Bonded-grain tools

Cermet sor- met] [ceramic + metal] (1948) n. (1) Composite materials consisting of two components, one being either an oxide, carbide, boride or similar inorganic compound and the other a metallic binder. (2) Any refractory composition made by bonding grains of ceramics, metal carbides, nitrides, etc, with a metal. Co-deposition of cermets with nickel in the electroless-nickel process provides excellent wear resistance and chemical resistance to molds, dies, extruder screws and other tooling components used in the plastics industry. 

Depth-sensing microindentation allows the reliable determination of Young s modulus and Vickers microhardness of the different phases made of grains larger than 2 to 5 jm. Variations in chemical bonding and short-range order can be extracted from the intensity, wave number, and bandwidth of Raman peaks. The wave number shifts can be used to map the strain (and calculate the stress). Analysis of the bandwidth offers a tool to ascertain whether the wave number shift is strain induced or related to structural evolution of the Raman probe. 

In contrast, random displacements of individual sites of a chain (or a few neighboring sites), when feasible, can be a valuable tool (see Fig. 1). For this approach to be applicable, the chain backbone cannot have rigid constraints (e.g., rigid bonds and bond angles). It is particularly effective for coarse-grained models that allow wide fluctuations of individual sites around their bonded neighbors. Relevant examples are the bond-fluctuation model and certain bead-spring models such as that employed by Binder... 

The bonding material is the material that secures the abrasive grain relative to each other in order to form the shape and structural integrity of the abrasive tool such as a grinding wheel, bonded abrasive segment, or abrasive belt. 

It is recognized that in practice, the wear of the abrasive tool can proceed only as fast as the bond fracture occurs. Prior to bond fracture, pieces of the abrasive are lost by fracture of the grain and to a lesser extent by attritions wear (Rowe 2009 Jackson and Hitchiner 2013). 

Rubber bonds consist of vulcanized natural or synthetic rubber-rubber bonds are relatively cool-grinding bonds, as the dulled grains can break off relatively easily and early, limiting frictional heat transfer into the abrasive tool. 

The essential function of the bonding system is to hold the abrasive grains on the grinding tool as long as they are sharp, and to release them when they are blunt. The major bond systems are metal-, resin-, and vitrified bonding (Konig and Klocke 2005). 

Optical microscopy can be applied to examine porosity, grain size, grain intergrowths, degree and type of ceramic bonding, fracture systems, and identification of contaminants and causes of failure. It can also be used as a tool to predict the likely behavior of materials in a variety of service environments. 

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