Wet Film Thickness Sensor/Device for Navy Platforms

Measuring dry film thickness (DFT) with microwave nondestructive evaluation (MNDE) to ¼ mil accuracy has been demonstrated by SMRC's recently introduced K-band MNDE DFT tool. Extending to wet film thickness (WFT) measurement over unknown DFT requires a dual-sensor approach. X-band data for WFT over DFT in high solids paint (80% Zn) are promising - changes in microwave response as the paint dries are clear indications that SAPACS WFT measurements are feasible. In Phase I three X-band MNDE sensors will be built with standoffs from 4" - 6" with at least 1/2 mil accuracy in WFT over DFT, and 1/4 mil over metal substrates. SMRC proposes to build a detailed SAPACS WFT measurement model to support developing a design that minimizes systematic and random noise due to SAPACS motion and hull morphology. Sensor calibration data for WFT and DFT will be collected for single and multiple layers and types of hull paints. The X-band units will be combined into a dual-sensor system in Phase I Option as a pre-prototype SAPACS WFT MNDE measurement tool. The WFT measurement model will be continuously updated with DFT/WFT calibration and sensitivity data, making it a realistic, valuable design tool for Phase II development.