METHOD FOR COATING METAL NANOPARTICLES ON OXIDE CERAMIC POWDER SURFACE

Abstract

The present invention discloses a method for uniformly coating metal nanoparticles without a carbon impurity on an oxide ceramic powder surface, which includes the steps of putting grinded and mixed a metal organic material and oxide ceramic powder into a rotational reaction chamber, then bubbling oxidizing gas under a rotational and heating condition to oxidize the metal organic material into a metal oxide, and finally bubbling reducing gas to reduce the metal oxide into nanoparticles in a metallic state, so as to implement the uniform coating of the nanoparticles in the metallic state, and avoid coarsening and growing problems of nanoparticles led by a long-term coating reaction under a high temperature. The present invention has a simple method and a short preparation period, and the metal nanoparticles prepared are uniformly dispersed and have wide application prospects in multiple fields like catalytic materials and conductive ceramics.

Claims

1. A method for coating metal nanoparticles on an oxide ceramic surface, comprising the following steps of: (1) blending oxide ceramic powder and a metal organic material according to a weight ratio of (1:1)(10:1), obtaining blended powders through grinding and mixing the materials for 1-3 h, putting the grinded and blended powder into a rotational reactor, and starting up the rotational reactor to make the rotational reactor rotate, wherein the metal organic material is a stable organometallic compound formed by bonding an alkyl group or an alkyl of an aryl with a metal atom; (2) bubbling mixed gas of oxygen and argon into the rotational reactor, keeping the temperature for 0.5-2 h after warning up to 400-500° C. at a rate of 5-10° C./min to oxidize the metal organic material into a metal oxide, and then closing a gas inlet valve for oxygen and argon; and (3) bubbling reducing gas into the rotational reactor to reduce the metal oxide in step (2) into nanoparticles in a metallic state, cooling at a rate of 5-10° C./min in the meanwhile, closing a gas inlet valve for reducing gas after cooling the temperature to a room temperature, stopping the rotation of the rotational reactor, opening the reactor, taking the powder out, sieving and collecting the powder.

2. The method according to claim 1, wherein the oxide ceramic powder is any one of Al.sub.2O.sub.3, ZrO.sub.2, SiO.sub.2, MgO and TiO.sub.2, with a particle size ranging from 100 nm to 100 μm, and a purity greater than 95%.

3. The method according to claim 1, wherein the metal organic material is any one of nickelocene, tetracarbonyl nickel and nickel acetate.

4. The method according to claim 1, wherein the metal organic material is Cu(DPM).sub.2.

5. The method according to claim 1, wherein the metal organic material is cobaltocene or hydroxyl cobalt.

6. The method according to claim 1, wherein the metal organic material is ferrocene.

7. The method according to claim 1, wherein a total pressure of the mixed gas of oxygen and argon bubbled in step (2) ranges from 200 to 1000 Pa, a partial pressure of the oxygen ranges from 50 to 200 Pa, and a rotation rate of the rotational reactor ranges from 15 to 60r/min.

8. The method according to claim 1, wherein the reducing gas in step (3) is any one of hydrogen, carbonic oxide and methane, and a partial pressure of the reducing gas ranges from 100 to 400 Pa.

9. The method according to claim 1, wherein the powder in step (3) is sieved for three times through a 50-200 mesh sieve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 is an X-ray diffraction diagram of Al.sub.2O.sub.3 powder coated with Ni nanoparticles in an embodiment 1: (a) before coating, and (b) after coating;

[0020] FIG. 2 is a transmission electron microscope photo of the Al.sub.2O.sub.3 powder coated with Ni nanoparticles in the embodiment 1;

[0021] FIG. 3 is an X-ray diffraction diagram of ZrO.sub.2 powder after being coated with Ni nanoparticles in a embodiment 3; and

[0022] FIG. 4 is a transmission electron microscope photo of the ZrO.sub.2 powder coated with Ni nanoparticles in the embodiment 3.

DETAILED DESCRIPTION

[0023] The followings are preferred embodiments of the invention, which are illustrative of the invention and are not construed as limiting the invention, and all improvements made according to the description fall within the protection scope as defined in the appended claims of the invention.

[0024] Embodiment 1 Coat Ni nanoparticles on Al.sub.2O.sub.3 powder surface.

[0025] Firstly, 5 g ordinary commercial Al.sub.2O.sub.3 powder (the particle size was 500 nm) and 0.5 g Ni(CO).sub.4 were mixed firstly, put into a rotational reactor, and then the reactor was rotated at a rotational rate of 45r/min. Mixed gas of oxygen and Ar was bubbled, wherein a total pressure of the mixed gas was 1000 Pa and a partial pressure of the oxygen was 100 Pa. The temperature was kept for 45 min after warming up to 450° C. at a heating rate of 8° C./min, so that Ni(CO).sub.4 was oxidized into nickel oxide, then an oxygen supply valve was closed, and carbonic oxide was bubbled to reduce the metal oxide (nickel oxide) into nanoparticles in a metallic state. A partial pressure of the carbonic oxide was 200 Pa, the reduction reaction time was 45 min, and then the temperature was cooled at a cooling rate of 8° C./min. The gas valve was closed after the temperature was cooled to a room temperature, the rotation and heating of the reactor were stopped, then the reactor was opened, the powder was taken out, sieved for three times by a 100 mesh sieve, and then collected. The collected powder was characterized, wherein the results were as shown in FIG. 1 and FIG. 2. Wherein, FIG. 1 was an X-ray diffraction diagram of Al.sub.2O.sub.3 powder coated with Ni nanoparticles in the embodiment 1. Wherein a illustrated a condition before coating, and b illustrated a condition after coating, which proved that the Al.sub.2O.sub.3 powder was successfully coated with Ni nanoparticles. FIG. 2 was a transmission electron microscope photo of the Al.sub.2O.sub.3 powder coated with Ni nanoparticles, and it may be seen from the figure that the Ni nanoparticles were uniformly coated on the Al.sub.2O.sub.3 powder surface.

[0026] Embodiment 2 Coat Cu nanoparticles on Al.sub.2O.sub.3 powder surface.

[0027] Firstly, 5 g ordinary commercial Al.sub.2O.sub.3 powder (the particle size was 100 nm) and 2 g Cu(DPM).sub.2 (copper dipivaloylmethanate) were mixed firstly, put into a rotational reactor, a feeding valve of the rotational reactor was closed, and the rotational reactor was started up to rotate at a rotational rate of 60r/min. Next, mixed gas of oxygen and argon gas was bubbled, wherein a total pressure of the mixed gas was 800 Pa and a partial pressure of the oxygen was 50 Pa. A heating rate was set as 5° C./min, the temperature was kept for 60 min after warming up to 400° C., so that Cu(DPM).sub.2 was oxidized into cupric oxide, then an oxygen supply valve was closed, and methane was bubbled to reduce a metal oxide CuO into nanoparticles in the metallic state. A partial pressure of the methane was 100 Pa, the reduction reaction time was 60 min, and then the temperature was cooled at a cooling rate of 5° C./min. A carbonic oxide inlet valve and an argon gas inlet valve were closed after the temperature was cooled to a room temperature, the rotation and heating of the reactor were stopped, then the reactor was opened, the powder was taken out, sieved for three times by a 200 mesh sieve, and then collected.

[0028] Embodiment 3 Coat Ni nanoparticles on ZrO.sub.2 powder surface.

[0029] Firstly, 5 g ordinary commercial ZrO.sub.2 powder (the particle size was 10 μm) and 5 g NiCp.sub.2 (nickelocene) were blended, put into a rotational reactor, and then the reactor was rotated at a rotational rate of 15r/min. Mixed gas of oxygen and Ar was bubbled, wherein a total pressure of the mixed gas was 800 Pa and a partial pressure of the oxygen was 200 Pa. The temperature was kept for 30 min after warming up to 450° C. at a heating rate of 7° C./min, so that NiCp.sub.2 was oxidized into NiO, then an oxygen supply valve was closed, and hydrogen was bubbled to reduce a metal oxide NiO into nanoparticles in a metallic state. A partial pressure of the hydrogen was 400 Pa, the reduction reaction time was 30 min, and the temperature was cooled at a cooling rate of 7° C./min. The gas valve was closed after the temperature was cooled to a room temperature, the rotation and heating of the reactor were stopped, then the reactor was opened, the powder was taken out, sieved for three times by a 100 mesh sieve, and then collected. The collected powder was characterized, wherein the results were as shown in FIG. 3 and FIG. 4. Wherein, FIG. 3 was an X-ray diffraction diagram of ZrO.sub.2 powder coated with Ni nanoparticles, which proved that the ZrO.sub.2 powder was successfully coated with the Ni nanoparticles. FIG. 4 was a transmission electron microscope photo of ZrO.sub.2 powder coated with Ni nanoparticles, and it may be seen from the figure that the Ni nanoparticles were uniformly coated on the ZrO.sub.2 powder surface.

[0030] Embodiment 4 Coat Co nanoparticles on TiO.sub.2 powder surface.

[0031] Taking a TiO.sub.2 powder surface coated with Co nanoparticles for example, 5 g ordinary commercial TiO.sub.2 powder (the particle size was 50 μm) and 2 g CoCp.sub.2 (Cobaltocene) were mixed firstly, put into a rotational reactor, and then the reactor was rotated at a rotational rate of 60r/min. Mixed gas of oxygen and Ar was bubbled, wherein a total pressure of the mixed gas was 200 Pa and a partial pressure of the oxygen was 50 Pa. The temperature was kept for 15 min after warming up to 400° C. at a heating rate of 10° C./min, so that CoCp.sub.2 was oxidized into cobaltous oxide, then an oxygen supply valve was closed, and methane was bubbled to reduce a metal oxide (cobaltous oxide) into nanoparticles in a metallic state. A partial pressure of the methane was 100 Pa, the reduction reaction time was 15 min, and then the temperature was cooled at a cooling rate of 10° C./min. The gas valve was closed after the temperature was cooled to a room temperature, the rotation and heating of the reactor were stopped, then the reactor was opened, the powder was taken out, sieved for three times by a 50 mesh sieve, and then collected.

[0032] Embodiment 5 the surface of SiO.sub.2 powder coated with Fe nanoparticles.

[0033] Taking a SiO.sub.2 powder surface coated with Fe nanoparticles for example, 5 g ordinary commercial SiO.sub.2 powder (the particle size was 100 μm) and 2 g FeCp.sub.2 (ferrocene) were mixed firstly, put into a rotational reactor, and then the reactor was rotated at a rotational rate of 60r/min. Mixed gas of oxygen and Ar was bubbled, wherein a total pressure of the mixed gas was 800 Pa and a partial pressure of the oxygen was 10 Pa. The temperature was kept for 30 min after warming up to 500° C. at a heating rate of 8° C./min, so that FeCp.sub.2 as oxidized into iron oxide, then an oxygen supply valve was closed, and carbonic oxide was bubbled to reduce iron oxide into nanoparticles in a metallic state. A partial pressure of the carbonic oxide was 200 Pa, the reduction reaction time was 30 min, and then the temperature was cooled at a cooling rate of 8° C./min. The gas valve was closed after the temperature was cooled to a room temperature, the rotation and heating of the reactor were stopped, then the reactor was opened, the powder was taken out, sieved for three times by a 50 mesh sieve, and then collected.

[0034] Embodiment 6 Coat Co nanoparticles on MgO powder surface.

[0035] Taking a MgO powder surface coated with Co nanoparticles for example, 6 g ordinary commercial MgO powder (the particle size was 50 μm) and 2 g CoCp.sub.2 (Cobaltocene)were mixed firstly, put into a rotational reactor, and then the reactor was rotated at a rotational rate of 60r/min. Mixed gas of oxygen and Ar was bubbled, wherein a total pressure of the mixed gas was 600 Pa and a partial pressure of the oxygen was 150 Pa. The temperature was kept for 20 min after warming up to 400° C. at a heating rate of 6° C./min, so that CoCp.sub.2 was oxidized into cobaltous oxide, then an oxygen supply valve was closed, and methane was bubbled to reduce a metal oxide Co.sub.2O.sub.3 into nanoparticles in a metallic state. A partial pressure of the methane was 100 Pa, the reduction reaction time was 15 min, and then the temperature was cooled at a cooling rate of 10° C./min. The gas valve was closed after the temperature was cooled to a room temperature, the rotation and heating of the reactor were stopped, then the reactor was opened, the powder was taken out, sieved for three times by a 50 mesh sieve, and then collected.

[0036] Embodiment 7 Coat Ni nanoparticles on SiO.sub.2 powder surface.

[0037] Taking a SiO.sub.2 powder surface coated with Ni nanoparticles for example, 5 g ordinary commercial SiO.sub.2 powder (the particle size was 100 μm) and 3 g Ni (CH.sub.3COO).sub.2.4H.sub.2O were mixed firstly, put into a rotational reactor, and then the reactor was rotated at a rotational rate of 50r/min. Mixed gas of oxygen and Ar was bubbled, wherein a total pressure of the mixed gas was 800 Pa and a partial pressure of the oxygen was 15 Pa. The temperature was kept for 30 min after warming up to 500° C. at a heating rate of 8° C./min, so that Ni (CH.sub.3COO).sub.2.4H.sub.2O was oxidized into nickel oxide, then an oxygen supply valve was closed, and carbonic oxide was bubbled to reduce the nickel oxide into nanoparticles in a metallic state. A partial pressure of the carbonic oxide was 200 Pa, the reduction reaction time was 30 min, and then the temperature was cooled at a cooling rate of 8° C./min. The gas valve was closed after the temperature was cooled to a room temperature, the rotation and heating of the reactor were stopped, then the reactor was opened, the powder was taken out, sieved for three times by a 50 mesh sieve, and then collected.