The pigment based on titanium dioxide reflective coatings

 

(57) Abstract:

The invention is intended for space applications and can be used to obtain aircraft. The pigment based on titanium dioxide contains granules of rutile. The particle size of 2.5 μm < < 6,0 µm, standard deviation S < 0,91 μm. The resistance to impact of electrons cosmic radiation increased 1.8 - 2.5 times. The change of the integral of the absorption coefficient as= 0,103 - 0,220. table 2.

The invention relates to a reflective pigments for coatings-class "solar reflectors and can be used in aircraft and space technology.

Known pigment based on titanium dioxide, to provide the best scattering of green light with a grain size of 0.25 μm [Belenky, E. F., Riskin N. In. Chemistry and technology of pigments. L.: Chemistry, 1960, 755 S.; Paints and coatings. Sat.under the editorship of R. Lambourne. S.-Petersburg, Chemistry, 1991, 351 S.]. However, particles of this size are less effective in scattering the yellow and red light and it is unknown how they behave under the action of electron radiation.

It is known [Grankin S. P., Mikhailov M. M. Kinetics of accumulation of color centers on the surface of rutile at all, S. 162-163] that during the grinding process the grinding particles fracture occurs by cleavage planes with more or less stable relations between elements TiO2so that the irradiation of electron flow are formed or F-centers, or ions Ti+3that also depends on the particle size of TiO2and the number of defects affects the spectrum of the diffuse reflection ().

Known pigment based on titanium dioxide, containing crystalline particles of rutile modification [Mikhailov, M. M., Butler, M. I. Kinetics of accumulation of color centers in rutile during electron irradiation. WPI.higher education institutions. Physics, 1983, No. 7, S. 30-34], selected as a prototype, and is not reflective coatings, the lack of which is the low resistance to the action of electrons in outer space.

The task is to increase the resilience of pigment TiO2to the action of electrons in outer space.

This technical result is achieved by the fact that the pigment based on titanium dioxide, containing crystalline particles of the rutile modification, according to the invention it contains grains and granules with an average size in the range of 2.5 < < 6,0 µm so that the average square discard the. It is known [Paints and coatings. Sat.under the editorship of R. Lambourne. S.-Petersburg, Chemistry, 1991, 351 S.] that the relative absorption coefficient (), is equal to the ratio

= K/S (1)

where K, S are the coefficients of volumetric absorption and scattering of light, respectively,

proportional to the inverse value of the average particle size of the powder of titanium dioxide.

But according to theory of Kubelka-Munch-Gurevich [Gurevich, M. M., Icko E. F., M. Seredenko, M. Optical properties of the coatings. - L.: Chemistry, 1984, 120 S.] the coefficient associated with the reflectance from the surface (R) ratio

< / BR>
therefore, with increasing r decreases, and the value of the integral coefficient of absorption of solar radiation (as) defined value

as= 1-R, (3)

while growing.

On the other hand changing asduring electron irradiation (as) is associated with volumetric defects [Grankin S. P., Mikhailov M. M. Kinetics of accumulation of color centers on the surface of rutile under electron irradiation. Sat.Physics of vacuum ultraviolet radiation and its interaction with matter. - M.: 1991, S. 162-163], depending on the magnitude of the specific surface (Sbeatsor sizes cha is e as.

The communication medium size particles and Sbeatsis [Gurevich, M. M., Icko E. F. , M. Seredenko, M. Optical properties of the coatings. - L.: Chemistry, 1984, 120 S.]

< / BR>
where A is a coefficient;

- the density of the powder.

Therefore, when the reduction in the average particle size of asshould increase.

Thus, the same parameter r acts simultaneously on two factors: factor and Sbeatsthat lead to the increase of asand between the two maximum values should be the minimum.

These provisions are explained in the following experimental results.

As pigment we have chosen titanium dioxide qualification OFS brands P10. Measure resistance to radiation is the change of the integral of the absorption coefficient asdefined by the expression

as= ask-aso, (5)

where ask, aso- the final and initial values of the absorption coefficient, defined by the formula (3).

The magnitude of the reflection coefficient R was determined by integrating the spectral dependence of the[Kositsyn L. G., Mikhailov, M. M., Kuznetsov N. I., Butler, M. I. Setup to study spectravoice "Range-1". The electron energy was 30 Kev, the flux - 41016cm-2.

Experimental values of aspigment TiO2separated into fractions, after electron irradiation are presented in table 1.

The average size of the original fraction was = 2,65-1.7 mm, so if the allocation fractions has been a narrowing of the distribution function particle (S < 0,91 μm), which led to a more dense and uniform structure of the powder.

Thus, neither small fraction of 0.25 μm or a large fraction of 7.5 μm does not give the desired result of increasing resistance to electrons, and the optimal size allow you to increase the resistance to the action of electrons cosmic radiation 1.8-2.5 times (experience N 4 PL. 1).

The method of separation of particles into fractions described in [Pavlushkin N. M. and other workshop on the technology of glass and metals. - M.: stroiizdat, 1970, 510 S.] and consists in the following. When shaking the powder in the vessel with water (capacity 3 l) formed suspension, particles which seacadets to the bottom according to Stokes ' law. With a pipette at risk with an installed depth over time, calculated by the formula

< / BR>
where is the viscosity;

is the density;

t - time;

h - the height (depth) systems by evaporation of the solution. The original data are presented in table 2.

The particle size of the powder was determined by the method of hooking under the microscope by measuring 150 to 200 grains. The average size was calculated by the formula

< / BR>
and standard deviation - expression [J. Squires. Practical physics. - M.: Mir, 1971, 246 S.]

e

The pigment based on titanium dioxide reflective coatings containing crystalline particles of rutile, characterized in that it contains grains and granules having an average particle size of 6.0 μm > > 2.5 μm, while the standard deviation S < 0,91 μm.

 

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12 cl, 4 ex

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4 cl, 2 dwg, 3 tbl

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1 tbl

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24 cl, 4 ex

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1 dwg, 1 tbl

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