Thermal diffusivity/conductivity of MgAlON-BN composites

Abstract

Thermal diffusivity and heat capacity of MgAlON and MgAlON-BN composites were measured in the temperature range of 25°C to 1300°C using a laser flash technique and a differential scanning calorimeter (DSC) technique, respectively. Based on these measurements, effective thermal conductivity of the composites was calculated using the values measured earlier in the same substance. The experimental effective thermal conductivity results of the composites containing different BN contents were found to show the similar trend, which decreased rapidly with increasing temperature below 900°C followed by a slow decrease with further increasing temperature. This can be explained by the fact that thermal conduction in both components, MgAlON and BN, was dominated by phonons. The phonon mean free path decreased with increasing temperature, limited by the characteristic length between two neighboring atoms. The BN addition has significant influence on the effective thermal conductivity. The effective thermal conductivity of the composites containing BN exhibited a small degree of anisotropy with respect to preferred orientation of the BN phase. The degree of anisotropy of the composites increased with increasing BN content, which is particularly pronounced at the higher BN additions. An equation suitable for the present composites has been derived based on Luo's model. The model was slightly modified in the present article. The predicted values calculated by the model were in good agreement with experimental results.

Testing of the Oxidation Resistance of MgAlON Materials with Non-isothermal Oxidation Method

“…[2][3][4] Therefore, MgAlON can be used as high-performance refractories. [1,[5][6] As mentioned above, MgAlON can be used in refractory materials. They can withstand harsh environments and support heavy loads at temperatures beyond those at which metals and polymers fail.…”

Microstructures and Properties of Carbon Refractories for Blast Furnaces with SiO2 and Al Additions

“…The thermal conductivity measured at 300°C was higher than that measured at 600°C, which can be attributed to the decrease in the phonon mean free path with increasing temperature. [21] The hearth carbon refractory specimen mainly contained two phases: continuous phase (solid phase) and discontinuous phase (pore). The thermal conductivity of the continuous phase (solid phase) was far greater than that of the discontinuous phase (pore), according to the simplified Maxwell model: [22] …”

Influence of pore structure parameters on thermal properties of corundum based castables

“…They are mostly influenced by temperature, chemical composition and microstructure [1][2][3], and the relationship between them and pore structure (which describes the microstructure of refractory materials) is studied frequently at present. Large apparent porosity leads to the thermal conductivity decreasing markedly [4], while pore configuration and pore size distribution are also the important factors influencing thermal conductivity [5,6].…”