Advance materialsComposite and ceramic

About ceramics and its properties.

CERAMIC MATERIALS:

History: Archaeologists have uncovered human-made ceramics that date back to at least 24,000 BC. These ceramics were found in Czechoslovakia and were in the form of animal and human figurines, slabs, and balls. These ceramics were made of animal fat and bone mixed with bone ash and a fine clay like material. It is thought that ancient glass manufacture is closely related to pottery making, which flourished in Upper Egypt about 8,000 BC. Experts believe that it was not until 1,500 BC that glass was produced independently of ceramics and fashioned into separate items. Ceramic is being used a lot in our daily life in the last several years and its new technology is constantly being discovered. We are moving towards the new application of ceramics.

Introduction: ceramic are in organic non-metallic materials that consists of metallic and nonmetallic elements bonded together primarily by ionic/covalent bond or both.

Ceramics are classified as inorganic and non-metallic materials which are essential to our daily lifestyles. Materials engineers are those who continuously improve its properties and design the processes in which products are made. Make  new types of ceramic products in everyday life. Ceramic having different uses for products in many areas. Ceramic are inorganic, non-metallic material that consist of metallic and non-metallic bonded together primarily by ionic and/or covalent bonds or both.

Based on their uses, ceramic can be classified as:      

Tradition Ceramics: Those ceramic materials which are in use right from ancient period till today. Clay is one of the most common ceramic raw materials. It is used widely because it is found in great quantities naturally and it is easily formed. There are extremely brittle, having high thermal stability, high chemical stability i.e. corrosion resistance, having high hardness. Ceramics are available as single crystal or in polycrystalline form. These have finer grain, which lead to more strength and toughness.

Example: white ware, tiles, bricks, sewer pipe, pottery and abrasive wheel etc.

Traditional ceramic

Industrial ceramic or advance ceramic: It is also called engineering ceramic or high-tech ceramic. These ceramic materials having high temperature resistance properties than metals. Advance ceramic use in turbine, automobile, aerospace components.

Examples: Al2O3 , Si2 , Si3N4 etc.

New ceramic thermal barrier coating is long, strong, and down to get the friction on(credit: The American Ceramic Society)

Mechanical properties:

At  room temperature, virtually all ceramic are brittle. Micro cracks, the presence of which is very difficult to control, result in amplification of applied tensile stresses and account for relativity low fracture strength. This amplification does not occur with compressive loads and consequently ceramics are stronger in compression.

Brittle Fracture of Ceramics: The brittle fracture process consists of the formation and propagation of cracks through the cross-section of material in the direction perpendicular to the applied load.

under some circumstances structure of ceramic material will during flow propagation of crack when stress are static in nature and phenomena is termed as static fatigue or delayed fracture. this fracture is sensitive to environmental condition it is because of combination of applied stress and breaking of ionic bonds due to moisture. Silicate glass is prone to it. Other examples: porcelin, Portland cement, high Alumina ceramics, barium titanate and silicon nitride.

Compressive strength: compressive strength in ceramics is many times greater than this tensile strength. This is clear from the fact that ceramics like brick, cement and glass are always used in compression and not in tension. Tempered glass is used for the glass doors, rear Windows of the cars and similar high strength applications for their high compressive strength.  

Hardness: When beneficial mechanical property of ceramics is their hardness which is often utilized when an abrasive or grinding action is required; in fact, the hardest known materials are ceramics. In general hardness lie between 500BHN to 2000BHN.

Shear strength: High shear strength and low fracture strength are generally characteristics of ceramics with the exception of a few materials such as clay. Therefore, they commonly fail in brittle manner or by fracture noncrystalline ceramics are always brittle below the softening temperature. thus, the failure occurs buy the brittle cleavage along particular crystallographic planes.

Tensile strength: Tensile strength in ceramics are theoretically high, but in practice are usually quite low. Failures are often due to stress concentrations at the pores, grain corner of micro crack.                     

In this article we have focused on some general important points of ceramic such as when ceramic has been in use and why it is important in our daily life, types of ceramics and discus about some important mechanical properties.

Tags

K Yashdeep

Hye there..! I am Yashdeep Kamal. I completed my Bachelor in Technology(Materials Science and Metallurgical Engineering). Engineer by passion, writer by choice. I have been writing about Composites, Ceramics, polymers, nanotechnology, advance materials and metallurgy etc. You can read about these topics here. Hope it may help you.

Related Articles

Leave a Reply

Your email address will not be published. Required fields are marked *

Back to top button