4 Discuss the features of different types of advanced materi

4. Discuss the features of different types of advanced materials with examples

Solution

Answere: Advanced materials are divided according to the there material properties and applications.

Solid materials have been conveniently grouped into three basic classifications:

1.Metals,

2.Ceramics, and

3.Polymers.

viz. semiconductors, biomaterials, automobile,smart materials, and nanoengineered materials;

Examples include electronic equipment (camcorders, CD/DVD players, etc.), computers, fiber-optic systems, Aero spacecraft, aircraft, and military rockets.

Semiconductors

Semiconductors have electrical properties that are intermediate between the eletrical conductors (viz. metals and metal alloys) and insulators (viz. ceramics and polymers). Furthermore, the electrical characteristics of these materials are extremely sensitive to the presence of minute concentrations of impurity atoms, for which the oncentrations may be controlled over very small spatial regions. Semiconductors have made possible the advent of integrated circuitry that has totally revolutionized the electronics and computer industries (not to mention our lives) over the past three decades.

Biomaterials

Biomaterials are employed in components implanted into the human body for replacement of diseased or damaged body parts.These materials must not produce toxic substances and must be compatible with body tissues (i.e., must not cause adverse biological reactions). All of the above materials—metals, ceramics, polymers,composites, and semiconductors—may be used as biomaterials.

Materials of the Future:
Smart Materials

Smart (or intelligent) materials are a group of new and state-of-the-art materials now being developed that will have a significant influence on many of our technologies.The adjective “smart” implies that these materials are able to sense changes in their environments and then respond to these changes in predetermined manners—traits that are also found in living organisms. In addition, this “smart” concept is being extended to rather sophisticated systems that consist of both smart and traditional materials. Actuators may be called upon to change shape, position, natural frequency, or mechanical characteristics in response to changes in temperature, electric fields, and/or magnetic fields.
Four types of materials are commonly used for actuators: shape memory alloys, piezoelectric ceramics, magnetostrictive materials, and electrorheological/magnetorheological fluids.

For example, one type of smart system is used in helicopters to reduce aero-dynamic cockpit noise that is created by the rotating rotor blades. Piezoelectric sensors inserted into the blades monitor blade stresses and deformations; feedback signals from these sensors are fed into a computer-controlled adaptive device,which
generates noise-canceling antinoise.

Nano engineered Materials
Until very recent times the general procedure utilized by scientists to understand the chemistry and physics of materials has been to begin by studying large and complex structures, and then to investigate the fundamental building blocks of these structures that are smaller and simpler. This approach is sometimes termed “top-down” science. However, with the advent of scanning probe microscopes , which permit observation of individual atoms and molecules, it has become possible to manipulate and move atoms and molecules to form new structures
and, thus, design new materials that are built from simple atomic-level constituents (i.e., “materials by design”).

This ability to carefully arrange atoms provides opportunities to develop mechanical, electrical, magnetic, and other properties that are not otherwise possible.We call this the “bottom-up” approach, and the study of
the properties of these materials is termed “nano technology”; the “nano” prefix denotes that the dimensions of these structural entities are on the order of a nano meter (10 9m)—as a rule, less than 100 nanometers (equivalent to approximately 500 atom diameters).

One example of a material of this type is the carbon nanotube. In the future we will undoubtedly find that increasingly more of our technological advances will utilize these nanoengineered materials.