Consider the following statements relating to mechanical properties of...
Ans. (a) 2. Compressive strength is many times higher than tensile strength.
Ceramics
1. They contain both metallic and non-metallic elements.
2. Characterized by their higher resistance to high temperatures and harsh environments than metals and polymers.
3. Typically good insulators to passage of both heat and electricity.
4. Less dense than most metals and alloys.
5. They are harder and stiffer, but brittle in nature.
6. They are mostly oxides, nitrides, and carbides of metals.
7. Wide range: traditional (clay, silicate glass, cement) to advanced (carbides, pure oxides, non-silicate glasses).
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Consider the following statements relating to mechanical properties of...
Explanation:
The correct statements regarding the mechanical properties of ceramics are as follows:
Tensile strength is theoretically high but in practice quite low:
Ceramics have strong covalent and ionic bonds, which theoretically give them high tensile strength. However, in practice, ceramics are brittle materials with limited ductility, making them susceptible to cracking and failure under tensile loading. Thus, the tensile strength of ceramics is relatively low compared to other materials.
Compressive strength is many times lower than tensile strength:
Ceramics have a higher compressive strength compared to their tensile strength. The strong covalent and ionic bonds in ceramics allow them to withstand compressive forces effectively. In contrast, ceramics have lower tensile strength due to their inherent brittleness. Therefore, the compressive strength of ceramics is many times higher than their tensile strength.
Shear strength is high:
Ceramics exhibit high shear strength due to the nature of their atomic bonding. The strong covalent and ionic bonds between atoms enable ceramics to resist shear forces effectively. This makes ceramics suitable for applications where shear forces are expected, such as cutting tools and abrasives.
Transverse strength is easy to ascertain:
Transverse strength refers to the ability of a material to withstand bending or flexural loads. It is determined by conducting a flexural test, where a sample is subjected to a three-point or four-point bending setup. Ceramics, being brittle materials, are prone to fracture under bending loads. Therefore, determining the transverse strength of ceramics can be challenging, as it requires careful handling and testing procedures to avoid premature failure.
Conclusion:
Based on the above explanations, the correct statements regarding the mechanical properties of ceramics are 1 and 3. Tensile strength in ceramics is theoretically high but low in practice, and ceramics exhibit high shear strength. Statement 2 is incorrect as ceramics have higher compressive strength compared to tensile strength. Statement 4 is also incorrect as determining the transverse strength of ceramics can be challenging due to their brittleness.
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