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Title: Hardness of single ice crystals
Authors: Butkovich, Theodore R.
Keywords: Ice
Ice crystals
Ice crystal hardness
Hardness tests
Publisher: U.S. Army Snow, Ice, and Permafrost Research Establishment.
Engineer Research and Development Center (U.S.)
Series/Report no.: Research report (U.S. Army Snow
Description: Research Report
Abstract: Brinell and scratch hardness tests were made on single ice crystals. The Brinell hardness tests were conducted with a modified Olsen Baby Brinell Hardness Tester and the hardness numbers obtained were computed from the standard Brinell formula. The scratch hardness tests were made with a Spencer Microcharacter and the hardness numbers were computed from a special formula developed for the instrument. The results of these measurements show that the hardness of single ice crystals increases with decreasing temperature; the Brinell hardness numbers range from about 4 at -5°C to 17 at -50°C. The greatest increase in the hardness values occurs at the higher temperatures. The temperature dependence of the scratch hardness was similar to that of Brinell hardness. An anisotropism of hardness is evident; the single ice crystal is harder parallel to the c-axis than in the direction normal to the c-axis. An apparent difference in surface structure with respect to orientation was noticed during the scratch hardness tests. A consistent wavy scratch was produced normal to the c-axis, while the scratch parallel to the c-axis was always straight.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Research Report

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