| Since the 80's of last century, the ecologic environment that mankind depend on has attracted the attention of all counties all over the world. Mr. Scotto and other scientists from the United States have established a lot of ground observation spots to measure ultraviolet and the results indicate that the quantity of ultraviolet has obviously increased with great impact on the ecologic environment and the health of mankind. Along with the increase of people's health consciousness, learners of materials science circles at home and abroad are more and more concerned with the shielding of ultraviolet. Most of the traditional ultraviolet (UV)-shielding agents, such as benzophenone, benzotriazole and salicylate, are organic compounds, which can only shield short UV waves and be easily decomposed, resulting in certain toxicity. Their shielding property will be gradually decreased with the increase of the time the coated layers are exposed to sunshine and will not work finally. With the development of nano- material technology, one of the most concerned materials researches is on applying the nano-inorganic particles with ultraviolet shielding property as ultraviolet shielding additives. In recent years, some inorganic particles, such as nano-zinc oxide, nano-titanium oxide , iron oxide red and etc., are widely used as ultraviolet shielding agents because they are of high chemical stability, thermal stability, none migratory characteristic, no flavor, innocuity, no stimulation and more safety. Most widely used are nano-zinc oxide and nano-titanium oxide, which are white and easily colored with valuable properties of strong ultravioletabsorbing ability, shielding both UVA and UVB and high visible light transmission. Therefore, the ultraviolet shielding inorganic agents, nano-zinc oxide and nano-titanium oxide, have been extensively used in all kinds of daily consumed chemical products, gradually replacing some organic ultraviolet shielding agents. At present, the research is mainly directed on the preparation of ultraviolet shielding mono- powders.Although nano-zinc oxide and nano-titanium oxide are both good for shielding ultraviolet, ultraviolet shielding ability of nano-titanium oxide in UVA is not as good as that of nano-zinc oxide while ultraviolet shielding ability of nano-titanium oxide in UVB is much better than that of nano-zinc oxide. It can be expected that a broad-spectrum ultraviolet shielding agent with better property may be prepared by combining the advantages of nano-zinc oxide and nano-titanium oxide. The research and application of nano-zinc oxide and nano-titanium oxide composite powders becomes a new and challenging task with a bright future.This paper has summarized the preparation of nanometer TiCVZnO composite powders and their UV-shielding abilities. The nanometer TifVZnO composite powders are prepared by using titanic hydroxide and zinc chloride as raw materials, and their ultraviolet shielding abilities have been studied and compared with that of nano-TiO2 and nano-ZnO mono- powders. Experiment and research mainly consist of three parts: (1) prepare nanometer TiCVZnO composite powders and study the impact of pH values, varieties and quantities of additives and molar ratios of Zn2+/Ti4+ on the particle sizes of nanometer TifVZnO composite powders; (2) probe the ultraviolet shielding function of nanometer TiCVZnO composite powders and study the influence of particle sizes, molar ratios of Zn2+/Ti4+ and calcinations temperatures on the ultraviolet shielding function of nanometer TitVZnO composite powders; (3) compare the ultraviolet shielding function of nano- TiCVZnO composite powders with that of mono- nano- TKVZnO powders and mechanically mixed powders. The conclusion is as follows: (1) If the composite powders have similar components, the ultraviolet shielding function improves with the diminishing of particle sizes ranging from 40nm to 130nm. (2) Based on the properties of mono-TiO2 powders and ZnO powders, the sample with lower Zn2+/Ti4+ molar ratio presents much better ultraviolet shielding result when the ultraviolet wavelength is shorter than 350nm, while the sample with higher Zn2+/Ti4+ molar ratio presents much better ultraviolet shielding result when the ultraviolet wavelength is longer than 350nm. When molar ratio of Zn +/Ti + is 1:1, nanometer TiCb/ZnO composite powders can effectively attenuate ultraviolet for both UVA and UVB. (3) Because the increase of calcination temperature will lead to the change of components and particle sizes of nanometer TifVZnO composite powders, the calcination temperature consequentially influences the ultraviolet shielding property of composite powders. The ultraviolet shielding function of nanometer IK^/ZnO composite powders is outstanding when reaction pH is 7, quantity of PEG400 is lml, molar ratio of Zn2+/Ti4+ is 1:1 and the calcination temperature is 800 °C. Through experiments, we have prepared a broad spectrum ultraviolet shielding agent with excellent property out of nanometer Ti02/ZnO composite powders. Its particle size (D50) is about 63nm and it can shield more than 90% ultraviolet.The preparation technology of nanometer Ti02/ZnO composite powders is not complicated and the cost of preparation is not high either. The nano- Ti02/ZnO composite powders are of excellent ultraviolet shielding property, innocuity, no harm and no pollution. Therefore, nanometer Ti02/ZnO composite powders have shown a very bright application future in respect of the fields such as paint industry, cosmetic industry and food industry and etc.
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