The Praparation Of Mesophase Pitch Based Hollow Carbon Bundled Fiber And The Study Of Sram

The development of structural absorbing materials is based on the development of advanced composites and compose the abilities of radar absorbing and stand in gloading. Carbon fiber structural radar absorbing materials (SRAM) are multifunctional composites. Carbon fiber structural radar absorbing materials have been widely used in stealth technology with good mechanical and stealth property. In this thesis, it is studied that the spinneret of the section shape of "Y" made the hollow pitch bundled fibers, the preparation of structural radar absorbing materials and the absorbing properties. The primary work are as follows:1. Research on the manufacture of mesophase pitch based hollow carbon bundled fibersThe composition and structure of AR mesophase pitch were studied by means of elemental analysis, FT-IR, polarized light microscope with hot-stage and so on. Hollow carbon fibers were obtained through melt-spinning by the section shape of "Y". As a result, AR mesophase pitch have good spinnability at355℃. It is made that the pitch hollow carbon fibers by particular technique.The effects of final temperature, increasing temperature rate on the fibers during stabilization process on the properties of hollow carbon fibers were studied. The optimum technology parameters were:final temperature:270℃, raising temperature rate:2℃/min. Under this condition carbon fibers with tensile strength:2000Mpa, tensile modulus:160Gpa were obtained.By the aid of X-ray, the effect of carbonization temperature on crystalline parameters of mesophase pitch hollow carbon fibers was studied.The results showed that with the increasing of carbonization temperature, d0.02decreased while La and Lc increased. The results of electromagnetism parameters measured by VNA indicated that the effect of the carbonization temperatures was more effective to the permittivity than the permeability. Decreasing frequency of the electromagnetic field increased the complex permittivity real part ε’of mesophase pitch based carbon fibers with different carbonization temperatures. Dielectric loss tgδε increased when the carbonization temperature increased.2. Research on the manufacture of hollow carbon fiber structural radar absorbing materials (SRAM) The effects of carbonization temperature, thickness of material and the proportion of hybrid fibers on the absorbing property of hollow carbon fibers structural radar absorbing materials were studied. The results showed:carbonization temperature:800℃, the hybrid proportion of hollow pitch carbon fiber and glass fiber:1:8, the thickness of material is4mm, the three layers SRAM has better radar absorbing property than others. Then, reflection loss of the SRAM is5dB in the frequency (5.64GHz～18GHz), the eligible bandwith is12.35GHz, the best radar absorbing is21.17dB.