Preparation And Structure Of ZrO₂ Fiber/Aerogel Composites

Because of its unique properties such as high porosity, large specific surface area and small density, aerogel material has a very high potential in many areas including acoustic, electrical, thermal and so on. For example, it can be used as adsorbent materials, insulation materials, insulation materials. But at the same time, aerogel material also has many defects such as low material strength, unstable structure and poor toughness, which hampers the large-scale application of aerogel material in the production and in the life. Therefore, in this paper, we use Zr O2 fiber to reinforce Zr O2 aerogel, and prepare Zr O2 fiber/aerogel composites which is of good macro-morphology and uniform microstructure.In this paper, ZrO₂ aerogels were synthesized by sol-gel method and reinforced by Zr O2 fibers. The physical mixing method and casting equipment molding method were used to prepare Zr O2 fiber/aerogel composites. It was studied that how reaction conditions such as the amount of Zr O2 fiber, the type of Zr O2 fiber, the amount of precursor which is zirconyl nitrate, the temperature of the water bath and the temperature of dipping,have impact on the macroscopic morphology, internal structure and other properties of Zr O2 fiber/aerogel composites during the proceed of the synthesis in the two methods. Scanning tunneling microscope（SEM）, N 2 adsorption-desorption（BET）, thermal gravimetric analysis test（TG） and other kinds of test were used to test and analyze the microscopic morphology and pore structure properties of the Zr O2 fiber/aerogel composites.From this study, the process of the synthesis of Zr O2 fiber/aerogel composites by physical mixing method which was finally determined was shown as followed by. The initial amount of zirconyl nitrate which was the precursor was 2.0g. The amount of the Zr O2 short fiber which was added in was 0.8g. The temperature of the water bath was selected to 70℃. The test result of BET specific surface area of the product Zr O2 fiber/aerogel composites was 559.28m2/g. The average pore diameter was 2.644 nm, and the density was 0.3796g/cm3. The process of synthesis by casting equipment molding method which was finally determined was shown as followed by. The Zr O2 long fiber was used as the molding base, and the amount used was 0.8g. The initial amount of zirconyl nitrate which was the precursor was 2.0g. The immersion temperature was selected to 70℃. The test result of BET specific surface area of the product Zr O2 fiber/aerogel composites was 470.01m2/g. The average pore diameter was 7.02 nm, and the density was 0.3396g/cm3.In the physical mixing method, the addition of the Zr O2 fibers played a supporting role to the aerogel structure, assumed a portion of the internal stress generated during the drying proceed, and made the collapses of the internal pore structure decrease. Compared with the result of the composites without addition of fiber, the specific surface area increased more than 12.3 times, and the density decreased by 58.9%. In the casting molding method, shaped Zr O2 fiber substrate can be used as the skeleton of composites to make aerogel directly and uniformly grow on it. That increased the crosslinked degree of Zr O2 molecules on the porosity wall. It also made the morphology surface of the composite materi al more loose and reinforced the structure. Compared with the result of the composites without addition of fiber, the specific surface area increased more than 10.1 times, and the density decreased by 63.3%.