| In recent years, with the development of space technology, there is an urgent hope to develop a new kind of high temperature structural materials with better performance to meet more requirements. Molybdenum disilicide (MoSi2), as an insoluble intermetallic compound,becomes one of the candidate materials because of its properties, like high melting point,moderate of density and good anti-oxidation performance in high temperature. For making molybdenum disilicide are widely used as high temperature structural material, some breakthroughs in enhancing its toughness at low temperature and strength at high temperature are necessary. It is significant that trying to improving property by layered structure and compounding.In this paper, MoSi2 and MoSi2-B4C green sheets are fabricated by tape casting technology. To getting suitable slurry properties, solid content, dispersant, binder, plasticizer contents and milling time are studied. The influences of tape casting processing parameters,binder and plasticizer content to green tapes' properties like, thickness, surface morphology and properties of MoSi2 and MoSi2-B4C green tapes are studied so that the best content and parameters are gotten. Furthermore the forming process and polymer removal process of multilayers MoSi2/MoSi2-B4C are studied.The results showed that: Under the condition of making the slurry staying a porper viscosity level, the content of solid reached 60wt%, and to dispersant, the value was 1.2wt%,and the binder content was controlled in 3.5wt%?4.4wt%. For MoSi2-B4C composite slurry,the solid and dispersant content were 58wt% and 1.5wt% respectively, and binder content was controlled in 3.4wt%-4.3wt%. These two kinds of slurry had the lowest viscosity when the ratio of plasticizer and binder was kept 0.8 to 1.2.The procedures of filtering and vacuum degassing were efficient ways to decrease agglomerate and bubble defects. Creating a semi-hermetic environment by covering a glass plate above tape casting films could avoid cracks during drying process at room temperature.Mold discharging agent was useful for tape release. For homogeneous modulus MoSi2 ceramic slurry, when the content of solid, dispersant, binder and plasticizer is 60wt%,1.2wt%,4.0wt% and 4.0wt% respectively, green tapes with good performances have been fabricated.Its green density,tensile strength and breaking elongation were 3.66g/cm3,6.48MPa,and 19.95% respectively. And for MoSi2-B4C composites, each value of contents becomes 58wt%,1.5wt%,4.2wt% and 4.2wt%. The values of green density,tensile strength and breaking elongation turn to 3.38g/cm3, 5.94MPa, 19% respectively.Before lamination,MoSi2 and MoSi2-B4C green tapes' surface were painted a layer of adhesive so that they could be adhered tightly. Binder removal procedure occured with a 5?/min heating rate. For making sure polymers were burning out completely, the temperature in furnace was kept for 0.5h, 2h, 2h, 1h when it reached 100?, 240?, 400?, 620?respectively. |
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