High-temperature-resistant high-conductivity fused magnesia powder and preparation method thereof

Abstract

The invention discloses high-temperature-resistant and high-conductivity fused magnesium oxide powder and a preparation method thereof, and the preparation method comprises the following steps: crushing, screening and dedusting a high-temperature fused magnesium oxide block material with the temperature of 2200-2800 DEG C to prepare magnesium oxide powder; calcining the obtained magnesium oxide powder in a high-temperature furnace to prepare multivalent iron reduced mixed magnesium oxide; mixing high-temperature and high-conductivity fillers C1 and C2 according to a weight ratio of (1-4): (1-7), and then heating to obtain a high-conductivity mixed filler; mixing the obtained high-conductivity mixed filler with calcined magnesium oxide powder according to a weight ratio of 1: (0.1-30) to prepare a high-conductivity high-temperature-resistant magnesium oxide base material; the preparation method comprises the following steps: drying a high-conductivity high-temperature-resistant magnesium oxide base material, sieving to obtain high-temperature-resistant high-conductivity fused magnesium oxide powder, and mixing the obtained high-temperature-resistant high-conductivity fused magnesium oxide powder with a hydrophobic conductive medium to prepare hydrophobic high-temperature-resistant high-conductivity fused magnesium oxide powder; the prepared magnesium oxide powder is extremely low in volume resistivity, has extremely high conductivity and high-temperature resistance, can effectively reduce resistance loss, improve electrolytic efficiency and reduce industrial energy consumption cost, and is suitable for the fields of high-performance electrolytic rods and high-precision electrodes.

Description

Technical Field

[0001] The present invention relates to the technical field of magnesium oxide powder, and particularly relates to a high-temperature resistant and high-conductivity fused magnesia powder and a preparation method thereof. Background Art

[0002] Magnesium oxide powder has characteristics such as high purity, good high-temperature resistance, excellent electrical insulation, and controllable conductivity under certain conditions, and is often used in the fields of electrolytic rods and electrode technology. In a high-temperature electrolysis environment, its high purity and high-temperature resistance ensure the stable structure of the material, which is not easily decomposed or deteriorated, guaranteeing the continuous and stable progress of the electrolysis process. The good electrical insulation can effectively isolate the current around the electrode, avoid leakage, and accurately guide the current to participate in the electrolysis reaction through a specific path.

[0003] However, the room-temperature volume resistivity of existing ordinary magnesium oxide powder (MgO) is about 2.4×10 8 Ω·cm, which still cannot meet the requirements of cutting-edge technical fields with strict requirements for material conductivity, such as high-performance electrolytic rods and high-precision electrodes. In these fields, too low conductivity will lead to significant resistance losses, greatly reducing the energy utilization efficiency and unable to meet the requirements of fast and efficient current conduction. For example, in the manufacturing process of a new generation of ultra-large-scale integrated circuits, the electrode material needs to have extremely low resistance to achieve high-speed signal transmission and processing. The high resistivity of ordinary magnesium oxide powder will seriously hinder the rapid migration of electrons, resulting in signal delay and distortion, and it is difficult to adapt to such application scenarios with extremely high electrical performance requirements. Summary of the Invention

[0004] The present invention provides a high-temperature resistant and high-conductivity fused magnesia powder and a preparation method thereof to solve the above problems.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A preparation method of a high-temperature resistant and high-conductivity fused magnesia powder includes the following steps:

[0007] S1: Crushing, screening, and dust removal are performed on high-temperature fused magnesia bulk materials at a temperature of 2200-2800°C to obtain magnesium oxide powder.

[0008] S2: The magnesium oxide powder obtained in step S1 is calcined in a high-temperature furnace to obtain multivalent iron-reduced mixed magnesia, and the color of the powder changes from white to light red. The calcined magnesium oxide powder is collected.

[0009] S3: High-temperature and high-conductivity fillers C1 and C2 are taken and mixed in a weight ratio of 1-4:1-7, and then heated to 800-1300°C to obtain a high-conductivity mixed filler.

[0010] S4: Mix the calcined magnesium oxide powder obtained in S2 and the highly conductive mixed filler obtained in S3 at a weight ratio of 1:0.01 - 0.3 to produce a highly conductive and high-temperature resistant magnesium oxide base material;

[0011] S5: Place the highly conductive and high-temperature resistant magnesium oxide base material obtained in S4 in a drying oven for drying treatment and then sieve it to obtain a high-temperature resistant and highly conductive fused magnesium oxide powder;

[0012] S6: Mix the high-temperature resistant and highly conductive fused magnesium oxide powder obtained in S5 with a hydrophobic conductive medium to produce a hydrophobic, high-temperature resistant and highly conductive fused magnesium oxide powder, and the content of the hydrophobic conductive medium is 40 - 1000 ppm.

[0013] Further, the high-temperature and high-conductive filler C1 is magnesium carbide;

[0014] The high-temperature and high-conductive filler C2 is magnesium oxide containing a metal element, the proportion of the metal element is not less than 10%, and the metal element is at least one of iron, cobalt, and nickel.

[0015] Further, in S3, the high-temperature and high-conductive filler C1 and the high-temperature and high-conductive filler C2 are mixed at a weight ratio of 1:1, 3:6, or 4:7.

[0016] Further, in S2, the volume resistivity of the calcined magnesium oxide powder is less than 1×10 6 Ω·mm.

[0017] Further, the hydrophobic conductive medium is graphite paint or conductive black grease.

[0018] Further, in S2, the calcination conditions are: calcination at 1000°C for 2 - 4 hours.

[0019] Further, in S5, the drying temperature is 300 - 500°C.

[0020] Further, in S4, the mixing method is to use a high-speed mixer to mix the highly conductive mixed filler and the calcined magnesium oxide powder.

[0021] A high-temperature resistant and highly conductive fused magnesium oxide powder prepared by the preparation method of the high-temperature resistant and highly conductive fused magnesium oxide powder described above.

[0022] Further, the volume resistivity of the high-temperature resistant and highly conductive fused magnesium oxide powder is lower than 100Ω·mm.

[0023] The beneficial effects of the present invention are:

[0024] A preparation method of high-temperature resistant and highly conductive fused magnesia powder disclosed in the present invention. The prepared magnesia powder has an extremely low volume resistivity, extremely high conductivity and high-temperature resistance, can effectively reduce resistance loss, improve electrolysis efficiency, reduce industrial energy consumption cost, and is applicable to the fields of high-performance electrolysis rods and high-precision electrodes. Detailed implementation manners

[0025] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] The principle involved in the present invention is:

[0027] Utilize the high-temperature resistance of fused magnesia. By adding conductive materials, magnesia can have both high-temperature resistance and improved conductivity. In addition, by adding conductive materials in different proportions, the adjustable volume resistivity of the conductivity of magnesia can be realized, with stronger flexibility.

[0028] Embodiment 1:

[0029] S1: Use fused magnesia lumps at a high temperature of 2200 - 2800 °C to obtain magnesia powder through crushing, screening and dust removal.

[0030] S2: Calcinate 1000 g of the magnesia powder obtained in S1 in a high-temperature furnace at 1000 °C for 3 hours to obtain multi-valent iron-reduced mixed magnesia. The color of the powder changes from white to light red, and collect the magnesia powder after calcination.

[0031] S3: Heat a mixture of 200 g of high-temperature and high-conductivity additive C1 (magnesium carbide) and 200 g of C2 (magnesia containing 10% iron element) to 1000 °C to obtain a highly conductive mixed filler.

[0032] S4: Place 1000 g of the magnesia powder after calcination in S2 and 300 g of the highly conductive mixed filler obtained in step S3 in a high-speed mixer for uniform mixing to obtain a highly conductive and high-temperature resistant magnesia base material.

[0033] S5: Place the highly conductive and high-temperature resistant magnesia base material obtained in S4 in a drying oven for drying treatment at 300 - 500 °C and then sieve it to obtain high-temperature resistant and highly conductive fused magnesia powder.

[0034] S6: Mix the high-temperature resistant and highly conductive fused magnesia powder obtained in S5 with graphite paint. Add 50 ppm of graphite paint (50 g) per ton of the high-temperature resistant and highly conductive fused magnesia powder to obtain a hydrophobic high-temperature resistant and highly conductive fused magnesia powder. After measurement, the volume resistivity of the obtained magnesia powder is 21 Ω·mm.

[0035] Example 2:

[0036] The difference between this example and Example 1 is only that, in this example, in S3, C1 (magnesium carbide) and C2 (magnesia containing 10% iron element) are mixed at a weight ratio of 3:6, that is, 100 g of C1 and 300 g of C2 are taken and mixed respectively. After measurement, the volume resistivity of the obtained magnesia powder is 45 Ω·mm.

[0037] Example 3:

[0038] The difference between this example and Example 1 is only that, in this example, in S3, C1 (magnesium carbide) and C2 (magnesia containing 10% iron element) are mixed at a weight ratio of 4:7, that is, 400 g of C1 and 700 g of C2 are taken and mixed respectively. After measurement, the volume resistivity of the obtained magnesia powder is 98 Ω·mm.

[0039] Comparative Example 1:

[0040] The difference between this comparative example and Example 1 is only that, in this comparative example, the high-temperature resistant and highly conductive fillers C1 and C2 are not added. After measurement, the volume resistivity of the obtained magnesia powder is 10 5 Ω·mm.

[0041] Comparative Example 2:

[0042] The difference between this comparative example and Example 1 is only that, in this comparative example, the weight ratio of the high-temperature resistant and highly conductive fillers C1 and C2 is 1:9, that is, 100 g of C1 and 900 g of C2 are taken and mixed respectively. After measurement, the volume resistivity of the obtained fused magnesia powder is 300 Ω·mm.

[0043] Comparative Example 3:

[0044] The difference between this comparative example and Example 1 is only that, in this comparative example, only 300 g of the high-temperature resistant and highly conductive filler C1 is added. After measurement, the volume resistivity of the obtained magnesia powder is 500 Ω·mm.

[0045] Comparative Example 4:

[0046] The difference between this comparative example and Example 1 is only that in this comparative example, only the high-temperature and high-conductivity filler C2300g is added. The resistivity of the prepared magnesium oxide powder is measured to be 10 Ω·mm. When using only C2, magnesium oxide containing metal elements, that is, magnetic magnesium oxide, its cost is much higher than the resistivity of the magnesium oxide powder prepared by mixing C1 and C2 as fillers. Therefore, in practical applications, electrofused magnesium oxide powder is not prepared by using only the filler of C2 added.

[0047] From the data of Examples 1-3 and Comparative Examples 1-4, it can be seen that adding magnesium carbide as a high-temperature and high-conductivity filler and magnesium oxide with a metal element content of not less than 10% can significantly reduce the resistivity of the prepared electrofused magnesium oxide. When the weight ratio of magnesium carbide and magnesium oxide with a metal element content of not less than 10% exceeds the range of 1-4:1-7 and when only magnesium carbide filler is added, the resistivity of the prepared electrofused magnesium oxide powder increases significantly. When only adding magnesium oxide filler with a metal element content of not less than 10%, its cost is significantly higher than the mixed filler of magnesium carbide and magnesium oxide with a metal element content of not less than 10%. In addition, the volume resistivity of the finally prepared electrofused magnesium oxide powder can be adjusted within the range of 100-10 5 Ω·mm by the ratio of the high-temperature and high-conductivity fillers C1 and C2 (exceeding the range of 1-4:1-7) to meet the usage requirements.

[0048] In summary, by adding magnesium carbide as a high-temperature and high-conductivity filler and magnesium oxide with a metal element content of not less than 10% to the calcined magnesium oxide in this application, the conductivity of the prepared electrofused magnesium oxide powder can be greatly improved, and within the scope disclosed in this application, it can reach a minimum of 21 Ω·mm, effectively reducing the resistance loss, improving the electrolysis efficiency, and reducing the industrial energy consumption cost. The melting points of the magnesium oxide lumps, the high-temperature and high-conductivity materials C1 and C2 used in this application are all greater than 2200 °C, so it has extremely high high-temperature resistance characteristics and is suitable for the fields of high-performance electrolysis rods and high-precision electrodes.

[0049] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing high temperature resistant and highly conductive fused magnesium oxide powder, characterized in that: The steps include: S1: crushing, screening and dust removal of high-temperature fused magnesium oxide blocks at a temperature of 2200-2800°C to obtain magnesium oxide powder; S2: calcining the magnesium oxide powder obtained in step S1 in a high temperature furnace to obtain polyvalent iron-reduced mixed magnesium oxide, the color of the powder changes from white to light red, and collecting the calcined magnesium oxide powder; S3: mixing high temperature and high conductivity fillers C1 and C2 in a weight ratio of 1 to 4:1 to 7, and then heating to 800 to 1300° C. to obtain a high conductivity mixed filler; S4: mixing the calcined magnesium oxide powder obtained in S2 and the high-conductivity mixed filler obtained in S3 at a weight ratio of 1:0.01-0.3 to obtain a high-conductivity, high-temperature-resistant magnesium oxide base material; S5: placing the high-conductivity, high-temperature-resistant magnesium oxide base material obtained in S4 in a drying furnace for drying and then sieving to obtain high-temperature-resistant, high-conductivity fused magnesium oxide powder; S6: mixing the high temperature resistant and highly conductive fused magnesium oxide powder obtained in S5 with a hydrophobic conductive medium to obtain a hydrophobic high temperature resistant and highly conductive fused magnesium oxide powder, wherein the content of the hydrophobic conductive medium is 40 to 1000 ppm.

2. The method for preparing high temperature resistant and highly conductive fused magnesium oxide powder according to claim 1, characterized in that: The high temperature and high conductivity filler C1 is magnesium carbide; The high-temperature and high-conductivity filler C2 is magnesium oxide containing metal elements, the metal elements account for no less than 10%, and the metal elements are at least one of iron, cobalt, and nickel.

3. The method for preparing high temperature resistant and highly conductive fused magnesium oxide powder according to claim 1, characterized in that: In S3, the high temperature and high electrical conductivity filler C1 and the high temperature and high electrical conductivity filler C2 are mixed in a weight ratio of 1:1, 3:6 or 4:

7.

4. The method for preparing high temperature resistant and highly conductive fused magnesium oxide powder according to claim 1, characterized in that: In S2, the volume resistivity of the calcined magnesium oxide powder is less than 1×10 6 Ω·mm.

5. The method for preparing high temperature resistant and highly conductive fused magnesium oxide powder according to claim 1, characterized in that: The hydrophobic conductive medium is graphite paint or conductive black grease.

6. The method for preparing high temperature resistant and highly conductive fused magnesium oxide powder according to claim 1, characterized in that: In S2, the calcination conditions are: calcination at 1000° C. for 2-4 hours.

7. The method for preparing high temperature resistant and highly conductive fused magnesium oxide powder according to claim 1, characterized in that: In S5, the drying temperature is 300-500°C.

8. The method for preparing high temperature resistant and highly conductive fused magnesium oxide powder according to claim 1, characterized in that: In S4, the mixing method is to use a high-speed mixer to mix the high-conductivity mixed filler and the calcined magnesium oxide powder.

9. A high temperature resistant and highly conductive fused magnesium oxide powder prepared by the method for preparing the high temperature resistant and highly conductive fused magnesium oxide powder according to claim 1.

10. The high temperature resistant and highly conductive fused magnesium oxide powder according to claim 9, characterized in that: The volume resistivity of the high temperature resistant and highly conductive fused magnesium oxide powder is lower than 100Ω·mm.