In-situ Hot Pressing Preparation And Properties Of Clay-based Ceramic-carbon Composite

Clay mineral is widely used for preparation of ceramic which is aboudant in nature. However, clay-based ceramic has poor mechanical properties. This study is focused on developing a clay-based ceramic-carbon composite by in-situ hot pressing organic modified clay and the properties of the products were characterized. The main conclusions are given as follows:(1) The structural evolution of palygorskite during calcinating were studied. Palygorskite transformed into enstatite, cordierite and cristobalite when calcined at 1200 ℃. Ceramic materials with excellent mechanical properties were obtained by hot-pressing palygorskites at 1000 ℃. Graphite carbon was detected in the ceramic which exhibites a flexural strength of 187 MPa. The existence of carbon have bonding effect to the ceramic which can contribute to the mechancial properties. As a result, the fracture mode of the ceramic transformed from intergranular fracture into intragranular fracture.(2) Palygorskite/carbon composite was prepared by hydrothermal method. Ceramic-carbon composite was obtained by hot pressing palygorskite/carbon composite. Compared with hot-pressed palygorskite in the absence of carbon, the conductivity of the composites were improved. Carbon-reinforced palygorskite-based ceramic-carbon composite was obtained by hot pressing of acetamide-modified palygorskite. Acetamide was carbonized during hot pressing. When the mass fraction is 15 wt.%, the bending strength of the carbon-reinforced palygorskite-based ceramic was 100 MPa, which showed a 33% increase compared with that of ceramic by hot pressing of palygoskite.(3) ceramic-carbon composite was prepared by hot-pressing montmorillonite (Cloisite 15). The flexural strength is 118 MPa and modulus is 46 GPa. Organic modified montmorilloite was obtained by intercalated octadecyl trimethyl ammonium chloride (OTAC). During hot pressing, montmorillonite transformed into cordierite and mullite ceramic. OTAC carbonized in the layer of montmorillonite. The montmorillonite-based ceramic formed. The graphite carobn in the composites can serve as binder and reinforcement. In-situ hot pressing waste clay can be obtained ceramic-carbon composite with semiconductive property.