Hardy Composites

CSIR GOLDEN JUBILEE SERIES-

HARDY "COMPOSITES

N S K PRASAD

N.S.K. PRASAD

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Publications & Information Directorate (CSIR) Dr K.S. Krishnan Marg New Delhi 110012 India

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Hardy Composites N.5.K. Prasad • © Publications & Information Directorate First Edition : November 1992 Second Edition Third Edition

: February 1994 : January 1996

ISBN: 81-7236-049-5

CSIR Golden Jubilee Series Publication No. 10 Series Editor Volume Editors: Cover Design Illustrations Production

: Dr. Bal Phondke S.K. Nag and Sukanya Datta : Pradip Banerjee : Mohan Singh, ML Mehta, Neeru Sharma, Sushila Vohra and Malkhan Singh : Radhe Sham, Vinod Sharma, K.B. Nagpal and s.c. Mamgain

Designed, Printed and Published by Publications & Information Directorate (CSIR) Dr K.S. Krishnan Marg, New Delhi 110012, India

For sale in India only.

Price: Rs. 30/-

The Council of Scientific & Industrial Research (CSIR), established in 1942, is committed to the advancement of scientific knowledge, and economic and industrial development of the country. Over the years CSIR has created a base for scientific capability and excellence spanning a wide spectrum of areas enabling it to carry out research and development as well as provide national standards, testing and certification facilities. It has also been training researchers, popularizing science and helping in the inculcation of scientific temper in the country. The CSIR today is a well-knit and action-oriented network of 41 laboratories spread throughout the country with activities ranging from molecular biology to mining, medicinal plants to mechanical engineering, mathematical modelling to metrology, chemicals to coal and so on. While discharging its mandate, CSIR has not lost sight of the necessity to remain at the cutting edge of science in order to be in a position to acquire and generate expertise in frontier areas of technology. CSIR's contributions to high-tech and emerging areas of science and technology are recognized among others for precocious flowering of tissue cultured bamboo, DNA fingerprinting, development of non-noble metal zeolite catalysts, mining of polymetallic nodules from the Indian Ocean bed, building an all-composite light research aircraft, high temperature superconductivity, to mention only a few. Being acutely aware that the pace of scientific and technological development cannot be maintained without a steady influx of bright young scientists, CSIR has undertaken a vigorous programme of human resource development which includes, inter alia, collaborative efforts with the University Grants Commission aimed ZItnurturing the budding careers of fresh science and technology graduates. However, all these would not yield the desired results in the absence of an atmosphere appreciative of advances in science

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and technology. If the people at large remain in awe of science and consider it as something which is far removed from their realms, scientific culture cannot take root. CSIR has been alive to this problem and has been active in taking science to the people, particularly through the print medium. It has an active programme aimed at popularization of science, its concepts, achievements and utility, by bringing it to the doorsteps of the masses through both print and electronic media. This is expected to serve a dual purpose. First, it would create awareness and interest among the intelligent layman and, secondly, it would help youngsters at the point of choosing an academic career in getting a broad-based knowledge about science in general and its frontier areas in particular. Such familiarity would not only kindle in them deep and abiding interest in matters scientific but would also be instrumental in helping them to choose the scientific or technological education that is best suited to them according to their own interests and aptitudes. There would be no groping in the dark for them. However, this is one field where enough is never enough. This was the driving consideration when it was decided to bring out in this 50th anniversary year of CSIR a series of profusely illustrated and specially written popular monographs on a judicious mix of scientific and technological subjects varying from the outer space to the inner space. Some of the important subjects covered are astronomy, meteorology, oceanography, new materials, immunology and biotechnology. It is hoped that this series of monographs would be able to whet the varied appetites of a wide cross-section of the target readership and spur them on to gathering further knowledge on the subjects of their choice and liking. An exciting sojourn through the wonderland of science, we hope, awaits the reader. We can only wish him Bon voyage and say, happy hunting.

Human endeavour towards continuous improvement in the quality of life has resulted in a host of new materials and new technologies. Material surfaces get exposed to various environments and also come in contact with other surfaces, similar or dissimilar. Tailoring of material surfaces to suit critical areas of technology has become an art. With the emergence of new fibres of plastics, glass and carbon steel is no longer the strongest material. An imaginative blending of materials with tailored surfaces and incorporation of reinforcement materials in fibrous and nO:l-fibrous plans have created 'Hardy Composite3'. The composite systems are made up of metal, polymer or a ceramic matrix, a particulate or fibrous filler acting as reinforcement and a compatibilizer which tailors the surface and acts as an effective interface between the matrix and the reinforcement. The inherent strength of composites and their ability to withstand critical environment have revolutionized our transportation and communication systems, engineering goods, chemical equipment and packaging materials. Human organ prostheses have also become versatile by the availability of these new materials. The hardy composites, apart from their impact on our present lifestyles, breathe the message that 'unity is strength' and that diverse people can intermingle effectively resulting in composite cultures.

Dedicated to

Science Lovers

Bare Facts In Adding Muscle Glossary Giving Shapely Details At Action Play Shape Joining Hands

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wo and two do not always make four. They can be juxtaposed to form the number twentytwo. This just emphasizes the fact that the whole is often better than the sum of its parts. It is the practical manifestation of this phenomenon which has given birth to a very broad and versatile class of man-made materials: composites.

Bare Facts

A composite, as its name suggests, is made by combining two or more dissimilar materials in such a way that the resultant material is endowed with properties superior to any of its parental ones. The ancients knew that when they made alloys of metals they often got good results. By melting together copper and tin they made bronze, the earliest known alloy. Bronze had qualities superior to its parent metals neither of which could be identified once the alloy was formed. To cite a chemical analogy, when sodium and chlorine, each individually harmful if ingested, react chemically, they form the harmless sodium chloride or common salt. Thus, both sodium and chlorine lose their individual identity to create a totally new compound with its own unique characteristics.

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Unlike an alloy or a chemically synthesized compound, however, the components of a composite neither take part in a chemical reaction nor do they dissolve or completely merge with one another. Nevertheless they remain strongly bonded together while maintaining an interface between one another and act in concert to give a much improved performance. Composites are not new. The first composite was probably born in Biblical times when man added chopped straw to clay to make stronger bricks. The trend continued unabated. The iron-rod reinforced concrete, widely used in modern buildings, is also an example of composites. This, however, is just the tip of the iceberg. As man's understanding of nature increased and he dug deeper into the treasure trove that nature offered, a host of new materials became available to him. But, with the inexorable march of civilization man felt that more novel materials were required. Necessity, it is said, is the mother of invention. So, to meet his ever increasing and diversifying needs, man started fabricating new materials from a judicious combination or manipulation of the old. A quantum leap in science and technology brought about the Industrial Revolution in the 19th century. As this revolution progressed and encompassed every aspect of human life, be it travel, work or play, an increasing need was felt for materials robust in nature and capable of resisting fatigue, environmental corrosion, pressure, stress and exposure to chemicals. These also had to be adaptable for use under extreme temperature variations. Newer and more versatile composite materials evolved as an answer to this need. Their emergence has had a tremendous impact in several fields like transportation, marine engineering, chemical equipment and machinery, construction, electrical and electronic equipment, sports goods and medical engineering. The aerospace and defence industries have also benefited greatly from the lightweight yet extremely hard composites that have evolved of late.

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Others Automobiles

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Major marlrets for advanced composite materials in 1995

These alternatives traditional materials

have taken the industry by storm. Composites are one of the fastest growing ind us tries with USA being the major consumer of composite materials. The global consumption of composites is now around two million tonnes annually and growing at the rate of 10 per cent every year.

Composites are materials based on the controlled distribution of one (or more) material(s), termed reinforcement, in a continuous phase of a second material called the matrix. The reinforcement is added to provide strength and stiffness to the composite. The matrix is also known as the binder material. Its function is to make the composite resistant to degradation. There is another, optional class of constituents in composites. This comprises fillers, additives and auxiliary chemicals. It is a matter of choice, dictated by the qualities a composite must possess, whether this class of compounds be br