Improved thermal shock resistance of magnesia-graphite refractories by the addition of MgO-C pellets

Magnesia-graphite (MgO-C) refractories with 12-20 wt% carbon contents are extensively used for the taphole sleeve bricks, bottom blowing elements, slag line bricks, etc. in steelmaking operations. To reduce the carbon content but to have the same or even superior thermal shock resistance with commercial available material compositions (14 wt% flaky graphite), we report here a new approach based on the granulating treatment of flaky graphite to improve the thermal shock resistance of MgO-C refractories (10 wt% flaky graphite). MgO-C pellets are firstly prepared by the crushing granulation method, and then introduced into such refractories. Addition of MgO-C pellets has no apparent influence on their flexural strength, but enhances their flexural strength after thermal shocks and residual strength ratio. Particularly, when 10 wt% flaky graphite of the specimens is replaced totally by MgO-C pellets, their thermal shock resistance is superior to that of the specimens containing 14 wt% flaky graphite. This new method opens up possibilities to obtain MgO-C refractories with improved thermal shock resistance. (C) 2017 Elsevier Ltd. All rights reserved.