THE FRICTION OF QUARTZ IN HIGH VACUUM

RESISTANCE TO SHEAR DEFORMATION IN A GRANULAR MASS IS MOBILIZED AT THE POINTS OF CONTACT BETWEEN PARTICLES. A MAJOR PART OF THIS RESISTANCE ARISES FROM INTER-PARTICLE FRICTION. THEREFORE, ANY FUNDAMENTAL STUDY INTO THE MECHANICS OF DEFORMATION OF GRANULAR SYSTEMS REQUIRES AN UNDERSTANDING OF THE NATURE OF SOLID-TO-SOLID FRICTION. DESPITE THIS THERE ARE FEW REPORTS IN THE LITERATURE OF FRICTION MEASUREMENTS ON MINERALS. THE PURPOSE OF THIS INVESTIGATION WAS TO DETERMINE THE FUNDAMENTAL FACTORS CONTROLLING THE FRICTIONAL PROPERTIES OF QUARTZ SURFACES, WITH EMPHASIS ON THE EFFECTS OF SURFACE CLEANLINESS. ULTRA- HIGH VACUUMS AND HIGH TEMPERATURES /TO 350 DEGREES C/ WERE COMBINED WITH CHEMICAL CLEANING AND CAREFUL HANDLING TECHNIQUES TO PRODUCE THE MAXIMUM SURFACE CLEANLINESS. THE COEFFICIENT OF STATIC FRICTION UNDER VARYING ENVIRONMENTAL CONDITIONS WAS MEASURED FOR QUARTZ, 304 STAINLESS STEEL, AND GRANITE. DIRECT SHEAR TESTS WERE RUN ON A QUARTZ SAND /40-60 MESH OTTAWA SAND/ AND ON 30-40 MESH GLASS BALLS. THE COEFFICIENT OF FRICTION OF SMOOTH QUARTZ WAS FOUND TO VARY FROM 0.1 TO 1.0 DEPENDING ON THE SURFACE CLEANLINESS. THE FRICTION OF ROUGH SURFACES SHOWED A MUCH SMALLER VARIATION, WHICH HAS IMPORTANT IMPLICATIONS FOR GRANULAR SOILS. ULTRA- HIGH VACUUM, COMBINED WITH A HIGH TEMPERATURE BAKE-OUT, PRODUCED SIGNIFICANT INCREASES IN BOTH THE ANGLE OF FRICTION OF QUARTZ AND THE PEAK FRICTION OF QUARTZ SAND. THE COHESION INTERCEPT FOR THE QUARTZ SAND ALSO INCREASED BY ABOUT 0.02 KG/CM2. A GOOD CORRELATION, USING THEORETICAL CURVES, WAS OBTAINED BETWEEN CHANGES IN THE ANGLES OF FRICTION FOR QUARTZ. THE HIGH VACUUM-HIGH TEMPERATURE TEST CONDITIONS SIMULATE ASPECTS OF THE LUNAR ENVIRONMENT. THEREFORE, THE TEST RESULTS MAY YIELD USEFUL INFORMATION REGARDING THE PROPERTIES OF POSTULATED LUNAR SOIL MODELS INVOLVING SIGNIFICANT THICKNESSES OF GRANULAR PARTICLES. /AUTHOR/

• Supplemental Notes:
  • R 66-18, RePORT NO 7, 119 PP, 28 FIG, 8 TAB, 2 APP
• Authors:
  • Bromwell, L G
• Publication Date: 0

Media Info

• Serial:
  • Mass Inst Technol Dept Civ Eng Res Rept

Subject/Index Terms

• TRT Terms: Cleaning; Coefficient of friction; Direct shear tests; Granite; Granular materials; Measurement; Properties of materials; Quartz; Shear strength; Soils; Stainless steel; Static stability; Temperature; Vacuum
• Uncontrolled Terms: Soil properties
• Old TRIS Terms: Angle of external friction; Chemical cleaning; Lunar; Static friction coefficient
• Subject Areas: Geotechnology; Highways; Maintenance and Preservation; Materials;

Filing Info

• Accession Number: 00228847
• Record Type: Publication
• Files: TRIS
• Created Date: Aug 15 2004 1:47AM