by B.H.S. Thimmappa
The Pathways in a New Era of Modern Materials
Materials have transformed every aspect of modern living. Engineering materials are used in the construction of artificial structures and components depending on their physical (conductivity, density, melting point, specific heat, thermal expansion, viscosity), chemical (corrosion, flammability, toxicity, stability, reactivity), mechanical (ductility, elasticity, hardness, plasticity, strength, malleability, weldability, formability, stiffness, creep, brittleness, castability) properties. Glass, paper, plastic, and metals are common materials that have mass and occupy space that we observe around us every day. These are manufactured materials from natural ones through artificial chemical processes. Coal, sand, wood, wool, and iron are examples of natural materials that come from animals, plants, or rocks. Some examples of advanced materials include light metals, composites, and steel. These materials have superior performance that is critical for specific applications. Ferromagnetic, piezoelectric, and ferroelectric materials are examples of functional materials having particular properties of their own. The smart materials include shape memory alloys and piezoelectric, photoelectric, thermoelectric, and magnetoelastic materials. These materials have properties that can be significantly changed in a controlled manner by an external stimulus such as electricity, heat, light, magnetic fields, or stress. Supermaterials having remarkable physical properties include amorphous metal, aerogel, carbon nanotube (CNT), e-textiles, graphene, metamaterials, transparent alumina, and nano-diamonds in the 21st century. These improved materials enable people to explore the design and use of new finished products/components/structures to improve their quality of material life. The substances harder than diamond include Wurtzite boron nitride, Lonsdaleite, Dyneema (ultra-high molecular weight polyethylene fiber), palladium micro-alloy glass, bucky paper, and graphene. Textile, leather, rubber, and paper are other common materials of daily use. Some examples of specialty chemicals include adhesives, catalysts, cosmetics, elastomers, food additives/flavors/fragrances, paints, polymers, and sealants. Examples of bulk chemicals include sulphuric acid, sodium hydroxide, and ammonia. Amorphous materials with short-range order (wax/glass) and crystalline materials with long-range order (salt/sugar) are other classes of materials. The types of magnetic materials include diamagetic/paramagnetic/ferromagnetic/ferrimagnetic/antiferromagnetic materials.There are other miscellaneous classes of materials such as metal products and alloys, beverages and food products, wood and paper products, textile and consumer goods, and those used in mining and metallurgy. The materials of the future include aerogel, artificial spider silk, bioplastic, carbon fibers, carbon nanotube, cross-laminated timber, graphene, metamaterials, metallic glass, metal foam, molecular superglue, nanomaterials, nanocomposite materials, and transparent alumina. The significance of materials science and engineering for the future development of societies is reflected in their central role in our daily lives and practically all manufacturing industries.
The spirit of asking questions is fundamental to the understanding of science/engineering/technology. In materials science, the pertinent questions of identity, structure-property relationships, causality, mechanism, control, benefits, costs, risks, and safety aspects include the following; What is this specific material made of? Why do materials behave as they do? How do its properties relate to its composition, structure, and bonding? Why does a material change? How do these changes happen? How can these changes be controlled? What are the consequences of such changes? How can the new material be designed for a particular application or those with multifunctional features? What are the safety precautions to be taken while handling such materials? How is residual waste material converted into a useful wealthy product? Some of the interesting questions that arise in materials science include the following; What is the densest crystal packing that is possible theoretically and is there any known example? How do secondary intermolecular attractions arise in different compounds? Why is copper opaque/ductile while glass is transparent/brittle? Why is it essential for some objects to be transparent/opaque? Why is glass transparent to visible light, but opaque to UV light? Why can aluminum oxide exist as a transparent, translucent, or opaque material? Why is a diamond a bad electrical conductor but an efficient thermal conductor? Why is it difficult to bend the steel rod compared to the aluminum rod? Why is a piece of dry wood non-conducting while a wire of copper conducts? How can we change properties like hardness, flexibility, and biocompatibility in a material? Why does the electrical conductivity of silicon increases on heating while that of silver decreases? Why does naphthalene (para-dichlorobenzene) solid evaporate? How can we explain the fact that good electrical conductors are also good thermal conductors? How can one understand the observations that when we release the load on a rubber band/spring, it comes back to its natural shape while a bent aluminum rod would not come back? What are the reasons for the viscosity of honey, mercury, and paraffin oil? Why does pure water always boil at the same temperature? Why are composites used instead of metals, ceramics, or polymers in certain applications? What is the mechanism behind functional smart materials? What does material science offer to society? Who can deny the role of materials in human existence? Why is it that a salt solution conducts electricity while sugar does not? How many moveable electrons are there in a material? How easily do they move? The answers to such questions could lead the learner to take the subject to higher levels of understanding, an understanding of the complex structure-property relationships, molecular mechanisms of material transformations, the development of an active system, to arrive at practical science-based solutions, customized products/solutions, and finally better materials management solutions.
Materials technology includes a range of materials used for manufacturing products, machines, and structures. For example, plastics are used in solid form as synthetic fibers for textiles, a film for packaging, and in composites like fiberglass. Metals like iron or aluminum continue to be essential for building machines and civil structures. Concrete is the prime material for building structures such as bridges. Some building materials like steel, concrete, and bricks are structural while others, such as ceramics and glass are mainly decorative. Appropriate frugal technology serves local needs using local resources such as stone and wood. Rubber is used for the soles of shoes and motor tires because of its resilience and elasticity. It is also used in rubber gloves and rainwear due to its flexibility and waterproof property. Plaster of Paris (PoP) has the distinct feature of setting into a hard mass in contact with water. It is used to make castings for statues, toys, and decorative materials, for setting broken or fractured bones in the correct position, and as a fireproofing material. Thin-film materials are used extensively in different types of sensor applications. Thin film solar cells like amorphous silicon, copper indium gallium selenide, cadmium telluride, and dye-sensitized solar cells are other examples of important novel materials. The nanoscale effects on steric and biological properties include increased selectivity for specific drug transportation and controlled release, increased permeability through membranes, and improved biocompatibility. The role of materials science research, technology, and innovations extends to almost all fields of human activity, and this particular domain has a transformational effect on the development in many areas which include healthcare, food processing, housing, energy, metals and minerals, and aerospace. The future of materials engineering is to obtain optimal performance by combining material design innovation with advances in technology involving several smart features. The recent advances in materials science/engineering include a transition to sustainable steel making, digital experience in welding, additive manufacturing in metallic objects, and making diamonds from gases. Advanced materials with highly specific properties include titanium fluoride phosphate cathode material, cellulose nanofibers, self-healing gel, platinum-gold alloy, composite metal foams, spider silk, biodegradable plastic, carbon concrete, and aerogel. The top ten materials industry trends include sustainable materials, smart and responsive materials, nanotechnology, additive manufacturing, material informatics, advanced composites, surface engineering, graphene and 2D materials, lightweight materials, and materials management 4.0. Material safety in an incredibly fast-developing field of material science matters. While living in a material world, make things better and make better things!
Important Properties of Engineering Materials
Some materials are hard/strong while others are soft/weak. Ordinary rubber becomes thinner in the middle when stretched while anti-rubber becomes fatter in the cross-section on stretching. Different materials have various properties because they contain different elements (atomic structure) and various compositions of ingredients, have different types of chemical bonds (bonding between atoms and molecules) and have different sizes of units (crystalline structures). The solid-state structure (micro + macrostructure) might include a variety of assemblies, e.g., molecular packing arrangement, or the geometry of linkage in an extended 3D structure may be different. Physical properties include mechanical and thermal properties (hardness, tensile strength, influence of coating, velocity of sound, thermal data and thermodynamic properties, thermal conductivity), electrical and magnetic properties (electron paramagnetic resonance, nuclear magnetic resonance, electrical conductivity, resistance, capacitance, impedance, inductance, switching effect, thermoelectric power, magnetic susceptibility, magnetoresistance, optical and spectroscopic properties (index of refraction, dielectric constant, infrared spectra, Raman spectra, absorption in the ultraviolet and visible range, photoconductivity, color dichroism, photoluminescence, The chemical properties include reactions of atoms, adsorption of gases, reactions with hydrogen/halogens, and reactions with main group/transition metals. The following factors taken together determine the properties of the material; composition, phases present and their distribution, defect structure (in the phases/between the phases), and residual stress. The properties of materials also depend on the properties of individual components, the relative amount of particles, their size, shape, distribution, orientation, and the degree of bonding. The goal of materials science/engineering is to design novel materials with a predetermined set of properties using suitable processing techniques, which gives them a particular microstructure and desired performance. The art of materials selection for automotive, aerospace, marine, and defense applications, and the design of integrated systems, smart materials, or advanced composite materials for military applications may require additional skills, experience, specific knowledge, and technologies.
The role of engineers has become very important for meeting the complex and specific challenges of making materials with required functional characteristics and solving technical issues with a specialized skill set and knowledge. The specific objective of this article is to provide common people with an introduction to the vast subject in a structured and useful manner to equip them with a basic familiarity with materials science/engineering. It is a learning journey through the fundamental principles underlying materials science/engineering and provides the essential vocabulary of these engineering sciences through inspirations, experiences, practices, and evolutions. A lot of energy is channeled into research to design advanced engineering materials with desired properties through collaborative research projects, exchange of faculty members, and online consultations. Materials will be at the core of multiple applications and start-ups in the area helping to move inventions into innovations for the market. There are nearly 100 material-based companies in the world and advances in materials are crucial to the continued vitality of countless industries. Maintaining competitiveness in the age of materials is difficult because of the interdisciplinary nature of research and the rapid creation of novel materials. The recent discovery of a new superconducting material, N-doped lutetium hydride at a temperature of just 69 degrees Fahrenheit or other such room temperature superconducting materials in the future could pave the way for ultra-efficient electrical grids and energy transfer lines. An astonishing variety of materials is possible considering the permutations and combinations of the number of elements in the periodic table and our life is too short to deliver innovative materials with totally different properties or substantially improved functionalities. The current trends in materials science research include materials that minimize environmental impacts, smart materials, sustainable materials, composite materials, catalyst materials, multifunctional materials, semiconductor materials, superconducting materials, advanced functional materials, ceramic nanomaterials, ionic liquids 4.0, biosafety materials, dental materials, multi-catalytic hybrid materials, and recycled materials. Boosting recycling and promoting lifestyles in harmony with nature is essential to achieve sustainable development goals (SDGs). The material remains silent if no questions are asked and diverse thinking in the design of materials creates brilliant breakthroughs. The triumphs of materials science skill rest on a chemical foundation and the artificial intelligence revolution in materials science will change the real-world material design scenario. Research aspects of material science involve synthesis and processing, structure and characterization, physical/chemical properties, and modeling and simulation. To make the greatest positive impact on the world, we must discover new cost-effective materials in the energy, defense, and domestic sectors. A trip towards innovations in engineering materials involves learning lessons by connecting to the past literature on materials, conducting experiments in the present, and hoping for a future where materials significantly contribute to one village, one world, and one family. There are no limits to what materials science can explore and the changing face of engineering science lies in the design of new materials!
References
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About the Author:
B.H.S. Thimmappa is a writer from Udupi, India