Bismuth alloy systems

The primary use of bismuth metal is in making alloys. Many bismuth alloys have low melting points. The metal itself melts at 520°F (271°C), but some bismuth alloys melt at temperatures as low as 160°F (70°C). This temperature is below the boiling point of water. These alloys are used in fire sprinkler systems, fuel tank safety plugs, solders, and other applications. 

Bismuth alloyed with tin or cadmium is used as a low melting alloy in automatic sprinkler systems for fire prevention. A typical alloy contains 30% Bi. If an 0.80 g sample is dissolved in 50 mL of acid and a chelate formed, how many extractions employing 20.0 mL of benzene will be required to reduce the Bi concentration to... 

The Ettingshausen effect, which has historically been assumed to be very small, is in fact quite large in the bismuth-antimony alloy system at temperatures below 200°K. By utilizing this effect in a cooling device, practical solid-state cooling is now feasible in the... 

An alloy consisting of 24% indium and 76% gallium is liquid at room temperature. Low-melting tin-bismuth alloys contain indium. They are used for safety fuses, in fire-alarm boxes and in sprinkler systems. Also indium alloys are used as solders for printed circuit boards. Indium alloys are easily composed for a specified melting range. Alloys of this type are used to give a signal dear for the Christmas ham or turkey to be taken out from the oven. 

Most fast-spectrum reactors operated around the world use liquid sodium metal as a coolant. Future fast-spectrum reactors may use lead or a lead-bismuth alloy, or even helium, as a coolant. One of the attractive properties of metals as coolants is that they offer exceptional heat-transfer properties in addition, some (but not all) metal coolants are much less corrosive than water. However, because sodium is reactive with air and water, fast-spectrum reactors built to date have a secondary sodium system to isolate the sodium coolant in the reactor from the water in the electricity-producing steam system. The need for a secondary system has raised capital costs for fast reactors and has limited thermal efficiencies to the range of 32 to 38 percent. Novel steam-generator designs, direct gas cycles, and different coolants are options that may eliminate the need for this secondary sodium loop and improve the economics of fast reactors (Lake et al 2002). 

Some alloys are softer than the component metals. The presence of big bismuth atoms helps to soften a metal and lower its melting point, much as melons would destabilize a stack of oranges because they just do not fit together well. A low-melting-point alloy of lead, tin, and bismuth is employed to control water sprinklers used in certain fire-extinguishing systems. The heat of the fire melts the alloy, which activates the sprinklers before the fire can spread. 

Calculate the relative number of atoms of each element contained in each of the following alloys (a) Wood s metal, which is a low-melting-point alloy used to trigger automatic sprinkler systems and is 12.5% tin, 12.5% cadmium, and 24% lead by mass in bismuth (b) a steel that is 1.75% by mass carbon in iron. 

Arsenic and antimony are metalloids. They have been known in the pure state since ancient times because they are easily obtained from their ores (Fig. 15.3). In the elemental state, they are used primarily in the semiconductor industry and in the lead alloys used as electrodes in storage batteries. Gallium arsenide is used in lasers, including the lasers used in CD players. Metallic bismuth, with its large, weakly bonded atoms, has a low melting point and is used in alloys that serve as fire detectors in sprinkler systems the alloy melts when a fire breaks out nearby, and the sprinkler system is activated. Like ice, solid bismuth is less dense than the liquid. As a result, molten bismuth does not shrink when it solidifies in molds, and so it is used to make low-temperature castings. 

Binary liquid metal systems were used in liquid-metal magnetohydrodynamic generators and liquid-metal fuel cell systems for which boiling heat transfer characteristics were required. Mori et al. (1970) studied a binary liquid metal of mercury and the eutectic alloy of bismuth and lead flowing through a vertical, alloy steel tube of 2.54-cm (1-in) O.D., which was heated by radiation in an electric furnace. In their experiments, both axial and radial temperature distributions were measured, and the liquid temperature continued to increase when boiling occurred. A radial temperature gradient also existed even away from the thin layer next to the... 

This system involves the use of some form of heating by air or steam in a chamber in a manner such that the vulcanization occurs immediately after the rubber is formed in an extruder or calender. This is a suitable process for extruded profiles and calendered sheets and conveyor belts. Liquid curing method (LCM) is also a continuous process which involves the use of suitable hot liquid baths in which extruded profiles can be passed through and vulcanized continuously. Items can be cured rapidly at temperatures from 200°C to 300°C however the compounds must be suitably designed to prevent porosity as this is a common problem with any extrudate. Suitable materials for curing medium includes bismuth-tin alloys, an eutectic mixture of potassium nitrate and... 

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