Carbides cemented

The term cemented carbides, also called hardmetals, refers to powder-conqiosite materials consisting of carbide particles bonded with metals or alloys. Extensive treatments are given in [1.94,95]. The most common cemented carbide is WC bonded with Co. Cobalt is used as a binder since it wets the angular WC particles particularly well. Nickel is added to increase corrosion and oxidation resistance of the Co binder phase. The metals Ta, Nb, and Ti may be added to form a (W, Ta, Nb, or Ti) C solid solution carbide phase which is an additional microstructural constituent in the form of rounded particles in the so-called complex grade, multigrade, or steel-cutting grade cemented carbides. Table 3.1-90 lists representative materials. 

ASTM specification Alloy system Condition Yield strength (MPa) (ksi) Tensile strength (MPa) 1 (ksi) Elongation (%) Elastic modulus (GPa) 1 (10 ksi)  

Nominal Grain Hardness Density Transverse Compressive Modulus Relative Coefficient of Thermal 

Tensile properties of cold-drawn and aged Duratherm 

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Cement clinker Cement-composites Cement copper Cemented carbide... 

Hafnium carbide [12069-85-1] can be used as surface coating on cemented-carbide cutting tools, shows promise as a stable field emission cathode... 

Brinell Tests of Steel Products Comparison Hardness Tester Practice Rockwell Test on Cemented Carbides Rockwell Test for Sintered Materials Knoop Test for Electrodeposited Coatings Webster Hardness Gauge Barcol Test of Aluminum Alloys... 

Carbides Cemented Carbide Producers Association 712 Lakewood Center North Cleveland, Ohio 44107 Standards Developed bj Cemented Carbide Producers Association ie, standard shapes, sizes, grades, and designations and defect classification. 

Compacting tools must be propedy designed, constmcted, and fitted to the press. These maybe made of heat-treated steel or cemented carbide, depending on the economics and number of parts to be produced. Carbide tools are more expensive however, they can be used much longer than steel tools. 

Cemented Carbides. Cemented carbides contain mostiy tungsten carbide and lesser amounts of other hard-metal components, embedded in a matrix of cobalt (see Carbides, cemented carbides). 

Cemented carbides exhibit extreme hardness and toughness which are retained at the elevated temperatures that may occur between tool and work during cutting. 

Niobium carbide is used as a component of hard metals, eg, mixtures of metal carbides that are cemented with cobalt, iron, and nickel. Along with tantalum carbide, niobium carbide is added to impart toughness and shock and erosion resistance. The spiraling rise in the price of tantalum has spurred the development of a hafnium carbide—niobium carbide substitute for tantalum carbide (68). These cemented carbides are used for tool bits, drill bits, shovel teeth, and other wear-resistant components turbine blades and as dies in high pressure apparatus (see Carbides). 

Cobalt. There is no U.S. mine production of cobalt. Refining of imported nickel—cobalt mattes has not occurred since the mid-1980s. About 1600 t of secondary cobalt was recycled from scrap by 13 faciUties in the United States representing - 22% of total U.S. consumption. The price of the metal was around 44/kg. Most is imported from Zaire and Zambia. Increasing quantities are coming from Russia. Historically, the price of cobalt has been quite volatile and dependent on the pohtical environment in those countries. Cobalt is used in superaHoys, 40% catalysts, 14% paint driers, 11% magnetic alloys, 10% and cemented carbides and other uses, 16%. 

Decorative. Titanium nitride has a golden color and is used extensively to coat steel and cemented carbide substrates for watch cases, watch bands, eyeglass frames, etc. It provides exceUent scratch resistance as weU as the desired aesthetic appearance, and it replaces gold coatings used previously. 

Refractory compound coatings of carbides, nitrides, and oxides on cemented carbide cutting tools, mainly by the CVD process, are estimated at 300 X 10 annually worldwide. 

A wide range of cutting-tool materials is available. Properties, performance capabilities, and cost vary widely (2,7). Various steels (see Steel) cast cobalt alloys (see Cobalt and cobalt alloys) cemented, cast, and coated carbides (qv) ceramics (qv), sintered polycrystalline cubic boron nitride (cBN) (see Boron compounds) and sintered polycrystalline diamond tbin diamond coatings on cemented carbides and ceramics and single-crystal natural diamond (see Carbon) are all used as tool materials. Most tool materials used in the 1990s were developed during the twentieth century. The tool materials of the 1990s... 

High Speed Steels. Toward the latter part of the nineteenth century, a new he at-treatment technique for tool steels was developed in the United States (3,17) that enabled increased metal removal rates and cutting speeds. This material was termed high speed steel (HSS) because it nearly doubled the then maximum cutting speeds of carbon—low alloy steels. Cemented carbides and ceramics have since surpassed the cutting speed capabiUties of HSS by 5—15 times. 

Cast-Cobalt Alloys. Cast-cobalt alloys were introduced about the same time as HSS for cutting tool appHcations. Popularly known as StelHte tools, these materials are Co-rich Cr—W—C cast alloys having properties and appHcations in the intermediate range between HSS and cemented carbides. 

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