Study on the Fe pre-saturation of containers in high-temperature and high-pressure experiments

<p indent="0mm">Iron-bearing magmatic compositions are very common in magmatic systems, however, in the high-temperature and high-pressure experiments of geological systems, the iron of iron-bearing samples could be easily migrated from the starting material into the noble metal containers for forming an alloy with the container, which would result in the iron loss of the starting material. This issue not only causes discrepancy between the actual composition and the intended composition of the starting material, but may also lead to uncontrolled oxygen fugacity of the experiment. To reduce the impact of iron loss of the starting material, the sample container needs usually to be pre-saturated with iron before the start of experiment. In this research, we constructed two electroplating devices on the iron pre-saturation for noble metal tubes and wires. By adjusting the electrical current intensity and the charged duration of the plating process for controlling the quality of iron electroplating, we have achieved precise control over the iron-presaturation of sample containers. Furthermore, we conducted experiments of the iron diffusion in noble metal containers to investigate the behavior of iron. Then we have verified the experimental conditions of completed diffusion for the AuPd tubes with iron mass fractions ≤0.20%, and have constrained the experimental conditions for the Pt wires with iron mass fractions of 0.5%–4.0%. Overall, this study has further improved the accuracy of the iron pre-saturation technique for noble metal sample containers.