Wear, 152 (1992) 193 193

Book Review

Ceramic Hardness

By I. 1. McColm, published by Plenum, New York, 1990, 324 pp., price $65.00.

Hardness testing has the potential to provide a weatth of information about the deformation behaviour of materials. It is particularly useful for the examination of advanced materials such as ceramics, because only small specimens are often available. Hardness testing is also relevant to tribology, since the properties that it measures are essentially those near-surface properties which are important in governing the behaviour of contacts between two surfaces. In fact, the hardness testing procedure is similar to asperity contact in many ways.

This book is a specialist review of the science of hardness testing as applied to ceramic materials. After considering some of the fundamentals of hardness testing, the book covers the hardness testing of single crystals before examining the effect of changes in test parameters such as load, environment (including temperature) and time. The important topic of hardness-induced cracking, and its application to fracture toughness testing, is then described in some depth. The book concludes with an extensive review of hardness data for a wide range of ceramic materials which has been selected from the literature. The book provides a valuable source book for those who need to use hardness testing as a tool for research on materials, and gives a quick route into the subject. A minor disappointment with the plan of the book was that there was no mention of the rapidly emerging area of nano-hardness testing, and the related microscopy techniques of atomic force microscopy. These new techniques extend indentation testing down to atomic dimensions.

However, the book suffers from a number of problems, both in the overall style and in the detailed content. Topics are often discussed without an adequate introduction leading to a text that seems to jump from subject to subject. A good example of this is the introduction to the book where what is surely the most fundamental equation in hardness testing (H is proportional to PI!, where H is the hardness, P the applied load, and A the contact area) is only brought in after twenty pages before the reader is then immersed in a complex discussion of the atomistic basis of hardness. Symbols are frequently ambiguous, and sometimes change without warning. Equations have been found that are miswritten and have the wrong cross-references.

It is unfortunate that the book suffers from these problems, as the field is now becoming quite complex and there is a need for a clear definitive book which can lead the reader in an informed way through the many pitfalls in indentation testing of ceramics. The overall impression, rightly or wrongly, is that the author did fully understand the theory he is describing well enough to describe it logically and comprehensibly. These problems mean that the book could never be used in isolation for serious study, as reference will always have to be made to the original cited papers to clarify the arguments in the book.

M. Gee Division of Materials Metrology

National Physical Laboratory Teddington

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Elsevier Sequoia, Lausanne