This paper presents highly precise measurements of thermal expansion of a hybrid carbon-fiber reinforced silicon carbide composite, HB-Cesictextregistered - a trademark of ECM, in the temperature region of sim310-10K. Whilst C/SiC composites have bee
n considered to be promising for the mirrors and other structures of space-borne cryogenic telescopes, the anisotropic thermal expansion has been a potential disadvantage of this material. HB-Cesictextregistered is a newly developed composite using a mixture of different types of chopped, short carbon-fiber, in which one of the important aims of the development was to reduce the anisotropy. The measurements indicate that the anisotropy was much reduced down to 4% as a result of hybridization. The thermal expansion data obtained are presented as functions of temperature using eighth-order polynomials separately for the horizontal (XY-) and vertical (Z-) directions of the fabrication process. The average CTEs and their dispersion (1{sigma}) in the range 293-10K derived from the data for the XY- and Z-directions were 0.805$pm$0.003times10$^{-6}$ K$^{-1}$ and 0.837pm0.001times10$^{-6}$ K$^{-1}$, respectively. The absolute accuracy and the reproducibility of the present measurements are suggested to be better than 0.01times10$^{-6}$ K$^{-1}$ and 0.001times(10)^{-6} K^{-1}, respectively. The residual anisotropy of the thermal expansion was consistent with our previous speculation regarding carbon-fiber, in which the residual anisotropy tended to lie mainly in the horizontal plane.
The electroweak gauge symmetry is allowed to be spontaneously broken by the strongly interacting vector-like gauge dynamics. When the gauge coupling of a theory runs slowly in a wide range of energy scale, the theory is a candidate for walking techni
color. This may open up the possibility that the origin of all masses may be traced back to the gauge theory. We use the SF method to see whether the gauge coupling of 10-flavor QCD walks or not. Preliminary result is reported.
The electroweak gauge symmetry is allowed to be spontaneously broken by the strongly interacting vector-like gauge dynamics. When the gauge coupling of a theory runs slowly in a wide range of energy scale, the theory is extremely interesting. This ma
y open up the possibility that the origin of all masses may be traced back to the gauge theory. We use the SF method to determine the scale dependence of the gauge coupling of 10-flavor QCD. Preliminary results are reported.
