Black alumina ceramic and preparation method and application thereof

Abstract

The present disclosure relates to a black alumina ceramic containing alumina and an amorphous phase, the weight ratio of SiO2, CaCO3, MgO, Co3O4, Mn3O4 and Fe2O3 in the amorphous phase being 1:(0.8-1.0):(0.4-0.6):(1.5-2.3):(2.5-3.0):(2.5-3.0). The black alumina ceramic of the present disclosure does not contain toxic elements, has high black chroma, large strength and drop height, and very low sintering temperature.

Description

Technical Field

[0001] This disclosure relates to the field of materials preparation, specifically to a black alumina ceramic, its preparation method, and its application. Background Technology

[0002] With the booming development of the semiconductor industry, alumina ceramics, as packaging shells for semiconductor integrated circuits, are finding broader applications. However, because semiconductor integrated circuits are highly photosensitive, the alumina ceramics used as packaging shells must have light-shielding properties, i.e., a dark color, preferably black. Currently, considerable research has been conducted both domestically and internationally. For example, patent CN110790577A introduces transition elements for coloring, but only mentions color and thermal shock resistance, without clearly describing mechanical properties such as strength. Furthermore, this patent uses calcined alumina powder, which theoretically requires a sintering temperature above 1550℃, resulting in high energy consumption. Patent CN114262212B mentions using a combination of transition elements for coloring, but the colorant contains toxic chromium, which could pollute the environment.

[0003] Therefore, developing alumina ceramics that can be sintered at low temperatures (below 1500℃) and have high strength and pure blackness will significantly promote the development of the industry. Summary of the Invention

[0004] The purpose of this disclosure is to provide a black alumina ceramic, its preparation method, and its application. The black alumina ceramic of this disclosure has a high black color intensity, as well as high strength and a large drop height. The method of this disclosure can prepare black alumina ceramic with high black color intensity, as well as high strength and a large drop height at a low sintering temperature.

[0005] To achieve the above objectives, the first aspect of this disclosure provides a black alumina ceramic containing alumina and an amorphous phase, wherein the weight ratio of SiO2, CaCO3, MgO, Co3O4, Mn3O4 and Fe2O3 in the amorphous phase is 1:(0.8-1.0):(0.4-0.6):(1.5-2.3):(2.5-3.0):(2.5-3.0).

[0006] Optionally, the weight ratio of SiO2, CaCO3, MgO, Co3O4, Mn3O4 and Fe2O3 in the amorphous phase is 1:(0.88-0.92):(0.49-0.51):(1.95-2.05):(2.7-2.8):(2.7-2.8).

[0007] Optionally, the black alumina ceramic contains, by elemental composition, 39.7-49.1% Al, 0.46-1.55% Si, 0.35-1.19% Ca, 0.3-0.99% Mg, 1.46-4.89% Co, 1.98-6.59% Mn and 1.92-6.41% Fe.

[0008] Optionally, the black alumina ceramic contains, by elemental composition, 42.3-46.7 wt% Al, 0.74-1.23 wt% Si, 0.56-0.93 wt% Ca, 0.48-0.8 wt% Mg, 2.34-3.89 wt% Co, 3.2-5.28 wt% Mn and 3.07-5.12 wt% Fe.

[0009] Optionally, the black alumina ceramic contains 75-92.5% by weight of alumina and the balance being an amorphous phase;

[0010] Preferably, the black alumina ceramic contains 80-88% by weight of alumina and the balance being an amorphous phase.

[0011] A second aspect of this disclosure provides a method for preparing black alumina ceramics, the method comprising:

[0012] S1. The dyeing calcination aid composition is calcined to obtain a flux; wherein the weight ratio of SiO2, CaCO3, MgO, Co3O4, Mn3O4 and Fe2O3 in the dyeing calcination aid composition is 1:(0.8-1.0):(0.4-0.6):(1.5-2.3):(2.5-3.0):(2.5-3.0);

[0013] S2. The flux, alumina, solvent, dispersant and binder are mixed, and the resulting mixture is subjected to molding and pressureless sintering.

[0014] Optionally, in step S1, the weight ratio of SiO2, CaCO3, MgO, Co3O4, Mn3O4 and Fe2O3 in the dyeing aid composition is 1:(0.88-0.92):(0.49-0.51):(1.95-2.05):(2.7-2.8):(2.7-2.8).

[0015] Optionally, the median particle size of the SiO2 particles in the dyeing and sintering aid composition is 0.5-1 μm, the median particle size of the CaCO3 particles is 1-1.5 μm, the median particle size of the MgO particles is 0.5-1 μm, the median particle size of the Co3O4 particles is 0.5-1 μm, the median particle size of the Mn3O4 particles is 0.5-1 μm, and the median particle size of the Fe2O3 particles is 0.5-1 μm.

[0016] Optionally, in step S1, the average particle size of the flux is 0.3-0.6 μm, preferably 0.4-0.5 μm.

[0017] Optionally, the method includes: mixing SiO2, CaCO3, MgO, Co3O4, Mn3O4 and Fe2O3 to obtain a dyeing calcination aid composition, and then performing a first grinding, calcination and a second grinding;

[0018] The first grinding process uses balls with a particle size of 5-10 mm and a grinding time of 2-6 hours; the second grinding process uses balls with a particle size of 0.2-0.4 mm and a grinding time of 2-6 hours; the calcination conditions include a temperature of 1400-1500℃ and a holding time of 1-3 hours.

[0019] Optionally, the molding process includes sequential spray drying and dry pressing; the spray drying conditions include: inlet air temperature of 200-240℃, outlet air temperature of 100-120℃, and centrifugal speed of 6000-8000 rpm; the dry pressing conditions include: hydraulic pressure of 50-100 MPa.

[0020] The pressureless sintering includes a first sintering, a second sintering, a third sintering, and a fourth sintering performed sequentially in a vacuum and / or an inert atmosphere;

[0021] The conditions for the first sintering include: a first starting temperature of 15-25℃, a first ending temperature of 500-600℃, a first heating rate of 1.0-2.0℃ / min, and a first holding time of 1-3h.

[0022] The second sintering conditions include: a second starting temperature of 500-600℃, a second ending temperature of 1000-1300℃, a second heating rate of 2-3℃ / min, and a second holding time of 1-3h.

[0023] The conditions for the third sintering include: a third starting temperature of 1000-1300℃, a third ending temperature of 1400-1500℃, a third heating rate of 2-3℃ / min, and a third holding time of 1-3h.

[0024] The conditions for the fourth sintering include: a fourth starting temperature of 1400-1500℃ and a fourth ending temperature of 15-25℃.

[0025] The third aspect of this disclosure provides an application of the black alumina ceramic provided in the first aspect of this disclosure and / or the black alumina ceramic prepared by the method provided in the second aspect of this disclosure in semiconductor devices.

[0026] The technical solution disclosed herein has the following advantages:

[0027] (1) The black alumina ceramic disclosed herein does not contain toxic elements and has a high black color, while also having high strength and a large drop height.

[0028] (2) The method disclosed herein can prepare black alumina ceramics with high black color, high strength and large drop height at low calcination temperature.

[0029] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Detailed Implementation

[0030] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0031] The first aspect of this disclosure provides a black alumina ceramic, which contains alumina and an amorphous phase, wherein the weight ratio of SiO2, CaCO3, MgO, Co3O4, Mn3O4 and Fe2O3 in the amorphous phase is 1:(0.8-1.0):(0.4-0.6):(1.5-2.3):(2.5-3.0):(2.5-3.0).

[0032] The black alumina ceramic disclosed herein contains alumina and an amorphous phase, wherein the amorphous phase has a specific composition ratio. The black alumina ceramic disclosed herein has a high black color intensity, and a large strength and drop hammer height.

[0033] In a preferred embodiment of this disclosure, the weight ratio of SiO2, CaCO3, MgO, Co3O4, Mn3O4, and Fe2O3 in the amorphous phase is 1:(0.88-0.92):(0.49-0.51):(1.95-2.05):(2.7-2.8):(2.7-2.8). When the composition of the amorphous phase in the black alumina ceramic is within the above-mentioned ratio range, the black alumina ceramic with the above composition has a higher black hue, as well as higher strength and drop weight height.

[0034] In one specific embodiment of this disclosure, the black alumina ceramic contains, by elemental composition, 39.7-49.1 wt% Al, 0.46-1.55 wt% Si, 0.35-1.19 wt% Ca, 0.3-0.99 wt% Mg, 1.46-4.89 wt% Co, 1.98-6.59 wt% Mn, and 1.92-6.41 wt% Fe. The black alumina ceramic having the above composition exhibits high black hue, as well as high strength and a large drop weight height.

[0035] In a preferred embodiment of this disclosure, the black alumina ceramic contains, by elemental composition, 42.3-46.7 wt% Al, 0.74-1.23 wt% Si, 0.56-0.93 wt% Ca, 0.48-0.8 wt% Mg, 2.34-3.89 wt% Co, 3.2-5.28 wt% Mn, and 3.07-5.12 wt% Fe. In the above preferred embodiment, the black alumina ceramic exhibits higher black hue and greater strength and drop weight height.

[0036] In one specific embodiment of this disclosure, the black alumina ceramic contains 75-92.5% by weight of alumina and the balance being an amorphous phase; preferably, the black alumina ceramic contains 80-88% by weight of alumina and the balance being an amorphous phase. In the above embodiment, the ratio of alumina to amorphous phase is appropriate, and the black alumina ceramic with the above-mentioned composition has a high black hue and greater strength and drop weight height.

[0037] The second aspect of this disclosure provides a method for preparing black alumina ceramics, the method comprising: S1, calcining a coloring sintering aid composition to obtain a flux; wherein the weight ratio of SiO2, CaCO3, MgO, Co3O4, Mn3O4 and Fe2O3 in the coloring sintering aid composition is 1:(0.8-1.0):(0.4-0.6):(1.5-2.3):(2.5-3.0):(2.5-3.0); S2, mixing the flux, alumina, solvent, dispersant and binder, and subjecting the resulting mixture to molding treatment and pressureless sintering.

[0038] In the method disclosed herein, a flux is first prepared by calcination, and then mixed with alumina and other materials for sintering. The flux helps to lower the sintering temperature, enabling the method to prepare black alumina ceramics at a lower sintering temperature. The prepared black alumina ceramics have high black color intensity, as well as high strength and large drop hammer height.

[0039] In one specific embodiment of this disclosure, in step S1, the weight ratio of SiO2, CaCO3, MgO, Co3O4, Mn3O4 and Fe2O3 in the dyeing aid composition is 1:(0.88-0.92):(0.49-0.51):(1.95-2.05):(2.7-2.8):(2.7-2.8).

[0040] In a preferred embodiment of this disclosure, the median particle size of the SiO2 particles in the dyeing and sintering aid composition is 0.5-1 μm, the median particle size of the CaCO3 particles is 1-1.5 μm, the median particle size of the MgO particles is 0.5-1 μm, the median particle size of the Co3O4 particles is 0.5-1 μm, the median particle size of the Mn3O4 particles is 0.5-1 μm, and the median particle size of the Fe2O3 particles is 0.5-1 μm. In this disclosure, the median particle size of each raw material in the dyeing and sintering aid composition is detected and calculated using a laser particle size analyzer. The flux prepared using raw materials with the above-mentioned particle sizes has a better fluxing effect.

[0041] In one specific embodiment of this disclosure, in step S1, the flux is an amorphous phase, and the average particle size of the flux is 0.3-0.6 μm, preferably 0.4-0.5 μm. The flux of this disclosure exhibits superior fluxing effect when the average particle size is within the above range. In this disclosure, the average particle size of the flux is detected by the following method: the flux is analyzed by transmission electron microscopy, 50 random flux particles within the field of view are selected, and the particle size of each flux particle is statistically analyzed, and the average particle size of the 50 flux particles is calculated.

[0042] According to this disclosure, the specific forms of the first and second grinding processes are not limited, and can be selected according to actual needs, such as ball milling and / or sand milling. In a preferred embodiment, the first grinding is ball milling, the second grinding is sand milling, and the flux is powder. In a specific embodiment of this disclosure, the method includes: mixing SiO2, CaCO3, MgO, Co3O4, Mn3O4, and Fe2O3 to obtain a dyeing calcination aid composition, followed by first grinding, calcination, and second grinding; the ball particle size used in the first grinding is 5-10 mm, and the time is 2-6 hours; the ball particle size used in the second grinding is 0.2-0.4 mm, and the time is 2-6 hours; the calcination conditions include: a temperature of 1400-1500℃ and a holding time of 1-3 hours. Preferably, SiO2, CaCO3, MgO, Co3O4, Mn3O4 and Fe2O3 are mixed and subjected to a first grinding, drying, calcination and a second grinding. This disclosure does not impose specific restrictions on the drying conditions, which can be selected according to actual needs. The drying can be carried out in a vacuum drying oven or a tube furnace.

[0043] In one specific embodiment of this disclosure, in step S2, based on the total weight of the flux and alumina, the amount of dispersant is 0.01-0.3% by weight, and the amount of binder is 1-4% by weight. This disclosure does not impose specific limitations on the amount of solvent used; it can be selected according to actual needs, as long as it can fully mix and disperse the flux, alumina, dispersant, and binder. For example, the solid content of the mixture can be 35-45% by weight. Within the above-mentioned dosage ratio range, black alumina ceramics with higher black color intensity and greater strength and drop weight height can be prepared.

[0044] According to this disclosure, the solvent, binder, and dispersant are well known to those skilled in the art. In one specific embodiment of this disclosure, the solvent is selected from one or more of water, alcohol, and esters. The esters are well known to those skilled in the art, such as ethyl acetate, methyl formate, ethyl formate, etc. The binder is selected from one or more of polyethylene glycol 4000, polyvinyl alcohol, and acrylic resin, preferably polyethylene glycol 4000 and PVA in a molar ratio of 1:1. The dispersant is selected from one or more of hydroxypropyl methylcellulose, ammonium polyacrylate, and polyacrylamide.

[0045] According to this disclosure, the mixing method in step S2 is not specifically limited, and methods well known to those skilled in the art can be used, such as ball milling, sand milling, stirring, etc. In a preferred embodiment, mixing the flux, alumina, solvent, dispersant, and binder includes: ball milling the flux, alumina, and a first solvent; sand milling the mixture obtained from ball milling, a second solvent, and a dispersant; and stirring the mixture obtained from sand milling with the binder. The black alumina ceramic prepared in this embodiment has a higher black color intensity and greater strength and drop weight height.

[0046] In one specific embodiment of this disclosure, the molding process includes sequential spray drying and dry pressing. The spray drying conditions include: an inlet air temperature of 200-240°C, an outlet air temperature of 100-120°C, and a centrifugal speed of 6000-8000 rpm; preferably, the inlet air temperature is 210-240°C, the outlet air temperature is 110-120°C, and the centrifugal speed is 6500-7500 rpm. The dry pressing conditions include: an oil pressure of 50-100 MPa, preferably 60-8 MPa. Dry pressing can be performed using equipment well known to those skilled in the art, such as a press.

[0047] According to this disclosure, the pressureless sintering includes a first sintering, a second sintering, a third sintering, and a fourth sintering performed sequentially in a vacuum and / or an inert atmosphere; the conditions for the first sintering include: a first starting temperature of 15-25℃, a first ending temperature of 500-600℃, a first heating rate of 1.0-2.0℃ / min, and a first holding time of 1-3h; the conditions for the second sintering include: a second starting temperature of 500-600℃, a second ending temperature of 1000-1300℃, a second heating rate of 2-3℃ / min, and a second holding time of 1-3h; the conditions for the third sintering include: a third starting temperature of 1000-1300℃, a third ending temperature of 1400-1500℃, a third heating rate of 2-3℃ / min, and a third holding time of 1-3h; the conditions for the fourth sintering include: a fourth starting temperature of 1400-1500℃ and a fourth ending temperature of 15-25℃. In one specific embodiment, the pressureless sintering is completed and the mixture is naturally cooled to room temperature. The inert atmosphere contains inert gases such as nitrogen, helium, and argon.

[0048] The third aspect of this disclosure provides an application of the black alumina ceramic provided in the first aspect of this disclosure and / or the black alumina ceramic prepared by the method provided in the second aspect of this disclosure in semiconductor devices.

[0049] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto.

[0050] Unless otherwise specified, all reagents used in the following examples and comparative examples were commercially available.

[0051] In Examples 1-5, the median particle size of the SiO2 particles in the dyeing aid compositions was 0.5 μm, the median particle size of the CaCO3 particles was 1 μm, the median particle size of the MgO particles was 0.7 μm, the median particle size of the Co3O4 particles was 0.7 μm, the median particle size of the Mn3O4 particles was 0.7 μm, and the median particle size of the Fe2O3 particles was 0.6 μm. The median particle size of the particles in the dyeing aid compositions was determined using laser particle size analysis.

[0052] The average particle size of the flux was analyzed by transmission electron microscopy. Fifty flux particles were randomly selected from the field of view, and their particle sizes were counted. The average particle size of the 50 flux particles was then calculated.

[0053] Example 1

[0054] S1. Silica (SiO2), calcium carbonate (CaCO3), magnesium oxide (MgO), cobalt tetroxide (Co3O4), manganese tetroxide (Mn3O4), and iron oxide (Fe2O3) were ball-milled and mixed in a mass ratio of 2:1.8:1:4:5.5:5.5. After drying, the mixture was calcined at 1470℃ for 2 hours, and then crushed and sand-milled to obtain a flux. The average particle size of the flux was 0.5 μm.

[0055] S2. Weigh 200g of powder, which contains 85% by weight of alumina powder and 15% by weight of the flux prepared in step S1. Based on the weight of the powder, mix the powder with water to form a slurry with a solid content of 40% by weight and ball mill it in a ball mill jar for 8 hours. Then, add 0.02% by weight of hydroxypropyl methylcellulose in a sand mill and sand mill it for 10 hours. Finally, add 4% by weight of the binder (PEG4000 and PVA in a molar ratio of 1:1) and stir for 0.5 hours to form a spray slurry with a solid content of 25% by weight.

[0056] The slurry is fed into a spray tower for spray drying (inlet air temperature 260℃, outlet air temperature 110℃, centrifugal speed 15 rpm) to form a spherical powder with strong flowability for dry pressing. Then it is dry pressed (a 200-ton press uses 8MPa hydraulic pressure) to obtain the shaped powder.

[0057] The shaped powder was sintered in a vacuum in the following manner: heating from room temperature (about 23°C) to 600°C for 400 minutes and holding for 2 hours; heating from 600°C to 1150°C for 270 minutes and holding for 2 hours; heating from 1150°C to 1400°C for 120 minutes and holding for 2 hours; cooling down to 900°C for 150 minutes; and finally naturally cooling to room temperature.

[0058] The prepared sample was subjected to high-energy XRF analysis, and its elemental composition was found to be: Al 45.1 wt%, Si 0.9 wt%, Ca 0.6 wt%, Mg 0.6 wt%, Co 2.4 wt%, Mn 3.2 wt%, and Fe 3.1 wt%. XRD analysis revealed the following phases: alumina 85.2 wt% and amorphous phase 14.8 wt%.

[0059] Example 2

[0060] Black alumina ceramics were prepared using the same method as in Example 1, except that in step S2, 200g of powder was weighed, which contained 80% by weight of alumina powder and 20% by weight of the flux prepared in step S1.

[0061] The prepared sample was subjected to high-energy XRF analysis, and its elemental composition was found to be: Al 42.4 wt%, Si 1.1 wt%, Ca 0.9 wt%, Mg 0.8 wt%, Co 2.7 wt%, Mn 4.2 wt%, and Fe 4.0 wt%. The XRD-detected phases included: alumina 80.1 wt% and amorphous phase 19.9 wt%.

[0062] Example 3

[0063] Black alumina ceramics were prepared using the same method as in Example 1, except that in step S2, 200g of powder was weighed, which contained 90% by weight of alumina powder and 10% by weight of the flux prepared in step S1.

[0064] The prepared sample was subjected to high-energy XRF analysis, and its elemental composition was found to be: Al 47.7 wt%, Si 0.46 wt%, Ca 0.4 wt%, Mg 0.32 wt%, Co 1.5 wt%, Mn 2.2 wt%, and Fe 2.0 wt%. XRD analysis revealed the following phases: alumina 80.1 wt% and amorphous phase 19.9 wt%.

[0065] Example 4

[0066] Black alumina ceramics were prepared using the same method as in Example 1, except that in step S1, the mass ratio of silicon dioxide (SiO2), calcium carbonate (CaCO3), magnesium oxide (MgO), cobalt tetroxide (Co3O4), manganese tetroxide (Mn3O4), and iron oxide (Fe2O3) was 1:0.8:0.45:2.2:2.75:2.75. The average particle size of the flux was 0.3 μm.

[0067] The prepared sample was subjected to high-energy XRF analysis, and its elemental composition was found to be: Al 45.1 wt%, Si 0.7 wt%, Ca 0.46 wt%, Mg 0.41 wt%, Co 2.36 wt%, Mn 3.0 wt%, and Fe 2.9 wt%. XRD analysis revealed the following phases: alumina 84.8 wt% and amorphous phase 15.2 wt%.

[0068] Example 5

[0069] Black alumina ceramics were prepared using the same method as in Example 1, except that in step S1, the mass ratio of silicon dioxide (SiO2), calcium carbonate (CaCO3), magnesium oxide (MgO), cobalt tetroxide (Co3O4), manganese tetroxide (Mn3O4), and iron oxide (Fe2O3) was 1:1:0.6:1.8:2.7:2.8; and the average particle size of the flux was 0.4 μm.

[0070] In step S2, 200g of powder is weighed, which contains 76% by weight of alumina powder and 24% by weight of the flux prepared in step S1.

[0071] The prepared sample was subjected to high-energy XRF analysis, and its elemental composition was found to be: Al 40.0 wt%, Si 1.13 wt%, Ca 0.96 wt%, Mg 0.87 wt%, Co 3.0 wt%, Mn 4.7 wt%, and Fe 4.8 wt%. The XRD-detected phases included: alumina 75.7 wt% and amorphous phase 24.3 wt%.

[0072] Example 6

[0073] Black alumina ceramics were prepared using the same method as in Example 1, except that the median particle size of SiO2 particles in the dyeing and sintering aid composition was 1.2 μm, the median particle size of CaCO3 particles was 1 μm, the median particle size of MgO particles was 0.4 μm, the median particle size of Co3O4 particles was 0.5 μm, the median particle size of Mn3O4 particles was 1.1 μm, and the median particle size of Fe2O3 particles was 0.4 μm.

[0074] In step S1, the dyeing calcination aid composition is calcined at 1600℃ for 5 hours, and then crushed and milled to obtain a flux. The average particle size of the flux is 0.8 μm.

[0075] Comparative Example 1

[0076] Black alumina ceramics were prepared using the same method as in Example 1, except that step S1 was omitted and the powder in step S2 was 100% by weight alumina powder.

[0077] The prepared sample was subjected to high-energy XRF analysis, and the elemental composition contained: Al 100% by weight. The phases detected by XRD included: aluminum oxide 100% by weight.

[0078] Comparative Example 2

[0079] Black alumina ceramics were prepared using the same method as in Example 1, except that step S1 was omitted, and the powder in step S2 was 100% by weight alumina powder. The powder was sintered in a vacuum without pressure by heating it from room temperature to 600°C for 400 min and holding it for 2 h, heating it from 600°C to 1150°C for 270 min and holding it for 2 h, heating it from 1150°C to 1600°C for 150 min and holding it for 2 h, then cooling it to 900°C for 150 min, and finally letting it cool naturally to room temperature.

[0080] The prepared sample was subjected to high-energy XRF analysis, and the elemental composition contained: Al 100% by weight. The phases detected by XRD included: aluminum oxide 100% by weight.

[0081] Comparative Example 3

[0082] (1) Silicon dioxide (SiO2), calcium carbonate (CaCO3), magnesium oxide (MgO), cobalt tetroxide (Co3O4), manganese tetroxide (Mn3O4), and iron oxide (Fe2O3) were mixed in a mass ratio of 1:0.9:0.5:2:2.75:2.75. The resulting mixture was then mixed with alumina powder in a mass ratio of 84.3:15.7 and ball-milled to obtain the powder.

[0083] (2) Based on the weight of the powder, the powder and water are used to prepare a slurry with a solid content of 40% by weight. The slurry is then ball-milled in a ball mill for 8 hours. Then, 0.02% by weight of hydroxypropyl methylcellulose is added to a sand mill and the slurry is sand-milled for 10 hours. Finally, 4% by weight of the binder (PEG4000 and PVA with a molar ratio of 1:1) is added to the powder and stirred for 0.5 hours to form a spray slurry with a solid content of 25% by weight.

[0084] The slurry is fed into a spray tower for spray drying (inlet air temperature 260℃, outlet air temperature 110℃, centrifugal speed 15 rpm) to form a spherical powder with strong flowability for dry pressing. Then it is dry pressed (a 200-ton press uses 8MPa hydraulic pressure) to obtain the shaped powder.

[0085] The shaped powder was sintered in a vacuum in the following steps: heating from room temperature to 600℃ for 400 min and holding for 2 h; heating from 600℃ to 1150℃ for 270 min and holding for 2 h; heating from 1150℃ to 1400℃ for 120 min and holding for 2 h; then cooling to 900℃ for 150 min; and finally naturally cooling to room temperature.

[0086] The prepared sample was subjected to high-energy XRF analysis, and its elemental composition was found to be: Al 45.2 wt%, Si 0.9 wt%, Ca 0.8 wt%, Mg 0.5 wt%, Co 2.7 wt%, Mn 3.8 wt%, and Fe 3.9 wt%. The XRD-detected phases included: alumina 78.5 wt%, mullite 5.2 wt%, and spinel 16.3 wt%.

[0087] Test case

[0088] The samples prepared in the examples and comparative examples were polished and laser-cut to produce the final samples.

[0089] (1) Average drop height: Using a drop hammer impact tester, place the final sample to be tested on the platform and drop it with a 60g hammer, starting from a height of 5cm. If no crack appears, increase the height by 5cm each time until a visible crack appears on the sample. Record the height value. Repeat this test process for 10 samples with dimensions of 50×50×1.5mm, record the height values, and calculate the average drop height.

[0090] (2) Average bending strength: Using a universal testing machine, the final sample to be tested was placed on a three-point bending clamp with a width of 32 mm and a pressing speed of 2 mm / min. The test process was repeated to test 10 samples with a size of 50×12.7×1.5 mm, and the bending strength was recorded and the average value was calculated to obtain the average bending strength.

[0091] (3) Density: The density was measured by the water displacement method.

[0092] (4) LAB value: The LAB value of the sample is detected by a spectrophotometer, where L is the brightness, L0 represents black and L100 represents white; A is the red-green color, which represents the color bias of the object between red and green, with positive values ​​representing red and negative values ​​representing green; B is the yellow-blue color, which represents the color bias of the object between yellow and blue, with positive values ​​representing yellow and negative values ​​representing blue.

[0093] Table 1

[0094]

[0095] In Table 1, ok indicates that the sample did not crack at the current drop height but cracked at the next drop height; ng indicates that the sample cracked at the current drop height.

[0096] As can be seen from the above, the method disclosed herein can achieve ceramic sintering at low calcination temperatures, and the resulting black alumina ceramic does not contain toxic elements and has high black color, strength, and drop height.

[0097] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0098] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0099] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A black alumina ceramic, characterized in that, Based on elemental composition, the black alumina ceramic contains 39.7-49.1 wt% Al, 0.46-1.55 wt% Si, 0.35-1.19 wt% Ca, 0.3-0.99 wt% Mg, 1.46-4.89 wt% Co, 1.98-6.59 wt% Mn and 1.92-6.41 wt% Fe; The black alumina ceramic was prepared by the following method: S1. The dyeing calcination aid composition is calcined to obtain a flux; wherein the weight ratio of SiO2, CaCO3, MgO, Co3O4, Mn3O4 and Fe2O3 in the dyeing calcination aid composition is 1:(0.8-1.0):(0.4-0.6):(1.5-2.3):(2.5-3.0):(2.5-3.0); S2. The flux, alumina, solvent, dispersant and binder are mixed, and the resulting mixture is subjected to molding and pressureless sintering.

2. The black alumina ceramic according to claim 1, wherein, The black alumina ceramic contains, by element, 42.3-46.7 wt% Al, 0.74-1.23 wt% Si, 0.56-0.93 wt% Ca, 0.48-0.8 wt% Mg, 2.34-3.89 wt% Co, 3.2-5.28 wt% Mn and 3.07-5.12 wt% Fe.

3. The black alumina ceramic according to claim 1, wherein, In step S1, the weight ratio of SiO2, CaCO3, MgO, Co3O4, Mn3O4 and Fe2O3 in the dyeing and burning aid composition is 1: (0.88-0.92): (0.49-0.51): (1.95-2.05): (2.7-2.8): (2.7-2.8).

4. The black alumina ceramic according to claim 1, wherein, The median particle size of the SiO2 particles in the dyeing and sintering aid composition is 0.5-1 μm, the median particle size of the CaCO3 particles is 1-1.5 μm, the median particle size of the MgO particles is 0.5-1 μm, the median particle size of the Co3O4 particles is 0.5-1 μm, the median particle size of the Mn3O4 particles is 0.5-1 μm, and the median particle size of the Fe2O3 particles is 0.5-1 μm.

5. The black alumina ceramic according to claim 1, wherein, In step S1, the average particle size of the flux is 0.3-0.6 μm.

6. The black alumina ceramic according to claim 5, wherein, In step S1, the average particle size of the flux is 0.4-0.5 μm.

7. The black alumina ceramic according to claim 1, wherein, The method includes: mixing SiO2, CaCO3, MgO, Co3O4, Mn3O4 and Fe2O3 to obtain a dyeing calcination aid composition, and then performing a first grinding, calcination and a second grinding. The first grinding process uses balls with a particle size of 5-10 mm and a grinding time of 2-6 hours; the second grinding process uses balls with a particle size of 0.2-0.4 mm and a grinding time of 2-6 hours; the calcination conditions include a temperature of 1400-1500℃ and a holding time of 1-3 hours.

8. The black alumina ceramic according to claim 1, wherein, The molding process includes sequential spray drying and dry pressing; the spray drying conditions include: inlet air temperature of 200-240℃, outlet air temperature of 100-120℃, and centrifugal speed of 6000-8000 rpm; the dry pressing conditions include: hydraulic pressure of 50-100 MPa. The pressureless sintering includes a first sintering, a second sintering, a third sintering, and a fourth sintering performed sequentially in a vacuum and / or an inert atmosphere; The conditions for the first sintering include: a first starting temperature of 15-25℃, a first ending temperature of 500-600℃, a first heating rate of 1-2℃ / min, and a first holding time of 1-3h. The second sintering conditions include: a second starting temperature of 500-600℃, a second ending temperature of 1000-1300℃, a second heating rate of 2-3℃ / min, and a second holding time of 1-3h. The conditions for the third sintering include: a third starting temperature of 1000-1300℃, a third ending temperature of 1400-1500℃, a third heating rate of 2-3℃ / min, and a third holding time of 1-3h. The conditions for the fourth sintering include: a fourth starting temperature of 1400-1500℃ and a fourth ending temperature of 15-25℃.

9. The application of the black alumina ceramic according to any one of claims 1-8 in semiconductor devices.

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