Thin wall ceramic tubes by extrusion of thermoplastic ZrO2 compounds

For various applications, for example as protective layer for a plastic shaft, filter structures, thermowells, and heat exchangers, ceramic tubes with a wall thickness less than 300 gm are interesting. Higher wear and lower filtration resistance, or faster heat transfer can be reached with such systems. Different binder systems like water based, duroplastic or thermoplastic binder systems are suitable to realise such finished and semi finished products. The problem with water based binder systems is the collapsing of the tubes after extrusion. Extruded duroplastic compounds cannot be recycled whereas thermoplastic binders can be recycled and do not collapse after extrusion, In this work, ZrO2 powder, wax and polyethylene were mixed in different percentage by volume. It could be shown that different percentage by volume of ZrO2 ceramic powder have an influence on the energy and time needed to homogenise the thermoplastic paste in the kneading process. For producing tubes with a thin wall thickness, the compound with 50 vol.-% ZrO2 showed the best results in all tests.