Mechanical Properties of Ceramic Materials

Let us look at the mechanical properties of polycrystaUine ceramics and composites in detail. Let c = AZ/Zq denote relative strain of material (where Zq stands for the initial length, AI—for length increase of the material subjected to load), and o— for load applied to the material. The load evokes in the material a stress, i.e. force acting on a unit of area of a given volume of material. Except for the immediate vicinity of defects of the crystalline stmcture, the stress has an identical value with the load, o. 

An elastic solid is characterised by a practically linear relationship between relative strain c, and applied load a (Fig. 3.2a) o = Cc, where C is an elasticity constant. Moreover, the strain is independent of time and is reversible, i.e. appearing when a load is applied to the material and disappears immediately when the load is removed (Fig. 3.2b). 

The elasticity constant often used is the Young s modulus E  

The brittleness of materials manifests itself by brittle fracture, a fracture of the material into two or more parts which is due to spontaneous propagation of cracks of a given critical size. The propagation, once initiated, occurs at a very rapid rate (2-5 km s ) at a low relative strain 8.  

Brittle Fracture Methods for estimating the risk of brittle fracture originate in concepts proposed by Griffith. To this end, let us assume that the material is in the 

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While mechanical properties of ceramic materials are usually quite adequate for the duties which they have to perform, it is essential to realise the limitations of the material, and to design and install any articles made from it in such a way as to minimise any weakness. Table 18.12 gives typical values for the mechanical properties of the different materials which are available. 

Atkinson, A. and Selquk, A., Mechanical properties of ceramic materials for solid oxide fuel cells, in Proceedings of Solid Oxide Fuel Cells V, U. Stimming, S.C. Singhal, H. Tagawa and W. Lehnet (Eds.), The Electrochemical Society, Pennington, NJ, 1997, p. 671. 

Rigby, G.R., The effect of expansion mismatch on the mechanical properties of ceramic materials , Trans. Indian. Ceram. Soc., 1972 31(1) 18-30. 

Rico, A., Garrido, M. A., Otero, E. Rodriguez, J. Roughness Effect on the Mechanical Properties of Ceramic Materials Measured from Nanoindentation Tests. Key Engineering Materials 333, 247-250 (2007). 

Garter, G. Barry, and M. Grant Norton. Ceramic Materials Science and Engineering. New York Springer, 2007. Covers ceramic science, defects, and the mechanical properties of ceramic materials and how these materials are processed. Provides many examples and illustrations relating theory to practical applications suitable for advanced undergraduate and graduate study. 

The mechanical properties of ceramic materials are strongly influenced by the strong interatomic bonds that prevail. Dislocation mechanisms, which create slip mechanisms in softer metals, are relatively scarce in ceramics, and failure may occur with very little plastic deformation. Ceramics also tend to fracture with little resistance. 

Carbon nanotubes (CNTs) have incredible mechanical properties and high aspect ratio [1-3], and they seem to be superior reinforcement fibers to improve the mechanical properties of ceramic materials. We have combined carbon nanofibers (CNFs) with the average diameter of 104 nm which were a type of multi-walled CNT with alumina [4,5]. 

The metal-ceramic composite appears to have a number of advantages it improves the mechanical properties of the material, allowing it to retain more of its superconductivity while making it more plastic the silver matrix protects the composite from the degrading processes that result from exposure of the material to moist air the metallic silver allows the material to cool quicker and more efficiently than the composite alone. 

Porosity of Ceramics, Roy W. Rice Intermetallic and Ceramic Coatings, edited by Narendra B. Dahotre and T. S. Sudarshan Adhesion Promotion Techniques Technological Applications, edited by K. L. Mittal and A. Pizzi Impurities in Engineering Materials Impact, Reliability, and Control, edited by Clyde L. Briant Ferroelectric Devices, Kenji Uchino Mechanical Properties of Ceramics and Composites Grain and Particle Effects, Roy W. Rice Solid Lubrication Fundamentals and Applications, Kazuhisa Miyoshi... 

Ceramic powder characteristics are important because the purity of the powder sets the maximum purity level of the final processed ceramic part, and the particle size and size distribution play major roles in defining the microstructure and properties of the final parts. Both the purity and the microstructure of sintered ceramics influence the properties of ceramic materials, including mechanical, thermal, electrical, and magnetic properties and chemical corrosion resistance. 

Zirconia (Zr02) is an extremely versatile ceramic that has found use in oxygen pumps and sensors, fuel cells, thermal barrier coatings, and other high-temperature applications, all of which make use of the electrical, thermal, and mechanical properties of this material. Proof of the interest and usefulness of zirconia can be seen from the voluminous literature found on this material. This chapter is intended to provide a concise summary of the physical and chemical properties of all phases of zirconia that underlie the appropriate engineering applications. 

Data on atmospheric carbon dioxide Mechanical, thermal, and other properties of ceramic materials... 

Mechanical properties of ceramics, pp. 339-407 in Materials Science and Technology, Vol. 11, edited by M. 

R. F. Cook and G. M. Pharr, Mechanical properties of ceramics, pp. 339-407 in Materials Science and Technology, Vol. 11, edited by M. Swain, VCH Publishers, Germany, 1994. 

This book is a comprehensive introduction to the mechanical properties of ceramics, and is designed primarily as a textbook for undergraduate and graduate students in materials science and engineering. 

Because some mechanical properties depend on how the material was tested, it is important and necessary to establish specified test methods. Standard test methods have been adopted for ceramics. In the United States ASTM International (originally the American Society for Testing and Materials, ASTM) is the primary organization developing standards for materials testing. ASTM Committee C-28 on Advanced Ceramics has completed several standards and ones related to mechanical properties and testing are listed in Table 16.1. Specialized subcommittees work on specific areas within the field of advanced ceramics. Coimnittee C28.01 is involved with standards related to mechanical properties and performance of monolithic ceramics. Committee C28.02 deals with reliability issues. The National Institute of Standards and Technology (NIST) has established several free databases that list mechanical properties of ceramics. 

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