misspelledsearch.com:

hardness tester

information page

If you cannot find the information you are searching for on this page, we suggest searching Google with the correct spelling "hardness tester":

For the mathematical concept of the difficulty of proving a conjecture, solving an equation, etc., see computational complexity theory. For water hardness, see hard water.

In materials science, hardness is the characteristic of a solid material expressing its resistance to permanent deformation. Hardness can be measured on the Mohs scale or various other scales.

There are three principal operational definitions of hardness:

1. Scratch hardness
2. Indentation hardness
3. Rebound, dynamic or absolute hardness

Scratch hardness

In mineralogy, hardness commonly refers to a material's ability to penetrate softer materials. An object made of a hard material will scratch an object made of a softer material. Scratch hardness is usually measured on the Mohs scale of mineral hardness. Pure diamond is the hardest known natural mineral substance and will scratch any other material. Diamond is therefore used to cut other diamonds; in particular, higher-grade diamonds are used to cut lower-grade diamonds.

The hardest substance known today is aggregated diamond nanorods, with a hardness 1.11 times diamond.

Estimates from proposed molecular structure indicate the hardness of beta carbon nitride should also be greater than diamond (but less than ultrahard fullerite). This material has not yet been successfully synthesized.

In the December 4th, 2005 issue of The Jerusalem Post, Professors Eli Altus, Harold Basch and Shmaryahu Hoz, with doctoral student Lior Itzhaki report the discovery of Polyyne, a material 40 times harder than diamond. It is a superhard molecular rod, comprised of acetylene units.

Indentation hardness

Primarily used in engineering and metallurgy, indentation hardness seeks to characterise a material's hardness, i.e. its resistance to permanent, and in particular plastic, deformation. It is usually measured by loading an indenter of specified geometry onto the material and measuring the dimensions of the resulting indentation.

There are several alternative definitions of indentation hardness, the most common of which are:

• Brinell hardness test (HB)
• Janka Wood Hardness Rating
• Knoop hardness test (HK) or microhardness test, for measurement over small areas
• Meyer hardness test
• Rockwell hardness test (HR), principally used in the USA
• Shore hardness, used for polymers
• Vickers hardness test (HV), has one of the widest scales

There is, in general, no simple relationship between the results of different hardness tests. Though there are practical conversion tables for hard steels, for example, some materials show qualitatively different behaviours under the various measurement methods.

Hardness increases with decreasing grain size. This is known as the Hall-Petch effect. However, below a critical grain-size, hardness decreases with decreases grain size. This is known as the inverse Hall-Petch effect.

For measuring hardness of nanograined materials, nanoindentation is used.

Rebound hardness

Also known as dynamic or absolute hardness, rebound hardness measures the height of rebound of an indenter dropped onto a material using an instrument known as a scleroscope. One scale that measures rebound hardness is the Bennett Hardness Scale.

References

• Dieter, George E. Mechanical Metallurgy (SI Metric Adaptation). Maidenhead, UK: McGraw-Hill Education, 1989. ISBN 0071004068.

See also

• Tensile strength
• Toughness
• Yield (engineering)
• Young's modulus
• Softness
• Soft matter
• Hard matter
• Nanoindentation

External links

• An introduction to materials hardness
• Engineering Stress-strain Curve

This hardness tester index site has been developed to help wayward users find the information they are looking for, no matter how they are mistakenly spelled or mistyped. This site is designed to help users find hardness tester information for the following query variants:

hardness	hardness ester	hardness estor	hardness estur
hardness estel	hardness testor	hardness testur	hardness testel
hardness teste	hardness tesght	hardness teter	hardness tetel
hardness tetor	hardness tetur	hardness titer	hardness titel
hardness titor	hardness titur	hardness testre	hardness tesetr
hardness tetser	hardness tseter	hardness etster	hardness testr
hardness teser	hardness tster	tester	halness tester
harnes tester	halnes tester	haress tester	harnss tester
hrness tester	haness tester	haldness tester	hardnes tester
haldnes tester	hartness tester	hartnes tester	harredness tester
harrednes tester	hrdness tester	hadness tester	harness tester
hardess tester	hardnss tester	hardmes tester	hardnses tester
hardenss tester	harndess tester	hadrness tester	hradness tester
ahrdness tester

If you would like to add or correct the content of this site, or if you are interested in supporting the efforts of misspelledsearch.com by placing your product information on these hardness tester pages, please contact mistype@gmail.com for details.