With the increasing importance of nanopowder materials in strategic fields like energy, defense, aerospace, etc., there is also a renewed interest in processing technologies to provide nanopowders these unique possibilities”. In this framework, microwave energy is receiving an special attention as processing technology.
Microwave sintering has emerged in recent years as a new method for sintering a variety of materials from nanopowders that has shown significant advantages against conventional sintering procedures. A summary of these are: (1) Rapid and uniform heating distribution. (2) Sintering materials with microwave consumes much lower energy than conventional sintering. (3) Diffusion process intensiﬁes by using microwave due to its enhanced mechanism. (4) Higher heating rates can be attained and thus the sintering time, reduces by using microwave sintering. (5) Generally higher density and better grain distribution can be achieved through microwave sintering. (6) Better physical and mechanical properties can be obtained using microwave sintering.
Despite of it is indisputable that microwave heating has many advantages over conventional heating, the industry is still reluctant to use this procesing technology in a regular manner and it still remains the idea that a microwave process is extremely complicated. In general, the use of microwaves represents the use of sophisticated technology in the nanopowder industry. Lack of sufficient and unified knowledge of this complex and radically different heating process has been the primary contributor to its low idustrial applicability. Despite of the significant progress has been made in the last years, emphasis should be on basic research to better understand the interaction between microwave energy and these materials.
With this purpose, the microwave area (DIMAS) of the research institute ITACA is participating in the project “In-situ monitoring of nanopowder processing by microwave dielectrometry (MONIDIEL, TEC2008-04109)” with the objective of developing specific equipment to better understand the interaction microwaves with materials with special focus on nanopowders. This project, financed by the Spanish Ministry of Science and Innovation, falls into the strategic action of the Spanish Research National Plan “nanoscience, nanomaterials new materials and new industrial processes”, to improve the industry competitivity. The action aims to create knowledge to be transferred later to the industry. Started in January 2009, the project has 3 years of duration.
Different equipment to monitor the dielectric properties of the nanopowder materials at microwave frequencies simultaneously with the heating also with microwave technology are under development in the project. Measurements of dielectric properties before and after the microwave heating are also under investigation. Besides this, attempt has been made to study the heating behaviour of materials in the electric and magnetic fields at microwave frequencies. The research is now focused on the use of these microwave equipment to monitor nanopowder processing in industrial applications