Chemistry and Physics of Mechanical Hardness
Chapter One
Introduction
1.1 WHY HARDNESS MATTERS (A SHORT HISTORY)
A most characteristic property of a solid is its hardness. This ranges from very
soft (talc) to very hard (diamond). Although hardness is an important general
characteristic of materials, it also has great utility. It determines the resistances
of surfaces to wear. It determines the effectiveness of all sorts of tools used
for cutting everything from textiles to hard rocks. A closely related function
is the polishing of gems, mirrors, lenses, and the like. It is an index of the
strengths of materials; particularly metals. Geologists find it useful for identifying
minerals; and it plays a key role in geophysical phenomena such as meteor
impacts. Unfortunately it can also be very destructive in military ordnance.
A property of more ubiquitous importance is hard to find.
The range of hardness numbers, measured in kilograms per square millimeter,
is large. It runs from one for a soft material like KI to about ten thousand
for the hardest material-diamond. In other words, it has a range ... read full excerpt from Chemistry and Physics of Mechanical Hardness (Wiley Series on Processing of Engineering Materials #5) ebook
