| Negative thermal expansion (NTE) material becomes one of the most interesting research field in recent years, Among them,ZrW2O8 with excellent isotropic NTE property and low thermal expansion coefficient (-8.9×10-6K-1) over a wide temperature range has been dramatically studied. NTE materials and its composites have potential applications in microelectronic, micromechanic, optics, medicine materials, low temperature sensor, electric thermal couple daily necessaries and so on.According to the characteristics of ZrW2O8 that is metastable at room temperature and will decompose at 770℃,epoxy resin, ZrO2 and Cu were chosen as matrix to fabricate electronic packing composite materials with controllable thermal expansion coefficient in this thesis and the properties of the obtained composites were studied.Pure ZrW2O8 powders with linear thermal expansion coefficient of -5.33×10-6/K and average particle size of 0.5-1μm were synthesized via step-by-step solid state reaction method. ZrW2O8 and epoxy resin were used as raw materials to prepare electronic packing material, the uniformity of ZrW2O8 powders in the matrix was enhanced by ultrasonic wave treatment. The glass transition temperature and dielectric constant were increased with the increasing of the ratio of ZrW2O8 powders in the composite while the linear thermal expansion coefficient and dielectric loss were decreased. Electric resistant property was also studied and the results showed that the electrical resistivity of E-51/ZrW2O8 was stabilized at about 3.03×106Ω·m in the temperature range from room temperature to 163####.The breakdown strength of the obtained packing material was greater than 10KV/m at room temperature which meets the practical requirements of microelectronic packing material. The tensile strength,flexural strength and the microhardness of E-51/ZrW2O8 packing material have been enhanced with the increasing content of ZrW2O8.The tensile strength and flexural strength were 99MPa and 158Mpa, respectively, when the ratio of E-51 to ZrW2O8 was 1 to 1, while the optimal microhardness was obtained when the ratio of E-51 to ZrW2O8 was fixed at 1 to 0.7. The obtained packing materials have good waterlogging tolerance property.ZrO2/ZrW2O8 composite materials with different ratios were prepared by step-by-step in-situ solid-state reaction using analytically ZrO2 and WO3 as starting materials. ZrO2/ZrW2O8 composite with high purity can be obtained by sintering at 1125 to 1200℃for 6 hours Compared to the direct in-situ solid-state reaction, the reaction temperature was decreased, reaction time was reduced, and the average grain size of the sample was also decreased. The average thermal expansion coefficient of the composite with 25wt% ZrW2O8 was 0.2153×10-6K-1 (nearly zero) at the temperature range 30-600℃.The density of ZrO2/25wt%ZrW2O8 composite can be enhanced to 96.1% of the theoretical density when 0.5wt% Al2O3 was added.ZrO2/ZrW2O8 composites were also prepared by chemical co-precipitation method using analytically [ZrO(NO3)2·5H2O] and [H40N10O41W12·xH2O] as starting material. ZrO2/ZrW2O8 composite with good crystallinity and smallgrain size can be obtianed by sintering at 1150℃for 2 hours.The homogeneity and density of the sample were efficiently enhanced by using chemical co-precipitation method.By prolonging the sintering time, the density of the composite was improved and the particle size was increased. The average thermal expansion coefficient of ZrO2/26wt%ZrW2O8 composite was -0.5897×10-6K-1,approximate to zero, in the temperature range from 30 to 600℃.When 0.3wt % Al(NO3)3·9H2O was added into ZrO2/26wt% ZrW2O8 composite, the density was reached 98.67% of the theoretical density. The mechanism of the accelerating of the sintering process by adding Al2O3 is that liquid Al2(WO4)3 with low-melting point is formed at the grain boundary, which would remove stomata to improve the density.The dielectric constant of the nearly zero thermal expansion ZrO2/ZrW2O8 composite prepared by solid-state method and chemical co-precipitation is greater than 11.61,while its dielectric loss is between 10-2and 10-1 and the Vickers hardness is greater than 453HV,the property of the composite can be improved by adding proper amount of sintering assistant. The volume electrical resistivity of ZrO2/ZrW2O8 composite prepared by mechanical mixing method shows strong negative temperature changing property between 100 and 500℃,the changing amplitude can reach 3 to 5 of the order of magnitude. The thermal conductivity coefficient of the zero thermal expansion ZrO2/ZrW2O8 composite is 14.11 W/(m·K) and the thermal conductivity coefficient will decrease with increasing temperature.Cu is coated on the surface of the ZrW2O8 particles by electroless plating method with the auxiliary action of ultrasonic wave, the phase structure of the composite powders was characterized by Powder X-ray diffraction (XRD), and the coating results were observed by scanning electron microscope (SEM) and the heat and weight change in the heating process of the composite was studied by TG-DSC method. The creation of Cu2O was inhibited by using 2-2'bipyridine and potassium ferrocyanide as double stabilizing agent . Nano Cu can be coated on the surface on the condition that the pH value was 12.5,the content of CuSO4·5H2O and HCHO were 3.5g/0.2L and 2.4ml/0.2L,respectively, and proper complexing agent was added. The increasing of pH value and the ratio of salt to HCHO would enhance the reaction speed and the grain size of Cu on the surface of ZrW2O8 will be further increased . Effects of component ratio of plating liquid on the speed of plating and weight gain are discussed. The mechanism of the creation of Cu2O during the electroless plating process and its elimination method is also studied.Cu/ZrW2O8 composite material was prepared by powder metallurgy method, the phase component of the composite material obtained under different pressures was analyzed, the microscopic structure and the fracture surface morphology of the composite material prepared with different volume percentage were observed. The density of the Cu/ZrW2O8 composite material with different volume percentage obtained under different pressures were also measured. The results showed that the density would increase with the increasing of the pressure and the content of Cu. The average linear thermal expansion coefficient of Cu/ZrWO8 composite are 9.21×10-6K-1,7.35×10-6K-1,4.85×10-6K-1 in the temperature range of 35-200℃with 45vol % ,55vol % and 65vol % ZrW2O8 in the composites. The thermal conductivity would increase with the increasing of the content of Cu and decrease with the increasing of the temperature.
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