Spark plasma sintering of aluminium nitride transparent ceramics.

Aluminium nitride (AlN) transparent ceramic was fabricated by a spark plasma sintering (SPS) technique. Samples were processed at 1800°C, 25 MPa pressure, and 6 Pa vacuum without sintering additives, and at different heating rates and sintering durations ranging from 4 to 20 min. X-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and transmission electron microscopy (TEM) investigation indicated that the ceramics prepared by SPS had good transparency, because of its high purity, fine particle size, and uniform microstructure. Dislocations and pores in crystals were observed by TEM, which adversely affect the transmittance of AlN transparent ceramics. Experiments showed that the SPS technique is an effective method for the fabrication of transparent ceramics. [ABSTRACT FROM AUTHOR]