Spectral selective absorption thermal control filler and preparation method thereof

Abstract

The invention provides a spectrum selective absorption thermal control filler and a preparation method thereof, the chemical composition of the spectrum selective absorption thermal control filler is Ti < 1-x > MxO < 2-0.5 x >, M represents one or more of Gd, Yb and Ga, x is more than 0 and less than or equal to 0.5, and titanium dioxide and trivalent oxide powder are subjected to solid-phase synthesis in a high-temperature environment. Titanium oxide is doped with trivalent oxide, oxygen vacancies are introduced while lattice distortion is generated, lattice symmetry is reduced, carrier concentration is improved, an infrared absorption band is widened, low solar absorption ratio is kept while high emissivity is obtained, and selective absorption of spectrums is achieved; and the infrared emissivity at 600 DEG C can reach 0.80-0.85, the solar absorptivity is 0.20-0.35, and an excellent high-temperature heat dissipation effect is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of heat control fillers, and particularly relates to a spectrum-selective absorption heat control filler and a preparation method thereof. BACKGROUND

[0002] The heat control coating refers to a kind of special application coating prepared on the surface of a spacecraft, which can adjust the thermal and optical properties of the spacecraft and thus realize the effect of heat control. With the development of space technology, the sources of electric energy of the spacecraft become various, and one of the main sources is converted from heat energy. In order to realize the supply of electric energy of the spacecraft, the heat source device of the spacecraft needs to work for a long time under high load, which leads to the fact that the spacecraft faces extremely high temperature working conditions. In addition, the spacecraft needs to be irradiated by the sun for a long time when working in orbit, so that the surface temperature is increased. Therefore, the surface of the spacecraft needs a high-efficiency heat dissipation coating with high temperature resistance, low absorption and high emissivity, which can dissipate heat to the space environment through infrared radiation to ensure that the temperature of the spacecraft is within a reasonable range.

[0003] According to the law of blackbody radiation, the peak wavelength of infrared emissivity of a material moves to a short wave direction as the temperature increases, for example, the peak wavelength of blackbody radiation at 600 DEG C decreases from about 10 pm at room temperature to about 3 pm, which overlaps with the solar absorption spectrum range to a certain extent, and the overlapping range increases as the temperature increases. The infrared radiation ability of a material depends on the absorption ability of the spectrum, which leads to the fact that the coating with high emissivity at high temperature often has high solar absorption ratio at the same time, which deteriorates the heat dissipation ability of the coating at high temperature. The commonly used high emissivity materials are added with Fe2O3, MnO2, Cr2O3, NiO and other oxides, so that the coating presents black color and absorbs the spectrum in the ultraviolet-visible and near-infrared wave bands, that is, has high solar absorption ratio.

[0004] Therefore, it is necessary to develop a new spectrum-selective absorption heat control filler, which selectively absorbs the spectrum energy in the near-infrared wave band, increases the absorption rate in the near-infrared wave band, reduces the spectrum absorption in the ultraviolet-visible wave band, reduces the solar absorption ratio, and thus improves the heat dissipation ability of the coating at high temperature. SUMMARY

[0005] In order to overcome the deficiencies in the prior art, the present application provides a spectrum-selective absorption heat control filler and a preparation method thereof, which solve the problem that the solar absorption ratio of the traditional high emissivity coating is high and the heat dissipation ability of the coating is significantly deteriorated.

[0006] The technical scheme provided by the present application is as follows:

[0007] In a first aspect, a spectrum-selective absorption heat control filler is provided, and the chemical composition of the spectrum-selective absorption heat control filler is Ti 1-x M x O2-0.5x M represents one or more of Gd, Yb, Ga, and 0 < x < 0.5.

[0008] In a second aspect, a method for preparing a spectrum-selective absorption thermal control filler includes the following steps:

[0009] Dry titanium dioxide and trivalent oxide powder are weighed according to stoichiometric ratio, and the trivalent oxide powder is one or more of gadolinium oxide, ytterbium oxide and gallium oxide powder;

[0010] The titanium dioxide and trivalent oxide powder are added into a ball mill tank, and the slurry is dried after ball milling, and the dried powder is sieved to obtain a powder with uniform particle size;

[0011] The sieved powder is subjected to solid-phase synthesis at high temperature, and is cooled in the furnace after heat preservation;

[0012] The powder after solid-phase synthesis is ground and ball milled, and the slurry is dried after ball milling, and the dried powder is sieved to obtain a spectrum-selective absorption thermal control filler.

[0013] In a third aspect, a thermal control coating includes the spectrum-selective absorption thermal control filler of the first aspect.

[0014] In a fourth aspect, a thermal control coating layer is formed by spraying the thermal control coating of the third aspect.

[0015] The spectrum-selective absorption thermal control filler and the preparation method thereof provided by the present application have the following beneficial effects:

[0016] (1) The spectrum-selective absorption thermal control filler and the preparation method thereof provided by the present application utilize trivalent oxide to dope titanium oxide, introduce oxygen vacancies while producing lattice distortion, reduce the lattice symmetry, increase the carrier concentration, and widen the infrared absorption spectrum band, thereby achieving spectrum-selective absorption while maintaining low solar absorption ratio and obtaining high emissivity. The infrared emissivity at 600 DEG C can reach 0.80-0.85, and the solar absorption ratio is 0.20-0.35, which has excellent high-temperature heat dissipation effect.

[0017] (2) The spectrum-selective absorption thermal control filler and the preparation method thereof provided by the present application have simple and easy-to-implement preparation method, and are easy to be industrialized. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 TiO2 powder prepared for Example 3 0.5 (Gd 0.3 Yb 0.3 Ga 0.4 ) 0.5 O 1.75 Micro-morphology of the thermal control filler.

[0019] Figure 2 Ti prepared in Example 1 0.5 Gd 0.5 O 1.75 Emissivity curve of thermally controlled filler at 600℃.

[0020] Figure 3 Ti prepared in Example 2 0.5 (Gd 0.5 Yb 0.5 ) 0.5 O 1.75 Emissivity curve of thermally controlled filler at 600℃.

[0021] Figure 4 Ti prepared in Example 3 0.5 (Gd 0.3 Yb 0.3 Ga 0.4 ) 0.5 O 1.75 Emissivity curve of thermally controlled filler at 600℃. Detailed Implementation

[0022] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0023] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0024] This invention provides a spectrally selective absorption thermal control filler with a chemical composition of Ti. 1-x M x O 2-0.5x M represents one or more of Gd, Yb, and Ga, and 0 < x ≤ 0.5, which is called multi-doped titanium oxide.

[0025] In a preferred embodiment, the chemical composition of the spectrally selective absorption thermal control filler is Ti. 1- x Gd x O 2-0.5x , 0 < x ≤ 0.5.

[0026] In a preferred embodiment, the chemical composition of the spectrally selective absorption thermal control filler is Ti. 1- x Yb x O 2-0.5x , 0 < x ≤ 0.5.

[0027] In a preferred embodiment, the chemical composition of the spectrally selective absorption thermal control filler is Ti. 1-x Ga x O 2-0.5x 0 < x < 0.5.

[0028] In a preferred embodiment, the chemical composition of the spectrally selective absorbing thermal control filler is Ti 1-x (Gd y Yb 1-y ) x O 2-0.5x 0 < x < 0.5, 0 < y < 1.

[0029] In a preferred embodiment, the chemical composition of the spectrally selective absorbing thermal control filler is Ti 1-x (Gd y Ga 1-y ) x O 2-0.5x 0 < x < 0.5, 0 < y < 1.

[0030] In a preferred embodiment, the chemical composition of the spectrally selective absorbing thermal control filler is Ti 1-x (Yb y Ga 1-y ) x O 2-0.5x 0 < x < 0.5, 0 < y < 1.

[0031] In a preferred embodiment, the chemical composition of the spectrally selective absorbing thermal control filler is Ti 1-x (Gd y Yb z Ga k ) x O 2-0.5x 0 < x < 0.5, 0 < y < 1, 0 < z < 1, 0 < k < 1, y + z + k = 1.

[0032] The present application also provides a preparation method of a spectrally selective absorbing thermal control filler, comprising the following steps:

[0033] S1: taking dry titanium dioxide and trivalent oxide powder, weighing according to the stoichiometric ratio, adding into a ball mill tank, taking deionized water as the ball milling medium, taking zirconium oxide balls as the grinding balls, ball milling mixing at 300-500 r / min for 8-12 h.

[0034] In this step, the trivalent oxide powder is one or more of gadolinium oxide (Gd2O3), ytterbium oxide (Yb2O3) and gallium oxide (Ga2O3) powder.

[0035] In the step, the mass ratio of the powder, the grinding ball and the deionized water is 1:(5-7):(3-5), the grinding ball is divided into three kinds of 10mm, 5mm and 2mm in diameter, and the mass ratio is 4:(2-4):(2-4).

[0036] S2: the slurry after ball milling is dried at 90-120 DEG C for 12-24h.

[0037] S3: the dried powder is sieved into small particle powder with uniform particle size by using a standard sieve of 100-400 mesh.

[0038] S4: the sieved powder is placed in an alumina crucible and put into a high-temperature furnace for solid-phase synthesis, the temperature is raised to high temperature at a rate of 1-3 DEG C / min, and then the furnace is cooled after a certain time of heat preservation.

[0039] In the step, the heat preservation temperature is 1300-1600 DEG C, and the heat preservation time is 12-24h.

[0040] S5: the powder after solid-phase synthesis is ground to a particle size of less than 1-3mm with a mortar, and then put into a ball mill tank, deionized water is used as the ball milling medium, and zirconia ball is used as the grinding ball, and the ball milling is carried out at 300-500r / min for 12-24h, so that the particle size of the powder after ball milling is 1-5um.

[0041] S6: the slurry after ball milling is dried at 90-120 DEG C for 12-24h.

[0042] S7: the dried powder is sieved into small particle powder with uniform particle size by using a standard sieve of 100-400 mesh, and a spectrum selective absorption heat control filler is obtained.

[0043] The present application dopes titanium dioxide with trivalent oxide, introduces oxygen vacancies at the same time of introducing lattice distortion, reduces the lattice symmetry, improves the carrier concentration, widens the infrared absorption spectrum band, maintains low solar absorption ratio while obtaining high emissivity, realizes spectrum selective absorption, and meets the high temperature heat dissipation demand of a spacecraft.

[0044] The band gap width of the heat control coating filler determines the selective range of the heat control coating to the sunlight spectrum, and high band gap width is beneficial to improve the reflection performance in the ultraviolet-visible light band. For the heat control coating applied in a space environment, the space high-energy particles have irradiation damage effect on the heat control filler, and the main action mechanism is ionization and displacement damage, and high band gap width and few energy levels are beneficial to improve the ionizing radiation stability of the material and improve the space environment temperature of the coating.

[0045] Both rare earth oxides and gallium oxide are high band gap materials, and the use of rare earth oxides and gallium oxide in the thermal control coating system can significantly improve the ultraviolet reflectivity of the coating and the ionizing radiation stability of the coating, reduce the solar absorptance of the coating, and improve the space environment stability. However, the inner electrons of some rare earth ions will transition from the ground state to the excited state, causing absorption in the visible and infrared regions and reducing the reflectivity. Yb2O3 and Gd2O3 have only a small number of energy levels in the 250-2500 nm energy range, and the absorption of the solar spectrum is low. 3+ The electronic configuration of Gd is 4f 7 , which belongs to the half-full state (7 spin-parallel unpaired electrons in the f orbital), which meets the Hund rule, has the lowest energy and is highly stable, has no energy level transition in the visible region, has high ionizing radiation stability, and has low absorption of the visible solar spectrum. The effectiveness of high-energy neutron radiation-resistant materials is proportional to the atomic number of the material. Among commonly used rare earth elements, Yb has the largest atomic number and good space environment stability. Therefore, the use of gadolinium oxide, ytterbium oxide and gallium oxide in the thermal control coating system can improve the infrared absorption, reduce the solar absorptance, and improve the space environment stability.

[0046] The thermal control filler provided by the application has high high-temperature emissivity and low solar absorptance, and can be used for the thermal protection of the hot end parts of a spacecraft and an aero-engine. The powder can be directly used to prepare a thermal control coating by air spraying, or can be used as a raw material for preparing a thermal control coating by thermal spraying after being spray granulated.

[0047] Examples

[0048] Example 1 Ti 0.5 Gd 0.5 O 1.75 Preparation of thermal control fillers

[0049] S1: 61.2g of dry titanium dioxide powder (containing 0.77mol of Ti atoms) and 138.8g of gadolinium oxide powder (containing 0.77mol of Gd atoms) were taken and added to a ball mill jar, 800g of deionized water, 400g of 10mm zirconia grinding balls, 300g of 5mm zirconia grinding balls, and 300g of 2mm zirconia grinding balls were added, and the mixture was ball milled at a speed of 400r / min for 12h;

[0050] S2: The slurry after ball milling was dried in an oven at 120℃ for 12h;

[0051] S3: The dried powder was sieved into small granular powder with a uniform particle size by using a 200 mesh standard sieve;

[0052] S4: The sieved powder was placed in an alumina crucible and put into a high-temperature furnace for solid phase synthesis, and the temperature was raised to 1400℃ at a rate of 1-3℃ / min, and then the furnace was cooled after being kept for 12h.

[0053] S5: The powder after solid phase synthesis is ground in a mortar to a particle size of less than 2 mm, added to a ball mill tank, 800 g of deionized water, 400 g of 10 mm zirconia grinding balls, 300 g of 5 mm zirconia grinding balls, and 300 g of 2 mm zirconia grinding balls are added, and ball milling is carried out for 8-12 h at a rotation speed of 400 r / min for 12 h;

[0054] S6: The slurry after ball milling is dried in an oven at 120°C for 12 h;

[0055] S7: The dried powder is sieved into small particle size powder with uniform particle size using a 200 mesh standard sieve to obtain Ti 0.5 Gd 0.5 O 1.75 thermal control filler. The prepared Ti 0.5 Gd 0.5 O 1.75 thermal control filler has a particle size of about 1-5 μm, a solar absorption ratio of 0.30, and an emissivity of 0.81 at 600°C, and the emissivity curve is shown in Figure 2 .

[0056] Ti 0.5 Ga 0.5 O 1.75 thermal control filler is prepared by the same method, and has a solar absorption ratio of 0.20 and an emissivity of 0.80 at 600°C.

[0057] Ti 0.5 Yb 0.5 O 1.75 thermal control filler is prepared by the same method, and has a solar absorption ratio of 0.35 and an emissivity of 0.82 at 600°C.

[0058] Example 2 Ti 0.5 (Gd 0.5 Yb 0.5 ) 0.5 O 1.75 Preparation of thermal control fillers

[0059] S1: Dry titanium dioxide powder 59.4 g (containing Ti atoms 0.74 mol), gadolinium oxide powder 67.4 g (containing Gd atoms 0.37 mol), and ytterbium oxide powder 73.2 g (containing Yb atoms 0.37 mol) are taken and added to a ball mill tank, 800 g of deionized water, 400 g of 10 mm zirconia grinding balls, 300 g of 5 mm zirconia grinding balls, and 300 g of 2 mm zirconia grinding balls are added, and ball milling is carried out for 8-12 h at a rotation speed of 400 r / min for 12 h;

[0060] S2: The slurry after ball milling is dried in an oven at 120°C for 12 h;

[0061] S3: The dried powder is sieved into small particle size powder with uniform particle size using a 200 mesh standard sieve;

[0062] S4: The sieved powder is placed in an alumina crucible and put into a high-temperature furnace for solid-phase synthesis, heated to 1400℃ at a heating rate of 1-3℃ / min, kept for 12h, and then cooled with the furnace;

[0063] S5: The powder after solid-phase synthesis is ground to a particle size of less than 2mm with a mortar, added into a ball mill tank, added with 800g of deionized water, 400g of 10mm zirconia grinding balls, 300g of 5mm zirconia grinding balls, and 300g of 2mm zirconia grinding balls, ball-mixed for 8-12h, and ball-milled at a rotating speed of 400r / min for 12h;

[0064] S6: The slurry after ball-milling and crushing is dried in an oven at 120℃ for 12h;

[0065] S7: The dried powder is sieved into small-particle powders with uniform particle size using a standard sieve of 200 mesh, to obtain Ti 0.5 Gd 0.5 O 1.75 thermal control filler. The prepared Ti 0.5 (Gd 0.5 Yb 0.5 ) 0.5 O 1.75 thermal control filler has a particle size of about 1-5μm, a solar absorption ratio of 0.31, and an emissivity of 0.82 at 600℃, and the emissivity curve is shown in Figure 3 .

[0066] Ti 0.5 (Gd 0.5 Ga 0.5 ) 0.5 O 1.75 thermal control filler is prepared by the same method, and has a solar absorption ratio of 0.28 and an emissivity of 0.82 at 600℃.

[0067] Ti 0.5 (Yb 0.5 Ga 0.5 ) 0.5 O 1.75 thermal control filler is prepared by the same method, and has a solar absorption ratio of 0.33 and an emissivity of 0.83 at 600℃.

[0068] Example 3 Ti 0.5 (Gd 0.3 Yb 0.3 Ga 0.4 ) 0.5 O 1.75 Preparation of thermal control fillers

[0069] S1: take dry titanium dioxide powder 69.2 g (containing Ti atom 0.87 mol), gadolinium oxide powder 47.1 g (containing Gd atom 0.26 mol), ytterbium oxide powder 51.2 g (containing Yb atom 0.26 mol), gallium oxide powder 32.5 g (containing Ga atom 0.35 mol), and add them to the ball mill tank, add 800 g of deionized water, 400 g of 10 mm zirconium oxide grinding balls, 300 g of 5 mm zirconium oxide grinding balls, 300 g of 2 mm zirconium oxide grinding balls, and ball mill for 8-12 h, ball mill at 400 r / min for 12 h;

[0070] S2: dry the slurry after ball milling in an oven at 120℃ for 12 h;

[0071] S3: use a 200 mesh standard sieve to sieve the dried powder into small particle powder with uniform particle size;

[0072] S4: place the sieved powder in an alumina crucible and put it into a high temperature furnace for solid phase synthesis, heat to 1400℃ at a heating rate of 1-3℃ / min, and keep for 12 h, then cool with the furnace;

[0073] S5: grind the powder after solid phase synthesis to a particle size of less than 2 mm with a mortar, add it to the ball mill tank, add 800 g of deionized water, 400 g of 10 mm zirconium oxide grinding balls, 300 g of 5 mm zirconium oxide grinding balls, and 300 g of 2 mm zirconium oxide grinding balls, and ball mill for 8-12 h at 400 r / min;

[0074] S6: dry the slurry after ball milling in an oven at 120℃ for 12 h;

[0075] S7: use a 200 mesh standard sieve to sieve the dried powder into small particle powder with uniform particle size, and obtain Ti 0.5 Gd 0.5 O 1.75 Thermal control filler, micro-morphology is shown in Figure 1 .

[0076] After testing, the prepared Ti 0.5 (Gd 0.3 Yb 0.3 Ga 0.4 ) 0.5 O 1.75 Thermal control filler, particle size is about 1-5 μm, solar absorption ratio is 0.32, and emissivity at 600℃ is 0.84, and the emissivity curve is shown in Figure 4 .

[0077] The present application is described in detail above in connection with specific embodiments and exemplary examples, but the description is not to be construed as limiting the present application. Those skilled in the art will understand that various equivalents to the described techniques and embodiments herein can be made in light of the spirit and scope of the present application, and that the scope of the present application is defined by the appended claims.

[0078] The contents not described in detail in the specification of the present application are known to those skilled in the art.

Claims

1. A spectrally selective absorption thermal control packing, characterized in that, The chemical composition of the spectrally selective absorption thermal control filler is Ti. 1-x M x O 2-0.5x M represents one or more of Gd, Yb, and Ga, and 0 < x ≤ 0.

5.

2. The spectrally selective absorption thermal control packing according to claim 1, characterized in that, The chemical composition of the spectrally selective absorption thermal control filler is Ti. 1-x Gd x O 2-0.5x , 0 < x ≤ 0.

5.

3. The spectrally selective absorption thermal control packing according to claim 1, characterized in that, The chemical composition of the spectrally selective absorption thermal control filler is Ti. 1-x Yb x O 2-0.5x , 0 < x ≤ 0.

5.

4. The spectrally selective absorption thermal control packing according to claim 1, characterized in that, The chemical composition of the spectrally selective absorption thermal control filler is Ti. 1-x Ga x O 2-0.5x , 0 < x ≤ 0.

5.

5. The spectrally selective absorption thermal control packing according to claim 1, characterized in that, The chemical composition of the spectrally selective absorption thermal control filler is Ti. 1-x (Gd y Yb 1-y ) x O 2-0.5x , 0 < x ≤ 0.5, 0 < y < 1.

6. The spectrally selective absorption thermal control packing according to claim 1, characterized in that, The chemical composition of the spectrally selective absorption thermal control filler is Ti. 1-x (Gd y Ga 1-y ) x O 2-0.5x , 0 < x ≤ 0.5, 0 < y < 1.

7. The spectrally selective absorption thermal control packing according to claim 1, characterized in that, The chemical composition of the spectrally selective absorption thermal control filler is Ti. 1-x (Yb y Ga 1-y ) x O 2-0.5x , 0 < x ≤ 0.5, 0 < y < 1.

8. The spectrally selective absorption thermal control packing according to claim 1, characterized in that, The chemical composition of the spectrally selective absorption thermal control filler is Ti. 1-x (Gd y Yb z Ga k ) x O 2-0.5x , 0<x≤0.5, 0<y<1, 0<z<1, 0<k<1, y+z+k=1.

9. The method for preparing the spectrally selective absorption thermal control filler according to any one of claims 1 to 8, characterized in that, Includes the following steps: Weigh dry titanium dioxide and trivalent oxide powder according to stoichiometric ratio, wherein the trivalent oxide powder is one or more of gadolinium oxide, ytterbium oxide, and gallium oxide powder; Titanium dioxide and trivalent oxide powders are added to a ball mill jar, ball milled, and the slurry is dried. The dried powder is then sieved to obtain powder with uniform particle size. The sieved powder was subjected to solid-phase synthesis at high temperature, and then cooled in the furnace after heat preservation. The powder synthesized from solid phase is ground and ball-milled. After ball milling, the slurry is dried and the dried powder is sieved to obtain the spectrally selective absorption thermal control filler.

10. The method for preparing the spectrally selective absorption thermal control filler according to claim 9, characterized in that, The holding temperature during solid-phase synthesis is 1300–1600℃, and the holding time is 12–24 h.

11. A thermal control coating, characterized in that, It comprises the spectrally selective absorption thermal control filler as described in any one of claims 1 to 8.

12. A thermal control coating, characterized in that, The thermal control coating as described in claim 11 is used for spraying and forming.

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