The Effects of Sulfuric Acid on the Flow and Fabric of Polycrystalline Ice

Abstract:

It is well established that the Earth’s large continental ice sheets contain a variety of naturally occurring impurities, both soluble and insoluble. Understanding how these impurities affect the rheology, intrinsic thermodynamic properties, and ultimate fate of these ice sheets, however, is much less understood. One such soluble impurity thought to be of critical importance and already shown to be significant in the flow of single crystal ice, is H₂SO₄ (sulfuric acid). In order to further investigate the effects that trace amounts (< 10 ppm) of sulfuric acid may also have on the flow and ductility of polycrystalline ice, we have conducted a series of mechanical tests at -10°C and -20°C. These tests have included uniaxial tensile creep tests at a constant load of 0.5 and 0.75 MPa and uniaxial compression tests at a constant strain rate of 1x10^-5 s^-1. Pre and post-test microstructural analysis has been performed via scanning electron microscopy, energy dispersive spectroscopy, and electron backscatter diffraction. Although these experiments are still ongoing, our tentative results show a temperature dependent difference in the strain rate between pure and sulfuric acid doped creep specimens and a difference in the peak stress achieved for our samples tested in compression.