Frictional forces between cohesive powder particles studied by AFM.
A range of commercially important powders (hydrated alumina, limestone, titania and zeolite) and glass ballotini were attached to atomic force microscope cantilevers, and inter-particle friction forces studied in air using lateral force microscopy (LFM). The in situ calibration procedure for friction forces is described. LF images, line profiles, LF histograms, surface roughness, pull-off forces, and the load dependence of friction in the range 0-25 nN were studied for both particle-particle and particle-wall (steel) contacts. The single-particle friction results are discussed in terms of contact mechanics theory. Particle-particle contacts showed load-dependent friction, involving single asperity contacts (non-linear behaviour) or multi-asperity contacts (linear behaviour). Particle-wall contacts usually showed little load dependence and were more adhesive. The results are also related to shear stress-normal stress data (yield loci) for the same materials from bulk shear testers.
Jones
Robert
R
Department of Physics, University of Lancaster, Lancaster LA1 4YB, UK. robert.jones@lancaster.ac.uk
Pollock
Hubert M
HM
Geldart
Derek
D
Verlinden-Luts
Ann
A
D017276:Friction; D018625:Microscopy, Atomic Force / Q000295:instrumentation / Q000379:methods; D011208:Powders / Q000737:chemistry*; D013499:Surface Properties
D011208:Powders