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
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
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
Bailey and Swift12 documented a reduction in Knoop hardness
after using home bleaching agents.
Effect of Insertion Method on Knoop Hardness
of High Viscous Glass Ionomer Cements.