Study On The Preparation And Infrared Radiation Porperties Of Tourmaline/Al₂O₃ Composite Materials

Because of its unique polarity structure, tourmaline has thermoelectric, piezoelectric properties, and can emit infrared rays, which can be widely used in areas such as environmental protection and human health. Compounding tourmaline and nanometer Al₂O₃ particles by some techniques, we can fabricate tourmaline/Al₂O₃ composite materials whose infrared radiation property can be enhanced. Therefore, it is theoretically and practically significant for utilizing tourmaline.A variety of methods are utilized to test the mineralogy characteristic of the pink tourmaline from Lushi, Henan Province. We also studied the electrical effects of tourmaline. Using Henan pink tourmaline as the main raw material, we fabricated the tourmaline/Al₂O₃ composite materials by chemical deposition and mechanochemical method respectively. In order to obtain the optimal experimental scheme, we discussed the main factors affecting experimental process, and characterized the composite particles. To explore the infrared radiation mechanism of composite materials, we studied the infrared radiation of nano-composite powders, which have been fabricated by various conditions. The main conclusions are as follows:The pink tourmaline from Lushi, Henan Province is lithium tourmaline. Tourmaline's piezoelectricity is related with the radius d of Y ionic at main positions and the electric charge q, that is, the piezoelectricity is enhanced with increasing d and q. The crystal pyroelectricity is positively correlated with dielectricity at normal temperature, but it was negatively correlated with the iron element. The order of pyroelectric function is: Henan lithium tourmaline>Yunnan lithium tourmaline >Hebei magnesium Tourmaline.According to the absorption match theory, tourmaline's radiation wavelength is well corresponding with the body's absorption of radiation wavelength (9.53-9.47μm), so it is good to human's health. The infrared emissive order of tourmaline is: iron tourmaline > magnesium tourmaline > lithium tourmaline. Because of its minimum charge and smallest dipole moment, lithium tourmaline has relatively minimal infrared radiation rate. The infrared emission of tourmaline depends on the change in dipole moment and the infrared vibration intensity.The experimental scheme of fabricating tourmaline/Al₂O₃ composite particles by chemical deposition is as follows: Al(NO₃)₃ solution concentration is 0.25mol/L; the rate of titrating ammonia is 10ml/min; the pH value is 9, and the temperature of cachinnating tourmaline/Al(OH)₃ precursor is 980℃. It shows that the tourmaline and Al₂O₃ in composite materials are in good crystal form by XRD and SEM analysis. It is calculated that the average diameter of Al₂O₃ is 47.86nm, which means we have achieved the composite materials of micron tourmaline and nano-Al₂O₃. The maximum infrared radiation rate of tourmaline/Al₂O₃ composite powder which is produced by chemical deposition is 0.89 when the mix ratio of tourmaline and Al₂O₃ is 3:1. The infrared radiation rate has been increased by 0.03, compared with lithium tourmaline. The result caters the need of our experiments.The experimental scheme of fabricating tourmaline/Al₂O₃ composite particles by mechanochemical method is as follows: grinding time is one hour; grinding speed is 950r/min; grinding media is ceramic balls. It shows that the tourmaline and Al₂O₃ in composite materials are in good crystal form through XRD and SEM analysis. When the mix ratio of tourmaline and Al₂O₃ is 3:1, the maximum infrared radiation rate of tourmaline/Al₂O₃ composite powder which is produce by mechanochemical method is 0.89. The infrared radiation rate has been increased by 0.02, compared with lithium tourmaline. As the compounding intensity of composite materials fabricated by mechanochemical method is less than that fabricated by chemical deposition, the rate of infrared radiation is lower relatively.This research is funded by the National Natural Science Foundation of China"research of environment action mechanism on the compound particles of polar mineral tourmaline with the semiconductor oxide (ZnO, etc.)".