20 documents found, page 1 of 2
Development and production of a CNC machined 420 stainless steel reinforced wit...
Cunha, A.; Pinto, J.; Cerqueira, M. F.; Silva, F. S.; Trindade, B.; Carvalho, O.Multi-material structures make it possible to obtain effective solutions to engineering problems by combining the benefits of different materials to meet the requirements of different working conditions. The aim of this multifunctional 420 stainless steel-copper structure is to create a hybrid solution in which copper acts as heat-transfer enhancer (through cooling channels) while maintaining the required mecha...
Development and production of a CNC machined 420 stainless steel reinforced wit...
Cunha, A.; Pinto, J.; Cerqueira, M. F.; Silva, Filipe Samuel; Trindade, B.; Carvalho, O.Multi-material structures make it possible to obtain effective solutions to engineering problems by combining the benefits of different materials to meet the requirements of different working conditions. The aim of this multifunctional 420 stainless steel-copper structure is to create a hybrid solution in which copper acts as heat-transfer enhancer (through cooling channels) while maintaining the required mecha...
Influence of temperature processing on the microstructure and hardness of the 4...
Cunha, A.; Marques, A.; Gasik, M.; Trindade, B.In this study, samples of 420 stainless steel were obtained by hot pressing from powder at temperatures from 1,100 to 1,200°C. The aim was to explore the influence of the processing temperature on their grain size, microstructure, densification and mechanical properties. The results showed that it is possible to produce dense samples at these sintering temperatures. The sintering temperature influenced the dens...
Effect of particle size of starting oxide powders on the performance of doped-l...
Oliveira, Fernando Almeida Costa; Marcelo, Teresa; Alves, Cátia; Santos, Mário João dos; Mascarenhas, João; Trindade, B.La9.33Si2Ge4O26 oxyapatite powders were synthesized at room temperature through mechanical alloying of La2O3, GeO2 and SiO2 precursor powders with different particle sizes as well as crystal structure in the case of silica powder (crystalline/amorphous). The mechanical alloyed mixtures were subsequently sintered by microwave heating at 1350 C for 1 h in order to obtain dense and homogeneous materials. All sinte...
Effect of particle size of starting oxide powders on the performance of doped-l...
Oliveira, Fernando Almeida Costa; Marcelo, Teresa; Alves, Cátia; Santos, Mário João dos; Mascarenhas, João; Trindade, B.La9.33Si2Ge4O26 oxyapatite powders were synthesized at room temperature through mechanical alloying of La2O3, GeO2 and SiO2 precursor powders with different particle sizes as well as crystal structure in the case of silica powder (crystalline/amorphous). The mechanical alloyed mixtures were subsequently sintered by microwave heating at 1350 C for 1 h in order to obtain dense and homogeneous materials. All sinte...
Novel two-step processing route combining mechanical alloying and microwave hyb...
Santos, Mário João dos; Alves, Cátia; Oliveira, Fernando Almeida Costa; Marcelo, Teresa; Mascarenhas, João; Cavaleiro, A.; Trindade, B.In this work, microwave hybrid sintering at 1300 and 1350 °C was carried out for densification of La9.33Si2Ge4O26 mechanically alloyed powder with apatite structure. The pellets sintered at these two temperatures present the same structure (apatite) with relative densities of 92 and 96%, respectively. Mechanical analysis performed on sintered materials revealed the following results: hardness of 7.1 and 8.0 GPa...
Effect of the sintering conditions on the morphology of La9.33Si2Ge4O26 oxyapat...
Macatrão, Mafalda; Santos, Mário João dos; Alves, Cátia; Oliveira, Fernando Almeida Costa; Marcelo, Teresa; Mascarenhas, João; Trindade, B.Solid oxide fuel cells (SOFCs) are devices that allow direct conversion of chemical to electrical energy through an electrochemical reaction in a cleaner and more efficient way than conventional processes (eg. gas turbines). They are characterized by the use of a solid oxide material as the electrolyte. Yttria-stabilised zirconia (YSZ) has traditionally been used in SOFCs electrolytes at temperatures in the ran...
Novel two-step processing route combining mechanical alloying and microwave hyb...
Santos, Mário João dos; Alves, Cátia; Oliveira, Fernando Almeida Costa; Marcelo, Teresa; Mascarenhas, João; Cavaleiro, A.; Trindade, B.In this work, microwave hybrid sintering at 1300 and 1350 °C was carried out for densification of La9.33Si2Ge4O26 mechanically alloyed powder with apatite structure. The pellets sintered at these two temperatures present the same structure (apatite) with relative densities of 92 and 96%, respectively. Mechanical analysis performed on sintered materials revealed the following results: hardness of 7.1 and 8.0 GPa...
On the influence of silica type on the structural integrity of dense La9.33Si2G...
Alves, Cátia; Marcelo, Teresa; Oliveira, Fernando Almeida Costa; Alves, L. C.; Mascarenhas, João; Trindade, B.Apatite-type rare earth based oxides, such as R-doped lanthanum oxides of general formula La9.33(RO4)6O2 with R = Ge, Si, exhibit high ionic conductivity and low activation energy at moderate temperatures, when compared to the yttria-stabilized zirconia electrolyte making them potential materials to be used in the range 500–700 °C, for intermediate temperature solid oxide fuel cells (IT-SOFCs). In this study, d...
Mechanical properties of sintered La9.33Si2Ge4O26 oxyapatite materials for SOFC...
Santos, Miguel; Alves, Cátia; Oliveira, Fernando Almeida Costa; Marcelo, Teresa; Mascarenhas, João; Fernandes, J.V.; Trindade, B.Mechanical properties of La9.33Si2Ge4O26 prepared by mechanical alloying and subsequent sintering at 1300–1400 °C for 1 h were evaluated. Hardness and Young's modulus values in the range 7.3–9.6 GPa and 106–135 GPa, respectively, were obtained from nanohardness tests. The fracture toughness values derived from the Palmqvist method varied between 3.5 and 3.9 MPa m1/2 from classical microindentation test with an ...