September 17, 2005

Our standard of living improved as we moved through the stone, bronze and iron ages. Today, we are in a technological era and materials available now have been creating a stir in many fields like telecommunications, transportation, medicine, textiles, astronomy, construction and warfare.

Besides the conventional metals and nonmetals, an unlimited range of new materials have proven their worth in modern times. Yet, more is being demanded due to stringent future requirements. These include lightweight alloys for automobiles, supersonic aircraft and space vehicles.

Today’s technology demands materials that cannot just withstand high-temperature applications, but also possess low density and a mix of mechanical properties such as creep resistance, low temperature damage tolerance and environmental resistance. Hence, research has today channeled beyond iron, nickel and titanium aluminides.

Ongoing research in the areas of silicides, certain aluminides, chromides and beryllides is not only limited to obtaining a fundamental understanding of the structure and deformation behaviour, but also to attain the knowledge to fabricate, machine, join and test components of such materials.

Material processing techniques are also modified to cope with the new fabrication problems. Plasma is used to modify surface properties such as the deposition of thin films, etching, nitriding, oxidation, and as a medium to enhance chemical reactions, especially those that take place during semiconductor fabrication.

The initial success of primary lithium and rechargeable lithium cells, and the growing demands for high energy-density batteries has inspired researchers to look for advanced lithium batteries. Active research is being carried out on battery material possessing excellent and quick recharge ability, longer life, low cost, low toxicity and recycle ability of battery waste material.

Likewise, the micro-batteries technology is also gaining attention due to the diminutive size of electronic devices. A large number of conducting polymers, such as poly-diphenylamine, polyvinyledene fluoride, and chitosan-based are being studied as material for electrodes of microbatteries. The fabrication of miniature and high-speed electronic devices requires large-scale (YI SI) and ultra large-scale (HI SI) integration circuits.

Such devices require silicone crystals with low density, small defects, low metal impurities and extremely low leakage currents. A large diameter wafer is also indispensable for the economical fabrication of chips.

All these constraints have directed scientists and engineers to look for new dimensions of crystal fabrication and characterization, besides improving the conventional methods. From the viewpoint of pollution, sensors capable of detecting and metering harmful gases like carbon monoxide are desired.

A large number of oxide-based semiconductors, like ZnO2 and SnO2, TiO2 and their varieties, are currently in use on a massive scale. More are in the research and development stages. Research is also underway on conducting polymers, bi-polymers, high temperature structural ceramics, high dielectric ceramics and polymers, ferro-electric materials, infrared sensitive films, high and low temperature superconductors, magneto-resistive and magnetic materials, semiconductors and optical fibre materials.

The present era is faced with greater challenges vis-a-vis material processing and development as compared to the past. The user and manufacturer both look for components that can last longer, work better but are cost efficient. These demands have broadened the horizon for materials from metals to ceramics, polymers, glasses and composites.

Materials development is a very slow process. The required tests for reliability are even slower. To begin with, a material with defined properties is developed. It is then repeatedly ascertained for acceptance.

If the results are satisfactory, the component is tested for end-use. Various properties like creep, stress, cracking and corrosion are tested. Other destructive and non-destructive tests are also carried out during the developmental stages.

The life assessment and design parameters of the materials depend largely upon mathematical modelling related to process simulation, designing of alloys, ordered-disordered alloys, lattice defects, phase diagrams, etc.

The process of acquiring know-how of certain technology requires help from experienced researchers, institutions, laboratories, and industries. Conferences and symposia are the best forum to interact with a large number of national and international experts.

Scientists and engineers in the developing world seek opportunities to discuss technical issues pertaining to their work with other competent researchers.

The International Society of Aerosols in Medicine (ISAM) is one such platform where scientists and engineers from all over the world, especially from the developing countries, interact to share and disseminate vital knowledge. It has been a biannual event for the last 17 years and their forthcoming ninth symposium will be held later this month. As in the past, the organizers aspire to make the event a great success for all those who are involved.

The writer is a professor at the Quaid-i-Azam University, Islamabad

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