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Griffith's theory of fracture
Finance & Accounting
Pages 4 (1004 words)
Ceramics and Metals have different atomic structure and ionic bonding. Ceramic materials have both ionic and covalent bonds. Ionic bond is the one that keeps them brittle. Ionic bond is lose and no definite direction…
When stress is applied, ions slide past each other then goes to different directions; ions of the same charge bumps and trying to repel each other; causing the atoms to spread. The material then breaks. In metals, the atomic structure consist more positively charged ions on a flow of negatively charge electrons. The electrons allows the positive charge ions to slide and roll past each other without breaking the bond when a certain stress is applied. This causes the metal to be tough. 2) Glass in general has a low tensile strength. This lies entirely with the fact that glass is a solid lacking crystalline structure or namely amorphous solid. Amorphous solid has a moving structure of molecules and are not compact, this results to having a low tensile strength than of other solids. However, there are methods of somehow improving glass’s tensile strength, strengthening them. One is by soaking the glass into a bath of potassium nitrate solution on an about 400 to 450 degrees Celsius having. Potassium nitrate has larger molecule structure than of a common sodium nitrate molecule in the surface of the glass. The process will now replace the sodium nitrate on a glass by the potassium nitrate in the bath solution, leaving the glass having a thick layer and a hard wedge. This is called “chemical strengthening”. ...
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