We report the growth of carbon nanofibers (CNFs) from carbon particles by chemical vapor deposition (CVD) with ultrasonic neblizer using ethanol as carbon source. Dense CNFs having diameters of several tens of nanometers have been successfully synthesized by the CVD without using any metal catalysts. The carbon particles formed from decompostion of fullerene were found to be suitable for the synthesis of CNFs. Details of the optimum conditions for producing CNFs and the expected growth mechanism are also described.

An epoxy-modified urethane rubber mixed with carbon particles is now chosen as the millimeter-wave absorber material in our study. The absorption characteristics of the absorber is measured under temperature changes. The weatherability of our absorber is also clarified based on absorption characteristics, thickness and hardness of the sample. As a result of the temperature characteristics of the absorber, the difference of the maximum absorption frequency under temperature changes is about 1 GHz, however the absorption of 20 dB or more is obtained between 54 and 58 GHz. The result of accelerated artificial exposure test is that 2.8% of the thickness of our sample is shrunk after 1000 hour exposure, and the hardness of rubber is hardened with increasing test time. It is also confirmed that the deterioration of the absorption ranges from 1 to 3 dB, although the absorption of about 20 dB is kept at the frequency range. As a consequence, it is confirmed that the wave absorber using the epoxy-modified urethane rubber mixed with carbon particles has good weatherability including our desired temperature characteristics, and it is suitable for outdoor use.