抄録
The shear thinning effect was studied for the fluoroapatite glass-ceramics containing isometric crystals (denoted as series 1) and those containing needle-like crystals (denoted as series 2). During extruding of series 2, a two-stage decrease in viscosity was observed by increasing shear rate. The first drop in viscosity occurred at low shear rates, which was accompanied by the orientation of needle-like fluoroapatite crystals. The second drop in viscosity occurred at high shear rates, that is, the shear-thinning flow of the glass matrix. The two-stage decrease in viscosity with increasing shear rate is described by a recently proposed phenomenological equation. The orientation of the needle-like crystals was simulated using finite element method (FEM).
