Alpha-sialon ceramic taking manganese as stable ion and preparation method of alpha-sialon ceramic

Abstract

The invention relates to alpha sialon ceramic taking manganese as stable ions and a preparation method thereof. The alpha-SiAlON ceramic with the manganese as the stable ion is represented by a general formula Mnm / 2Si < 12-m-n > Al < m + n > OnN < 16-n >, m ranges from 1 to 3.6, and n ranges from 0 to 3. The novel alpha-SiAlON ceramic is prepared from Si3N4, AlN, MnO and other powder as raw materials through spark plasma sintering, air pressure sintering or hot pressed sintering and other methods, and the preparation method is simple and convenient. The alpha-SiAlON ceramic taking manganese as stable ions has high hardness and excellent fracture toughness, and is expected to be widely applied to various occasions with relatively high requirements on mechanical properties such as ceramic hardness and toughness.

Description

Technical Field

[0001] This invention belongs to the field of high-mechanical-performance structural ceramics, and relates to an alpha-silicon ceramic with manganese as a stable ion and its preparation method. The alpha-silicon ceramic of this invention is expected to be widely used in various applications requiring high mechanical properties such as hardness, toughness, and strength of ceramics. Background Technology

[0002] Alpha-Syreneson (α-SiAlON) is a solid solution of α-Si3N4, first reported in the 1970s. In α-Si3N4, some Si-N bonds are replaced by Al-O and Al-N bonds, while suitable metal ions M are introduced into the interstitial spaces of the crystal lattice. v+ To maintain electricity price balance, α-SiAlON is formed, with the chemical formula M. x Si 12-m-n Al m+n O n N 16-n (x=m / v), M v+ As a stable ion, α-SiAlON has been a research hotspot in the field of structural ceramics for decades, including self-toughened α-SiAlON, transparent α-SiAlON, and α-SiAlON phosphors.

[0003] Stable ion M v+ The stable ions have a significant impact on the structure and properties of α-SiAlON. In fact, each type of stable ion corresponds to a type of α-SiAlON material. The existing stable ions are usually Li, alkaline earth metals Mg and Ca, and rare earth elements Y, Nd, and Yb, etc. Most of them were discovered in the 1970s and 1980s, and there has been no substantial expansion since then.

[0004] For example, patent document CN102300955A discloses an α-type silon phosphor, which is composed of general formula (M). x (Eu y (Si, Al) 12 (O, N) 16 The specification states that M is an element selected from the group consisting of Li, Mg, Ca, Y, and lanthanides excluding La and Ce, and includes at least one of them, Ca; the oxygen content is less than 1.2% by mass; and the primary particles constituting α-type silane are columnar. This patent document obtains a phosphor with a high aspect ratio and large particle size, exhibiting excellent fluorescence properties, by controlling the amount of oxygen derived from calcium within an appropriate range.

[0005] Patent document CN120958103A discloses an α-type silane phosphor, which is composed of the general formula (Ca... x Eu y (Si) 12-(m+n Alm+n (O) n N 16-n The expression represents the α-type silon phosphor, where 0 < x < 2.0; 0 < y ≤ 0.5; 0.3 ≤ x + y ≤ 2.0; 0 < m ≤ 4.0; 0 < n ≤ 3.0. This α-type silon phosphor possesses a crystal structure that readily and efficiently emits fluorescence, thus exhibiting improved luminescence properties.

[0006] The stable ions of the α-type silon phosphor mentioned in the above literature are still alkaline earth metals and rare earth elements, and no major breakthrough has been achieved. Summary of the Invention

[0007] The problem the invention aims to solve

[0008] Given the above situation, it is necessary to expand the types of stable ions to supplement the shortcomings of the existing α-SiAlON system, thereby hoping to bring more room for functional property regulation of α-SiAlON.

[0009] Solution for solving the problem

[0010] This invention provides a novel α-SiAlON ceramic (Mn-α-SiAlON) with manganese as a stable ion, and characterization revealed that it has good hardness and toughness.

[0011] Specifically, the present invention provides an α-SiAlON ceramic with manganese as a stable ion, the chemical composition of which is represented by the following general formula:

[0012] Mn m / 2 Si 12-m-n Al m+n O n N 16-n

[0013] Where m takes values ​​from 1 to 3.6, and n takes values ​​from 0 to 3.

[0014] According to the α-SiAlON ceramics described above, m takes the value of 1.6-3 and n takes the value of 0.8-2.5.

[0015] According to the α-SiAlON ceramic described above, the value of m is 1-1.2, and the value of n is 0.5-0.6.

[0016] The present invention also provides a method for preparing the above-described α-SiAlON ceramic, which includes the following steps:

[0017] Step S1: Weigh the raw materials according to the formula, mix them, and then put them into a ball mill jar for ball milling to obtain powder raw materials;

[0018] Step S2: The powder raw material is subjected to discharge plasma sintering, gas pressure sintering or hot pressing sintering, and then cooled to obtain α-SiAlON ceramic with manganese as the stable ion.

[0019] According to the preparation method described above, in step S1, a solvent is added during grinding, and grinding is carried out with a grinding ball to powder mass ratio of 3:1 to 1:1 to obtain a slurry; the slurry is dried and then sieved to obtain a powder raw material.

[0020] The ball milling time is 0.5-12 hours.

[0021] According to the preparation method described above, in step S2, when the powder raw material is subjected to discharge plasma sintering, the sintering temperature is 1400-1900 ℃, the mechanical pressure is 30-200 MPa, and the holding time at the highest temperature is 3-30 min.

[0022] When the powder raw material is subjected to gas pressure sintering, the sintering temperature is 1800-2000 ℃, the nitrogen pressure is 0.1-10 MPa, and the holding time at the highest temperature is 0.5-6 h.

[0023] When hot-pressing and sintering powder raw materials, the sintering temperature is 1700-2000 ℃, the mechanical pressure is 0-100 MPa, and the holding time at the highest temperature is 0.5-6 h.

[0024] The effects of the invention

[0025] This invention is the first to use the transition metal element manganese as a stable ion for α-SiAlON. The introduction of 3d electrons is expected to bring more room for the regulation of the functional properties of α-SiAlON.

[0026] The novel α-SiAlON ceramic with manganese as a stable ion provided by this invention has a hardness that basically reaches the highest value of α-SiAlON ceramics and can also have excellent toughness.

[0027] The α-SiAlON ceramics of the present invention can be prepared by methods such as spark plasma sintering, gas pressure sintering or hot pressing sintering, and the preparation methods are simple. Attached Figure Description

[0028] Figure 1 The X-ray diffraction pattern of the sample obtained in Example 1 is shown.

[0029] Figure 2 The X-ray diffraction patterns of each sample obtained in Comparative Example 1 are shown. Detailed Implementation

[0030] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0031] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0032] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0033] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0034] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0035] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0036] A first aspect of the present invention provides an α-SiAlON ceramic with manganese as a stable ion, which is represented by the following general formula:

[0037] Mn m / 2 Si 12-m-n Al m+n O n N 16-n

[0038] Where m takes values ​​from 1 to 3.6, and n takes values ​​from 0 to 3.

[0039] In some preferred embodiments, m can be 1.6-3 and n can be 0.8-2.5. More specifically, m can be 1.2, 1.5, 1.8, 2.0, 2.5, 2.8, 3.0, 3.5, etc., and n can be 1.0, 1.2, 1.5, 1.8, 2.2, etc.

[0040] In some preferred embodiments, m can be 1-1.2 and n can be 0.5-0.6.

[0041] The relative density of the α-SiAlON ceramic with manganese as the stabilizing ion of the present invention can be above 98%, for example, 98.1%, 98.3%, 98.5%, 98.7%, etc.; the Vickers hardness of the α-SiAlON ceramic with manganese as the stabilizing ion of the present invention can be 19~24 GPa, for example, 20 GPa, 21 GPa, 22 GPa, 23 GPa, etc.; and the fracture toughness can be 5.5 MPa·m. 1 / 2 For example, it could be 6.0 MPa·m 1 / 2 6.5 MPa·m 1 / 2 7.0 MPa·m 1 / 2 7.5 MPa·m 1 / 2 8.0 MPa·m 1 / 2 8.5 MPa·m 1 / 2 9.0 MPa·m 1 / 2 wait.

[0042] A second aspect of the present invention provides a method for preparing α-SiAlON ceramics with manganese as a stable ion, comprising the following steps:

[0043] Step S1: Weigh the raw materials according to the formula, mix them, and then put them into a ball mill jar for ball milling to obtain powder raw materials;

[0044] Step S2: The powder raw material is subjected to discharge plasma sintering, gas pressure sintering or hot pressing sintering, and then cooled to obtain α-SiAlON ceramic with manganese as the stable ion.

[0045] In step S1, an appropriate amount of solvent, such as anhydrous ethanol, can be added during grinding. The grinding ratio of grinding balls to powder, i.e., the ball-to-powder ratio, is 3:1 to 1:1 to obtain a slurry. After drying the slurry, it is sieved to obtain the powder raw material. The ball milling time can be 0.5-12 hours.

[0046] In step S2, the sieved powder material can be loaded into an SPS (spark plasma sintering) mold, sintered under vacuum and mechanical pressure, and then cooled to obtain an α-SiAlON ceramic sample with manganese as a stable ion; or, the sieved powder material can be pre-formed using a tablet press and then cold isostatically pressed, placed in a crucible, sintered under a nitrogen atmosphere, and then cooled to obtain an α-SiAlON ceramic sample with manganese as a stable ion; or, the sieved powder material can be directly loaded into a hot press mold, pressed into tablets using a tablet press, cold isostatically pressed, loaded into a hot press mold, hot-pressed and sintered under a nitrogen atmosphere, and then cooled to obtain an α-SiAlON ceramic sample with manganese as a stable ion.

[0047] When sintering the powder raw material using discharge plasma, the sintering temperature can be 1400-1900 ℃, the mechanical pressure can be 30-200 MPa, and the holding time at the highest temperature can be 3-30 min. Preferably, the sintering temperature is above 1700 ℃, and the holding time is above 5 min, thereby obtaining single-phase AlphaSyron ceramics with manganese ions as the stable ions.

[0048] When the powder raw material is subjected to gas pressure sintering, the sintering temperature can be 1800-2000 ℃, the nitrogen pressure can be 0.1-10 MPa, and the holding time at the highest temperature can be 0.5-6 h.

[0049] When hot pressing and sintering powder raw materials, the sintering temperature can be 1700-2000 ℃, the mechanical pressure can be 0-100MPa, and the holding time at the highest temperature can be 0.5-6 h.

[0050] This invention presents a novel α-SiAlON with manganese as a stable ion, prepared for the first time by means of discharge plasma sintering, gas pressure sintering or hot pressing sintering. The obtained α-SiAlON has both high hardness and excellent fracture toughness, and is expected to be widely used in various applications where high mechanical properties of ceramics such as hardness, toughness and strength are required.

[0051] Example

[0052] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0053] Example 1

[0054] Step S1: According to the general formula: Mn m / 2 Si12-m-n Al m+n O n N 16-n The chemical composition (m=1.6, n=0.8) was selected, and silicon nitride powder, aluminum nitride powder, and manganese monoxide powder were used as raw materials, and the raw materials were weighed according to the mass ratio.

[0055] The weighed powders were placed into a ball mill jar, and an appropriate amount of anhydrous ethanol was added. The mixture was ball-milled at a ratio of 3:1 for 12 hours to obtain a powder slurry.

[0056] The powder slurry was dried in an oven at 60°C for 12 hours, and then sieved through a 60-mesh sieve to obtain the powder raw material for later use.

[0057] Step S2: Weigh an appropriate amount of the dried and sieved powder raw material and pour it into an SPS mold lined with carbon paper. Wrap the mold with insulating carbon felt and place it in the SPS furnace. Evacuate the furnace and set the initial mechanical pressure to 30 MPa. Then, raise the temperature from room temperature to 600℃ within 3 minutes, and then raise it to 1200℃ at a heating rate of 100℃ / min, while increasing the mechanical pressure from 30 MPa to 100 MPa. Maintain the mechanical pressure at 100 MPa and raise the temperature to the final temperature of 1700℃ at a heating rate of 100℃ / min. Finally, hold the temperature and pressure for 10 minutes, stop heating, and allow the sample and mold to cool naturally. After cooling to room temperature for about 1 hour, remove the mold and sample, and then remove the sample from the mold. At this point, alpha-silicon ceramic with manganese ions as the stable ion is obtained. Its X-ray diffraction pattern is shown below. Figure 1 As shown.

[0058] from Figure 1 It can be seen that the obtained alpha-silon ceramic is a single-phase α-SiAlON, containing no other crystalline phases. The obtained alpha-silon ceramic has a relative density of 99%, a Vickers hardness of 23 GPa, and a fracture toughness of 6.5 MPa·m. 1 / 2 .

[0059] Example 2

[0060] According to the general formula: Mn m / 2 Si 12-m-n Al m+n O n N 16-n Using a chemical composition of (m=1, n=0.5), except that the holding time at 1700℃ was reduced from 10 min to 5 min, an AlphaSalon ceramic with manganese ions as the stable ion was obtained through the same method as in Example 1. The ceramic exhibited a relative density of 98%, a Vickers hardness of 24 GPa, and a fracture toughness of 5.8 MPa·m. 1 / 2 .

[0061] Example 3

[0062] According to the general formula: Mn m / 2 Si 12-m-n Al m+n O n N 16-n A chemical composition of (m=2.5, n=1.5) was selected, and alpha-silicon ceramics with manganese ions as the stable ions were prepared by hot pressing sintering. The preparation process of the powder raw materials was similar to that in Example 1. The hot pressing sintering conditions were: sintering temperature of 1800℃, mechanical pressure of 30 MPa, and holding time at the highest temperature of 1 h. The obtained alpha-silicon ceramics had a relative density of 99%, a Vickers hardness of 22 GPa, and a fracture toughness of 7.5 MPa·m. 1 / 2 .

[0063] Example 4

[0064] According to the general formula: Mn m / 2 Si 12-m-n Al m+n O n N 16-n A chemical composition of (m=3, n=2.5) was selected, and alpha-silicon ceramics with manganese ions as the stable ions were prepared by gas pressure sintering. The preparation process of the powder raw materials was similar to that in Example 1. The gas pressure sintering conditions were: sintering temperature of 1900℃, nitrogen pressure of 5 MPa, and holding time at the highest temperature of 2 h. The obtained alpha-silicon ceramics had a relative density of 98%, a Vickers hardness of 20 GPa, and a fracture toughness of 8.7 MPa·m. 1 / 2 .

[0065] In the above embodiments, hardness and fracture toughness were tested using a Vickers hardness tester under a 1 kg load.

[0066] Comparative Example 1

[0067] Except for converting manganese monoxide powder into iron oxide, cobalt oxide, copper oxide, zinc oxide, zirconium oxide, molybdenum oxide, tin oxide, and hafnium oxide, the product was obtained by operating in the same manner as in Example 1.

[0068] X-ray diffraction analysis was performed on each sample of Comparative Example 1, and the results are as follows: Figure 2 As shown (the oxides used are represented by ions in the diagram). From Figure 2 As shown, no alpha-silicon was formed using iron oxide, cobalt oxide, copper oxide, zinc oxide, zirconium oxide, molybdenum oxide, tin oxide, or hafnium oxide; the measured products were mainly silicon nitride.

[0069] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto. The technical solution of the present invention, with simple modifications, can be used to prepare α-SiAlON porous ceramics and powders with manganese as a stable ion.

[0070] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. An α-SiAlON ceramic with manganese as a stable ion, characterized in that, Its chemical composition is represented by the following general formula: Mn m / 2 Yes 12-m-n To the m+n OR n N 16-n Where m takes values ​​from 1 to 3.6, and n takes values ​​from 0 to 3.

2. The α-SiAlON ceramic according to claim 1, characterized in that, m takes values ​​from 1.6 to 3, and n takes values ​​from 0.8 to 2.

5.

3. The α-SiAlON ceramic according to claim 1, characterized in that, m takes values ​​from 1 to 1.2, and n takes values ​​from 0.5 to 0.

6.

4. A method for preparing α-SiAlON ceramic according to any one of claims 1 to 3, characterized in that, It includes the following steps: Step S1: Weigh the raw materials according to the formula, mix them, and then put them into a ball mill jar for ball milling to obtain powder raw materials; Step S2: The powder raw material is subjected to discharge plasma sintering, gas pressure sintering or hot pressing sintering, and then cooled to obtain α-SiAlON ceramic with manganese as the stable ion.

5. The preparation method according to claim 4, characterized in that, In step S1, a solvent is added during grinding, and grinding is carried out at a mass ratio of grinding balls to powder, i.e., a ball-to-powder ratio of 3:1 to 1:1, to obtain a slurry; the slurry is dried and then sieved to obtain powder raw material; The ball milling time is 0.5-12 hours.

6. The preparation method according to claim 4 or 5, characterized in that, In step S2, when the powder raw material is subjected to discharge plasma sintering, the sintering temperature is 1400-1900 ℃, the mechanical pressure is 30-200 MPa, and the holding time at the highest temperature is 3-30 min. When the powder raw material is subjected to gas pressure sintering, the sintering temperature is 1800-2000 ℃, the nitrogen pressure is 0.1-10 MPa, and the holding time at the highest temperature is 0.5-6 h. When hot-pressing and sintering powder raw materials, the sintering temperature is 1700-2000 ℃, the mechanical pressure is 0-100 MPa, and the holding time at the highest temperature is 0.5-6 h.

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