Ceramic material tensile strength

Properties. Properties of stmctural siHcon nitride ceramics are given in Table 2. These values represent available, weU-tested materials. However, test methodology and the quaHty of the specimens, particularly their surface finish, can affect the measured values. Another important material property is tensile strength. Values obtained on Norton s NT154 material are 750 MPa at RT, 500 MPa at 1200°C, and 350 MPa (50,000 psi) at 1400°C (62). 

Vitahium FHS ahoy is a cobalt—chromium—molybdenum ahoy having a high modulus of elasticity. This ahoy is also a preferred material. When combiaed with a properly designed stem, the properties of this ahoy provide protection for the cement mantle by decreasing proximal cement stress. This ahoy also exhibits high yields and tensile strength, is corrosion resistant, and biocompatible. Composites used ia orthopedics include carbon—carbon, carbon—epoxy, hydroxyapatite, ceramics, etc. 

Nonoxide fibers, such as carbides, nitrides, and carbons, are produced by high temperature chemical processes that often result in fiber lengths shorter than those of oxide fibers. Mechanical properties such as high elastic modulus and tensile strength of these materials make them excellent as reinforcements for plastics, glass, metals, and ceramics. Because these products oxidize at high temperatures, they are primarily suited for use in vacuum or inert atmospheres, but may also be used for relatively short exposures in oxidizing atmospheres above 1000°C. 

Describe briefly how the tensile strength of ceramic materials is determined by their microstructures. How may the tensile strength of ceramics be improved ... 

Fig. 9.30 The strength of a ceramic material as a function of the volume percentage of pores during a tensile test.

Materials in the form of fibers are often vastly stronger than the same materials in bulk form. Glass fibers, for examples may develop tensile strengths of 7 MPa (1,000,000 psi) or more under laboratory conditions, and commercial fibers attain strengths of 2,800 to 4.8 MPa (400,000 to 700,000 psi), whereas massive glass breaks at stresses of about 7 MPa (1000 psi). The same is true of many other materials whether organic, metallic, or ceramic. 

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