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Aluminum oxide short-fiber enhanced magnesium-oxide-based foam ceramic filter and preparation method thereof

A ceramic foam and magnesia-based technology, applied in the filtration and purification of aluminum and its alloy melts, magnesia-based ceramic foam filter and its preparation, alumina short fiber reinforced magnesia-based ceramic foam filter and its preparation , which can solve the problems of operation limitation, increase matrix magnesium oxide lattice distortion, respiratory system and skin damage, etc., and achieve good strength, simple process and high efficiency

Active Publication Date: 2018-09-04
JIANGSU FAVOUR AUTOMOTIVE NEW STUFF SCI TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Chinese patent documents CN1011306B (pure magnesia foam ceramic filter and its preparation process), CN101138691A (preparation method of magnesia foam ceramic filter for casting), etc., prepare foam ceramics with pure magnesia as raw material, because MgO has a very high melting point and coefficient of thermal expansion (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 foam 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
Fluoride is a strong co-solvent and mineralizer commonly used in ceramic industry sintering, Chinese patent documents CN100536986C (magnesia foam ceramic filter), CN1473947A (foam ceramic for magnesium and magnesium alloy melt purification), CN101785944B (for magnesium Fluorite (melting point 1423°C) and magnesium fluoride (melting point 1248°C) are added to the preparation method of magnesium oxide foam ceramic filter for magnesium melt filtration. The solid solution of fluoride not only increases the oxidation of the matrix during the sintering process The lattice of magnesium is distorted, and it is easy to form a low-melting liquid phase, thereby reducing the sintering temperature of magnesia ceramics; however, during the sintering process, F in fluoride combines with Si, Al, Fe, and Ca, and most (in ceramic tiles) About 70% in production) volatilization in gaseous form not only erodes the green body itself and damages the quality of sintered ceramics, but more seriously, it will cause fluoride pollution when discharged into the atmosphere. Fluoride can enter the human body through the respiratory tract, digestive tract and skin , has a toxic effect on the central nervous system and myocardium, and low-concentration fluorine pollution can lead to brittle calcification of teeth and bones. The discharge standard of fluoride must be lower than 5.0mg / m2 in the "Ceramic Industry Pollutant Discharge Standard" (GB25464-2010) 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 flux inclusions in the magnesium melt
Water glass, silica sol and ethyl silicate are used as binders in the preparation slurry of the disclosed ceramic foam filters such as Chinese patent literature CN101138691A, and the SiO between the sintered ceramic foam particles 2 The presence of components makes it easy to react with magnesium and its alloy melts according to (4), which also reduces the chemical stability of foamed ceramics
However, diboron trioxide is easy to react with magnesium and aluminum, and is not stable in magnesium and aluminum alloy melts; at the same time, because diboron trioxide is soluble in solvents such as water and ethanol, it can strongly absorb water in the air to form boric acid. The diboron trioxide added in the preparation process of foam ceramics is dissolved in water to form a boric acid aqueous solution, which is easy to react with magnesium oxide to form magnesium borate precipitation and reduce its effect
Gallium oxide is a homogeneous oxide of diboron trioxide, which forms spinel-type MgGa with magnesium oxide at a lower temperature 2 o 4 It plays a role in reducing the sintering temperature, but the amount of gallium resources is very small (gallium is a strategic reserve metal), and the high price of gallium oxide limits its application in ordinary ceramics.

Method used

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  • Aluminum oxide short-fiber enhanced magnesium-oxide-based foam ceramic filter and preparation method thereof
  • Aluminum oxide short-fiber enhanced magnesium-oxide-based foam ceramic filter and preparation method thereof
  • Aluminum oxide short-fiber enhanced magnesium-oxide-based foam ceramic filter and preparation method thereof

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Effect test

Embodiment 1

[0052] According to the ratio of nano-titanium oxide accounting for 1% of the mass of the ceramic powder and commercial alumina short fibers (about 10 μm to 20 μm in diameter and 50 μm to 100 μm in length) accounting for 1% of the mass of the ceramic powder, the particle size was weighed to be 30 nm. Nano-titanium oxide, commercial alumina short fibers and a particle size of 250 mesh (middle diameter d 50 Prepare ceramic powder for lightly burned magnesia powder with a thickness of 58 μm; mix and prepare a rheological agent according to the mass ratio of polyvinyl butyral and hydroxypropyl methylcellulose at a ratio of 1:1.

[0053] According to mass percentage, 15% of nano-alumina sol with a solid content of 20% (select a commercial nano-alumina sol with a nearly neutral pH value, the same below), 0.8% of rheological agent, and the rest are ceramic powders for batching. First, add the light-burned magnesia powder into the ball mill tank according to the ratio, and add nano-al...

Embodiment 2

[0057] According to the ratio that nano-titanium oxide accounts for 2% of the mass of the ceramic powder, and alumina short fibers account for 3% of the mass of the ceramic powder, the nano-titanium oxide with a particle size of 60nm, commercial alumina short fibers and a particle size of 60nm are weighed. 500 mesh (middle diameter d 50Prepare ceramic powder for lightly burned magnesia powder (25 μm); mix and prepare rheological agent according to the mass ratio of polyvinyl butyral and hydroxypropyl methylcellulose at a ratio of 1:1.

[0058] According to mass percentage, 20% of nano-alumina sol with a solid content of 25%, 1.5% of rheological agent, and the rest are ceramic powder for batching. First, add the light-burned magnesia powder into the ball mill tank according to the proportion, mix the nano-alumina sol, nano-titanium dioxide, alumina short fiber, rheological agent and an appropriate amount of absolute ethanol and ultrasonically treat it for 60 minutes to make the...

Embodiment 3

[0062] According to the ratio that nano-titanium oxide accounts for 1.5% of the ceramic powder mass, and alumina short fibers account for 2% of the ceramic powder mass, the nano-titanium oxide with a particle size of 50nm, commercial alumina short fibers and a particle size of 325 mesh (middle diameter d 50 Prepare ceramic powder for lightly burned magnesia powder (45 μm); mix and prepare rheological agent according to the mass ratio of polyvinyl butyral and hydroxyethyl cellulose at a ratio of 1:1.

[0063] According to mass percentage, 25% of nano-alumina sol with a solid content of 22%, 1.0% of rheological agent, and the rest are ceramic powder for batching. First, add the light-burned magnesia powder into the ball mill tank according to the proportion, mix the nano-alumina sol, nano-titanium dioxide, alumina short fiber, rheological agent and an appropriate amount of absolute ethanol and ultrasonically treat it for 45 minutes to make the alumina short-fiber powder After t...

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Abstract

The invention discloses an aluminum oxide short-fiber enhanced magnesium-oxide-based foam ceramic filter with chemical stability and excellent thermal shock resistance capable of sintering in a low temperature and a preparation method thereof. The preparation method comprises the following steps: (1) according to a mass percent, compounding by 15%-25% of nano-aluminum sol, 0.8%-1.5% of rheologicalagent, and the balance of magnesia ceramics powder containing aluminum oxide short-fiber and nano-titania, adding absolute ethyl alcohol, ball-milling, and uniformly mixing to prepare ceramic slurryof which the solid content is 60%-70%; (2) immerging a polyurethane foamed plastic template in the ceramic slurry, extruding the polyurethane foamed plastic template through a roller press so as to remove redundant immerging slurry, preparing a biscuit, and removing an ethyl alcohol solvent in a ventilating chamber in 40-50 DEG C, and drying the biscuit; and (3) placing the dried biscuit in a sintering furnace, warming to 1350-1550 DEG C, and sintering in a high temperature, cooling to room temperature along with the furnace, to obtain the magnesium-oxide-based foam ceramic filter.

Description

technical field [0001] The invention relates to a magnesium oxide-based foam ceramic filter and a preparation method thereof, in particular to an alumina short fiber reinforced magnesium oxide-based foam ceramic filter and a preparation method thereof, belonging to the field of metal materials and metallurgy. The filter prepared by the invention is particularly suitable for filtering and purifying magnesium and its alloy melts, and can also be used for filtering and purifying aluminum and its alloy melts. Background technique [0002] Magnesium is chemically active. During casting and processing, it is very easy to chemically react with oxygen, nitrogen and water vapor. The resulting products remain in the magnesium, affecting the internal quality of the product and deteriorating the performance of the product. According to the types and properties of inclusions in magnesium alloys, inclusions are generally divided into two categories: metal inclusions and non-metal inclusio...

Claims

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Application Information

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IPC IPC(8): C04B35/66C04B35/80C04B35/04C04B38/06
CPCC04B35/803C04B35/04C04B35/66C04B38/067C04B2235/3232C04B2235/5224C04B2235/5436C04B2235/5454C04B2235/602C04B2235/606C04B2235/656C04B2235/6562C04B2235/6567C04B2235/94C04B2235/96C04B38/0615C04B35/053C04B35/6261C04B35/6342C04B35/6365C04B35/80C04B2111/00793C04B2235/3218C04B2235/526C04B2235/5264C04B2235/6028C04B2235/616C04B2235/77
Inventor 刘子利刘思雨刘希琴李健
Owner JIANGSU FAVOUR AUTOMOTIVE NEW STUFF SCI TECH
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