Uncertainty Improvements of Metallic Resistivity Measurements by the Four-Point Probe Method

Besides well-known destructive methods for material degradation, the electrical resistivity method has been used as one of nondestructive evaluation methods because of easy measurement. To use the method, however, careful geometrical corrections and thickness measurements are required. The high current probe assembly and accurate thickness measurement device were developed to improve overall measurement uncertainty. If dual configuration Four-Point Probe method with the developed devices is used, overall measurement uncertainty of electrical resistivity could be reduced to 0.44 % at 95 % confidence level. Proper selection of the probe spacing matched with sample thickness is very important to determine accurate electrical resistivity. When sample thickness is less than probe spacing, it is expected that dual configuration Four-Point Probe technique can be used in nondestructive evaluation of plant equipment materials.