Scleroscope

Many types of hardness tests have been devised. The most common in use are the static indentation tests, eg, Brinell, Rockwell, and Vickers. Dynamic hardness tests involve the elastic response or rebound of a dropped indenter, eg, Scleroscope (Table 1). The approximate relationships among the various hardness tests are given in Table 2. 

Recommended Practice for Scleroscopic Hardness Testing of Metallic Materials Test Method for Rubber Property International Hardness Test Method for Rubber Property Durometer Hardness... 

Recommended Practice for Scleroscope Hardness Testing MetaUic Materials Rockwell Hardness of Bone Cements... 

The Scleroscope scale ranges from 0 to 140 the cahbration point of 100 is the hardness of fully quenched but untempered steel. Standard test blocks embodying this condition are used for cahbration. 

Scleroscope hardness numbers are convertible to other hardness scales (see ASTM E140) (2). 

Sklerenchym, n. (Biol.) sclerenchyma. sklerosieren, v.i. become indurated, harden. Skleroskophkrte, /. scleroscope hardness. Skonto, m. discoimt,... 

Scleroscope hardness It is a dynamic indentation hardness test using a calibrated instrument that drops a diamond-tipped hammer from a fixed height onto the surface of the material being tested. 

Other methods of determining the hardness of a material include a variety of "penetration" tests that yield hardness values measured in scales known as the Brinell, Rockwell (B or C), and scleroscope scales. These scales provide reliable hardness values for most materials, including ceramics, glass, metals and alloys, and wood (see Table 21). Unfortunately, as can be seen in the table, the various tests provide somewhat different hardness values for the same materials. 

LITHIUM AND LITHIUM COMPOUNDS] (Vol 15) Scleroscope hardness numbers... 

Wallerius-Hauy method methods based on Reau- Rosival Scott tower Shore scleroscope... 

Hardness of some rocks measured with Shore scleroscope (after Shepherd, from Winkler, 1973)... 

A separate group of methods of limited usefulness in regard to brittle materials, making use of impact action with an indenter or steel ball, with registration of elastic rebound of a hammer or beater from the sample, consists of measurements with the Shore scleroscope, the duroscope and several other testers based on this principle, where the results come close to those obtained by the Brinell method. Working on the same principle is also the impact hardness tester, in which the depth of the indent or scratch made by a diamond indenter is measured. 

In testing the abrasiveness of floor finish of man-made materials, special variations of Shore s scleroscope are commonest. For ceramic and rock floor tiles, the commonest testers are Bohme s disc and the Teledyne Abra-der. For sewage and chemical stoneware, the standards now in force recommend abrasiveness tests with the use of a sandblasting jet blower. For technical reasons, a more precise Mackensen blower method for stoneware testing has been in use in Poland for several years. From the experience gained over years, a standard recommending Mackensen s method has been laid down for stoneware abrasiveness tests. Research results proved the usefulness of this method also for other ceramic materials. 

SCLEROMETER. An apparatus for determining the hardness of a material by measuring the pressure on a standard point that is required to scratch the material. A scleroscope is a similar apparatus, which measures hardness by determining the rebound of a standard ball dropped on the subject material from a fixed height. 

Contact problems have their origins in the works of Hertz (1881) and Boussinesq (1885) on elastic materials. Indentation problems are an important subset of contact problems (17,18). The assessment of mechanical properties of materials by means of indentation experiments is an important issue in polymer physics. One of the simplest pieces of equipment used in the experiments is the scleroscope, in which a rigid metallic ball indents the surface of the material. To gain some insight into this problem, we consider the simple case of a flat circular cylindrical indentor, which presents a relatively simple solution. This problem is also interesting from the point of view of soil mechanics, particularly in the theory of the safety of foundations. In fact, the impacting cylinder can be considered to represent a circular pillar and the viscoelastic medium the solid upon which it rests. 

Another type of hardness measurement is that involving the dynamic deformation or indentation of the material specimen. In the most direct method an indenter is dropped on to the metal surface and the hardness is expressed in terms of the energy of impact and the size of the resultant indentation (Martel, 1895). In the Shore rebound scleroscope (Shore, 1918) the hardness is expressed in terms of... 

Properties Linear coefficient of expansion 32 x 107 in/C, elasticity coefficient 6.230 kg/sq mm, hardness (scleroscope) 120, d 2.25, specific heat 0.20, refr index 1.474 dispersion 0.00738, light and heat transmission higher than the best plate glass, dielectric constant 4.5 (25C), upper working tem-... 

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