Tools for studying water vapor at high temperatures

Many papers deal with the effect of water vapor on the high-temperature corrosion behavior of metallic materials. Experimental procedures are an essential consideration in the study of oxidation in steam, O 2 -H 2 O or air-H 2 O atmospheres, H 2 -H 2 O atmospheres, etc. The influence of various laboratory-controlled experimental parameters on the steam oxidation response of materials has been reviewed, and best practice recommendations are proposed in many papers. There are two main ways of enriching a gas in water vapor. The first consists in bubbling a gas (H 2 , air, N 2 , Ar, etc.) through a water bath held at a fixed temperature (thermostat). For example, synthetic air bubbled through a water bath held at 46°C gives a 10% H 2 O enrichment of the gas. The SiMap laboratory in Grenoble uses two successive water baths to obtain the desired water vapor content. The first bath is used to pre-enrich the gas by bubbling at a temperature below the target temperature. The second bath is heated to the temperature required for water vapor enrichment. The LICB team in Dijon and the LVVEEM team at Le Puy en Velay use a slightly different setup that involves a cooling tower: the gas is made to flow through a distilled water bath held at 70-80°C, and the H 2 O fraction is controlled and adjusted by passing the gas through a cooling tower heated to the correct temperature. Hayashi et al. use the same process to perform water vapor experiments. The experimental setup presented in Figure 1 possesses three water sources, which makes it very convenient for conducting long-term experiments as it is possible to switch from the first to the second or third bath, as many times as needed. Successive experiments in H 2 16 O, H 2 18 O and D 2 O can also be carried out by placing each isotope in a separate bath.