Zirconium dioxide short fiber and basic magnesium sulfate whisker composite enhanced magnesia-based crucible and preparation method thereof

Abstract

The invention discloses a preparation method of a zirconium dioxide short fiber and basic magnesium sulfate whisker composite enhanced magnesia-based crucible which can be sintered at the low temperature and has excellent chemical stability and thermal shock resistance. The method comprises steps as follows: (1) 15%-25% of nano aluminum sol, 0.8%-1.5% of a rheological agent and the balance of fused magnesia ceramic powder containing nano lanthanum oxide, zirconium dioxide short fiber and basic magnesium sulfate whisker are prepared in percentage by mass, deionized water is added, the mixture is subjected to ball milling and mixed uniformly, then, vacuum exhausting is performed, and ceramic slurry with the solid content of 70%-80% is prepared; (2) a crucible biscuit is prepared; (3) the dried biscuit is put in a sintering furnace to be sintered at the high temperature and then cooled with the furnace, and a magnesia-based crucible blank is obtained; (4) the magnesia-based crucible blankis subjected to vacuum impregnation treatment in aluminum sol, then, surface polishing treatment is performed, high-temperature secondary sintering is performed after drying, a product is cooled withthe furnace to the room temperature, and the magnesia-based crucible is obtained.

Description

technical field [0001] The invention relates to a magnesia-based crucible and a preparation method thereof, in particular to a magnesia-based crucible reinforced by composites of zirconia short fibers and basic magnesium sulfate whiskers and a preparation method thereof, belonging to the field of metal materials and metallurgy. The magnesium oxide-based crucible prepared by the invention is particularly suitable for smelting magnesium and its alloys. Background technique [0002] In recent years, the demand for lightweight has led to the rapid development of the application of magnesium alloys and aluminum alloys. Whether it is wrought magnesium, aluminum alloys or cast magnesium, aluminum alloys, the production is inseparable from casting equipment. The chemical properties of magnesium are lively, and it is easy to react with oxygen, nitrogen and water vapor. It is easy to be oxidized and burned during the melting and refining process, and the product remaining in the magne...

AI Technical Summary

Problems solved by technology

Chinese patent document CN103030407B (a kind of preparation method of high-strength, high-density, high-purity magnesia crucible), Chinese patent document CN1011306B (pure magnesia foam ceramic filter and its preparation process) etc. use pure magnesia as raw material to prepare magnesia Ceramics, because MgO has a high melting point and thermal expansion coefficient (13.5×10 -6 / °C) is high, therefore, it leads to difficult sintering (sintering temperature is not lower than 0.8 times its melting point) and poor thermal shock resistance, which limits the application and development of MgO ceramics

add V 2 o 5 In powder form, MgO will react with V at 1190°C 2 o 5 form an approximate composition of Mg 3 V 2 o 8 The liquid phase promotes sintering and can significantly reduce the sintering temperature of MgO foam ceramics, but V 2 o 5 Harmful to the respiratory system and skin during use, and has strict restrictions on operation

with V 2 o 5 Similarly, cobalt oxide is also a good low-temperature sintering aid, but its application is limited as a highly toxic substance and rare resource

Add fluorite (melting point 1423 ℃) and magnesium fluoride ( Melting point 1248°C), the solid solution of fluoride not only increases the lattice distortion of the matrix magnesium oxide during the sintering process, but also easily forms a low melting point liquid phase, thereby reducing the sintering temperature of the magnesia ceramics; however, during the sintering process F in fluoride is combined with Si, Al, Fe, Ca, and most of them (about 70% in ceramic tile production) volatilize in gaseous form, which not only corrodes the green body itself and damages the quality of sintered ceramics, but more seriously, it is discharged to The atmosphere will cause fluoride pollution. Fluoride can enter the human body through the respiratory tract, digestive tract and skin, and has toxic effects on the central nervous system and myocardium. Low-concentration fluorine pollution will cause brittle calcification of teeth and bones. "(GB25464-2010) stipulates that the discharge standard of fluoride must be lower than 5.0mg / m 3 Therefore, using fluoride as a low-temperature sintering aid for magnesia ceramics will inevitably increase the emission of gaseous fluoride and increase the burden of environmental protection investment; in addition, fluoride ions in the residual solid-solution fluoride in ceramics exist in the form of replacing oxygen ions, resulting in crystal The chemical stability of the intergranular bonding is reduced, and it is difficult to resist the long-term erosion of the flux in the magnesium melt

Chinese patent literature CN104496492B (a composite magnesium-carbon refractory crucible and its preparation method) and other disclosed ceramic foam filter preparation slurry adopts silica sol etc. 2 The presence of components makes it easy to react with magnesium and its alloy melts according to formula (4), which also reduces the chemical stability of ceramics

Although the crucible formed by isostatic pressing has the advantages of high density and high yield, and the crucible body is not easily deformed during the sintering process, it is also found that the crucible formed by isostatic pressing has the advantages of high cost, low efficiency, poor thermal stability, rapid heating and During the cooling process, the crucible is prone to cracking and peeling, and the service life is short

Images