From the introductory review in Chapter 1 and from the great preponderance of data to be reported in Chapters 3 to 6, it can be seen that for ceramic hardness studies the vastly dominant technique is that of static indentation. Now some practical aspects of indentation hardness measurements will be considered. Figure 1.3 shows that in a seemingly arbitrary way indentation hardness values and measurements have been determined by the range of the applied load. However, the ranges are not altogether arbitrary because the apparatus needed to make the measurements is characteristic of each of these three zones. Since many of the scientific uses of this technique lie in the microhardness regime 0.0098 N to 1.96 N and the low-load regime 1.96 N to 9.81 N, it is worthwhile concentrating on equipment and techniques necessary for measurement in these ranges. The generally high hardness values of ceramics and the complexity of equipment and technique needed to obtain and measure very small indents means that, in general, low-load hardness work is encountered rather than the microhardness ranges, although the distinction will always remain arbitrary, depending upon the materials under examination, which can lead to indents of greatly different size with a given load. It is after all the difficulties associated with measuring the size of the resultant indent trace and any cracks that may be present that determine to a large extent whether the equipment needed is for micro-, low-load, or macrohardness. In general we can make the following broad classifications among loads, equipment and expertise.
KeywordsVickers Hardness Ceramic System Indentation Hardness Rockwell Hardness Indent Depth
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