The influence of gravity in sintering

Application of percolation theory in predicting shape distortion during liquid-phase sintering

“…[16]. Gravity has no effect on the [31] critical point of shape distortion. A possible explanation is When h ϭ 0, the critical coordination number approaches that there is a dramatic decrease in the compact rigidity at 1.5/ and the critical contiguity approaches that of Eq.…”

“…neck section resolved into the direction of gravity and the A normal force on the bonds creates a compressive stress pressure distribution parameter (q), we get gradient, such that there is enhanced material transport away from necks with the normal direction aligned parallel to the F j ϭ qX 2 4 cos j [18] axial direction. [31][32][33][34] The consequence is more shrinkage in the axial direction than in the radial direction. However, the model presented in this article does not consider anisotropic where j is the angle between the gravity direction and normal direction for the neck section j.…”

“….0014 (N * c Ϫ 1.5) and [33] For the 93 pct W-4.9 pct Ni-2.1 pct Fe alloy sintered at the C* ss ϭ 0.375 N * c Ϸ 0.75 ϩ 0.75 [34] The backbone fraction is determined by Eq. [4].…”

Finite Element Simulation of Liquid Phase Sintering with Tungsten Heavy Alloys

“…Hence, prior to liquid formation, shear viscosity, expressed in a form very similar to the bulk viscosity, can be approximated by assuming =K ¼ 0:6 as suggested by the analysis of Riedel et al 4) However, there are considerable conceptual and experimental difficulties that we encountered in using a shear viscosity of the form given in eqs. (8) and (9).…”

“…Experiments by Lenel et al 9) on copper and Upadhyaya and German 10) on tungsten heavy alloys (WHAs) illustrate the importance of gravity and friction on the densification and distortion behavior during sintering. Raman and German 11) considered the influence of gravity on the distortion of tungsten heavy alloys and proposed a rheological model to predict the shape.…”