Phase Formation Between Iridium Thin Films and Zirconium Carbide Prepared by Spark Plasma Sintering at Relatively Low Temperatures

Abstract

Zirconium carbide (ZrC) samples were prepared by spark plasma sintering (SPS), at temperatures of 1700 °C, 1900 °C and 2100 °C at 50 MPa for 10 minutes. The phase and microstructure after the sintering process was investigated. The relative density of ZrC ceramic pellets formed at 1700 °C, 1900 °C and 2100 °C was measured and found to be 96.5 %, 98.9 % and 99.5 % respectively. The grain size of ZrC ceramic pellets was calculated and it was found to increase from 71.88 nm, 79.15 nm and 83.59 nm as the sintering temperature increased from 1700 °C, 1900 °C to 2100 °C respectively. The hardness of ZrC ceramic pellets was found to be 7.40 GPa, 17.00 GPa to 18.40 GPa at 1700 °C, 1900 °C to 2100 °C respectively. The preferred orientation at 1700 °C, 1900 °C and 2100 °C was the (200) plane. Iridium (Ir) thin films were deposited on ZrC ceramics by electron beam deposition method and annealed in vacuum at temperatures of 600 °C and 800 °C for 2h. The phase composition, solid-state reactions and surface morphology were investigated by grazing incidence x-ray diffraction (GIXRD), and scanning electron microscopy (SEM). XRD was used to identify the phases present in the as-deposited and annealed samples. XRD analysis showed that Ir2Zr was the initial phase formed at 600 °C. At temperature 800 °C, Ir reacted with the ZrC to form IrZr. The SEM images of as-sintered samples at 1700 °C, 1900 °C and 2100 °C showed that the ZrC surface was heterogeneous and uneven consisting of agglomerated granules with a few pores. The number of pores was observed to reduce with sintering temperature. After depositing Ir films on ZrC substrate, the structure of the Ir film followed that of the substrates. After annealing the Ir-ZrC samples at 600 °C and 800 °C, the further agglomeration of surface granules was observed.