Grain mechanism

Fig. 1. With-grain mechanical properties of artificial graphite (1). To convert MPa to psi, multiply by 145.

Young s modulus. The modulus of elasticity is also highly anisotropic. The modulus of elasticity perpendicular to the grain is l/20th of the modulus parallel to the grain. Mechanical properties also depend on imperfections of the wood. Knots in the wood can decrease the... 

Ytterbium metal has possible use in improving the grain refinement, strength, and other mechanical properties of stainless steel. One isotope is reported to have been used as a radiation source substitute for a portable X-ray machine where electricity is unavailable. Few other uses have been found. 

Fig. 3. An overview of atomistic mechanisms involved in electroceramic components and the corresponding uses (a) ferroelectric domains capacitors and piezoelectrics, PTC thermistors (b) electronic conduction NTC thermistor (c) insulators and substrates (d) surface conduction humidity sensors (e) ferrimagnetic domains ferrite hard and soft magnets, magnetic tape (f) metal—semiconductor transition critical temperature NTC thermistor (g) ionic conduction gas sensors and batteries and (h) grain boundary phenomena varistors, boundary layer capacitors, PTC thermistors.

Gun Propellents. Although the stresses on individual gun propellant grains are less severe because of the small size, these propellants must withstand much higher weapon pressures and accelerations. Formulation options are usually more limited for gun propellants than for rocket propellants because the products of combustion must not foul or corrode a gun, should have a low flame temperature, and should exhibit minimum flash and smoke characteristics. Gun propellants are examined microscopically for porosity, are tested for mechanical characteristics, and fired in closed bombs to determine the burning characteristics. 

S olid Propellant Mging, Mechanical Pehavior and Grain Structural Integrity, CPIA Pubhcation LS 77-27, CPIA, Johns Hopkins University, Laurel, Md., 1977. 

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