Testing Methodologies and Effects Associated with Ceramic Materials

Abstract

Ceramics are being used in numerous industrial and scientific applications. Advanced ceramics, in particular, have great future possibilities for use in a wide variety of applications as these are typically wear and corrosion resistant, lightweight, and thermodynamically stable. In addition, many advanced ceramics have electrical properties that make them advantageous for use in electronic applications such as electronic packaging. With the steadily increasing use of ceramics in industry, there exists an increasing demand to characterize and quantify the properties of ceramics. This leads to higher demand for improved testing techniques to yield more exact data used for activities such as design, safety analysis, quality control, and scientific understanding. This present study gives a brief overview of the major test methods currently being used, relative advantages and disadvantages to each other, and some common sources of error. In addition, a listing of standards that are both relevant and directly applicable to ceramics are given for various testing methods. This chapter considers the most common mechanical testing methods which are usually expected to be performed by students entering the first time into a lab. Tensile test-related parameters are evaluated. Very popular tests of ceramics are the various hardness tests (for example Vickers hardness test), which is not only a cost saving test, but also requires shorter times, since no specific specimen preparation, except of a smooth (often polished) surface is required. On small size specimens, Knoop hardness test is the general approach to obtain hardness data. Another accepted method of evaluating the mechanical properties of a ceramic is by a bending (flexural) test. The tests can be performed by three or four point bending tests. Compression tests are more popular than tension tests, since they tend to close pores, cracks and other flaws resulting in higher test results than by those obtained by tension, which tends to open rather than close cracks and microcracks. Toughness is an important criterion in ceramic properties (mechanical) evaluation. Because of the brittle nature of ceramics, special instrumented Charpy Impact Test machines were developed, primarily to evaluate the dynamic toughness of such materials. Creep and Fatigue tests are not included in this chapter and they will be evaluated in separate chapters. Because of the large scatter in the experimental results, Weibull statistical distribution is applied to obtain a mean value of the experimental results. In this manuscript, the descriptions of assorted testing methodologies associated with ceramics are presented.