[NZP]: A new family of ceramics with low thermal expansion and tunable properties

Ceramic materials belonging in the sodium zirconioum phosphate (NZP), family were prepared and characterized, with the view to identify a ceramic material, that may be used as honeycomb material in three way catalysts (TWC). Two different families were studied. rst one belongs to the system Ca1−xBaxZr4P6O24 (x = 0–1). This system was chosen because CaZr4P6O24 contracts while BaZr4P6O24 expands on heating. The material for x = 0.25 has a thermal expansion coefficient value close to zero and its flexural strength varies between 36 and 50 MPa for porosity of 17–28%. However, this system is quite unstable in acidic environments. r NZP system, namely Ba1+xZr4P6−2xSi2xO24 (x = 0–0.4) was investigated. The effect of the addition of Si substituting P was studied. As x increases, the thermal expansion coefficient decreases. For x = 0.22, the material is chemically stable and has a TEC value close to zero. Its porosity was quite high (36–47%) combined with flexural strength in the range of 20–40 MPa. onally, it was proved that materials with adequate physical and mechanical properties can be produced at relatively fast firing schedules. Optimum calcination time is 4 h and optimum sintering time is 8 h.