Si3N4-BN-MAS ceramic composite material and preparation method thereof

Abstract

The invention discloses a Si3N4-BN-MAS ceramic composite material and a preparation method thereof, belonging to the technical field of silicon nitride-based ceramic composite materials. The objective of the invention is to overcome the technical problems of high cost and low efficiency caused by too high sintering temperature, too great sintering pressure and poor machining properties during production of conventional silicon nitride-based ceramic composite materials. The Si3N4-BN-MAS ceramic composite material provided by the invention is prepared from MgO powder, Al2O3 powder, amorphous SiO2 powder, alpha-Si3N4 powder and hexagonal BN powder. The preparation method comprises the following steps: step 1, mixing 1.0 to 1.5% of MgO powder, 3.2 to 3.8% of Al2O3 powder, 5.0 to 5.5% of SiO2 powder, 0.01 to 50% of BN powder and alpha-Si3N4 (being the balance), adding a medium and then carrying out ball milling; step 2, then carrying out drying, grinding and sieving successively; step 3, filing a mold with a substance obtained after sieving and carrying out pre-press molding; step 4, carrying out sintering under the protection of an inert gas so as to obtain the Si3N4-BN-MAS ceramic composite material. The preparation method is applied to the field of preparation of Si3N4-BN-MAS ceramic composite materials.

Description

technical field

[0001] The invention belongs to the field of silicon nitride-based ceramic composite materials; 3 N 4 -BN-MAS ceramic composite material and its preparation method. Background technique

[0002] In recent years, with the rapid development of aerospace technology and the improvement of spacecraft flight Mach number, higher requirements have been put forward for heat-resistant and wave-transmitting materials for aircraft radome. The continuous rise of the flight Mach number makes the radome need to withstand higher aerodynamic shock and aerodynamic heat, while maintaining high transparency and low distortion rate of electromagnetic waves under this condition. Therefore, the development of heat-resistant and wave-transmitting materials with excellent mechanical properties, heat resistance and dielectric properties is of great significance to aerospace, military and national defense and other fields.

[0003] However, the current traditional ceramic materials ...

Examples

specific Embodiment approach 1

[0036] Specific embodiment one: the Si described in this embodiment 3 N 4 -The preparation method of BN-MAS ceramic composite material is to finish according to the following steps:

[0037] Step 1, by mass fraction, the MgO powder of 1.37%, the Al of 3.49% 2 o 3 Powder, 5.14% SiO 2 powder, 0.01% of BN powder and the balance of α-Si 3 N 4 After the powders are mixed, put them in a container, add an appropriate amount of absolute ethanol, and ball mill at a rate of 150r / min for 24 hours; wherein, the ratio of the mass of the balls to the total mass of all the above powders is 6:1;

[0038] Step 2, then drying at 90°C for 1 hour, grinding, and passing through a 100-mesh sieve to obtain a mixed powder;

[0039] Step 3, the mixed powder obtained in step 2 is packed into a mould, and then pre-pressed under a pressure of 10MPa;

[0040] Step 4, then place it in a sintering furnace, pass nitrogen gas as a protective gas, and sinter for 1 hour at a temperature of 1700 ° C and a...

specific Embodiment approach 2

[0042] Specific embodiment two: the difference between this embodiment and specific embodiment one is: in step one, by mass fraction, the MgO powder of 1.37%, the Al of 3.49% 2 o 3 Powder, 5.14% SiO 2 powder, 30% of BN powder and the balance of α-Si 3 N 4 Powder mix. Other steps and parameters are the same as in the first embodiment.

[0043] Si prepared in this embodiment 3 N 4 -BN-MAS composite ceramics have good performances: the main phase after sintering is β-Si 3 N 4 、Si 2 N 2 O; the fracture morphology is dense, and there are more columnar β-Si in the material 3 N 4 , lamellar Si 2 N 2 O grains, the two often exist in the form of cross lamination; the density is 88.36%, the apparent porosity is 2.75%, the bending strength is 461.4±15.6MPa, the fracture toughness is 3.67GPa, the dielectric constant is 4.7±0.21, and the dielectric loss The tangent of the angle is 6.03×10 -3 . The prepared composite ceramics were subjected to thermal shock at 600°C, 800°C, ...

specific Embodiment approach 3

[0044] Specific embodiment three: the difference between this embodiment and specific embodiment one is: in step one, the MgO powder of 1.37%, the Al of 3.49% 2 o 3 Powder, 5.14% SiO 2 powder, 50% of BN powder and the balance of α-Si 3 N 4 Powder mix. Other steps and parameters are the same as in the first embodiment.

[0045] The Si prepared by the method of this embodiment 3 N 4 -BN-MAS composite ceramics have good performances: the main phase after sintering is β-Si 3 N 4 、Si 2 N 2 O, h-BN; the fracture morphology is dense, and there is a small amount of columnar β-Si in the material 3 N 4 , lamellar BN grains, the two often exist in the form of cross lamination; the density is 79.92%, the apparent porosity is 4.36%, the flexural strength is 225.9±12.4MPa, the fracture toughness is 3.03GPa, and the dielectric constant is 4.71± 0.18, the dielectric loss tangent value is 4.57×10 -3 . The prepared composite ceramics were subjected to thermal shock at 600°C, 800°C...

technical field

[0001] The invention belongs to the field of silicon nitride-based ceramic composite materials; 3 N 4 -BN-MAS ceramic composite material and its preparation method. Background technique

[0002] In recent years, with the rapid development of aerospace technology and the improvement of spacecraft flight Mach number, higher requirements have been put forward for heat-resistant and wave-transmitting materials for aircraft radome. The continuous rise of the flight Mach number makes the radome need to withstand higher aerodynamic shock and aerodynamic heat, while maintaining high transparency and low distortion rate of electromagnetic waves under this condition. Therefore, the development of heat-resistant and wave-transmitting materials with excellent mechanical properties, heat resistance and dielectric properties is of great significance to aerospace, military and national defense and other fields.

[0003] However, the current traditional ceramic materials ...

Examples

specific Embodiment approach 1

[0036] Specific embodiment one: the Si described in this embodiment 3 N 4 -The preparation method of BN-MAS ceramic composite material is to finish according to the following steps:

[0037] Step 1, by mass fraction, the MgO powder of 1.37%, the Al of 3.49% 2 o 3 Powder, 5.14% SiO 2 powder, 0.01% of BN powder and the balance of α-Si 3 N 4 After the powders are mixed, put them in a container, add an appropriate amount of absolute ethanol, and ball mill at a rate of 150r / min for 24 hours; wherein, the ratio of the mass of the balls to the total mass of all the above powders is 6:1;

[0038] Step 2, then drying at 90°C for 1 hour, grinding, and passing through a 100-mesh sieve to obtain a mixed powder;

[0039] Step 3, the mixed powder obtained in step 2 is packed into a mould, and then pre-pressed under a pressure of 10MPa;

[0040] Step 4, then place it in a sintering furnace, pass nitrogen gas as a protective gas, and sinter for 1 hour at a temperature of 1700 ° C and a...

specific Embodiment approach 2

[0042] Specific embodiment two: the difference between this embodiment and specific embodiment one is: in step one, by mass fraction, the MgO powder of 1.37%, the Al of 3.49% 2 o 3 Powder, 5.14% SiO 2 powder, 30% of BN powder and the balance of α-Si 3 N 4 Powder mix. Other steps and parameters are the same as in the first embodiment.

[0043] Si prepared in this embodiment 3 N 4 -BN-MAS composite ceramics have good performances: the main phase after sintering is β-Si 3 N 4 、Si 2 N 2 O; the fracture morphology is dense, and there are more columnar β-Si in the material 3 N 4 , lamellar Si 2 N 2 O grains, the two often exist in the form of cross lamination; the density is 88.36%, the apparent porosity is 2.75%, the bending strength is 461.4±15.6MPa, the fracture toughness is 3.67GPa, the dielectric constant is 4.7±0.21, and the dielectric loss The tangent of the angle is 6.03×10 -3 . The prepared composite ceramics were subjected to thermal shock at 600°C, 800°C, ...

specific Embodiment approach 3

[0044] Specific embodiment three: the difference between this embodiment and specific embodiment one is: in step one, the MgO powder of 1.37%, the Al of 3.49% 2 o 3 Powder, 5.14% SiO 2 powder, 50% of BN powder and the balance of α-Si 3 N 4 Powder mix. Other steps and parameters are the same as in the first embodiment.

[0045] The Si prepared by the method of this embodiment 3 N 4 -BN-MAS composite ceramics have good performances: the main phase after sintering is β-Si 3 N 4 、Si 2 N 2 O, h-BN; the fracture morphology is dense, and there is a small amount of columnar β-Si in the material 3 N 4 , lamellar BN grains, the two often exist in the form of cross lamination; the density is 79.92%, the apparent porosity is 4.36%, the flexural strength is 225.9±12.4MPa, the fracture toughness is 3.03GPa, and the dielectric constant is 4.71± 0.18, the dielectric loss tangent value is 4.57×10 -3 . The prepared composite ceramics were subjected to thermal shock at 600°C, 800°C...

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