High Compressive Strength Ceramics

For a metal the compressive strength is near that of the tensile strength while for a ceramic the compressive strength may be 10 times the tensile strength.

High compressive strength ceramics.

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 reinforcing agents or by other means. Ceramics have compressive strengths about ten times higher than their tensile strength. The average of the coefficients of variation was 3. The literature on compressive strengths of crystalline ceramics especially at room temperature suggests that microplasticity may be the mechanism of much compressive failure since 2 the yield stress microhardness 3 is the upper limit of both ambient and elevated temperature compressive strengths and 2 data on grain size dependence are consistent with the fetch equation.

The compressive strength is then simply the yield stress of the metal. It is ideal for applications that require dimensional stability high thermal stability and low thermal expansion in forms that can be made to very tight tolerances. Ceramics tend to be weak in tension but strong in compression. Alumina for example has a tensile strength of 20 000 psi 1138 mpa while the compressive strength is 350 000 psi 2400 mpa.

High strength boards are designed to meet the toughest knocks and pressure maintaining its strength over a long productive life. Tables of compressive strengths of ceramics are available. The compressive strength was only slightly affected by the magnitude of the intermediate principal stress. The tensile strength of ceramics and glasses is low because the existing flaws internal or surface cracks act as stress concentrators.

Get high quality answers from experts. This is because flaws do not propagate under compression. Why do ceramics have high yield strength. A new uniaxial compression test developed for high strength ceramics has successfully measured the strength of 94 alumina al 2 o 3 testing was done using a procedure developed specifically for obtaining strengths to 10 gpa on very difficult to machine ceramics.