Study on Carbonization Thermal Dynamic Process of Coal Tar Refined Soft Pitch

摘要

The carbonization thermal dynamic process of coal tar refined soft pitch(CTRSP) is studied by using a polarizing microscope with a heat stage. The pitch is preprated and it's characteristics are that the soft point of 30°C, group compositions consist of 54.80% heptane soluble, 48.77% heptane insoluble but toluene soluble, 5.95% toluene insoluble but quinoline soluble and 0.08% quinoline insoluble, relative average molecular weight of about 292, average molecular structure of five- rings linear arrangement and cata-condensed structure. The polarizing microphotographs show that temperature of mesophase spherules beginning formation in the pitch is 440°C. To avoid speed of spherules generated is too fast, the temperature is decreased to 420°C at a rate of 10°C/min, and these spherules grow slowly at 420°C for 5 min. Then during temperature is raised to 500°C at rate of 3°C/min, these spherules change into bigger mesophase spheres because of absorbing matrix or colliding and coalescence between spherules. These bigger mesophase spheres absorb matrix or colliding and combine between bigger spherule again, finally because of gravity at 500°C, big mesophase spheres deform gradually, and develop into the semi-coke with streamline or clipper-built and/or coarse- fibrotic modality.