Evaluation of matrix of coke strength by nano-indentation method

Nano-indentation method is proposed to measure the elastic modulus of matrix of coke and to study the relativity of the elastic modulus to raw coal. Coke strength is the most important qualities to retain the permeability in a blast furnace. Then coke strength must be clarified. Matrix of coke elastic modulus and its relation to raw coal are essential for theoretical approach based on Mechanics of Materials to reveal the fracture behavior of coke. Nano-indentation method, which couples the equation obtained by finite element analysis with the load-displacement curves in the microscopic region measured by ultra-micro-hardness tester, enables us to determine the elastic modulus of coke substrate except the effect of pores. The matrix elastic modules of cokes made from four kinds of coal are measured for each coke texture. Elastic modules of flow texture, coarse mosaic texture and fine mosaic texture that are the texture originated in reactives are 17-18 GPa for every raw coal, so they can be regarded as same strength. The elastic modulus of inerts is higher than that of the textures organized in reactives, and increases as coal rank increases. As a result it follows that matrix of coke is simplified to a composite material composed of two kinds of materials, reactives and inerts.