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Knoop hardness scale

There are several hardness scales for describing the resistance of a material to indentation or scratching. This table lists a number of common materials in order of increasing hardness. Values are given, when available, on three different hardness scales the original Mohs Scale (range 1 to 10) the modified Mohs Scale (range 1 to 15), and the Knoop Hardness Scale. In the last case, a load of 100 g is assumed. [Pg.2151]

Material CAS Registry Number Mohs scale Ridgeway s scale WoodeU s scale Knoop hardness, kN/m " ... [Pg.9]

Sihcon carbide is well known as a hard material occupying a relative position on Mohs scale between alumina at 9 and diamond at 10 (see Hardness). The average values for Knoop hardness under a load of 100 g are... [Pg.464]

On ihe Mohs scale diamond is 10 and quartz 7. An abemative measure is the Knoop hardness (kgmm ) as measured with a 100-g load typical values on this scale are diamond 7000, boron carbide 2750, corundum 2100. topaz 1340, quartz 820. hardened tool steel 740. [Pg.242]

Alaterial CAS Registry Number Alohs scale Ridgeway s3 scale WoodeU sb scale Knoop hardness, kN/m2d... [Pg.9]

Knoop scale. Comparative hardness scale, ranges from glass (300-600) to diamond (6000-6500). [Pg.731]

Other common hardness tests involve the use of diamond pyramids. In the Vickers hardness test, a square pyramid is used and in the Knoop hardness test, the pyramid is elongated. The area term in the former test is the actual indentation area and in the latter, the projected area. From the impression geometries, shown in Fig. 6.30, the Vickers Hardness Number (VHN) and Knoop Hardness Number (KHN) can be shown to be VHN=1.854F/a and KHN=14.2F/L, respectively. A common hardness test in the USA is the RockweO hardness test, which uses various indenter types and loads. The result of these tests is a dimensionless number and leads to the use of various hardness scales (e.g., Rockwell B, Rockwell C). [Pg.189]

Hardness scale See Mohs, scale, knoop hardness number, pencil hardness, and rocker hardness tester. [Pg.481]

Diamond is the hardest material known to man. The hardness of diamond on the Mohs hardness scale is 10. The second hardest material is corundum (sapphire [AI2O3]), which has a hardness of 9. Corundum, as well as diamond, is transparent to visible radiation. The real difference in hardness is quite large because the absolute hardness of diamond is 7,000 Knoop and of the corundum is 2,000 Knoop [24]. Bulk modulus of diamond is 4420 kbar [25] but is only 2400 kbar for synthetic sapphire. However, because the cost of sapphire is much lower than that of the diamond and also sapphire is more transparent to UV light, sapphire anvil cells (SAC) are often used for an optical cell for pressure <100 kbar. Sometimes cubic zirconia anvils are also used for pressure <30 kbar [26]. [Pg.72]

The extreme hardness of enamel (6-5 on Moh s scale) results from the intrinsic hardness of apatite (Knoop hardness 430kgmm" ). The density of mature enamel approaches 3-01 gml" compared with 3-1 gml" for hydroxyapatite. [Pg.466]

Hardness -nos n (before 12c) (1) The resistance to local deformation. (2) Ability of a coating film, as distinct from its substrate, to resist cutting, indentation, or penetration by a hard object. An arbitrary scale of hardness is based upon ten selected minerals. For metals the diameter of the indentation made by a hardened steel sphere (Brinnell) or the height of rebound of a small drop hammer (Shore Scleroscope) serve to measure hardness. See Barcol Hardness, Brinell Hardness, Durometer, Indentation Hardness, Knoop Hardness Number,... [Pg.357]

Hardness Scale See Scale, Knoop Hardness Number, Pencil Hardness, and Rocker Hardness Tester. [Pg.357]

Hardness. The resistance to indentation or deformation of a material is known as its hardness. There are many hardness scales and methods of measurement. Most methods involve indenting a test specimen by impressing a weighted diamond stylus of a prescribed shape on it, and measuring the area or depth of the indentation. The ratio of applied force to area of indention is defined as the hardness. The scales used most frequently for ceramic materials are Mohs, Vickers, Brinnell, Rockwell, and Knoop. These are discussed here. [Pg.23]

Hardness number Mohs scale Ridgeway s extension of Mohs scale Knoop hardness of expanded scale materials... [Pg.25]

Ceramics are among the hardest substances known, and their hardness is correspondingly difficult to measure. Most methods rely on the ability of one material to scratch another and the measurement is presented on a relative scale. Of the available methods, the Knoop method is the most frequently used. In this approach, the surface is highly polished and a pointed diamond stylus under a light load is allowed to impact on the material. The depth of the indentation formed by the stylus is measured and converted to a qualitative scale called the Knoop or HK scale. The Knoop hardness of selected ceramics is given in Table 4.8. [Pg.256]

C and at 1850°C under 1 atm Nj. Two crystal structures alpha (1400°C) and beta (1400-1800°C), both hexagonal. Hardness approximately 2200 on Knoop KlOO scale. Excellent corrosion and oxidation resistance over a wide temperature range. Typical applications molten-metal-contacting parts, wear surfaces, special electrical insulator components and metal forming dies. Under evaluation as gas turbine and heat engine components as well as antifriction bearing members. [Pg.786]

Arbitrary hardness scales have been established that allow some correlation between hardness and yield strength. There are a variety of different methods including Brinell, Rockwell, Vickers, and Knoop, each with its own hardness scale. The reader is referred to ASTM Standards ElO, E18, E92, and E384 for details. The primary value of hardness testing is that it provides a nondestructive method for assessing the strength of a material and is useful for certifying that the actual materials used for specific components in a system meet the required material specifications. [Pg.179]

Mineral Grain size, No. (mm) Hardness, on Mohs scale //M Hardness determined by Knoop method HK Cleav- ability Degree of brittleness... [Pg.65]

Hardness measured in units of Mohs scale Mineral Chemical formula Vickers ffv (with micro- measurement) Knoop Hk tropy Khrushchev coeffi- 1 hardness cient, classes r -H 1 H° " h2 J = 0.7 p Nv Hlbcoc Optimum calculated, oad of by ova- j indeixter, rennykh (1963) ... [Pg.153]

Hardness measured in units of Mohs scale Mineral Chemical formula Measured ha Vickers Hv (with micro- measurement) rdness Knoop If Aniso- tropy coeffi- cient h2 H0 in Khrushchev hardness classes Ho = 0.7 J/fly Hi heor calculated by Pova-rennykh (1963) Optimum load of indenter P, mN... [Pg.157]


See other pages where Knoop hardness scale is mentioned: [Pg.505]    [Pg.2188]    [Pg.2134]    [Pg.2351]    [Pg.1976]    [Pg.2323]    [Pg.2096]    [Pg.505]    [Pg.2188]    [Pg.2134]    [Pg.2351]    [Pg.1976]    [Pg.2323]    [Pg.2096]    [Pg.59]    [Pg.198]    [Pg.7]    [Pg.631]    [Pg.10]    [Pg.1072]    [Pg.1096]    [Pg.3642]    [Pg.183]    [Pg.62]    [Pg.194]    [Pg.576]    [Pg.219]    [Pg.152]    [Pg.125]    [Pg.219]    [Pg.64]   
See also in sourсe #XX -- [ Pg.62 ]




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