Preparation And Properties Of Woodceramics And Metallized Woodceramics

With the development of the material science, the renewable bio-resources play an important role in the high-performance composites. Woodceramics were prepared by the wood materials as the main raw materials through the appropriate physical and chemical reaction process, and the final products were the carbon materials, carbide or oxide ceramics and ceramic matrix composite materials.Agricultural waste bagasse as the main raw material was impregnated by the epoxy resin. The different mass ratio m(epoxy resin): m(bagasse)=1: 1,1: 1.5,1: 2,1: 2.5 were used to prepare the woodceramics at the different sintering temperature 800℃, 900℃, 1000℃and 1100℃, respectively in this work. Meanwhile, in order to improve the strength of woodceramics, the metallized woodceramics were prepared by mixing bagasse, epoxy resin and aluminum powder.Themogravimetric and diffential scanning calorimeter analysis (TG-DSC) were applied to reveal the pyrolysis behavior of woodceramics. The microstructure and phase composition of woodceramics were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The influence of the mass ratio of the epoxy resin and bagasse and the sintering temperature on the residual carbon rate, the volume shrinkage, the plane size, the thickness shrinkage, the volume resistivity and the compressive strength were investigated. As analysing the friction properties, the pore size distribution and the wear mechanism of woodceramics were studied and discussed. At the same time, the microstructure and the phase composition of woodceramics and metallized woodceramics were compared and analysed by scanning electron microscopy (SEM) and x-ray diffraction (XRD). Then the mechanical properties and pore size distribution were compared between the woodceramics and metallized woodceramics. The Experimental results show that:(1) Woodceramics were prepared by using epoxy resin and bagasse for the first time, and woodceramics is a kind of porous carbon material with biological tubular structure. When the mass ratio of the epoxy resin and bagasse is 1: 1.5-1: 2.5, the pore size distribution of woodceramics is within 2-4μm for the single-peak structure. When the mass ratio of the epoxy resin and bagasse is 1: 1, the pore size distribution of woodceramics are 3-6μm and 10-20μm because the peaks are presented dual peak structure and the total porosity increases with the content of bagasse. The total porosity of woodceramics increases with the incerase of the sintering temperature. When the sintering temperature is 1100℃, there are contain the richest pores.(2) The loss weight rate of woodceramics are 10% and 12% from room temperature to 100℃and 100℃-1150℃, respectively. When the sintering temperature is a constant, the graphitization degree of woodceramics increases with the decrease of the bagasse amount. When the bagasse content increase more 50% than that of the epoxy resin, the residual carbon rate of woodceramics may reduce 3%-6% and the volume shrinkage rate increases 1%-1.3%, the plane size and thickness shrinkage of woodceramics are positively correlated with the bagasse content. With the increase of the bagasse amount, the volume resistivity of woodceramics is larger and the compressive strength is lower. When the mass ratio is set, with the increase of the sintering temperature, the graphitization degree of woodceramics increases. When the sintering temperature increases every 100℃, the residual carbon rate of woodceramics reduces by about 1%-2% and the volume shrinkage rate increases to 0.5%-1%, the plane size and thickness shrinkage of woodceramics are positively correlated with the sintering temperature. With the increase of the sintering temperature, the volume resistivity decreases and the compressive strength of woodceramics increases.(3) Woodceramics mainly dominate the abrasive wear and adhesive wear. Under the same friction conditions, the friction coefficient of woodceramics decreases with the increase of the sintering temperature. With the increase of the bagasse content, the friction coefficient of woodceramics decreases. The friction coefficient of woodceramics increases with the increase of speed, but the friction coefficient decreases with the increase of the load. When the mass ratio of epoxy resin and bagasse is 1, and the sintering temperature is 1100℃, the anti-friction property is the best. (4) The metallized woodceramics were fabricated by the magnetic stirring firstly, then using the mechanical stirring by the addition of aluminium powder. The partial holes of woodceramics is reserved. The sintering holding time should be controlled less than two hours to prevent the formation of Al₃C₄. The porosity of the metallized woodceramics is less than that of woodceramics. The peak of the pore size distribution is 0.32μm and 5μm, respectively. The compressive strength of metallized woodceramics is decuple higher than that of woodceramis because of the decrease of the porosity and the bridge effect of the aluminum.