Calibration and Uncertainty Estimation for Water Content Measurement in Solids

In the field of water content measurement, the calibration of coulometric methods (e.g., coulometric Karl Fischer titration or evolved water vapor analysis) is often overlooked. However, as coulometric water content measurement methods are used to calibrate secondary methods, their results must be obtained with the highest degree of confidence. The utility of calibrating such instruments has been recently demonstrated. Both single and multiple point calibration methods have been suggested. This work compares these calibration methods for the evolved water vapor analysis technique. Two uncertainty estimation approaches (Kragten’s spreadsheet and M-CARE software tool) were compared as well, both based on the ISO GUM method.

(Ti,Sn) Solid Solution Based Gas Sensors for New Monitoring of Hydraulic Oil Degradation

The proper operation of a fluid power system in terms of efficiency and reliability is directly related to the fluid state; therefore, the monitoring of fluid ageing in real time is fundamental to prevent machine failures. For this aim, an innovative methodology based on fluid vapor analysis through metal oxide (shortened: MOX) gas sensors has been developed. Two apparatuses were designed and realized: (i) a dedicated test bench to fast-age the fluid under controlled conditions; (ii) a laboratory MOX sensor system to test the headspace of the aged fluid samples. To prepare the set of MOX gas sensors suitable to detect the analytes’ concentrations in the fluid headspace, different functional materials were synthesized in the form of nanopowders, characterizing them by electron microscopy and X-ray diffraction. The powders were deposited through screen-printing technology, realizing thick-film gas sensors on which dynamical responses in the presence of the fluid headspace were obtained. It resulted that gas sensors based on solid solution TixSn1–xO2 with x = 0.9 and 0.5 offered the best responses toward the fluid headspace with lower response and recovery times. Furthermore, a decrease in the responses (for all sensors) with fluid ageing was observed.

A Computational Fluid Dynamics-Based Sensitivity Analysis of the Chemical Vapor Analysis Process to Synthesize Carbon Nanotubes

Over the last years, there has been a high interest in carbon nanotubes' (CNTs) applications due to their unique properties, mainly at mechanical and electrical levels. However, current synthesis processes, such as chemical vapor deposition (CVD), are highly unpredictable and inconsistent, which leads to an exhaustive trial-and-error methodology when extrapolating results. A sensitivity analysis based on computational fluid dynamics (CFD) is performed here to two distinct setups of the CVD process as a way to understand the synthesis process. Setups were computationally designed and simulated for various synthesis scenarios, where only the hydrocarbon flow and the process temperature were changed. Measuring synthesis conditions, such as concentrations and velocity, inside the tube furnace, for these scenarios allows the identification of which compound affects most each condition. Results showed that, when envisioning the process extrapolation, the synthesis conditions can be tuned via the accessed parameters.

Novel Methodology Based on Thick Film Gas Sensors to Monitor the Hydraulic Oil Ageing

A new methodology for the real time monitoring of hydraulic oil aging based on the vapor analysis using metal oxide semiconductor (MOX) gas sensors has been successfully developed. A dedicated hydraulic test bench was designed and realized to age the oil under controlled condition. Gas chromatographic analyses were performed to detect oil volatile compounds (VOCs) and their concentrations at increasing oil working time. Moreover, a laboratory sensor system have been realized to test the headspace of the same samples. Both measurements highlighted a decrease of the VOCs concentrations.