CAJ | 학술논문

氧化物共晶陶瓷具有优异的超高温力学性能和抗氧化性。为获得具有精细组织的共晶陶瓷，采用有限元法计算模拟了 Al2 O3/MgAl2 O4共晶陶瓷的区域熔炼定向凝固过程。计算结果表明，热重引起的自然对流，呈逆时针环形流，整个凝固过程中流动强度先减小后增大，固液界面呈明显的凹形界面。 ACRT强迫对流的特征为逆时针、顺时针对流胞交替呈现，强度比自然对流大1~2个数量级。施加 ACRT 后，凝固过程中固液界面仍然呈凹形界面，但是凹陷深度显著减小；当坩埚最大转速增大时，对流强度显著增加，固液界面的凹陷深度进一步减小，直至趋近于平界面。
양화물공정도자구유우이적초고온역학성능화항양화성。위획득구유정세조직적공정도자，채용유한원법계산모의료 Al2 O3/MgAl2 O4공정도자적구역용련정향응고과정。계산결과표명，열중인기적자연대류，정역시침배형류，정개응고과정중류동강도선감소후증대，고액계면정명현적요형계면。 ACRT강박대류적특정위역시침、순시침대류포교체정현，강도비자연대류대1~2개수량급。시가 ACRT 후，응고과정중고액계면잉연정요형계면，단시요함심도현저감소；당감과최대전속증대시，대류강도현저증가，고액계면적요함심도진일보감소，직지추근우평계면。
Oxide eutectic ceramics was expected to have excellent mechanical property and oxidation resistance at super high temperature.In order to get eutectic ceramics with fine structure,the solidification process of Al2 O3/MgAl2 O4 eutectic ceramics with zone-melting was simulated with finite element.The results showed that the natural convection caused by the thermogravimetric effect was a counterclockwise annular flow,of which flow intensity increases at first,and then decreases as the solidification proceeds.The solid-liquid inter-face keeps a concave one and its concavity decreases at first and then increases.The forced convection caused by ACRT presents that a clockwise flow cell and a counterclockwise one dominate the front of the solid-liquid inter-face alternately,and its intensity was over that of the natural flow by 1-2 orders of magnitude.However the sol-id-liquid interface was still a concave one during the solidification,though the concavity depth decreases obvi-ously.As the crucible maximum rotation rate increases,the forced convection intensity increases,the indenta-tion depth of the solid-liquid interface decreases further.