Ceramic matrix composites find increasing use in high technology applications because of their enhanced toughness and wear resistance. Reliable joining techniques are however needed for the development of intricate shapes made of ceramic composites. In this present work, sintered alumina-30% zirconia ceramic composites were joined by hybrid heating using microwave radiation (2.45 GHz, 700 W), along with sodium silicate glass powder as an interlayer. The joints/welds were studied using XRD, SEM, EPMA, microhardness, and 3 point bend tests.

Ramalingam Krishnamurthy

Alumina

Bonding

Diffusion in solids

Microanalysis

Microwave heating

Scanning electron microscopy

Toughness

Wear resistance

X ray diffraction analysis

Zirconia

Electron probe microanalysis

INTERLAYERS

JOINING MICROWAVE HYBRID HEATING

Ceramic matrix composites

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Joining of ceramic composites by microwave heating

Materials Letters

Microwave heating is caused by the ability of the materials to absorb microwave energy and convert it to heat. This article represents a review on fundamentals of microwave heating and their interaction with materials for various applications in a comprehensive manner. Experimental studies of single, multimode, and variable frequency microwave processing were reviewed along with their applications. Modeling of microwave heating based on Lambert's law and Maxwell's electromagnetic field equations have also been reviewed along with their applications. Modeling approaches were used to predict the effect of resonances on microwave power absorption, the role of supports for microwave heating, and to determine the nonuniformity on heating rates. Various industrial applications on thermal processing have been reviewed. There is tremendous scope for theoretical and experimental studies on the athermal effects of microwaves. Some of the unresolved problems are identified and directions for further research are also suggested. © 2011 American Institute of Chemical Engineers (AIChE).

AIChE Journal

Microwave material processing-a review

Microwaves are electromagnetic radiation in the frequency range of 300 MHz-300 GHz. For improved performance of products, microwave irradiation becomes an attractive route by way of cost reduction, reduced time and energy savings. In the present study, cemented tungsten carbide (WC) cutting tools were exposed to microwave (2.45 GHz) radiation. Response of the WC tool to microwave radiation has been evaluated in terms of microstructural changes, hardness survey, cobalt phase change through XRD and XPS analysis. Activation of grains, selective heating of WC grains and formation of compound W2C-Co phase have enhanced the metallurgical properties of cemented WC inserts. © 2002 Elsevier Science B.V. All rights reserved.

Enhancing the metallurgical properties of WC insert (K-20) cutting tool through microwave treatment

The application envelop of atmospheric plasma sprayed ceramic composites can be widened considerably by reducing/eliminating inherent surface defects by treating them through techniques like microwave irradiation. In microwave processing, microwave energy is directly applied to the material. High-frequency microwaves (>1 GHz usually) penetrate into the bulk of the material and the volumetric interaction of the electromagnetic fields with the material results in dielectric (volumetric) heating. This leads to higher heating efficiency with faster processing. Ceramics are transparent to microwaves at low temperatures, however, start absorbing microwaves at higher temperatures resulting change in microstructure and material characteristics. This paper presents microwave processing of atmospheric plasma sprayed alumina-titania ceramic composite coatings in conventional microwave heating system and evaluation of the processed materials through XRD, SEM, microhardness survey and surface finish with illustrat ions. Results indicate microwave irradiation induces densification of the material and possible flow of dominant gamma-alumina phase that leads to glazing of coated surface. Glazed surfaces exhibit enhanced microhardness as well as surface finish. © 2001 Elsevier Science B.V. All rights reserved.

Microwave glazing of alumina-titania ceramic composite coatings

Journal	Data powered by TypesetMaterials Letters
Publisher	Data powered by TypesetElsevier
ISSN	0167577X
Open Access	No