Knoop hardness test

(redirected from Knoop scale)

Knoop hard·ness num·ber (KHN),

(nūp),

a number obtained by dividing the load in kg applied to a pyramidal diamond of specific size divided by the projected area of the impression: KHN = L/A, where A= the projected area of the impression in mm² and L = the load in kg; used for measurements of hardness of any materials, especially very hard and brittle substances such as tooth dentin and enamel.

Knoop hardness test

(noop),

KHT

A test of surface hardness, using a stylus with a pyramidal diamond indenter. The long diagonal of the resulting indentation determines the hardness of the substance.

Knoop hard·ness test

(knūp hahrdnĕs test)

Dental measurement to determine hardness of brittle materials; uses a diamond or rhombic indenting tool; test result provides dental clinicians with the Knoop hardness number.

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References in periodicals archive ?

When CBN was tested on the Knoop scale - a measure of the hardness of ultrahard material it was found to average only about 4700 kg/[mm.sup.2] vs values of 7000 for diamond.