GLASS FRACTURE SURFACES SEEN WITH AN ATOMIC-FORCE MICROSCOPE

Fracture surfaces of Suprasil 2, Herasil 2, AR glass and Duran glass r ods have been studied by an atomic force microscope (AFM) in the conta ct mode. They could be characterized in the fracture mirror, the mist and the hackle zones. The RMS (root mean square) roughness in the frac ture mirror of all glasses investigated increased with growing distanc e from the origin of the fracture. On several fracture surfaces of dif ferent glasses steps have been observed, due to fracture in shear mode . Furthermore changes in the fracture sur-faces during scanning have a lso been observed. They are thought to stem from reactions of the fres hly broken glass surface with the surrounding atmosphere and forces be tween the scanning tip and the soft surface.