Fabrication of near-zero thermal expansion of fully dense β-eucryptite ceramics by microwave sintering

Peñaranda‐Foix

et al. 2014

Ceramics International

Microwave sintering has emerged in recent years as a novel method for sintering a variety of materials that have shown significant advantages against conventional sintering procedures. This work involved an investigation of microwave hybrid fast firing of alumina-zirconia nanocomposites using commercial alumina powder and monoclinic nanometric zirconia. The suspensions were prepared separately in order to obtain 5, 10 and 15 vol.% of ZrO 2 in the alumina matrix. The samples were sintered in a 2 monomode microwave furnace at 2.45 GHz in air at different temperatures in the range 1200-1400 ºC with 10 min of dwelling time and 200 ºC/min of heating rate. The effect of sintering temperature in densification, mechanical properties and microstructure behaviour of the composites was investigated.Higher density, hardness and Young's modulus, excellent fracture toughness properties and homogeneous microstructure were achieved by microwave sintering in comparison to conventional heating. Microstructure analysis showed that the alumina grains had not grown significantly, indicating that the zirconia particles provided a hindering effect on the grain growth of alumina.

Section: Introductionmentioning

confidence: 99%

“…To minimize grain growth and to enhance mechanical properties, microwave sintering has been proposed. This fast sintering technique is regarded as a promising method to inhibit grain growth because of short sintering duration [14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties and microstructural evolution of alumina–zirconia nanocomposites by microwave sintering

Peñaranda‐Foix

et al. 2014

Ceramics International

“…Microwave sintering has several advantages such as rapid and volumetric heating, improved production rate, enhancement in densification and grain growth prohibition of ceramics [17,18].…”

Section: Introductionmentioning

confidence: 99%

Microwave, Spark Plasma and Conventional Sintering to Obtain Controlled Thermal Expansion β‐Eucryptite Materials

Int J Applied Ceramic Tech

Moreno

et al. 2014

Self Cite

Lithium aluminosilicate was fabricated by conventional and non-conventional sintering:microwave and spark plasma sintering, from 1200 to 1300 ºC. A considerable difference in densification, microstructure, coefficient of thermal expansion behavior and hardness and Young's modulus was observed. Microwave technology made possible to obtain fully dense glass-free lithium aluminosilicate bulk material (>99%) with near-zero and controlled coefficient of thermal expansion and relatively high mechanical properties 1 (7.1 GPa of hardness and 110 GPa of Young's modulus) compared to the other two processes. It is believed that the heating mode and effective particle packing by microwave sintering are responsible to improve these properties.

“…The E field has a maximum (E r and E M components) in the center, where the samples are located in a quartz tube [18]. A movable short-circuit at the bottom of the cavity allows to tune the cavity dynamically, due to the changes in the dielectric constant of the heated test sample during the sintering process [24].…”

Section: Microwave Setupmentioning

confidence: 99%

“…Microwave radiation of ceramic components has recently gained new relevance in the fields of sintering and joining ceramics due to its advantages over conventional heating techniques. [14][15][16][17] Benavente and coworkers [18] developed microwave equipment specially designed to fabricate ceramic materials of lithium aluminosilicate (LAS) in solid state with high density and have high mechanical properties (hardness and Young's modulus). The important characteristics associated with microwave sintering of ceramic materials are rapid and uniform volumetric heating, improved production rate, enhanced densification and inhibition of grain growth.…”

Section: Introductionmentioning

confidence: 99%

High thermal stability of microwave sintered low-εr β-eucryptite materials

Peñaranda‐Foix

et al. 2015

Ceramics International

Self Cite

Low-temperature sinterable microwave LiAlSiO 4 -based solid-state material was investigated with regard to microwave dielectric properties as functions of the sintering temperature. β-eucryptite materials and alumina-reinforced β-eucryptite composites were sintered by microwave technology at 1100 ºC and 1200 °C. The combination of fast heating and the dramatic reduction in cycle time, along with the non-conventional heating source, opens the way to produce materials with desired multifunctional properties. 2The microstructure and crystalline composition of the materials were characterised, and the mechanical, thermal and microwave dielectric behaviours were analyzed. X-ray diffraction showed good chemical stability in materials without between-phase reactions during the microwave sintering process. The excellent mechanical (~8 GPa of hardness and ~100 GPa of Young's modulus), thermal (-0.23·10 -6 K -1 ) and microwave dielectric properties (ε r = 4.10; Q = 1494) were obtained from the LAS/Al 2 O 3 composites sintered at a very low temperature (1100 ºC). The results achieved show the possibility of designing ceramic nanocomposites at low sintering temperatures using microwave technology with near-zero thermal expansion coefficients, high mechanical and chemical stability and low dielectric properties.