Effect of matrix composition on physical properties of Al₃CON in-situ reaction reinforced corundum composite

Abstract

60% white corundum used for aggregate, 5% aluminium powder for fixed additions and 35% various additives for matrix were prepared for specimens 1#,2#,3#. They were mixed uniformly with the suitable resin as a binder and pressed under pressure of 315 ton forging press, then dried at 200 °C for 24 h. Effects of various additives on 1500 °C×2 h creep properties of Al₃CON reinforced corundum composite were researched. The experimenal results show that creep coefficients of specimens 1#,2#,3# at 1500 °C×2 h are 1.4×10⁻⁴, −9.4×10⁻⁴, −22.6×10⁻⁴, respectively. Crushing strength of the slide plate added with suitable additive A after fired at 1500 °×3 h reaches to 225 MPa, the creep rate is positive all the time from 0% to 0.014% at 1500 for 2 h. °C The microstructure result analysis shows that reinforced phases of Al₃CON fiber composite have been formed after fired with Al powder in coke at high temperatures for specimen 1#, and the strength of the composite is increased. The hot modulus of rupture is up to 59 MPa at 1400 °C and the RUL is obviously higher than that at 1700 °C. Its service life is two times as that of Al₂O₃-C slide plate when used in the process of pouring steel. The mechanism of creep rate resistance of the composites can be discovered by means of SEM and EDAX analysis. It is concluded that the active Al₃CON and Al₂O₃ multiphases that were formed by N₂ in gas, C, Al and Al₂O₃ inside the matrix of the composites during in-situ reaction, which gives the composites outstanding creep rate resistance for the dense zone resulting from Al₃CON oxidation that inhibits contraction at the high temperature. Besides, the matrix will turn into the multiphase with high refractoriness, N content and its Al₃CON reinforced fiber will further increase accordingly. In addition, Al₃CON formed by Al₂O₃ and C, Al in the matrix with N₂ in gas will inhibit the creep rate and also greatly improve the creep rate resistance of the composites.

Keywords

matrix / additives / creep rate / corundum / Al₃CON / composite / HMOR

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