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The hydrogen induced damage of generic Fe-C-Ti and Fe-C-V ferritic alloys was investigated to assess the influence of precipitates on the hydrogen sensitivity of a material. The precipitates, formed during heat treatment, were evaluated by scanning transmission electron microscopy (STEM). The hydrogen/material interaction was evaluated by: 1) melt and hot extraction to determine the total and diffusible hydrogen content, respectively, 2) permeation experiments to calculate the diffusion coefficient, 3) thermal desorption spectroscopy to determine the hydrogen trapping characteristics of the materials. Furthermore, two different types of hydrogen induced damage were evaluated, i.e. hydrogen assisted cracking and blistering, resulting from electrochemical hydrogen charging with and without the application of an external load, respectively. Evaluation of the hydrogen induced damage and the role of the precipitates was performed by combining optical microscopy, scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). An important though divertive role of diffusible hydrogen is observed in both damage mechanisms for the investigated microstructures. On the one hand, a large amount of diffusible hydrogen compared to strongly trapped hydrogen promotes hydrogen assisted cracking of materials, while on the other hand, the blistering phenomenon is delayed under such conditions.

Both primary and secondary copper production encounter a limitation in the process efficiency due to droplet losses in slags. One of the causes for the mechanical entrainment of these droplets is their interaction with solid spinel particles, hindering the sedimentation of the copper droplets. Previous experiments with synthetic slags provided insights into this interaction and yielded two possible mechanisms: separately formed droplets and particles become attached to one another due to fierce agitation of the slag and metal phases; or the spinel particles and metal droplets form as the result of a chemical reaction together with a new droplet or alongside a droplet that was already present in the system. This experimental study aims to investigate the hypothesis of the formation of copper droplets sticking to spinel particles due to a chemical reaction further. A slag that is initially free from Cu droplets was prepared. After creating controlled conditions to induce the chemical reaction, the formation of sticking dropletswas observed. The results from this experiment therefore confirm the previously proposed reactive mechanism.

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