Iron, compounds metallurgy

The term ferrite is commonly used generically to describe a class of magnetic oxide compounds which contain iron oxide as a principal component. In metallurgy (qv), however, the term ferrite is often used as a metaHographic indication of the a-iron crystalline phase. 

Sodium cyanide [143-33-9] NaCN, is a white cubic crystalline soHd commonly called white cyanide. It was first prepared in 1834 by heating Pmssian blue, a mixture of cyanogen compounds of iron, and sodium carbonate and extracting sodium cyanide from the cooled mixture using alcohol. Sodium cyanide remained a laboratory curiosity until 1887, when a process was patented for the extraction of gold and silver from ores by means of a dilute solution of cyanide (see Metallurgy, extractive). A mixture of sodium and potassium cyanides, produced by Edenmeyer s improvement of the Rodgers process, was marketed in 1890. 

Silicon carbide is comparatively stable. The only violent reaction occurs when SiC is heated with a mixture of potassium dichromate and lead chromate. Chemical reactions do, however, take place between silicon carbide and a variety of compounds at relatively high temperatures. Sodium silicate attacks SiC above 1300°C, and SiC reacts with calcium and magnesium oxides above 1000°C and with copper oxide at 800°C to form the metal silicide. Silicon carbide decomposes in fused alkalies such as potassium chromate or sodium chromate and in fused borax or cryolite, and reacts with carbon dioxide, hydrogen, air, and steam. Silicon carbide, resistant to chlorine below 700°C, reacts to form carbon and silicon tetrachloride at high temperature. SiC dissociates in molten iron and the silicon reacts with oxides present in the melt, a reaction of use in the metallurgy of iron and steel (qv). The dense, self-bonded type of SiC has good resistance to aluminum up to about 800°C, to bismuth and zinc at 600°C, and to tin up to 400°C a new silicon nitride-bonded type exhibits improved resistance to cryolite. 

Amalgams. Liquid mercury is a fairly good solvent for all metals except iron and platinum. The alloys that are formed by dissolving metals in mercury are called amalgams, many of which involve inter-metallic compounds of the type MHg, where x is quite variable. Aside from their many applications in scientific work, amalgams are used in dentistry and in connection with the metallurgy of silver and gold. 

Compared to carbon, the related element silicon is relatively unimportant, so far as uses for the uncombined element are concerned. Most of the silicon produced commercially is used in the metallurgical and glass industries. In metallurgy, it is ued in the manufacture of a useful iron-silicon alloy known as ferrosilicon. Silicon is also used as an additive in organic products such as plastic and rubber compounds, and elemental silicon is a fundamental material in semiconductor and microprocessor manufacturing. 

Metallurgy produces gaseous as well as solid exhalates depending on the type of the production and technology used. Fluorine exhalates from aluminium works are very harmful, as also are tars and arsenic compounds. Iron and steel works produce fly ash, its main components being similar to those in the fly ash from coal, only with different abundances (a high... 

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