Next Generation Carbon-Containing Refractory Composites

Abstract

Carbon-containing refractory bricks are used extensively in the steel industry worldwide. Since the first generation became commercially available in the 1970’s, their processing, microstructures and properties have been improved dramatically, and the service lives of industrial furnaces have thus been extended substantially. In addition to the work on carboncontaining refractory bricks, much effort has been, and is being, made worldwide towards the development of carbon-containing refractory castables. In this paper, the latest R & D towards new generation carboncontaining refractory bricks as well as carbon-containing refractory castables have been highlighted. In the first part, current techniques used to improve mechanical properties of carbon-containing refractory bricks are summarised. A new concept using a catalytic-growth technique to create insitu oxide nanofibres and/or carbon nanotubes in carbon-containing refractory bricks is introduced. The second part addresses some important technical issues of low carbon carbon-containing refractory bricks. Besides the concern about thermal shock resistance, other new problems arising from the use of nanosized carbon, such as the accelerated MgO-C reaction and carbon oxidation, are discussed. In the final part of the paper, technical difficulties hindering the development of carbon-containing castables as well as measures to overcome them are discussed. A novel molten salt synthesis technique developed recently at Sheffield to prepare high quality carbide coatings on graphite is introduced.

Improvement of water/resin wettability of graphite using carbon black nano particles coating via ink media

“…However, the use of carbon material especially graphite has been greatly restricted due to the poor water wettability and low tendency to be mixed with resins lead to substantial limitation in applying graphite into structural bodies like refractories and composites [2]. In this regard achieving good water wettability and superior mixing ability with resin binder is crucial to utilize full potential of graphite in all applications [3].…”

Coating of graphite flakes with MgO/carbon nanocomposite via gas state reaction

“…One of the most efficient methods is modifying the surface of graphite with hydrophilic materials like oxides [5]. Zhang and Lee applied pitch on the surface of graphite to overcome these drawbacks [6].…”

Reinforced Cellular Carbon Matrix–MgO Composites for High Temperature Applications: Microstructural Aspects and Colloidal Processing

“…tailored moduli of elasticity, thermal shock resistance, that cannot be technically or economically provided by conventional low carbon MgO-C refractories. [1] Here we report different colloidal synthetic processing routes for tailoring reinforced cellular and reticulated glassy carbon structures in the macro-, meso-, and microscale, which then gives rise to very high thermal shock resistance characteristics. The cellular interconnected glassy carbon network is processed by replication of PU foams with phenolic resins and subsequent carbonization in inert atmospheres.…”

“…[1,28,29] In order to achieve original thermal shock resistance at low carbon levels the following strategies have been proposed: [30] i) Optimization of the bricks elastic moduli and strength via careful microstructure design using fine graphite to replace coarse graphite, because the former could be dispersed in the matrix more homogeneously than the latter using nanosized carbon and carbon nanofibers by using coated (e.g. SiC coated carbon nanopowders and carbon nanofibers) in order to achive homogeneous dispersions in aqueous media and to prevent rapid oxidation due redox reactions and criticial oxygen concentrations by tailoring the microstructure of low elastic moduli MgO grains (e.g.…”

“…Although much effort has been made and is being made in this working field, poor wettability of graphite raw materials has negative effect on the viscosity and solid content of the slurries. [1] It is therefore an objective of the ongoing research of new generation MgO-C refractories for steelmaking industries to meet the following raw material and sintering condition requirements: [5] i) Processing of antioxidant free and low impurity MgO-C bricks (highest cleanness levels of steel). ii) Minimization of decarburization of refractory bricks at suitable reducing sintering conditions (converter gas atmospheres).…”