A surface metallized ceramic microsphere with high bonding strength and its preparation method and application

Abstract

The present invention belongs to the technical field of ceramic metallization preparation, and discloses a surface metallized ceramic microsphere with high bonding strength, and a preparation method and application thereof. The method is to obtain a mixed powder M‑SiO2‑Al2O3‑Re2O3 by ball-milling and drying metal nanopowder, SiO2, Al2O3 and Re2O3, spray a binder on the surface of the ceramic microsphere using a sugar coating machine and a 0.5 mm caliber spray gun, and then place the mixed powder in the sugar coating machine to soften the binder so that the ceramic microsphere is coated with a M‑SiO2‑Al2O3‑Re2O3 conductive layer, vacuum sintered after debinding, and heated to 1550-1750°C to obtain a surface metallized ceramic microsphere with high bonding strength. The bonding strength between the metal layer of the surface metallized ceramic and the ceramic substrate is 50-60MPa, the thickness of the metal layer is 20-50μm, and the resistivity at room temperature is 5×10 ‑6 ~10×10 ‑5 Ω·m.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramic metallization preparation, and more specifically, relates to a surface metallized ceramic microsphere with high bonding strength and a preparation method and application thereof. Background Art

[0002] Ceramics have low density, high strength, high hardness, high temperature resistance, wear resistance and corrosion resistance. They are materials with very good comprehensive properties and are widely used in aerospace, mechanical industry, chemical industry, biomedicine and other fields. However, some ceramics themselves do not have conductivity. The current method to improve the conductivity of ceramics is mainly to introduce a large amount (20-40 vol%) of the second conductive phase into the matrix material. However, too much second conductive phase will cause some important properties of the matrix material to degrade, and will also reduce the density of the ceramic material. Based on the above application background, it is urgent to develop a new preparation method so that the surface of the ceramic microspheres has high thermal conductivity and conductivity after metallization, and the bonding surface between the surface metal layer and the ceramic microsphere matrix has extremely high strength, while ensuring that the ceramic matrix has the original high performance. Summary of the invention

[0003] In order to solve the shortcomings and deficiencies in the prior art, the primary purpose of the present invention is to provide a method for preparing surface metallized ceramic microspheres with high bonding strength. The method comprises spraying a binder on the surface of the ceramic microspheres, and then coating the surface with a metal conductive layer. During sintering, the glass phase of the ceramic body and the glass phase formed by the oxide in the metal layer migrate with each other, thereby obtaining surface metallized ceramic microspheres with high bonding strength.

[0004] Another object of the present invention is to provide metallized ceramic microspheres with high surface bonding strength prepared by the above preparation method.

[0005] Another object of the present invention is to provide an application of the above-mentioned metallized ceramic microspheres with high surface bonding strength.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for preparing surface metallized ceramic microspheres with high bonding strength comprises the following specific steps:

[0008] S1. Mix nano-metal powders M, SiO2, Al2O3 and Re2O3, add solvent and ball milling medium for ball milling, and obtain mixed powder M-SiO2-Al2O3-Re2O3 after drying and sieving.

[0009] S2. The ceramic microspheres are placed in a sugar coating machine at a speed of 300 to 500 r / min, and a 0.5 mm diameter spray gun is used to spray the binder in the horizontal tangential direction of the top of the ceramic microsphere at a pressure of 140 to 200 KPa at 20 cm above the ceramic microspheres, and the binder is applied to the top of the ceramic microspheres at room temperature. Blast air is applied to dry the ceramic microspheres. After spraying for 5 to 30 minutes, the surface of the ceramic microspheres is uniformly coated with the binder.

[0010] S3. 100 to 200 g of the mixed powder M-SiO2-Al2O3-Re2O3 was evenly added to a sugar coating machine at a speed of 300 to 500 r / min to soften the binder on the surface of the ceramic microspheres. After 5 to 60 min of coating, the ceramic microspheres were dried and sieved to obtain a surface-coated M-SiO2-Al2O3-Re2O3 conductive layer.

[0011] S4. The ceramic microspheres of the conductive layer are placed in an air debinding furnace to remove the binder, heated to 250-300°C, kept warm for 2-5 hours, then heated to 450-500°C, kept warm for 3-6 hours, and then cooled with the furnace. The air flow rate during the whole process is 30-50 L / min.

[0012] S5. The microspheres are placed in a high-temperature vacuum brazing sintering furnace and sintered, the temperature is raised to 1300-1400°C, and then raised to 1550-1750°C and kept warm. The vacuum degree during the sintering process is 1.3-1.8×10 -3 Pa, to produce metallized ceramic microspheres with high bonding strength.

[0013] Preferably, the nano-metal powder described in step S1 is Cr, Mo or W, the particle size of the nano-metal powder is 25-100 nm, and the purity is 99-99.999%, the particle size of the SiO2 is 50-150 nm, and Re in the Re2O3 is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu; the particle size of Re2O3 is 3-6 μm, and the particle size of Al2O3 is 50-100 nm, and the purity is 99-99.99%; the mass ratio of M:SiO2:Al2O3:Re2O3 is (65-80):(7-12):(7-12):(6-11), and the mass ratio of the ball milling medium:solvent:mixed powder is (2-4):1:1.

[0014] Preferably, the ceramic microspheres in step S2 are ZrO2 microspheres, Al2O3 ceramic microspheres or Si3N4 ceramic microspheres, and the diameter of the ceramic microspheres is 1.0 to 1.5 mm.

[0015] Preferably, the binder in step S2 is a PVA aqueous solution, pineol and ethyl cellulose, paraffin and CCl4.

[0016] More preferably, the mass ratio of paraffin wax to CCl4 is (1-10):(90-99), the mass ratio of pineol to ethyl cellulose is (95-98):(2-5), and the concentration of the PVA aqueous solution is 8-15wt%.

[0017] Preferably, the heating rate in step S4 is 1-2°C / min.

[0018] Preferably, the heating rate of 1300-1400° C. in step S5 is 15-20° C. / min, the heating rate of 1550-1750° C. is 10-15° C. / min, and the insulation time is 1-3 h.

[0019] The invention discloses a surface metallized ceramic microsphere with high bonding strength. The surface metallized ceramic microsphere is prepared by the method described.

[0020] Preferably, the bonding strength between the metal layer and the ceramic matrix of the surface metallized ceramic microsphere is 50-60 MPa, the thickness of the metal layer of the surface metallized ceramic microsphere is 20-50 μm, and the resistivity of the surface metallized ceramic microsphere at room temperature is 5×10 -6 ~10×10 -5 Ω·m.

[0021] The surface metallized ceramic microspheres with high bonding strength are used in the electrical or nuclear energy fields.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention coats a layer of metal nanopowder on the surface of the ceramic microsphere, and does not need to introduce a large amount of metal secondary phase into the ceramic matrix material, so that the ceramic matrix material can maintain the original comprehensive mechanical properties.

[0024] 2. The metal layer thickness of the surface metallized ceramic microspheres prepared by the present invention is extremely thin (35-50 μm) and has extremely high conductivity.

[0025] 3. The bonding strength between the metal layer and the ceramic matrix in the surface metallized ceramic microspheres prepared by the present invention is extremely high. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a SEM photograph of the surface metallized ZrO2 ceramic microspheres prepared in Example 1. DETAILED DESCRIPTION

[0027] The content of the present invention is further described below in conjunction with specific examples, but it should not be construed as limiting the present invention. If not specifically indicated, the technical means used in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0028] Example 1

[0029] 1. Mo, SiO2, Al2O3 and Yb2O3 are mixed in a mass ratio of 65:12:12:11, the grinding ball medium is ZrO2, the solvent is anhydrous ethanol, and the mass ratio of ZrO2 grinding ball: mixed powder: anhydrous ethanol is 2:1:1. After ball milling on a roller ball mill for 24 hours, dry and obtain Mo-SiO2-Al2O3-Yb2O3 mixed powder.

[0030] 2. Prepare a binder with paraffin and CCl4 in a mass ratio of 5:95, place ZrO2 microspheres with a particle size of 1.0 mm in a sugar coating machine, rotate the sugar coating machine at a speed of 500 r / min, and use a 0.5 mm caliber spray gun to spray the binder in the horizontal tangential direction of the top of the ZrO2 ceramic microsphere at a pressure of 150 KPa at 20 cm above the ceramic microsphere, and apply room temperature forced air drying at the same time. The spraying time is 10 min.

[0031] 3. Sprinkle 100g of Mo-SiO2-Al2O3-Yb2O3 mixed powder evenly into a sugar coating machine with a rotation speed of 500r / min, and apply 80°C air blowing for 30min. After drying and sieving, ZrO2 microspheres coated with a conductive layer are obtained. The conductive layer is Mo-SiO2-Al2O3-Yb2O3, and its thickness is 40μm.

[0032] 4. The dried ZrO2 ceramic microspheres coated with a conductive layer are placed in a debinding furnace to remove the binder, and the temperature is increased to 250°C at a rate of 1°C / min and kept at this temperature for 3 hours, and then increased to 450°C at a rate of 1°C / min and kept at this temperature for 3 hours, and then cooled with the furnace. The air flow rate during the whole process is 40L / min.

[0033] 5. The debinded ZrO2 ceramic microspheres were placed in a high-temperature vacuum brazing sintering furnace for sintering. The temperature was raised to 1350°C at a rate of 15°C / min, and then raised to 1600°C at a rate of 10°C / min and kept at this temperature for 2h. The vacuum degree during the sintering process was 1.3×10 -3 Pa, prepared Mo-SiO2-Al2O3-Yb2O3 metallized ZrO2 ceramic microspheres.

[0034] The bonding strength between the metal layer and the ceramic matrix of the metallized ZrO2 ceramic microspheres prepared in this embodiment is 58 MPa, the thickness of the surface metal layer is 40 μm, and the resistivity at room temperature is 60×10 -6 Ω·m.

[0035] Figure 1 is a SEM photo of the surface metallized ZrO2 ceramic microspheres in Example 1. Figure 1 It can be seen that the surface of the coated ZrO2 ceramic microspheres is smooth, indicating that a uniform metal layer of Mo-SiO2-Al2O3-Yb2O3 can be coated on the surface of ZrO2 ceramic microspheres using a sugar coating machine and a 0.5 mm diameter spray gun.

[0036] Example 2

[0037] Metallized ZrO2 ceramic microspheres were prepared according to the method of Example 1, which differs from Example 1 in that the raw materials in step 1 of this embodiment are Cr, SiO2, Al2O3 and Y2O3, and Cr-SiO2-Al2O3-Y2O3 metallized ZrO2 ceramic microspheres are obtained.

[0038] The bonding strength between the metal layer Cr-SiO2-Al2O3-Y2O3 and the ceramic matrix ZrO2 in the metallized ZrO2 ceramic microspheres prepared in this embodiment is 55MPa, the thickness of the surface metal layer is 35μm, and the resistivity at room temperature is 90×10 -6 Ω·m.

[0039] Example 3

[0040] Metallized Al2O3 ceramic microspheres were prepared according to the method of Example 1, which differs from Example 1 in that the raw materials in step 1 of this embodiment are W, SiO2, Al2O3 and Y2O3, and W-SiO2-Al2O3-Y2O3 metallized Al2O3 ceramic microspheres are prepared.

[0041] The bonding strength between the metal layer W-SiO2-Al2O3-Y2O3 and the ceramic matrix Al2O3 in the metallized Al2O3 ceramic microspheres prepared in this embodiment is 45 MPa, the thickness of the surface metal layer is 45 μm, and the resistivity at room temperature is 10×10 -5 Ω·m.

[0042] Example 4

[0043] Metallized Si3N4 ceramic microspheres were prepared according to the method of Example 1, which was different from Example 1 in that the raw materials in step 1 of this embodiment were Mo, SiO2, Al2O3 and Y2O3, the binder in step 2 was a 10wt% PVA aqueous solution, and no forced air drying was required during the whole process to obtain Mo-SiO2-Al2O3-Y2O3 metallized Si3N4 ceramic microspheres.

[0044] The bonding strength between the metal layer Mo-SiO2-Al2O3-Y2O3 and the ceramic matrix Si3N4 in the metallized Si3N4 ceramic microspheres prepared in this embodiment is 55MPa, the thickness of the surface metal layer is 40μm, and the resistivity at room temperature is 70×10 -6 Ω·m.

[0045] Example 5

[0046] Metallized Si3N4 ceramic microspheres were prepared according to the method of Example 1, which is different from Example 1 in that the raw materials in step 1 of this embodiment are W, SiO2, Al2O3 and Yb2O3, the binder in step 2 is pine alcohol and ethyl cellulose in a mass ratio of 97:3, and there is no need to apply forced air drying during the whole process to obtain W-SiO2-Al2O3-Yb2O3 metallized Si3N4 ceramic microspheres.

[0047] The bonding strength between the metal layer W-SiO2-Al2O3-Yb2O3 and the ceramic matrix Si3N4 in the metallized Si3N4 ceramic microspheres prepared in this embodiment is 60MPa, the thickness of the surface metal layer is 50μm, and the resistivity at room temperature is 10×10 -5 Ω·m.

[0048] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing surface metallized ceramic microspheres with high bonding strength, characterized in that: The specific steps include: S1. The nano-metal powders M, SiO2, Al2O3 and Re2O3 are mixed, and a solvent and a ball milling medium are added for ball milling. After drying and sieving, a mixed powder M-SiO2-Al2O3-Re2O3 is obtained. S2. The ceramic microspheres are placed in a sugar coating machine with a rotation speed of 300-500 r / min, and a 0.5 mm diameter spray gun is used to spray the binder at a pressure of 140-200 KPa at 20 cm above the ceramic microspheres in the horizontal tangential direction of the top of the ceramic microspheres, and at the same time, room temperature air is applied for drying. After spraying for 5-30 min, ceramic microspheres with a uniform surface coating of the binder are obtained; S3. The mixed powder M-SiO2-Al2O3-Re2O3 is uniformly added to a sugar coating machine at a speed of 300-500 r / min to soften the binder on the surface of the ceramic microspheres. After coating for 5-60 minutes, the ceramic microspheres with a surface-coated M-SiO2-Al2O3-Re2O3 conductive layer are obtained after drying and sieving. S4. Place the ceramic microspheres of the conductive layer in an air debinding furnace to remove the binder, heat to 250-300°C, keep warm for 2-5 hours, then heat to 450-500°C, keep warm for 3-6 hours, and then cool with the furnace. The air flow rate during the whole process is 30-50 L / min. S5. The ceramic microspheres obtained in step S4 are placed in a high-temperature vacuum brazing sintering furnace for sintering, the temperature is raised to 1300-1400°C, and then raised to 1550-1750°C and kept warm. The vacuum degree during the sintering process is 1.3-1.8×10 -3 Pa, to produce metallized ceramic microspheres with high bonding strength.

2. The method for preparing surface metallized ceramic microspheres with high bonding strength according to claim 1, characterized in that: The nano metal powder described in step S1 is Cr, Mo or W, the particle size of the nano metal powder is 25-100 nm, and the purity is 99-99.999%. The particle size of SiO2 is 50-150 nm. Re in Re2O3 is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu; the particle size of Re2O3 is 3-6 μm, and the particle size of Al2O3 is 50-100 nm, and the purity is 99-99.99%. The mass ratio of M:SiO2:Al2O3:Re2O3 is (65-80):(7-12):(7-12):(6-11), and the mass ratio of the ball milling medium:solvent:mixed powder is (2-4):1:

1.

3. The method for preparing surface metallized ceramic microspheres with high bonding strength according to claim 1, characterized in that: The ceramic microspheres in step S2 are ZrO2 microspheres, Al2O3 ceramic microspheres or Si3N4 ceramic microspheres, and the diameter of the ceramic microspheres is 1.0-1.5 mm.

4. The method for preparing surface metallized ceramic microspheres with high bonding strength according to claim 1, characterized in that: In step S2, the binder is a PVA aqueous solution, pinene alcohol and ethyl cellulose, paraffin and CCl4.

5. The method for preparing surface metallized ceramic microspheres with high bonding strength according to claim 4, characterized in that: The mass ratio of the paraffin wax to CCl4 is (1-10): (90-99), the mass ratio of pineol to ethyl cellulose is (95-98): (2-5), and the concentration of the PVA aqueous solution is 8-15wt%.

6. The method for preparing surface metallized ceramic microspheres with high bonding strength according to claim 1, characterized in that: The heating rate in step S4 is 1-2 °C / min.

7. The method for preparing surface metallized ceramic microspheres with high bonding strength according to claim 1, characterized in that: In step S5, the heating rate of 1300-1400°C is 15-20°C / min, the heating rate of 1550-1750°C is 10-15°C / min, and the insulation time is 1-3 h.

8. A surface metallized ceramic microsphere with high bonding strength, characterized in that: The surface metallized ceramic microspheres are prepared by the method described in any one of claims 1-7.

9. The surface metallized ceramic microspheres with high bonding strength according to claim 8, characterized in that: The bonding strength between the metal layer and the ceramic matrix in the surface metallized ceramic microsphere is 50-60 MPa, the thickness of the metal layer of the surface metallized ceramic microsphere is 20-50 μm, and the resistivity of the surface metallized ceramic microsphere at room temperature is 5×10 -6 ~10×10 -5 Ω×m.

10. Use of the surface metallized ceramic microspheres with high bonding strength as claimed in claim 8 or 9 in the electrical or nuclear energy fields.

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