|Budget Amount *help
¥1,900,000 (Direct Cost : ¥1,900,000)
Fiscal Year 1997 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1996 : ¥1,400,000 (Direct Cost : ¥1,400,000)
Carbonized cotton cloth, cotton wool, and recycle paper were used as substrates, and silicon carbide was infiltrated from a gas mixture of SiCl_4, CH_4, and H_2 by pressure pulsed chemical vapor onfiltration (PCVI) in order to obtain a highly porous shape of silicon carbide for use to refractory filter or catalyst carrier. Among the cotton cloths, flunnel was the best for above purpose, the carbonized flunnel had a porosity of 95%. After 5000 pulses of PCVI,the porosity decreased to about 90%. The pores distributed below 70mum, and the pressure drop of the sample of 20 mm long against the air flow rate of 1.1 m/s was 8 kPa. The weight decrease of the PCVIed sample during air oxidation at 1000ﾟC saturated below 5 hours, and the flexural strength of the samples PCVIed with 5000 and 15000 pulses were 1 and 10 MPa, respectively. Cotton wool was immersed in water, rolled tightly, and carbonized. The porosities before and after 20000 pulses of PCVI at 1100ﾟC were 90% and 82%, respectively. The average pore diameters after 10000 and 20000 pulses of PCVI were 10 and 6 mum, respectively. Pressure drop of the sample of 10 mm thick and after 10000 pulses to air flow of 1.1 m/s was 15 kPa, and flexural strength after 20000 pulses was 25 MPa. These properties are considered to be suitable for use to refractory filters. Filter paper and recycle paper were scattered into pieces in boiled water, pressed to column, and carbonized. Average pore size was as small as 6 mum, and that after 10000 pulses 5 mum, because the monofilament of the papers were thin compared with that of cotton. Therefore, pressure drop of the sample of 5 mm thick after 10000 pulses under an air flow rate of 0.8 m/s was as high as 8 kPa. A substrate made from carbonizing of corrigated cardboard was also PCVIed, and thin wall (0.02 mm) SiC honeycomb was obtained with 10000 to 20000 pulses of CVI.