• Rodrigues Pais Alves, Manuel Fellipe

Abstract

<jats:p>This study aims to evaluate the effects of sintering parameters in crystalline phases, microstructure and mechanical properties of composites obtained through the Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>-TiO<jats:sub>2 </jats:sub>ceramic system. Cylindrical specimens, containing molar ratio of 3 Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>: 1 TiO<jats:sub>2</jats:sub>, were uniaxially pressed at 100 MPa. The applied sintering parameters were varied in five distinct temperature ranges (1300°C, 1400°C, 1500°C, 1575°C or 1600°C) for 2h and 1600°C for 10h. After sintering, samples were characterized by relative density, X-ray diffraction, scanning electron microscopy and mechanical properties (hardness and fracture toughness). After sintering the results point to a microstructure with grains near to 2.5mm, independent of the present phases and crystalline phases composed of: Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> rhombohedral, TiO<jats:sub>2</jats:sub> tetragonal e Al<jats:sub>2</jats:sub>TiO<jats:sub>5</jats:sub> orthorhombic. The specimens sintered at 1600°C-10h feature densification 30% higher them the ones sintered at 1300°C-2h, reaching a density higher than 85% of theoretical density. The composite presents hardness higher than 1000HV and fracture toughness upper than 2.2MPam<jats:sup>1/2</jats:sup>. The better results for the mechanical properties were found in the composites sintered at 1600°C-10h, that showed a bigger relative density than all analyzed specimens, and only phases of Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> and Al<jats:sub>2</jats:sub>TiO<jats:sub>5</jats:sub> could be found, what means that all TiO<jats:sub>2</jats:sub> was consumed in the sintering of the new composite.</jats:p>

Topics

• density
• grain
• scanning electron microscopy
• x-ray diffraction
• crystalline phase
• composite
• hardness
• ceramic
• fracture toughness
• sintering
• densification