Papers by Keyword: Sinter Forging

Abstract: Superplastic joining of 3mol% Yttria stabilized tetragonal zirconia polycrystal (3Y-TZP) is examined using 5wt%TiO2-doped 3Y-TZP as an insert material, in order to decrease the joining temperature and stress and to realize the local deformation near the joining surface. The joining tests are conducted by uniaxial compression in a temperature range of 1523 to 1723K. The joined specimen is characterized by a scanning electron microscopy (SEM), showing a clean interface with no cavitation. Four point bending tests are conducted to evaluate the joining strength, resulting an average flexural strength of 960MPa in the specimen joined at 1573K for sample compressed at 10MPa for 30 min, which is 80% of the strength of 3Y-TZP matrix. The temperature of 1573K is 100K lower than that obtained in sample without the insert material. Fracture occurs not at joining surface but at matrix in bending test. Residual stress is suggested to be introduced during joining process.

Abstract: The Si3N4- Si2N2O composites are fabricated with amorphous nano-sized silicon nitride powders by the liquid phase sintering (LPS) method. XRD analysis shows sintered body consists of β-Si3N4 and Si2N2O. SEM experiment conforms that the average grain size of sintered body is less than 300nm. The complex-shape gears can be formed by a sinter-forging technology when the sintering temperature is 1600°C and the superplastic forging temperature is only 1550°C. Rod-shaped grains aligned along the perpendicular direction of pressure and the mechanical properties increase about 10% after the materials were forged.