Preparation method for ceramic composite material, ceramic composite material, and wavelength converter

1. A method for preparing a ceramic composite material, comprising:

preparing an aluminum salt solution and a fluorescent powder according to a mass ratio of Al 2 O 3 to fluorescent powder of (0.1 to 1):100;

dispersing the fluorescent powder in a buffer solution with a pH value of 4.5 to 5.5 to obtain a suspension;

titrating the suspension with the aluminum salt solution to obtain a fluorescent powder coated with an Al 2 O 3 hydrate film;

calcining the fluorescent powder coated with the Al 2 O 3 hydrate film to obtain an Al 2 O 3 -coated fluorescent powder;

mixing an alumina powder having a particle diameter of 0.1 μm to 1 μm and an alumina powder having a particle diameter of 1 μm to 10 μm according to a molar ratio of 100:(0.1 to 5), so as to obtain a mixed alumina powder;

mixing the Al 2 O 3 -coated fluorescent powder and the mixed alumina powder to obtain a mixed powder, wherein the Al 2 O 3 -coated fluorescent powder accounts for 40% to 90% by weight of the mixed powder; and

pre-pressing and sintering the mixed powder to obtain the ceramic composite material.

2. The method for preparing the ceramic composite material according to claim 1 , wherein the fluorescent powder comprises at least one Ce 3+ -doped fluorescent powder selected from the group consisting of Ca 3 Al 2 Si 3 O 12 , Ca 3 Sc 2 Si 3 O 12 , Gd 3 Al 5 O 12 , Gd 3 Ga 5 O 12 , Tb 3 Al 5 O 12 , Tb 3 Ga 5 O 12 , Y 3 Al 5 O 12 , Y 3 Ga 5 O 12 , Lu 3 Al 5 O 12 , Lu 3 Ga 5 O 12 and Y 3 Mg 2 AlSi 2 O 12 .

3. The method for preparing the ceramic composite material according to claim 2 , wherein the fluorescent powder has a particle diameter in a range of 13 μm to 20 μm.

4. The method for preparing the ceramic composite material according to claim 1 , wherein the aluminum salt solution has a concentration of 0.01 mol/L to 1 mol/L.

5. The method for preparing the ceramic composite material according to claim 1 , wherein in the step of titrating the suspension with the aluminum salt solution, a temperature of the suspension is in a range of 40° C. to 70° C., a stirring frequency is in a range of 100 r/min to 300 r/min, and a titrating rate is in a range of 5 mL/min to 50 mL/min.

6. The method for preparing the ceramic composite material according to claim 5 , after finishing the step of titrating the suspension with the aluminum salt solution, further comprising:

maintaining the temperature of the suspension and stirring for 1 h to 2 h, and adjusting a pH value into a range of 6 to 7 with a sodium hydroxide solution.

7. The method for preparing the ceramic composite material according to claim 5 , before the step of calcining the fluorescent powder coated with the Al 2 O 3 hydrate film to obtain an Al 2 O 3 -coated fluorescent powder, further comprising:

centrifuging the fluorescent powder coated with the Al 2 O 3 hydrate film;

repeating steps of washing the fluorescent powder coated with the Al 2 O 3 hydrate film with water and then dehydrating the fluorescent powder coated with the Al 2 O 3 hydrate film for 3 to 5 times, and then drying at a temperature in a range of 75° C. to 85° C.

8. The method for preparing the ceramic composite material according to claim 1 , wherein a calcination temperature is in a range of 300° C. to 600° C., and a calcination duration is in a range of 2 h to 5 h.

9. The method for preparing the ceramic composite material according to claim 1 , wherein the step of pre-pressing is carried out under a pressure of 5 MPa to 15 MPa.

10. The method for preparing the ceramic composite material according to claim 1 , wherein the sintering is carried out in an argon atmosphere, a sintering temperature is in a range of 1250° C. to 1550° C., a holding time is in a range of 30 min to 360 min, and a sintering pressure is in a range of 30 MPa to 200 MPa.

11. The method for preparing the ceramic composite material according to claim 1 , wherein in the step of mixing the alumina powder having a particle diameter of 0.1 μm to 1 μm and the alumina powder having a particle diameter of 1 μm to 10 μm according to the molar ratio of 100:(0.1 to 5), an alumina powder having a particle diameter of 0.01 μm to 0.1 μm is additionally added, wherein a molar ratio of the alumina powder of 0.01 μm to 0.1 μm to the alumina powder of 0.1 μm to 1 μm is (0.1 to 1):100.

12. The method for preparing the ceramic composite material according to claim 1 , wherein the step of mixing the Al 2 O 3 -coated fluorescent powder and the mixed alumina powder comprises:

dispersing the mixed alumina powder into a PEG 4000-ethanol solution having a concentration of 1% to 3% by weight, placing the obtained mixture into a ball-milling tank and performing ball-milling for 6 h to 24 h; and

adding the Al 2 O 3 -coated fluorescent powder into the ball-milling tank, and further performing ball-milling for 30 min to 60 min.

13. The method for preparing the ceramic composite material according to claim 1 , wherein the Al 2 O 3 -coated fluorescent powder accounts for 50% to 70% by weight of the mixed powder.