Alloys containing tellurium

A copper alloy, containing 0.02—0.04% tellurium, 0.002—0.015% phosphorous, and 0.002—0.05% oxygen is recommended for use in automobile radiators (79). A continuously cast Amtel copper alloy, containing 0.4—0.6% tellurium, 0.007—0.012% phosphorous, 0.02% sulfur max, and a copper-silver—tellurium—phosphorous alloy (99.90% max) was developed by AMAX Base Metals R D, Inc. (80). 

Lead Alloys. A tellurium—lead alloy containing 0.02—0.1% tellurium, with or without antimony, was introduced in 1934 (81) as tellurium lead or Teledium. This alloy has higher recrystallization temperatures and corrosion resistance and takes a significandy longer time to soften at 25°C after cold work. 

B. Copper. Copper (mp 1,083°C), is a moderately soft metal which has a high electrical and thermal conductivity. Electrolytic copper, 99.9% pure, is used for electrical wire and free-cutting alloys, containing small amounts of sulfur or tellurium, are commonly used for sheet or bar stock. Copper may be machined, brazed, and soldered. However, because of its toughness, it is much less easy to machine than brass. It tends to work-harden but may be annealed by heating, followed by rapid quenching. 

Tellurium lead is a lead alloy containing a fraction of a percent of tellurium. This alloy has better resistance to fatigue failure caused by vibration because of its ability to work-harden under strain. 

Another drawback is met with in the continuous machine when extruding lead alloys containing antimony, tellurium, or other alloying metals. Small quantities of the alloying metals deposit in the screw pitches after a short time of operation which cause an irregular flow of the lead through the die and render the sheathing useless. 

Fig. 5.8). With this U(IV)/U(III) ratio in fuel salt for aU alloys under study films containing tellurium and other corrosion products were found on the metal surface.

A 99.5% Cu—0.5% Te alloy has been on the market for many years (78). The most widely used is alloy No. CA145 (number given by Copper Development Association, New York), nominally containing 0.5% tellurium and 0.008% phosphorous. The electrical conductivity of this alloy, in the aimealed state, is 90—98%, and the thermal conductivity 91.5—94.5% that of the tough-pitch grade of copper. The machinahility rating, 80—90, compares with 100 for free-cutting brass and 20 for pure copper. 

Copper. The physical properties of pure copper are given in Table 11. The mechanical properties of pure copper are essentially the same as those for ClOl and CllO. The coppers represent a series of alloys ranging from the commercially pure copper, ClOl, to the dispersion hardened alloy C157. The difference within this series is the specification of small additions of phosphoms, arsenic, cadmium, tellurium, sulfur, zirconium, as well as oxygen. To be classified as one of the coppers, the alloy must contain at least 99.3% copper. 

Tellurium-containing donors, synthesis and manufacture of, 22 212 Tellurium-copper alloys, 24 425-426 Tellurium crystals, 24 405-406 Tellurium decafluoride, 24 419 Tellurium dibromide, 24 420 Tellurium dichloride, 24 419-420 Tellurium diethyldithiocarbamate, 24 411 Tellurium dimethylthiocarbamate, 24 428 Tellurium dioxide, 24 407-408, 409, 411, 420, 428... 

Metal Coatings. Tellurium chlorides, as well as tellurium dioxide in hydrochloric acid solution, impart permanent and attractive black antique finish to silverware, aluminum, and brass. Anodized aluminum is colored dark gold by tellurium electro deposition. A solution containing sodium tellurate and copper ions forms a black or blue-black coating on ferrous and nonferrous metals and alloys. Addition of sodium tellurite improves the corrosion resistance of electroplated nickel. Tellurium diethyldithiocarbamate is an additive in bright copper electroplating (see Electroplating). 

Betts Electrolytic Process. The Betts process starts with lead bullion, which may carry tin, silver, gold, bismuth, copper, antimony, arsenic, selenium, tellurium, and other impurities, but should contain at least 90% lead (6,7). If more than 0.01% tin is present, it is usually removed from the bullion first by means of a tin-drossing operation (see Tin AND TIN alloys, detinning). The lead bullion is cast as plates or anodes, and numerous anodes are set in parallel in each electrolytic cell. Between the anodes, thin sheets of pure lead are hung from conductor bars to form the cathodes. Several cells are connected in series. 

This beautiful and useful metal is found in the metallic state also, as chloride and as sulphuret. It occurs also alloyed with gold, tellurium, antimony, copper, and arsenic. Almost all varieties of galena (the ore of lead) contain a small proportion of sulphuret of silver and in many places, it is found worth while to extract this silver from the lead smelted from the ore. The separation of lead from silver is effected by cupellation that is, by heating the alloy in a current of air, when the lead is oxidised, and the oxide is either absorbed by the cupel or porous... 

The alloys were prepared by the direct fusion together of tellurium (vacuum-sublimed twice), In-0 grade indium, and V-4 grade arsenic. The components were fused together in quartz ampoules evacuated to 10" mm Hg in a furnace which was shaken periodically or rotated. The synthesis temperature was 970-980°C. The ampoules containing the melts were maintained at the maximum temperature for two hours, then cooled at a rate of 50-100 deg/h. Some of the melts were also quenched from the liquid state in water. In all cases, there was virtually no sublimate on the walls of the ampoules after synthesis. 

The crystals are placed in a 400-ml. beaker, covered by inverting a 1000-ml. beaker over the other, and heated at a hot-plate temperature of 400 to 430° for 2 hours. The tellurium(IV) oxide is cooled and bottled immediately to avoid slow darkening due to reduction by organic matter from the atmosphere. In a typical experiment, 21 g. of Te02 (84 per cent of theory) was obtained from a tellurium sample containing Cu, 0.05 per cent Fe, 0.015 per cent Pb, 0.005 per cent Se, 0.05 per cent alloyed with 0.3 per cent each As, Sb, and Bi. The product was found to contain Te, 79.91 per cent (theory 79.95 per cent) Cu, 0.00002 per cent Fe, 0.0007 per cent Pb, 0.0018 per cent Se, As, Sb, and Bi, less than 0.001 per cent. 

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