Abstract The effect of modification with Al2O3 nanoparticles (1-10 wt.%) on the reflection spectra of BaSO4 powders in the range of 0.2-2.2 μm and integral absorption coefficient of solar radiation (as) was studied. With a lower reflectivity of Al2O3 nanoparticles in comparison with BaSO4 powder, its increase in the entire range of the solar spectrum in the modified powder was obtained. The modification efficiency, determined by the ratio of the absorption coefficient as of the unmodified and modified powders, is 1.77 times at the optimum concentration of nanoparticles equals 5 wt.%. The determining factor of such increase was experimentally established – that is the change in the size and concentration of grains and granules of BaSO4 powder during modification. The obtained results were compared with the results of BaSO4 powder modification by SiO2 nanoparticles. The achieved effect is a significant result for spacecraft, in which BaSO4 powders can be used as a pigment for thermal control coatings of the "optical solar reflectors" class.

中文翻译：

---

Al2O3纳米颗粒改性对提高BaSO4颜料反射率的影响

摘要 研究了Al2O3 纳米颗粒(1-10 wt.%) 改性对0.2-2.2 μm 范围内BaSO4 粉末的反射光谱和太阳辐射积分吸收系数(as) 的影响。与 BaSO4 粉末相比，Al2O3 纳米粒子的反射率较低，因此在改性粉末的整个太阳光谱范围内都得到了增加。改性效率由未改性和改性粉末的吸收系数之比决定，在纳米粒子的最佳浓度等于 5 wt.% 时为 1.77 倍。这种增加的决定因素是通过实验确定的——即改性过程中 BaSO4 粉末的晶粒和颗粒的大小和浓度发生了变化。所得结果与SiO2纳米颗粒对BaSO4粉体改性的结果进行了比较。取得的效果对于航天器来说是一个重要的结果，其中 BaSO4 粉末可以用作“光学太阳能反射器”类热控制涂层的颜料。