Characterization of a Functionally Gradient Ceramic Based on CaZrO3 – MgO

Babo, Débora Rafaela Telha de; Nunes-Pereira, João; Silva, Pedro D.; Pena, Pilar; Baudin, Carmen; Pereira Silva, A

http://hdl.handle.net/10400.6/14361

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Authors

Babo, Débora Rafaela Telha de

Abstract(s)

In the case, where the structure is exposed to severe conditions of operation, such as high strength, wear and high-temperature gradients (e.g. engine components, insulation system, thermal barrier and thermal shield) must be applied. In this work, it was developed and characterized a functional gradient ceramic coating. A ceramic composite based in CaZrO3 – MgO was used in order to design a material with successive layers of molar composition 2:3, 1:1 and 1:3 of CaZrO3:MgO, respectively. A dense material was obtained by sintering assisted reaction (Figure 1). Thermal conductivity at room temperature, hardness, fracture toughness, surface energy, and microstructure were characterized.The results show for monolithic specimens of 2:3 CZ, 1:1 CZ and 1:3 CZ a H of 9,9 GPa, 9,8 GPa and 10,1GPa; a Kc of 1,6 MPa.m1/2, 1,7 MPa.m1/ and 2,1 MPa.m1/2; a k of 0,59 W/mK; 0,76 W/mK and 0,79 W/mK; and a surface energy (SE) of 43,27 mN/m, 51,39 mN/m and 46,55 mN/m, respectively. The functional gradient ceramic shows a H of 10,7 GPa, a Kc of 1,97 MPa.m1/2; a k of 0,82 W/mK and SE of 53,98 mN/m. The individual composition and the functional gradient ceramic show a similar relative density of 4,3 g/cm3 and a porosity of 0,2%. This design methodology has the advantage of allowing the properties of the same material to suit different substrates.

Keywords

Functionally Gradient Ceramic Ceramic multiphasic composites Calcium zirconate (CaZrO3) Magnesium oxide (MgO) Ceramic coating Thermal conductivity Microstructure Vickers hardness Surface energy Fracture toughness Porosity