ed.), Handbook of the Physicochemical Properties of the Elements, IFI / Plenum, New York–Washington (1968), p. 941.
A. Angot, Mathematics for Electrical and Radio Engineers [Russian translation], Nauka, Moscow (1965), p. 779.
Z. Hashin and S. Shtrikman, “A variational approach to the theory of the elastic behavior of multiphase materials,” J. Mech. Phys. Sol., 11, No. 2, 127–140 (1963).
G. V. Samsonov and I. M. Vinnitskii, Refractory Compounds: Handbook [in Russian], 2nd Edition, Metallurgiya, Moscow (1976), p. 560.
M. S. Kovalchenko, “Pressure sintering kinetics of tungsten and titanium carbides,” Int. J. Refr. Met. Hard Mat., 39, 32–37 (2013).
J. Freedel, Dislocations [Russian translation], Mir, Moscow (1967), p. 644.
Author information
Authors and Affiliations
Corresponding author
Additional information
Translated from Poroshkova Metallurgiya, Vol. 57, Nos. 1–2 (519), pp. 50–63, 2018.
Rights and permissions
About this article
Cite this article
Kovalchenko, M.S., Tolochyn, O.I. & Litvin, R.V. Densification Dynamics of Fine-Grained WC+25 wt.% Co Cermet During Low-Temperature Impact Sintering in Vacuum. Powder Metall Met Ceram 57, 38–48 (2018). https://doi.org/10.1007/s11106-018-9953-5
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11106-018-9953-5