I Ultra-low Expansion Gloss V-AK"; 60°c I . o 10.0 Fig. 8. Proof-test diagram for (A) data for ultralow-expansion glass collected at 60°C, represented by power function, v =AK,", and (B) data for fused S O , represented by exponential function. Numbers on curves are proof-test ratios, UJU,.Service Stress, 0,. MN/rn2 Service Stress, q , MN/m2 essential that the functional dependence of stress intensity factor on crack velocity be known; otherwise, large differences in predicted lifetime can occur. For Space-Shuttle applications, the extrapolation does not result in excessive errors in lifetime prediction. The glass studied in the work was of the anomalous type in fracture behavior and similar to other high-SiO, glasses.

Abstract-Artificial alteration of thirty-five trioctahedral .and one dioctahedral micas by solutions varying in strength from 0.001 to 1.00 molal magnesium sulfate was found to approximate a normal exchange reaction after surface effects are eliminated. The equilibrium constants for the reaction:range from 0.0001 to 0.0028 and average 0.0010 in value. X-ray diffraction study reveals that iron-rich micas tend to develop a 1 : 1 mixed-layer biotite-vermiculite structure in weak magnesium sulfate solutions whereas magnesium-rich biotite and phlogopite alter to vermiculite. Mica composition also influences the degree of alteration of mica to vermiculite. High fluorine and octahedral multivalent cation contents tend to retard the reaction whereas high magnesium content and perhaps high calcium contents tend to favor the alteration. The equilibrium constant data indicate that vermiculite and hydrobiotite are more stable than trioctahedral micas in most weathering environments.

Die Phasenbeziehungen im System Bi2O3‐WO3 werden zwischen 500 und 1100°C untersucht.