Quartz abrasive properties

Silica, Microcrystalline - ml-kro- kris-to-lin n Si02 Pigment White 27 (77811). Extender pigment obtained from extensive geologic formations of hard, compact, homogeneous, microcrystalline silica located in the vicinity of Hot Springs, Arkansas. Can be considered as a very finely divided or micro form of quartz in a bound state of subdivision. Excellent dielectric and low abrasive properties. Density, 2.65 g/cm (22.1 lb/ gal) O.A., 20.0 mean particle size, 4.0 pm. Novaculite is a generic name. Syn Novacite. 

Abrasives - Rubber products requiring abrasive properties, such as ink erasers and polishing wheels, use abrasive fillers like ground quartz, pumice, or carborundum. 

Silica. SiHca (qv) comes in various forms including quartz [14808-60-7]. It has found wide use as an abrasive in the past, particularly as an inexpensive coated abrasive for woodworking. The term sandpaper is stiU used as a generic term for coated abrasives in many quarters although the use of sand in coated abrasives has been almost entirely elkninated because of the hazard of siHcosis to the user and its inferior grinding properties (especially for metals). 

Hardness. The hardness (qv), or related property abrasiveness, is an important filler property. Hardness is determined by comparison to materials of known hardness on the Mohs scale. On this nonlinear scale, diamond is rated 10, quartz 7, calcite 3, and talc 1. The abrasiveness of a filler is also dependent on psd and the presence of impurities, eg, ka olin clay (Mohs hardness of 3) can be quite abrasive because of the presence of quartz impurities. 

Several essential properties of cristobalite have influence on its applications. They include lower density than quartz (higher volume at the same mass), purity (low catalytic effect on many polymeric systems, excellent properties in exterior coatings due to low level of iron oxide), very low moisture (no need for drying in moisture sensitive systems), pure white color, less abrasive due to filler particle morphology. 

Powdered mineral fillers tend to increase compressive strength, hardness and modulus of the compound. However, when used in large amounts, there is a considerable reduction in bending strength. Fibrous fillers are used to increase tensile and impact strength. Surface properties of moldings can be improved by use of a suitable powdered mineral in the gelcoat only. Powdered quartz or zircon in the gel coat can improve hardness and abrasion resistance. Properties, which may be selectively altered by use of fillers, include ... 

Mechanical properties make them useful in metal alloys production Ti for aircraft industry for construction cement (CUjSiOj) in ceramics industry BN, SiC as lubricants graphite, M0S2 as abrasives diamond, quartz (SiO. ... 

In addition to its chanical properties, the efficient use of a coal also requires a knowledge of its physical properties, such as its density (which is dependent on a combination of rank and mineral matter content), hardness, and grindability (both related to coal composition and rank). Other properties include its abrasion index (derived mainly from coarse-grained quartz) and the particle size distribution. Float-sink testing may also be included with the analysis process. This involves separating the (crushed) coal into different density fractions as a basis for assessing its response to coal preparation processes. Float-sink techniques may also be used to provide a coal sample that represents the expected end product of a preparation plant, in order to assess the quality of the coal that will actually be sold or used rather than the in situ or ROM material represented by an untreated (raw) coal sample. 

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