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2015): The influences of particle-particle interaction and viscosity of carrier fluid on characteristics of silica and calcium carbonate suspensions-coated Twaron® composite, Journal of Experimental Nanoscience, ABSTRACTThe effects of particleÀparticle interaction and viscosity of carrier fluid on steady and dynamic rheological responses and quasi-static penetration resistance of Twaron® fabrics treated with shear thickening and shear thinning suspensions have been investigated. The suspensions have been made by mechanically dispersing 60 nm silica (SiO 2 ) and calcium carbonate (CaCO 3 ) nanoparticles in poly ethylene glycol (PEG) with molecular weights of 200 and 400 g/mol. The CaCO 3 suspensions display shear thinning behaviour along with the total dominance of the elastic state over the viscous state while the SiO 2 suspensions exhibit shear thickening behaviour with the emergence of both the elastic and viscous states. With the increase of molecular weight of PEG, viscosity, viscoelastic modules and instability of the suspensions increase and critical shear rate and frequency of transition to elastic state diminish. The PEG200 and PEG400-contained SiO 2 suspensions-treated Twaron® composites at 35 wt.% have quasi-static penetration resistances which are nearly 2.63 and 2.48 times and maximum absorbed energies which are about 1.54 and 1.55 times higher, respectively, than those of the corresponding CaCO 3 ones. However, the influence of increasing the PEG's molecular weight is not as considerable as the effect of particleÀparticle interaction on the enhancement of penetration resistance performance.

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Advanced tactical missiles need radomes of higher strength capable of withstanding higher velocities and temperatures and longer ight durations. Radomes must be stable at temperature above 1400 C and must have a low and steady thermal dielectric constant, low thermal expansion coe cient, high resistance to thermal shock, high sti ness and strength, high chemical stability, and high resistance against moisture. Silicon nitride, in comparison with other materials used in the fabrication of radomes (e.g., fused Silica, pyroceramics, etc.), enjoys superior properties, and it can also be used at ight speeds higher than Mach 7. In this paper, various types of raw materials used in the fabrication of radomes have been investigated.