Effective viscosity of partially melted ice in the ammonia‐water system

The steady‐state deformation of partially melted ice in the ammonia‐water system was studied by means of a concentric cylinder viscometer in shear stresses, 10 kPa∼0.1 MPa, temperatures, 180∼210 K and NH3 contents, 4.0∼8.4%. The flow law found was of a non‐Newtonian power‐law type; the stress exponent was 4.0±0.1. The activation energy at constant melt fractions was 33.7±0.8 kJ/mol, which was close to that of viscosity for aqueous ammonia solutions. However, the effective viscosity of partially melted ice estimated at 0.1 MPa was 107 ∼ 1010 Pa s, which is about ten orders of magnitudes larger and smaller than that of the ammonia‐water mixture in the liquid and solid phases (below a peritectic point, 176 K), respectively.