Advances in Synthesis of Metallic, Oxidic and Composite Powders

Dear Colleagues,

The high demand for new materials, such as metals, oxides, and composites, raises the need for an advanced synthesis of different materials, which are crucial for technological applications. Different process synthesis routes, such as atomization, reduction in aqueous phase, crystallization, chemical precipitation, high pressure reaction in autoclave, and electrolysis, can be used to create controlled powder characteristics with specific properties for a particular application or industry. Advances in synthesis explores a range of materials and techniques used for powder metallurgy and the use of this technology across a variety of application areas such as medicine, catalysis and automotive industry. This Special Issue, "Advances in the Synthesis of Metallic, Oxidic and Composite Powders", is dedicated to the latest scientific achievements in an efficient preparation of metals, oxides and composite materials. In this issue, we will be focus on description of the synthesis of metal, oxide and composite particles from the water, metalorganic and colloid solution using different synthesis methods. The main challenge of this issue is the controlled synthesis via process parameters (conditions and modes atomization, the concentration of solution, residence time of aerosol in a reactor, presence of additives, flow rate, decomposition and reduction temperature, different precursors with reducing agents, and surrounding atmosphere) in order to guide the process to obtain powders with such a morphology that satisfies more and more complex requirements for the properties of advanced engineering materials.

The synthesis of powders has two different strategies: “Top-Down” and “Bottom-Up”. The meaning of “Top-Down” is based on mechanical grinding of initial materials to small dimensions. It is necessary to decrease the powder size in order to perform Hall-Petch strengthening and apply a severe plastic deformation to powder particles to perform work hardening. High energy milling has a potential for realizing the new ideas of materials designers. The meaning of “Bottom-Up“ is related to the physico-chemical preparation methods in gas phase (ultrasonic spray pyrolysis, flame pyrolysis and chemical vapor deposition) and in liquid phase (sol gel, hydrothermal processes, precipitation, electrolytic synthesis, high pressure reactions in an autoclave and crystallization). The precipitation methods are usually used for the purification of spent solution.

In this regard, new approaches in material and synthesis design, structural engineering and morphological characteristics are provided. Preparation of metal particles by spray pyrolysis of metal salts is especially challenging. Using aerosol synthesis, a single-step and multistep preparation process of different core-shall particles is possible, thus avoiding several steps like drying, shrinkage, solute precipitation, thermolysis, and sintering to form uniform spherical particles in nanosized and submicron range. Technical limitations of this technique, as well as a comparison with other synthesis methods (difficulty in controlling morphology-porous or hollow particles, relatively low production rate and process of large volume of gas), will be partly considered in order to prevent or solve these problems.

Especially, the newest results in the synthesis of nanosized particles by ultrasonic spray pyrolysis method and other methods will be published. By addressing the complex problems faced in the synthesis procedures, the scaling–up of the aerosol droplet production and other methods shall be considered.

Dr. Srecko Stopic
Prof. Dr. Bernd Friedrich
Guest Editors

Manuscript Submission Information

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• Powder metallurgy
• Hydrometallurgy
• Atomization
• Spray pyrolysis
• Electrochemistry
• Sol-gel
• Metal
• Oxide
• Composite
• Reduction
• Grinding
• Crystallization