Microwave versus conventional sintering: A review of fundamentals, advantages and applications

Efforts to use microwaves in material processing are gradually increasing. However, the phenomena associated with the processing are less understood; popular mechanisms such as dipolar heating and conduction heating have been mostly explored. The current paper reviews most of the significant phenomena that cause heating during microwave–material interaction and heat transfer during microwave energy absorption in materials. Mechanisms involved during interaction of microwave with characteristically different materials – metals, non-metals and composites (metal matrix composites, ceramic matrix composites and polymer matrix composites) have been discussed using suitable illustrations. It was observed that while microwave heating of metal based materials is due to the magnetic field based loss effects, dipolar loss and conduction loss are the phenomena associated with the electric field effects in microwave heating of non-metals. Challenges in processing of advanced materials, particularly composites have been identified from the available literature; further research directions with possible benefits have been highlighted.

Microwave–material interaction phenomena: Heating mechanisms, challenges and opportunities in material processing

A new approach to joining of bulk copper using microwave energy

Microwave material processing is a novel energy efficient technology with improved mechanical properties, minimized defects and economical and environmental advantages making it a convenient application for various types of materials. Although, microwave interaction with matter has been largely investigated and published in food processing, ceramics and chemistry, no particular work has been involved in collecting the interactions of microwaves with metals and placing a special emphasis on their interaction with metals and metal-based formulations, and here resides the aim of the review: consolidating the fundamentals of microwave heating applications as a time and energy saving application and addressing its various applications and mechanisms with metal interactions seeking a more sustainable environment. This review reports the latest literature findings on microwave processing fundamentals and highlights the advanced technological improvement applied on metals in this field. It focuses on the relevant industrial applications related to the development of microwave technology on metals and its possible future processing in this specific scope of investigation.

Microwave dielectric heating: Applications on metals processing

Microwave synthesis and properties of fine-grained oxides dispersion strengthened tungsten

This study aims at microwave sintering of pure tungsten powder of as-received grade and tungsten powder activated by high-energy milling (HEM). Both the powder compacts are sintered under identical conditions and their sinterability is compared and analyzed for process optimization. Activated powder responds to microwaves and shows significant densification in a relatively shorter duration. The scope of the present work is to understand the effects of high-energy milling on the sinterability of tungsten in microwave and to make a comparative assessment between as-received (coarser) and activated (finer) tungsten powder in terms of their response to microwave sintering, densification and microstructure.

Amitava Chakraborty

Papers

Microwave sintering of tungsten