REDUCENANO

The Reduce-Nano project has set the fundamental goal of obtaining stable metal nanoparticles that can be used as a raw material for powder metallurgy using advanced nano-oxides obtained using Flame Spray Pyrolysis (FSP) through developing and optimising chemical reduction processes. To successfully achieve that goal, in the first place, thanks to the properties of many applications, like promoting electric car development and the difficulty of production using traditional methods, a selection of the systems that are the goal of the FeAl and FeNi study has been done. And work has been done on optimising the FSP production process.

Liquid mixtures with metal compound precursors have thus been developed, evaluated and adapted. The mixtures have been used to feed the FSP device optimising the key parameters that make homogeneous nanoparticle production with specific compositions possible. And, secondly, an evaluation of different reduction methods has been done evaluating key parameters like temperature, atmosphere and reduction agents. The deep characterisation of the materials of every stage of the project was completed to facilitate the reduction processes and obtain the best properties, respectively.

In that way, the technical activities have made it possible to determine that the steps for carrying out the validation of the process of obtaining metal alloys using nanostructured metal oxides as a raw material have been done correctly. The following has been achieved.

Metal systems have been selected that may have important properties for developing environmentally friendly products, like electric cars. Those systems are very difficult to obtain by traditional methods due to the presence of aluminium, which is easily oxidizable, in their composition.

Key parameters of the FSP technology were defined, like the precursor mixture (solvent, stoichiometry, metal precursors, etc.), feed flow, nozzle diameter, flame temperature, time present in the flame, carrier gasses, etc. that have made it possible to optimise the production of various batches of nanoparticles with specific compositions of the proposed systems that may simplify subsequent reduction processes.

The metal oxides produced were used to determine the starting point for the reduction processes and the passivation processes of the reduced materials.

The two most promising and efficient strategies for reducing the metal oxides were identified, which are the carbothermic route and the route using solid reduction agents based on Ca. That shows the viability of obtaining small samples of Fe and Ai nanoparticles produced using FSP technology, even at low temperatures, as long as a suitable selection of the operating parameters of the chemical reduction processes is done.

Additionally, the project has made it possible to determine the initial point for selecting other metal systems that have properties that are very interesting in terms of corrosion protection at high temperatures or manufacturing light alloys that can promote emerging technologies, like electric cars or wind energy, and that may be easily produced by adopting the processes developed in the Reduce-Nano project for the production and reduction of metal nano-oxides. It opens the door to continue the collaboration of the partners regarding optimising the production of advanced metal nanomaterials