Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Topography of the GF surfaces for the density of 1.0 g/cm3 (a–c), 1.3 g/cm3 (d–f), and 1.6 g/cm3 (g–i) obtained from the fractions of 40–80 μm following the experimental studies at the sliding velocity of 1 μm/s (a,d,g), frequency 0.1 Hz (b,d,h), and 1 Hz (c,f,i).
