Fuels metals used

Compatibility and Corrosion. Gas turbine fuels must be compatible with the elastomeric materials and metals used in fuel systems. Elastomers are used for O-rings, seals, and hoses as well as pump parts and tank coatings. Polymers tend to swell and to improve their sealing abiUty when in contact with aromatics, but degree of swell is a function of both elastomer-type and aromatic molecular weight. Rubbers can also be attacked by peroxides that form in fuels that are not properly inhibited (see Elastomers, synthetic Rubber, natural). 

CP-1 was assembled in an approximately spherical shape with the purest graphite in the center. About 6 tons of luanium metal fuel was used, in addition to approximately 40.5 tons of uranium oxide fuel. The lowest point of the reactor rested on the floor and the periphery was supported on a wooden structure. The whole pile was surrounded by a tent of mbberized balloon fabric so that neutron absorbing air could be evacuated. About 75 layers of 10.48-cm (4.125-in.) graphite bricks would have been required to complete the 790-cm diameter sphere. However, criticality was achieved at layer 56 without the need to evacuate the air, and assembly was discontinued at layer 57. The core then had an ellipsoidal cross section, with a polar radius of 209 cm and an equatorial radius of309 cm [20]. CP-1 was operated at low power (0.5 W) for several days. Fortuitously, it was found that the nuclear chain reaction could be controlled with cadmium strips which were inserted into the reactor to absorb neutrons and hence reduce the value of k to considerably less than 1. The pile was then disassembled and rebuilt at what is now the site of Argonne National Laboratory, U.S.A, with a concrete biological shield. Designated CP-2, the pile eventually reached a power level of 100 kW [22]. 

Weldon et al, Evaluation of Metal Fuels for Use in Pyrotechnic Delays , Australian Weapons Research Establishment Technical Memorandum CPD 162 (1970) 37) R.H. Weldon et al,... 

The energetics of the reaction between the fuel element and the oxidizer is determined by the state of the outer electron orbits of the element and the oxidizer. The fuel elements are divided into two categories metals and non-metals. Typical metals used as fuel components are li. Mg, Al, Ti, and Zr, and typical non-metals used as fuel components are B, C, and Si. Some other metalHc elements used in py-rolants, such as Ba, W, and Pt, are not shown in Fig. 10.1. The physicochemical properties of solid elements and their oxidized products are shown in Table 10.4. 

Aluminum (Al) is a silver-colored light and soft metal used as a major component of aluminum alloys, which are used to construct aircraft and vehicles, similar to Mg alloys. However, Al is known as a readily combustible metal. Thus, Al particles are used as major fuel components of pyrolants. Al particles are mixed with ammonium perchlorate particles and polymeric materials to form solid propellants and underwater explosives. The reaction between aluminum powder and iron oxide is known as a high-temperature gasless reaction and is represented by ... 

Al and Mg particles are favored metals in the formulation of pyrolants because of their high potential for ignitability and combustion. However, the combustion products of Al and Mg particles tend to agglomerate to form relatively large metal oxide particles. Since the densities and heats of combustion of Ti and Zr are higher than those of Al and Mg, Ti and Zr are more favorable for use as fuel metals in ducted rockets. 

Thorium is used to make ceramics, lantern mantles, and metals used in the aerospace industry and in nuclear reactions. Thorium can also be used as a fuel for generating nuclear energy. More than 30 years ago thorium oxides were used in hospitals to make certain kinds of diagnostic x-ray photographs. Further information on the properties and uses of thorium can be found in Chapters 3 and 4 of this profile. 

Alkaline fuel cells (AFCs) were one of the first fuel cell technologies developed, and they were the first type widely used in the US space program to produce electrical energy and water onboard spacecraft. These fuel cells use a solution of potassium hydroxide in water as the electrolyte and can use a variety of non-precious metals as a catalyst at the anode and cathode. High-temperature AFCs operate at temperatures between 100°C and 250°C. However, more-recent AFC designs operate at lower temperatures of roughly 23°C to 70°C. 

For example, the electrolyte of alkali fuel cells is a solution of potassium hydroxide (an alkaline, which has a high pH). Solid oxide fuel cells use compoimds of metal oxides as electrolytes. (Fuel cell names are generally... 

Carbon steel is the most common metal used throughout fuel storage, handling, and transportation systems. The term carbon steel describes steel containing carbon as the principal alloying element added to control hardness and strength. The carbon content can range from approximately 0.05% to about 1.4%. Above 1.4%, steel becomes brittle and loses cohesiveness and hardness. 

Cylinder and piston ring wear have been observed when using alcohol fuels. Metal loss could be due to wear caused by removal of the lubricating oil film by liquid alcohol during cold starting or by the corrosive action of formic acid or other acids formed during the combustion process. Use of more corrosion- and wear-resistant metal alloys in engine construction have helped resolve this problem. 

Basically, PVC plastisol propellants are systems of binder,.oxidizer, and metallic fuel (if used). Minor ingredients, normally comprising less than 2% of the total, consist of wetting agent, stabilizer, opacifier, and burning rate modifier. The composition of three typical PVC plastisol propellants is shown in Table I. 

Incendiary type warhead (with gelled formulations like Napalm and solid formulations based on pyrophoric metals)-used against fuel and ammunition dumps etc. 

A number of cells have been developed which make use of the oxygen of the air as the cathodic reagant. These so-called air-depolarized cells are examples of hybrid cells, which are discussed more fully in Chapter 9. Many recent advances in metal-air batteries can be attributed to the research carried out in the 1960s on high current density air electrodes for ambient hydrogen/oxygen fuel cells using aqueous electrolytes. 

Except for No. 2, fuel oil should not be considered as auxiliary fuel when using a catalytic system because of the sulfur and vanadium the fuel oil may contain (7). In some cases even the sulfur in No. 2 fuel oil can present a problem. Galvanized metal should not be used in process ovens or ductwork because zinc is a catalyst poison. 

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