Papers by Author: Guang Hui Wei

Abstract: Using Al, MgO and Al₂O₃ as raw materials, Al₂O₃-MgAlON composite was synthesized in N₂ atmosphere by hot-press sintering at 900°C. Cracks prepared on the sample surface were healed at 1200°C×6hrs. Phase composition and element chemical state of sample were studied before and after healing. The results showed that: after healing process Al and MgO phase disappeare, and AlN and MgAlON phase appear, all kinds of elements in Al₂O₃-MgAlON material change their chemical state after the healing treatment, the changed electronic binding energy is Al 0.05ev, Mg 0.08ev, O 2.58ev or N 1.02ev respectively, and the chemical composition and crystal structure of MgAlON phase also change, all these change are helpful for crack healing process of Al₂O₃-MgAlON material.

Abstract: Cordierite material was prepared by talc, bauxite and kaolin, and the coefficient of thermal expansion (CTE) of cordierite crystals could be determined by high temperature X-ray diffractmeter: the volume and average liner CTE is 2.31×10^-5°C-1 and 0.84×10^-5°C-1 (200°C -800°C) respectively; With the temperature increasing, the CTE in a or b axis direction increases, and in c axis direction decreases rapidly below 400°C then slowly, cordierite crystal is of obvious thermal expansion anisotropy. The orientation of crystal in sample is random, expansion and shrinkage partly counteract, so that the CTE of cordierite materials is low.