Silicon Nitride Ceramic

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Silicon Nitride Ceramic

Silicon Nitride Ceramic

Advanced Technical Ceramics - A Comprehensive History and Guide

Introduction

Have you ever wondered about the myriad materials from which stuff is made that we come across in our daily life? The numerous materials which have unique characteristics and which are used for making various articles used in everyday life- these materials attract the attention of the young inquisitive minds in engineering classrooms all over the world.

Today, let me introduce you to the world of "CERAMICS".

"Ceramics" are the materials which are often misunderstood as materials used merely for pottery and decorative objects. Even though the word ceramic is derived from the Greek word "Keramos", meaning potter's clay or pottery, what many people don't realize is that ceramics play an important role almost everywhere you see and many times in places that you can't.

Besides the everyday objects of glassware and floor tiles, the ceramics of today are critical in helping computers and other electronic devices operate, in medical devices for improving people's health in various ways, in providing global telecommunications, and in protecting soldiers and vehicles during combat.

Ceramics are generally defined as inorganic, non-metallic materials that are made from powdered chemicals. They are typically crystalline in nature (their atoms are arranged in a systematic manner) and are compounds formed between metallic and non-metallic elements such as aluminum and oxygen (alumina, Al2O3), calcium and oxygen (calcia, CaO), silicon and nitrogen (silicon nitride, Si3N4), and so on.

Various "advanced ceramic" products are manufactured by combining high-purity chemicals into desired shapes and then heating them to very high temperatures. The shaped ceramic products thus made can have many desirable properties such as heat resistance, hardness, strength, low electrical conductivity, and unique electro-mechanical characteristics. Thus advanced ceramics are ceramics which are made by tightly controlled methods and therefore they exemplify an "advancement" over the general definition. As a consequence of these refined methods, a new class of ceramics called "advanced ceramics" is born.

Long lasting and harder than steel, advanced ceramics may be found in aircraft engines, automotive engines, cutting tools used for making metal products, the skin of space shuttles, knives, bullet proof armor, artificial hip-joints, computers and microelectronics.

History

One of the first uses of advanced ceramics was for corrosion-resistant stoneware vessels in the chemical industry as early as the 1750s.Then came porcelain, which was first used in dentistry in the 1850s. With the invention of electric light in the 19th century, ceramic materials based on porcelain for electrical insulation were developed.

This was followed by the blooming of the radio and television broadcasting industry in the 20th century, which needed special heat resistant materials that could withstand the high-frequency electromagnetic fields. As a result, electro-ceramics such as steatite were developed. Subsequently, other electro-ceramics such as magnetic ceramics (ferrites) were developed, followed by capacitor ceramics (titanates) and electro-mechanical ceramics (piezoelectric ceramics). In the later part of the 20th century, the need for protecting tiny transistors and ICs from ambient conditions led to the development of ceramic packaging materials which facilitated further miniaturization.

Concurrent with the development of electro-ceramics, another sub-class of advanced ceramics which came to be called structural ceramics progressed, which had high structural and chemical integrity characterized by properties such as extremely high hardness, stiffness, and heat and chemical resistance. These structural ceramics found applications in various industries, for example in the space industry as heat and wear resistant tiles and nose cones on space shuttles, in the aerospace industry as bearings and turbine rotors, in the chemical industry as chemical resistant seals and conduits, in the defence industry as bullet-proof vests and armor plates for vehicles, in the biomedical industry as hip-joints, knee-joints and orbital implants, and so on.

Further Developments

As ceramic technology has rapidly progressed over time, the definition of advanced ceramics has expanded to include a much wider range of compositions used in a large variety of applications. In broader terms advanced ceramics also include glass (which has a non-crystalline or amorphous random atomic structure), enamel (a type of glassy coating), glass-ceramics (a glass which is partly crystallized), and inorganic cement-type materials (cement, concrete, plaster and lime).

Advanced ceramics include yet another sub-class of ceramics called refractories. Refractories are critical materials which reduce heat losses from industrial ovens, also called kilns, and at the same time they resist very aggressive conditions including chemical and acid attack, very high temperatures (up to 3200°F), abrasion, mechanical impact, and more. These refractory ceramics enable manufacturers of commodities such as metals, alloys, cement, glass, etc to operate efficiently and profitably. Thus they play a very important role in growing the global economy.

Advanced ceramics continue to be developed even further; new ceramics and their combinations are constantly being improved and newer products are continually being introduced in various industries.

The progress in advanced ceramics is so rapid that the advanced ceramics of today are strikingly different from those made even a few years ago. Ceramic engineers eagerly anticipate further rapid developments of newer ceramic materials and their combinations that will find even more exciting applications in the future.

Want to know more about advanced technical ceramics, how they are made and their various uses? Interested in following the latest developments of these materials? Interested in getting information and technical advice in this field? Just visit http://www.ceramics411.com

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