Fig. 2.

Forces between a negatively charged silicon nitride AFM probe and control, heat-treated and RFGD-treated Ti6Al4V samples or a mica surface in water. Atomic forces of attraction or repulsion were measured for control and treated surfaces in picopure water at pH 5.6. The Z distance decreases as the sample surface is brought closer to the silicon nitride tip. Long-range electrostatic forces are measured at Z distances greater than 10 nm whereas interactions between 0–10 nm are dominated by van der Waals forces. A force of repulsion upon approach is signified by an increase in the size of the deflection of the tip compared to baseline deflection. A force of attraction is signified by a decrease in the size of the deflection of the tip compared to baseline deflection. Three disks were analyzed for each experimental group. The data obtained for each individual metal disk represent an average of 30–40 force curves acquired at 15 different sample locations for each disk. The three averaged force curves obtained for the disks in each experimental group were then averaged to obtain the final force curves presented in the figure.