ACTIVATEEL SINTERING OF MOLYBDENUM BY ADDINGTWO METALS NICKEL-COBALT

As a refractory metal-molybdenum are widly used in various fieleds. Decreasing sintering temperature is an important problem in the preparation of molybdenum materials. This paper mainly dealt with characteristics of low temperature sintering of molybdenum by adding small amount of Ni-Co and that compared with the sintering of pure molybdenum, Mo-Co、Mo-Ni and Mo-Ni-Co systems. The sintering activation energies for these systems were determined. The low temperature sintering mechanism of molybdenum powder was studied. It was found that Ni-Co is a stronger activator at all temperatures studied. The activation energy of Mo-Ni-Co system is the lowest in above four sintering systems. These results proved that the addittion of two metals Mo-Co gives more apperciable densification than monometal cobalt or riickel# It shows the effect of synergism activation of nickel and cobalt on the sintering of molybdenum. The activated mechanism of two metals activator Ni-Co for the sintering of molybdenum is similar to monometal-nickel,We ascribe the activation effect of Ni-Co on the sintering of molyjdenum to comprehensive action, which includes solution-reprecipitation diffusion and other physics-chemistry processes,The predominant shrinkage mechanism for molybdenum is grain boundary diffusion.