烧结温度和树脂含量对木陶瓷的物相及结构的影响

Effects of sintering temperature and PF resin content on phases and microstructure characteristics of woodceramics

为了探讨浸渍用酚醛(PF)树脂的分子量、树脂含量和烧结温度对木陶瓷的物相及微观结构的影响,采用低分子量PF树脂、常压浸渍杨木纤维制备木陶瓷,使用XRD、SEM等技术研究了PF树脂的分子量、树脂含量和烧结温度与木陶瓷的物相构成和形貌特征之间的关系。XRD分析表明:提高烧结温度,木陶瓷(002)晶面的Bragg衍射角右移,衍射峰变窄、变强,石墨烯片层堆积厚度和微晶胸径增加,晶面间距减小,微晶层的排列趋于规整、有序,有石墨特征的析出相出现,可石墨化倾向增加;但PF树脂含量对物相构成的影响较小,且PF树脂分子量的大小与物相构成无明显关系。SEM分析表明:木陶瓷保持了木材作为天然生物体的部分结构特征,其微观结构与烧结温度、树脂含量和杨木纤维的结构及分布情况有关。PF树脂含量的增加有助于木陶瓷形成三维网状结构,但会使表观密度增加和显气孔率降低;而提高烧结温度将会导致木陶瓷显气孔率的增加。当烧结温度为1 000℃、PF树脂含量为130%时,木陶瓷的显气孔率和表观密度分别为39.3%和0.77 g/cm3。

The purpose of this study is to understand the effects of PF resin molecular weight, sintering temperature and PF resin content on the phases and microstructure characteristics of woodceramics. Woodceramics was made from poplar fiber impregnated with low molecular weight PF resin under regular pressure. The molecular weight, PF resin content and its phases and microstructure characteristics were analyzed with XRD and SEM. Results from XRD analysis showed that, as sintering temperature increased, interplanar Bragg diffraction angle （002） shifted to the right and diffraction peak was narrowed and strengthened, along with the increase of its Lc （crystallite size along the c-axis ）and La（coherent length of the graphite crystallite in the basal plane）values and decrease of d002 （002 intreplanar space）values. It also showed that arrangements for crystallite became well ordered, precipitation phases of graphitization appeared and tendency of graphitization increased. However, PF resin content had a weak impact on its phase, so did molecular weight. SEM analysis showed that biologic characteristics of the native wood were partially kept in woodceramics and the microstructure characteristics of woodceramics were related to sintering temperature, PF resin content, structure and distribution of poplar fiber. The analysis also indicated that the increase of PF resin content enhanced the formation of a three- dimensional structure, decreased apparent porosity and increased apparent density. In addition, elevation of sintering temperature resulted in the increase of apparent porosity. The apparent density and apparent porosity of woodceramics were about 0.77 g/cm3 and 39.3% when it was prepared from poplar fiber with 130% phenolic resin content and 1 000℃ sintering temperature.