Micron-Tourmaline Coated With ZnO: Preparation And Its Electromagnetism Shield Capability Study

As part of the project of National Natural Science Foundation of China (No. 40172104)–"Tourmaline Spontaneous Polarizing Mechanism and Its Environment-purifying Ability Research",this dissertation gives a deeply research on tourmaline electromagnetic characteristics, which is based on a huge amount of material analysis for a three- year study from 2002 to 2005. The research work aims to enhance the electromagnetic shielding capability of tourmaline powder by having micron tourmaline coated with active zinc oxide.Through the test on crushed tourmaline crystals, the author studied the surface electric property of micron tourmaline, analyzed inorganic material coating theory, and established a reasonable coating-experiment process. The author carried out these experiments to test the physical characteristics of final coated powders, which included infrared spectrum (FTIR) test, X-ray photoelectron spectrum (XPS) test, X-ray diffraction (XRD) test, electronics microscope scanning (SEM) test, electromagnetic shielding test, and parameters of microwave absorbing test, etc. Through contrast studies and comparative analysis among final coated powders, tourmaline powders and common zinc oxide powders, the author determined their electromagnetic shielding capabilities and microwave absorbing performances.The results of experiments have directly revealed the piezoelectric effect of tourmaline crystal: the superficial static voltage will gradually increase with the pressure growing on top and bottom of tourmaline crystal; the surface electricity property of micrometer tourmaline powder will gradually reduce from positive value to negative value with the increasing of solution pH value. According to the feasible experiment process and coating principle analysis, the author makes an experimental research on micron-tourmaline coated with active zinc oxide, tests and analyzes the microwave absorbing and damping performances of tourmaline and its powders coated with active zinc oxide.It is suggested that the superficial static voltage between top and bottom of tourmaline crystal will reach its maximum (the maximum range: 7~51mV, the average value: 18.9mV) when it is enduring its ultimate pressure, i.e., it is just at the critical point of breaking into pieces. Such piezoelectric effect also exists on the cylinder of tourmaline crystal, its maximum superficial static voltage is 5~9 mV, that is 1/3~1/4 of the strongest static voltage on its ends.The testing on the surface electricity property of micrometer tourmaline powder demonstrates that the electric point of dravite is 5.38, and the tourmaline powder particle is electronegative under neutral conditions, as the metal ions on surface will release themselves into the solution, while the zinc oxide powder particle is...