| Abstract | PRTs were soaked at different temperatures, and the resulting changes caused by oxidation and the subsequent dissociation of the formed oxide were observed. Soaking below 400 °C initiated oxidation, in some platinum resistance thermometers (PRTs), and then their resistance steadily increased with increasing temperatures up to about 525 °C. When soaking near 525 °C, the resistance of the PRT remained stable, suggesting that the thermal energy “kT” equals the energy that binds oxygen to platinum, at the existing oxygen pressure. At temperatures higher than 525 °C the formed oxide dissociated. The higher the temperature, the higher the thermal energy and thus the higher the rate of dissociation. One hour of soaking near the Al point dissociated the oxide that took hundreds of hours to accumulate. Three out of seven PRTs tested however would not oxidize while soaking for several months. Further soaking, however, did initiate oxidation in two of the three PRTs. |
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