Thermal and mechanical shock

Two alloys containing tungsten are commercially available. The first, containing about 3 wt % rhenium, is used for heating filaments. The rhenium contributes improved resistance to thermal and mechanical shock. The second alloy contains about 25 wt % rhenium. This latter alloy is sold as sheet, rod, and heavy wire and may be fabricated for various uses. An important use of these rhenium alloys is in the constmction of thermocouples. Various combinations, 3 wt % Re—97 wt % W, or 25 wt % Re—75 wt % W, are usehil for measurement of temperatures to 2500°C (see Temperaturemeasurement). 

Irons cast, malleable, and high silieon (14.5 pereent). Their lack of ductility and their sensitivity to thermal and mechanical shock. 

Boro.silicate gla.s.s and impregnated graphite. Their lack of ductihty and sensitivity to thermal and mechanical shock should be taken into account. 

Nickel/silicon alloy (10% silicon, 3% copper, and 87% nickel) is fabricated only as castings and is rather brittle, although it is superior to the iron/silicon alloy with respect to strength and resistance to thermal and mechanical shock. It is comparable to the iron/silicon alloy in corrosion resistance to boiling sulfuric acid solutions at concentrations above 60%. Therefore, it is chosen for this and other arduous duties where its resistance to thermal shock justifies its much higher price compared with iron/silicon alloys. 

It is not subjected to hydrogen embrittlement as is tantalum, niobium and nickel alloys, and thus is able to sustain thermal and mechanical shock after exposure to gaseous hydrogen at high temperatures. 

Improve thermal and mechanical shock, increase elongation, and obtain higher impact strength and flexibility in a material. 

Thermal expansion properties, which may be important in some processing situations, such as freeze-drying. The physical design of the container also influences its resistance to thermal and mechanical shock. 

Davies, J. A. et al., J. Chem. Soc., Dalton Trans., 1980, 2246-2249 Extremely sensitive to thermal and mechanical shock, occasionally detonating spontaneously without external stimulus, it should only be prepared and used in solution. The solid is an extreme hazard, and the acetone-solvated complex is also explosive. 

Zinc sulfide (Cleartran) 50,000-770 2.2 Reacts with strong oxidizing agents relatively inert with typical aqueous, normal acids and bases and organic solvents good thermal and mechanical shock properties low refractive index causes spectral distortions at 45° C... 

In military environments, operating conditions are extremely harsh the hardware must maintain reliability and ability in severe conditions, including thermal and mechanical shock vibration,... 

On the other hand, if the solution is too dilute, then the surface tension of the solution will approach that of the pure solvent, and then the restoring force, which is the difference between the surface tension of the clean surface (than of the pure solvent) and the equilibrium surface tension of the solution, will be too small to withstand the usual thermal and mechanical shocks. Thus, according to this mechanism, there should be an optimum concentration for maximum foaming in any solution producing transient foams. (In these solutions the foam stabilization effects are much less important than the foam-producing effects, and therefore the latter can be measured more or less independently of the former.) This maximum in the foam valume-concentration curve of solution producing transient foams has been well verified experimentally. 

BaF 66 666-800 1.5 Insoluble in water soluble in acids and NH4CI does not fog sensitive to thermal and-mechanical shock... 

Liquid hydrogen azide also explodes on thermal or mechanical shock [31]. The freshly prepared liquid reportedly does not explode spontaneously, but tends to do so upon aging [31]. Solid hydrogen azide explodes likewise on thermal and mechanical shock spontaneous explosions are not reported. 

Basic copper(II) azides occur as four distinct phases (Table XI), which have been described as water-insoluble, explosive solids. They are less sensitive to thermal and mechanical shock than the normal azide the Cu(N3)2 Cu(OH)2 phase explodes at 245°C (normal azide, 202°C) and deflagrates on impact. In principle these compounds are formed by partial hydrolysis of Cu(N3)2, or by partial azidation of Cu(OH)2 ... 

As a preventive solution to the problem of NOx emissions, catalytic combustion has come to the forefront during the last two decades. The focus of major interest here is its application in gas turbines for power generation and for transportation by road, water or air. Any catalyst for catalytic combustion, however, has to face extreme demands above 1000°C in the presence of oxygen and steam, in uninterrupted operation for at least one year also, resistance to impurities or poisons in the fuel and to severe thermal and mechanical shocks. Promising developments in catalytic supports, washcoats and active materials are reviewed briefly. 

It is a primary explosive. It explodes violently upon thermal and mechanical shock. It requires lesser energy for initiation than lead azide and also fires with a shorter time delay. The heats of combustion and detonation are 1037 and 454 cal/g, respectively (i.e., 156 and 68 kcal/mol, respectively). The detonation velocity is 6.8 km/sec (at the crystal density 5.1 g/cm ). The pure compound explodes at 340°C (644°F) (Mellor 1967). The detonation can occur at much lower temperatures in an electric field when initiated by irradiation. Also, the presence of impurities can lower down the temperamre of detonation. Such impurities include oxides, sulfides, and selenides of copper and other metals. 

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