Electrical Characteristic
Electrical characteristics quantify the opposition to current flow within a specific metal composition. The target alloy resistivity is a fundamental value for the design of eddy current sensors and heating elements. The measurement is specific to the metallurgical state of the sample and does not apply once the material reaches its melting point.
Material Composition
Adding alloying elements like nickel or chromium to a base metal will increase the resistance by disrupting the crystal lattice. A consistent target alloy resistivity is necessary for repeatable measurements in production line testing. If the resistivity varies, the sensor output will change even if the dimensions of the part remain the same.
This property is measured in ohm meters and is often highly sensitive to temperature.
Measurement Standard
Calibration blocks are manufactured from metals with a certified value to provide a baseline for the instruments. The target alloy resistivity is verified using a four point probe method to eliminate the effect of contact resistance. This ensures that the measured value reflects the bulk properties of the material rather than surface conditions.
Engineers use this data to select the correct operating frequency for the sensing application.
Temperature Coefficient
Resistance increases as the metal gets hotter and the atoms vibrate more vigorously. The target alloy resistivity must be corrected for the ambient temperature to maintain accuracy in field conditions.
