Abrasion number

Figure 6. Abrasion numbers of a (CH3)2Si0-Si02 composite. The number represents the fraction of unaffected grains of an average diameter of 0.3 mm (in percentage) after a special abrasion test (15). The hatched area represents abrasive behavior recognized to be satisfying by test persons. The dashed line represents data that were not useful because of elasticity.

The increase of the abrasion number (not representing higher abrasion) at higher (CH3)2SiO contents is misleading and due to the increasing elasticity of the grains, which is not covered by the test. For the hydrolysis and... 

Abrasion Number - This measurement is made around the same exposure which produced the Hardness Number. One measures the particle size distribution using a set of Tyler sieves before and after the wearing exposure. The Abrasion Number is the ratio of the final mean particle diameter to the initial mean particle diameter, expressed as a percentage. Change of mean diameter should not exceed 30%. Both hardness and abrasion resistance are functions of... 

Stmeture. The stmcture designation may or may not be given. It is numeric 0 represents the closest possible packing of abrasive grits, and ascending numbers correspond to incrementally less abrasive per unit volume of wheel (wider spaced grits). 

The fabric may also be given one or more of a number of other finishing treatments, either ia tandem with web formation and bonding or off-line as a separate operation, as a means of enhancing fabric performance or aesthetic properties. Performance properties iaclude functional characteristics such as moisture transport, absorbency, or repeUency flame retardancy electrical conductivity or static propensity abrasion resistance and frictional behavior. Aesthetic properties iaclude appearance, surface texture, and smell. 

The characteristics of interior paints that require testing and analysis include hiding and appearance, package stabiHty, adhesion, spatter resistance, flow and leveling, color and sheen uniformity, touch-up, stain removal, burnish resistance, and block and print resistance. A popular test that assesses the wet abrasion resistance of an interior paint is to measure its scmb resistance. A mechanical device is used to scmb a paint film of a specified thickness with a standard bmsh and abrasive cleanser suspension. The number of scmb cycles (back and forth movements of the weighted bmsh) at various end points (first cut through, or 50% removal of the film) is then recorded. Scmb resistance usually holds steady or decreases slightly as PVC is increased, but drops quickly once the CPVC is exceeded in a paint formulation. 

Inflated Diaphragm Method (ASTM D3886). This method is appHcable both to woven and knitted fabrics. The specimen is abraded by mbbing either unidirectionally or multidirectionally against an abradant having specified surface characteristics. The specimen is supported by an inflated mbber diaphragm under a constant pressure. Evaluation of abrasion resistance can be either by determination of the number of cycles required to wear through the center of the fabric completely or by visual examination of the specimens after a specified number of cycles. 

In addition to chemical analysis a number of physical and mechanical properties are employed to determine cemented carbide quaUty. Standard test methods employed by the iadustry for abrasive wear resistance, apparent grain size, apparent porosity, coercive force, compressive strength, density, fracture toughness, hardness, linear thermal expansion, magnetic permeabiUty, microstmcture, Poisson s ratio, transverse mpture strength, and Young s modulus are set forth by ASTM/ANSI and the ISO. 

In the United States, a number of physical tests are performed on siUcon carbide using standard AGA-approved methods, including particle size (sieve) analysis, bulk density, capillarity (wettabiUty), friabiUty, and sedimentation. Specifications for particle size depend on the use for example, coated abrasive requirements (134) are different from the requirements for general industrial abrasives. In Europe and Japan, requirements are again set by ISO and JSA, respectively. Standards for industrial grain are approximately the same as in the United States, but sizing standards are different for both coated abrasives and powders. 

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