CHARACTERIZATION OF DEFECT GROWTH STRUCTURES IN ION-PLATED FILMS BY SCANNING ELECTRON-MICROSCOPY

Copper and gold films (0.2-2 μm thick) were ion plated onto polished 304 stainless steel surfaces. These coatings were examined for coating growth defects using scanning electron microscopy. Three types of defects were distinguished: nodular growth, abnormal or runaway growth and spits. The cause and origin of each type of defect was traced. Nodular growth is primarily due to inherent substrate microdefects, abnormal or runaway growth is due to external surface inclusions and spits are due to non-uniform evaporation. All these defects have adverse effects on the coatings. They induced stresses and produce porosity in the coatings and thus weaken their mechanical properties. Friction and wear characteristics are affected by coating defects, since the large nodules are pulled out and additional wear debris is generated. © 1979.