Ceramics Have Greatest Resistance To Compression

Ceramics tend to be weak in tension but strong in compression.

Ceramics have greatest resistance to compression.

Ideally ceramics should be compressively stressed in use although engineering applications may frequently introduce tensile stresses in the component. Another way at looking at resistance to failure for ceramic materials is to examine the energy required to drive cracks through the system. Introduction structural ceramics have excellent mechanical properties such as high strength low specific weight and corrosion resistance even at high temperature. In addition aluminas are susceptible to corrosion from strong acids steam and sodium.

4 2 generally resistance to compression is the measure of the greatest strength of a monolithic advanced ceramic. Aluminas have good creep resistance up to about 1 500 f above which other ceramics perform better. Ideally ceramics should be compressively stressed in use although engineering applications may frequently introduce tensile stresses in the component. The ionic and covalent bonds of ceramics are responsible for many unique properties of these materials such as high hardness high melting points low thermal expansion and good chemical resistance but also for some undesirable characteristics foremost being brittleness which leads to fractures unless the material is toughened by.

Ceramics are very sensitive to cracks impurities and porosity and thus generally have low toughness. There is a need to know accurately the strength of brittle materials in compression both to distinguish between competing statistical micromechanical theories of strength and to provide data necessary for engineering designs for the optimum use of these materials as load bearing elements. Generally a ceramic with more defects is weaker. In compression however the flaws in the material do not cause stress concentrations or crack propagation as they do in tension.

4 2 generally resistance to compression is the measure of the greatest strength of a monolithic advanced ceramic. Glass ceramics 1 3 glasses 1 material k mpa m1 2 ic ceramics are defect limited. Ceramics thus were considered an ideal material for heat engines because they would make it possible to raise the combustion temperature and would improve the thermal efficiency.