Radha Raman Mishra

A Review of Research Trends in Microwave Processing of Metal-Based Materials and Opportunities in Microwave Metal Casting

ABSTRACT Microwave processing of materials has emerged as a new method for processing of a variety of materials in the recent years. Microwaves have been used effectively with significant advantages, particularly in food processing and chemical synthesis. They are also found to be efficient for processing polymers, ceramics, polymeric composites, and ceramic composites. The physics of interaction of microwaves with characteristically different materials is not yet explored well; consequently, there are challenges in microwave processing of metal-based materials. Industrial processing of bulk metal is yet to be popular in spite of the fact that the feasibility of metal powder sintering was demonstrated a few decades ago. This article provides a summary of fundamental aspects of microwave processing of metal-based materials and their interaction with metallic materials. The processing challenges have been surveyed; developments in terms of techniques and tooling have been analyzed. Possible effects of microwave processing on metallic materials, in particular metal powders, bulk metals, bulk metal-metal powder systems, and sheet metals have been presented. Future research aspects of microwave processing of metallic materials with reference to metal casting have been identified.

Systematic investigation and in vitro biocompatibility studies on implantable magnetic nanocomposites for hyperthermia treatment of osteoarthritic knee joints

The inefficacy of the currently used treatment modalities for osteoarthritis has elicited considerable research interest in the exploration of alternative methods. Hyperthermia treatment, generally used in the case of lesions, maybe considered as a viable solution owing to the economic and ergonomic factors involved. In the present study, Cr-doped Fe2O3 embedded in PVDF matrix is proposed as the biocompatible magnetic-dielectric composite to provide thermo-regulated prolonged treatment. A systematic study was carried out to characterize the physical properties of the prepared formulation. Further, cellular uptake studies were done to ensure bioviability. Finite element method studies using COMSOL were used to simulate the hyperthermia treatment of osteoarthritic knee joint. The approach proposed here may be used further to develop a novel class of therapeutic devices for the treatment of osteoarthritis.

Multi-physics simulation of in situ microwave casting of 7039 Al alloy inside different applicators and cast microstructure

In the present study, finite element models of three different applicators (A1, A2, and A3) having different power densities were developed to study melting of the charge and solidification of the melt during in situ microwave casting. Multi-physics simulations were carried out to understand the effect of applicator specific processing conditions on the distribution of electric field inside the cavities at 2.45 GHz for Al 7039 alloy as charge. The alloy was cast inside the selected applicators and the mold temperature was monitored. The experimental results showed reasonable agreement with the simulation data. Simulation results revealed that the distribution of electromagnetic field inside A3 offers the lowest melting time of the charge (141% less than A1); however, it also caused the highest preheating of the graphite mold with respect to A1 (30% higher) and A2 (25% higher). It was found that the applicator-specific solidification conditions affect grain structure, intermetallic precipitation, and their distribution inside the casts. Coarser intermetallic phases (57 µm) and grains (97 ± 54 µm) were present in the Cast 3 developed using A3 due to higher preheating of the mold and slower cooling rate of the melt as compared to that in A1 and A2.

Role of particle size in microwave processing of metallic material systems

ABSTRACT Processing of metallic materials using microwave energy has been a challenge. However, exploiting the size factor of particles in these candidate materials opened up further opportunities. The amount of heat evolved inside a particle per unit volume primarily depends upon its size, shape, electromagnetic and thermal properties. Finer particles can potentially absorb more microwave energy than coarser units and get heated rapidly with higher uniformity. It results in better properties in the processed part and energy economy. This work reviews the relevant literature and summarises fundamentals of microwave heating of metallic materials. Roles of particle size in processing these materials have been discussed. Challenges in microwave processing of finer metallic particles have been identified; opportunities for future research are outlined.