Preparation and properties of porous ZrB2 ceramics via combining in-situ boro/carbothermal reduction and partial sintering approach

In this manuscript, high performance porous ZrB2 ceramics were firstly fabricated via a novel and facile method combining in-situ boro/carbothermal reduction (BCTR) reaction (at 1300 ? for 2 h) and partial sintering technique (at 1900 C for 1 h) using ZrO2, B4C, and carbon black as material precursors. The porosity, linear shrinkage, mechanical properties, and thermal conductivity of the porous ZrB2 ceramics can be regulated by varying particle size of ZrO2 and B4C powders. B4C and carbon black performed as reducing agent and pore-foaming agent for in-situ synthesis porous ZrB2 ceramics. The as-obtained porous ZrB2 ceramics with pore size in the 2-26 mu m range exhibited low linear shrinkage of 0.5-7.8%, high porosity of 65-72%, relatively high compressive strength of 3-28 MPa and low thermal conductivity of 3-9 W m(-1)K(-1). Effect of CO partial pressure on synthesizing ZrB2 and pore formation mechanism were also discussed in details. The comprehensive properties of as-obtained porous ZrB2 ceramics make them as candidate porous materials for thermal insulation applications.

Automated summary

High performance porous ZrB2 ceramics were successfully fabricated using a novel method, and the properties of the ceramics can be regulated by varying the particle size of the powders. The ceramics exhibited low linear shrinkage, high porosity, relatively high compressive strength, and low thermal conductivity.