A method for improving wet formability and sinterability of ceramic nanopowder

Abstract

The invention provides a method for improving wet process formability and sinterability of ceramic nano-powder and belongs to the field of ceramic preparation. According to the invention, ceramic nano-powder is treated by the combination of pelleting and calcining, on the one hand, the nanoscale and high activity (high crystal boundary area has high sintering promoting power) of the ceramic nano-powder are kept, on the other hand, multiple primary particles are controllably calcined together to form second particles (polycrystals or single grain crystals), and therefore, the particles (grain crystals) of the ceramic nano-powder are enlarged, and forming becomes easy. Meanwhile, the crystalline degree of the particles of the ceramic nano-powder is increased by calcining, defects on the surfaces of the particles are reduced, original microcrystals with multiple surface defects (uneven surface) are transformed into microcrystals with relatively smooth surfaces, the specific surface area is reduced, a sizing agent reaches a relatively high solid content in wet process forming, the density of a formed green body is greatly improved, and further a dense sintering body is obtained at relatively low temperature, and the bottleneck problem of difficulty in forming and sintering of the ceramic nano-powder can be effectively solved.

Description

technical field

[0001] The invention belongs to the technical field of ceramic preparation, in particular to a method for improving the wet formability and sinterability of ceramic nano powder. Background technique

[0002] The definition of ceramic nanopowder is that the diameter is less than 100nm. On the one hand, due to its high specific surface area and high activity, it can significantly reduce the sintering temperature. The sintering temperature of ceramic materials is generally relatively high. If the sintering temperature can be effectively reduced, it is of great practical value; Small (less than 100nm), the size of the ceramic grains after sintering is also very small, because the size of the ceramic grains depends largely on the size of the raw ceramic powder. Smaller (submicron) ceramic grains can significantly reduce the size of microscopic defects (such as pores), and can also significantly improve the mechanical strength and toughness of ceramic materials an...

Examples

Embodiment 1

[0057] The specific surface area is 75m 2 / g Nano-GDC (Gd 0.1 Ce 0.9 o 1.95 ) powder 100g was added to 200g absolute ethanol, 1g acetylacetone was added, ball milled at 400 rpm for 60min, then ball milled at 200 rpm for 5h, after adding 3gPVB, ball milled at 200rpm for 12h (zirconia balls with a diameter of 0.3 mm). After the ball-milled slurry is dried at 80°C, it is granulated in a mortar (the pressure used during granulation is 30 MPa), and the particle size is 75-250 μm (60-200 mesh screen). The granulated powder was calcined at 900°C for 4h. Then, the calcined powder is ball milled by a general ball milling process to eliminate the aggregates that may be generated during calcination, and the modified nanometer GDC powder is obtained. According to the XRD data and the Scherrer formula, the GDC grains before and after calcination at 900°C were 11nm and 30nm, respectively. It can be seen from TEM that the GDC powder is composed of agglomerated polycrystalline particles...

Embodiment 2

[0062] Set the specific surface area to 25m 2 100 g of nano-NiO powder per gram is added in 120 g of absolute ethanol, 1 g of acetylacetone is added, ball milled at 200 rpm for 5 hours after ball milling at 400 rpm for 20 minutes, and ball milled at 200 rpm for 5 hours after adding 2 g of PVB (zirconia mill ball, 0.8 mm in diameter). The ball-milled slurry is dried at 80° C. and then granulated in a mortar, with a particle size of 41-94 μm (160-325 mesh screen). The granulated powder was calcined at 800°C for 4h. Then, the calcined powder is ball milled by a general ball milling process to eliminate the aggregates that may be generated during calcination, and the modified NiO powder is obtained. According to the XRD data and the Scherrer formula, the NiO grains before and after calcination are 18nm and 530nm, respectively. Calcined NiO and 5YSZ powders and pore-forming agents (PMMA, polymethyl methacrylate) are mixed in a certain proportion by tape casting, and the percenta...

technical field

[0001] The invention belongs to the technical field of ceramic preparation, in particular to a method for improving the wet formability and sinterability of ceramic nano powder. Background technique

[0002] The definition of ceramic nanopowder is that the diameter is less than 100nm. On the one hand, due to its high specific surface area and high activity, it can significantly reduce the sintering temperature. The sintering temperature of ceramic materials is generally relatively high. If the sintering temperature can be effectively reduced, it is of great practical value; Small (less than 100nm), the size of the ceramic grains after sintering is also very small, because the size of the ceramic grains depends largely on the size of the raw ceramic powder. Smaller (submicron) ceramic grains can significantly reduce the size of microscopic defects (such as pores), and can also significantly improve the mechanical strength and toughness of ceramic materials an...

Examples

Embodiment 1

[0057] The specific surface area is 75m 2 / g Nano-GDC (Gd 0.1 Ce 0.9 o 1.95 ) powder 100g was added to 200g absolute ethanol, 1g acetylacetone was added, ball milled at 400 rpm for 60min, then ball milled at 200 rpm for 5h, after adding 3gPVB, ball milled at 200rpm for 12h (zirconia balls with a diameter of 0.3 mm). After the ball-milled slurry is dried at 80°C, it is granulated in a mortar (the pressure used during granulation is 30 MPa), and the particle size is 75-250 μm (60-200 mesh screen). The granulated powder was calcined at 900°C for 4h. Then, the calcined powder is ball milled by a general ball milling process to eliminate the aggregates that may be generated during calcination, and the modified nanometer GDC powder is obtained. According to the XRD data and the Scherrer formula, the GDC grains before and after calcination at 900°C were 11nm and 30nm, respectively. It can be seen from TEM that the GDC powder is composed of agglomerated polycrystalline particles...

Embodiment 2

[0062] Set the specific surface area to 25m 2 100 g of nano-NiO powder per gram is added in 120 g of absolute ethanol, 1 g of acetylacetone is added, ball milled at 200 rpm for 5 hours after ball milling at 400 rpm for 20 minutes, and ball milled at 200 rpm for 5 hours after adding 2 g of PVB (zirconia mill ball, 0.8 mm in diameter). The ball-milled slurry is dried at 80° C. and then granulated in a mortar, with a particle size of 41-94 μm (160-325 mesh screen). The granulated powder was calcined at 800°C for 4h. Then, the calcined powder is ball milled by a general ball milling process to eliminate the aggregates that may be generated during calcination, and the modified NiO powder is obtained. According to the XRD data and the Scherrer formula, the NiO grains before and after calcination are 18nm and 530nm, respectively. Calcined NiO and 5YSZ powders and pore-forming agents (PMMA, polymethyl methacrylate) are mixed in a certain proportion by tape casting, and the percenta...

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