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Title:
Establishing the Influence of Drill Materials, Drill Geometry and Coatings on Drill-wear and Drilling Performance for Sustainable Dry Drilling on Mars
PI: I. S. Jawahir
Co-PI: K. E. Rouch, O. W. Dillon
Graduate Student: S.P. Manthri
Sponsor: Kentucky Science & Engineering Foundation
Abstract
The drills tested for Martian drilling are crown type drill bits made of hard alloy, metal-bonded diamond impregnated core drills and hollow steel tube with polycrystalline diamond compact bits. The drill bit recommended for Martian drilling will have the ability to penetrate a variety of formations such as ice, sedimentary rocks like sandstone, limestone etc. and volcanic rocks such as basalt. Based on the visible/near-infrared spectroscopic observations, Martian crust is expected to be dominated by basalt rock. The high compressive strength of basalt (>120 Mpa) poses a challenge while designing a drill bit suitable for drilling on Mars. Essential rock properties to be considered while drilling are rock strength, abrasivity and rock type. The compressive strength of fresh basalt is much more than that of weathered basalt. Hence conducting experiments on fresh basalt would be an ideal approach. However, it is difficult to prevent basalt rock from weathering while conducting experiments in the laboratory. The compressive strength and abrasivity of granite is approximately equal to that of fresh basalt. Thus the drilling experiments are planned on two types of rocks, weathered basalt and granite.
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Fig.1 Microscopic picture of freshly exposed diamond in core bit at 250x magnification |
Fig.2 Thrust Force variation while core drilling basalt sample
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