Knoop hardness test

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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 ?
For example, in 1962, the Knoop hardness values for stainless steel files reported by Craig and Peyton ranged from 525-565.10 In 1996, Brockhurst and Denholm reported significant differences in microhardness between endodontic files from two different manufacturers.8 In their study, the Vickers hardness range was from 400 to 651 VHN, falling below the hardness required for cutting instruments (550-650 VHN).
The data were expressed in Knoop hardness number (kg/ [mm.sup.2]) to calculate the [DELTA]S, since there were two slightly but differing values (both with a good relation between CSMH and Transverse Microradiography) in the literature to convert the values in mineral volume percent [Featherstone et al, 1983; Kielbassa et al., 1999].
The popularity of this test spawned a number of test scales, including the Vickers hardness test (1921), the Rockwell test scale (conceived in 1908), and the Knoop hardness test (1939).
A companion paper has additional information including edge chip resistance and Knoop hardness measurements for both veneering ceramics (14).
(7.) Ferro, D, Barinov, SM, Rau, JV, Latini, A, Scandurra, R, Brunetti, B, "Vickers and Knoop Hardness of Electron Beam Deposition ZrC and HfC Thin Films on Titanium." Surf.
The originator of the Rockwell hardness tester has introduced its Tukon 2500 Minuteman ELT automated Vickers/ Knoop hardness tester.
Paul Darley said the seal, which has a Knoop hardness of 2800, dissipates heat and has better corrosion resistance than other seal materials and thus is a major barrier against leakage.
It is comprised of fluoropolymer, polymer binder and inorganic filler film hardener, the fluoropolymer to polymer binder weight ratio being 0.5 to 2.0:1 and the filler film hardener to fluoropolymer weight ratio being at least 1.4:1, at least 30% weight of the filler film hardener comprising large ceramic particles having an average particle size of at least 14 micrometers and a Knoop hardness of at least 1200.
Now consider that this cutting tool possesses Knoop hardness of 3400, lasts five or six times longer than contemporary tungsten carbide inserts, yet costs only two to three times as much.
After 24 h, five indentations (10 g for 5 s) were performed on each sample using a microhardness tester (HMV 2; Shimadzu, Tokyo, Japan) to obtain the initial Knoop hardness number (KHN1).
Bailey and Swift12 documented a reduction in Knoop hardness after using home bleaching agents.