Processing, Mechanical and Optical Properties of Additive-Free ZrC Ceramics Prepared by Spark Plasma Sintering

Abstract

In the present study, nearly fully dense monolithic ZrC samples are produced and broadly characterized from microstructural, mechanical and optical points of view. Specifically, 98% dense products are obtained by Spark Plasma Sintering (SPS) after 20 min dwell time at 1850 °C starting from powders preliminarily prepared by Self-propagating High-temperature Synthesis (SHS) followed by 20 min ball milling. A prolonged mechanical treatment up to 2 h of SHS powders does not lead to appreciable benefits. Vickers hardness of the resulting samples (17.5 ± 0.4 GPa) is reasonably good for monolithic ceramics, but the mechanical strength (about 250 MPa up to 1000 °C) could be further improved by suitable optimization of the starting powder characteristics. The very smoothly polished ZrC specimen subjected to optical measurements displays high absorption in the visible-near infrared region and low thermal emittance at longer wavelengths. Moreover, the sample exhibits goodspectral selectivity (2.1–2.4) in the 1000–1400 K temperature range. These preliminary results suggest that ZrC ceramics produced through the two-step SHS/SPS processing route can be considered as attractive reference materials for the development of innovative solar energy absorbers.

An overview of ultra-refractory ceramics for thermodynamic solar energy generation at high temperature

“…The increasing interest in these materials is due to their unique combination of properties, including the highest melting points of any group of materials, >3000°C, elevate strength at extreme temperature, like 600-800 MPa at 1500-2100°C [11], high thermal conductivity, 80-110 W/mK up to 2000°C [12] and chemical stability. Recently, it has been found that most of these compounds also have the characteristic of being intrinsic solar selective materials [13][14][15][16][17][18][19], but the understanding of the optical properties of these materials is still very scanty, especially at high temperature. UHTCs have thus the potential to be suited for application in high temperature solar receivers, once their basic properties have been properly investigated and correlated to the bulk and surface characteristics.…”

“…Particular emphasis was devoted to identify their correlation with relevant material characteristics, such as compositions, porosity, surface finishing. Several ultra-refractory boride and carbides have been studied in the framework of the project [13][14][15][16][17], allowing to identify the most promising materials for solar absorber applications. This work describes, as a case study, an extensive work on ZrB 2based ceramics, consolidated through different processes, with or without MoSi 2 as secondary phase, textured or with controlled porosity.…”

Kinetic role of C/Zr ratio in the reaction process, combustion behavior, and synthetic product of 70 wt.% (xC–Zr)–30 wt.% Cu

“…Among various preparation methods, the combustion synthesis technology has attracted much attention for its easy operation and low energy consumption 14–16 . In addition, the combustion synthesis has been widely used to combine with other routes to prepare composites containing ZrC 17–30 . As these ceramic particles are mainly derived from the combustion synthesis reaction, understanding the kinetic characteristics is vital to achieving a desired microstructure.…”

“…[14][15][16] In addition, the combustion synthesis has been widely used to combine with other routes to prepare composites containing ZrC. [17][18][19][20][21][22][23][24][25][26][27][28][29][30] As these ceramic particles are mainly derived from the combustion synthesis reaction, understanding the kinetic characteristics is vital to achieving a desired microstructure. Conventionally, the influence of the kinetic parameters on the combustion behaviors and synthesized products was predicted by thermodynamic calculations and/or reaction mechanism.…”

Spark plasma sintering of structure‐tailored ultrahigh‐temperature components: First step to complex net shaping

“…The maximum processing temperatures in SPS of ZrC powder were reduced by bringing the initial particle size down into the nanometer range through ball‐milling and sol‐gel methods . The self‐propagating high‐temperature synthesis was combined with SPS to produce monolithic ZrC ceramics at relatively lower temperatures, in which the optical properties of the obtained specimens were found to be good for solar energy applications …”