Fuel for thought? The direct oxidation of methane to methanol occurs at atmospheric pressure between 50 and 250 °C in a fuel‐cell‐type reactor (see picture). The efficiency of the electrochemical activation of oxygen is higher than that for the catalytic activation of oxygen.

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Al/Cu bonding in the air can be accomplished at the temperature range between eutectic temperature of Al-Cu system and melting point of Al. The change of microstructure in Al/Cu bond was investigated by SEM observation and EPMA analysis. The observed specimens were obtained by the difference of displacement of bonded specimen. Mushroom shape of L is observed in Al side at the first step of the initial stage of bonding process. The phase in Cu side begins to be observed significantly at the second step of the initial stage. The time difference is brougt by the difference of each diffusion coefficient. The ratio of bonding area of this bonding method depends on the formation ratio of the phase in Cu side. L phase begins to be removed by the bonding load after the initial stage. L, α, θ(Al2Cu) and η2 (AlCu) are observed in the bond as the major microstructure of the bond at room temperature. Formation mode of the pre-existed θ layer affects the shape of next θ grain formed from liquid. Al oxide film can glow by the absorption of oxygen from the resolved Cu oxide film. The diffusion route is made by the separation of Al and Cu oxide film at the first step of the initial stage. Reaction diffusion occurs through the area where the separation of oxide film occurs and forms liquid in bond during this bonding process.

The possibility and the mechanical properties of Al/Cu dissimilar bonding with liquefaction by the reaction diffusion in air were investigated at the temperature range between the melting point of aluminum and the eutectic temperature of Al-Cu system equilibrium diagram. The surface of each specimen was prepared by a simple preprocessing with the polishing and the cleaning by acetone. The Al/Cu dissimilar joint could be obtained by this bonding process in air. The bonding pressure is an important factor for this bonding process. The increment of bonding temperature and the decrement of oxygen concentration of air also promote solid state diffusion at Al/Cu interface. All bonded specimens in this study were fractured by the brittle fracture mode like cleavage fracture. The phases observed mainly in fracture surface is θ phase. The tensile strength of specimen bonded in air is similar with that of specimen by the diffusion bonding in vacuum.