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CN-122010575-A - Magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic and preparation method thereof

CN122010575ACN 122010575 ACN122010575 ACN 122010575ACN-122010575-A

Abstract

The invention relates to a magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic and a preparation method thereof. The method comprises the steps of mixing silicon magnesium nitride powder, yttrium oxide powder and absolute ethyl alcohol, conducting ultrasonic dispersion to obtain a mixture I, bombarding the surface of chopped carbon fibers by using low-temperature plasma treatment equipment, then soaking the surface of the chopped carbon fibers in silane coupling agent aqueous solution to obtain modified chopped carbon fibers, mixing the magnetic chopped carbon fibers obtained by bombarding a target material through magnetron sputtering with the mixture I to obtain a mixture II, pouring the mixture II into a mold, enabling the magnetic chopped carbon fibers to be arranged in a directional mode along the magnetic field direction by using a magnetic field generating device, placing the mold containing the mixture II in a pressing plate center of a hydraulic machine, conducting vacuum drying to obtain a mixture III, and finally conducting segmented low-pressure sintering to obtain the magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic. The product prepared by the invention has good interface bonding and can obviously improve the fracture toughness and the stability of flexural strength.

Inventors

  • WANG XING
  • LI YALE
  • DING JUN
  • LUO YIXIN
  • LIU ZHENGLONG
  • YU CHAO
  • DENG CHENGJI

Assignees

  • 武汉科技大学

Dates

Publication Date
20260512
Application Date
20260129

Claims (10)

  1. 1. A preparation method of magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic is characterized by comprising the following steps of Mixing 95-98wt% of silicon magnesium nitride powder and 2-5wt% of yttrium oxide powder for 5-8 hours to obtain a mixture, adding absolute ethyl alcohol accounting for 100-600 wt% of the mixture into the mixture, and performing ultrasonic dispersion for 20-40 minutes to obtain a mixture I; Secondly, bombarding the surface of the chopped carbon fiber for 15-30 min by using low-temperature plasma treatment equipment, soaking the bombarded chopped carbon fiber in a silane coupling agent aqueous solution for 30-60 min, and drying to obtain a modified chopped carbon fiber; The silane coupling agent is 1-4wt% of the mass of the chopped carbon fiber; thirdly, placing the modified chopped carbon fiber into direct-current magnetron sputtering equipment, bombarding a target material through magnetron sputtering, and depositing a uniform magnetic coating on the surface of the modified chopped carbon fiber to obtain magnetic chopped carbon fiber; Step four, selecting a die with parallel diversion trenches, pouring a mixture II containing magnetic chopped carbon fibers into the die, placing a magnetic field generating device with the temperature of 0.3-0.6T along the diversion trenches, and scraping the mixture II with a scraper for 2-5 times along the magnetic field direction to enable the magnetic carbon fibers to be arranged in an oriented manner along the magnetic field direction; Step five, placing a die containing the mixture II in the center of a pressing plate of a hydraulic press, boosting the pressure to 0.5-0.8 MPa, maintaining the pressure for 10-15 min, and carrying out vacuum drying to obtain a mixture III; And step six, placing the mixture III in a gas pressure sintering furnace, heating to 1050-1200 ℃ at a speed of 3-6 ℃ per minute in a nitrogen atmosphere, preserving heat for 2-5 hours, heating to 1500-1650 ℃ at a speed of 4-7 ℃ per minute, preserving heat for 2-5 hours under a condition of 5-8 MPa, and naturally cooling to obtain the magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic.
  2. 2. The preparation method of the magnetic chopped carbon fiber reinforced magnesium silicon nitride ceramic according to claim 1, wherein the content of MgSiN 2 of the magnesium silicon nitride powder is more than or equal to 98wt%, and the granularity of the magnesium silicon nitride powder is more than or equal to 100nm.
  3. 3. The method for preparing the magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic according to claim 1, wherein the purity of the yttrium oxide powder is more than or equal to 99wt%, and the granularity of the yttrium oxide powder is more than or equal to 50nm.
  4. 4. The method for preparing the magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic according to claim 1, wherein the drying is performed at the temperature of 60-80 ℃ and the vacuum degree of 0.08-0.10 MPa, and the drying time is 6-8 hours.
  5. 5. The method for preparing the magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic according to claim 1, wherein the magnetic target is one of an iron target, a cobalt target and a nickel target.
  6. 6. The method for preparing the magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic according to claim 1, wherein the method for mixing the magnetic chopped carbon fiber with the mixture I is as follows: Blowing off the magnetic chopped carbon fibers by using inert gas, adding the blown-off magnetic chopped carbon fibers into the mixture I according to the mass ratio of 3-6:100, and performing ultrasonic dispersion for 15-30 min to obtain dispersed magnetic chopped carbon fibers; The addition amount of the phenolic resin is 2-5wt% of the dispersed magnetic chopped carbon fiber.
  7. 7. The method for preparing a magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic according to claim 6, wherein the inert gas is argon, helium, or a mixed gas of argon and helium.
  8. 8. The method for preparing a magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic according to claim 6, wherein the resin is a thermosetting phenolic resin or a thermoplastic phenolic resin.
  9. 9. The method for preparing the magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic according to claim 1, wherein the temperature of vacuum drying is 60-80 ℃, the vacuum degree of vacuum drying is 0.08-0.10 MPa, and the time of vacuum drying is 1-5 h.
  10. 10. The magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic is prepared by the preparation method of the magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic according to any one of claims 1-9.

Description

Magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic and preparation method thereof Technical Field The invention belongs to the technical field of magnesium silicon nitride ceramics. In particular to a magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic and a preparation method thereof. Technical Field Magnesium silicon nitride, which is a group II-IV nitride semiconductor of an orthorhombic system, has a crystal structure similar to that of aluminum nitride and can be regarded as being deformed from a wurtzite structure of AlN in which two Al 3+ are sequentially replaced with one Mg 2+ and one Si 4+ to form an orthorhombic structure formed by joining tetrahedral units, and this structure imparts a series of excellent properties to MgSiN 2, including high thermal stability, good thermal conductivity, high electrical resistivity, low dielectric constant, and low thermal expansion coefficient similar to that of AlN, and is therefore attracting attention of technological staff. W.A. Croen et al (W.A. Croen, M.J. Kraan. Preparation, et al. Microstructure and Properties MgSiN2Ceramics. J Eur Ceram Soc, 1993,12: 413-420.) prepared MgSiN 2 and AlN ceramics by pressureless sintering under nitrogen atmosphere at 1500 ℃ and compared the mechanical and thermal properties of the two. Research shows that MgSiN 2 ceramic shows more excellent comprehensive mechanical properties compared with AlN ceramic. However, the MgSiN 2 ceramic prepared by the sintering process has obvious defects, and the fracture toughness is low, so that brittle fracture is easy to occur when the silicon magnesium nitride is acted by external force. Shukiko Tanaka et al (Shukiko Tanaka, Kiyoshi Itatani, et al. Effect of silicon nitride addition on the thermal and mechanical properties of magnesium silicon nitride ceramics J. Journal of the European Ceramic Society, 2004, 24(7): 2163-2168.) prepared a sample by hot press sintering, adding silicon nitride to MgSiN 2, sintering with Yb 2O3 as sintering aid, and the presence of liquid phase during sintering process causes Si 3N4 crystal grains to elongate, and prevents crack growth, thereby improving toughness. However, the Si 3N4 and MgSiN 2 matrix of the method are physically combined by liquid phase sintering, so that the interface binding force is weak, and the phase interface is easy to have defects when the interface is impacted by external force or suddenly changed in temperature. Shukiko Tanaka et al (Shukiko Tanaka, Kiyoshi Itatani, et al. The effect of rare-earth oxide addition on the hot-pressing of magnesium silicon nitride. J Eur Ceram Soc, 2002, 22:777-783.), in order to investigate the effect of rare earth oxide content on the performance of MgSiN 2 ceramics, prepared MgSiN 2 ceramics by hot press sintering. While the addition of Y 2O3 is best for increasing the relative density and Vickers hardness of the material, the addition of Yb 2O3 is most suitable for increasing the thermal conductivity of the material. The hot-pressed sintering method has the advantage of improving the density of the material, but the high-pressure environment of hot-pressed sintering can limit the escape of gas in the sintering process, so that tiny pores remain in the matrix, and closed pores are formed under high pressure, thereby becoming a new crack source and affecting the stability of the flexural strength of the material. Disclosure of Invention The invention aims to overcome the defects of the prior art and aims to provide a magnetic chopped carbon fiber reinforced silicon magnesium nitride ceramic which has good interface bonding and can remarkably improve fracture toughness and flexural strength stability and a preparation method thereof. In order to achieve the above purpose, the technical scheme adopted by the invention comprises the following specific steps: Mixing 95-98wt% of silicon magnesium nitride powder and 2-5wt% of yttrium oxide powder for 5-8 hours to obtain a mixture, adding absolute ethyl alcohol accounting for 100-600 wt% of the mixture into the mixture, and performing ultrasonic dispersion for 20-40 minutes to obtain a mixture I. Secondly, using an argon-oxygen mixed gas as a plasma source, bombarding the surface of the chopped carbon fiber for 15-30 min by using low-temperature plasma treatment equipment, soaking the bombarded chopped carbon fiber in a silane coupling agent aqueous solution for 30-60 min, and drying to obtain a modified chopped carbon fiber; The silane coupling agent accounts for 1-4wt% of the mass of the chopped carbon fiber. And thirdly, placing the modified chopped carbon fiber into direct-current magnetron sputtering equipment, bombarding a target material through magnetron sputtering, depositing a uniform magnetic coating on the surface of the modified chopped carbon fiber to obtain the magnetic chopped carbon fiber, and mixing the magnetic chopped carbon fiber with the mixture I to obtain a mixture II containing the