水泥样品中水动态的准弹性中子散射（QENS）谱分析

发布时间：2018-01-11 00:10

本文关键词：水泥样品中水动态的准弹性中子散射（QENS）谱分析　出处：《暨南大学》2016年硕士论文　论文类型：学位论文

【摘要】：中国散裂中子源(China spallation neutron source,CSNS)作为国家重要的科技基础设施,将在2018年建成。CSNS建成后,将为国内外科学研究者提供物理学、医药、生命科学、化学等学科的多学科、高科技应用的大型研究平台。中子粉末衍射仪在CSNS设施中是用户量最大、使用最广泛的谱仪,准弹性中子散射(quasi-elastic neutron scattering,QENS)的相关信息能够通过背散射谱仪获得。QENS实验是研究水泥样品中水动态的一种新颖的实验方法。水泥样品中存在有结合水和受限水,其各自的含量随水泥样品的老化时间、添加剂、水与水泥(w/c)质量比、环境温度等因素的不同而变化,处于受限状态的水的动态特性影响着水泥的力学特性和耐久性,因此,研究水泥样品中受限水的动态具有重要的意义。本文基于老化时间分别为7、14、30天的波特兰水泥样品(OPC)以及水与水泥质量比分别为10%、17%、30%的水化硅酸钙(C-S-H)样品的QENS谱实验数据,通过采用四个高斯项的和的能量分辨函数来代替一个高斯项的能量分辨函数,采用改进的经验扩散模型(empirical diffusion model,EDM),编制Matlab程序,对归一化后的QENS谱数据进行非线性最小二乘拟合。由此导出描述水泥样品中水动态的相关物理参数,同时得到较好的QENS谱拟合曲线。这些拟合参数分别是不动水系数A,不动水指数BWI,自扩散系数Dt,跳跃之间的平均停留时间τ0,QENS谱展宽的半高宽Γ,它们可定量描述水泥样品中水的动态过程,从而为QENS实验在水泥样品受限水动态研究中的应用提供一种合理实用的谱分析方法。
[Abstract]:China spallation neutron source is an important national scientific and technological infrastructure. After the completion of .CSNS in 2018, it will provide the multi-discipline of physics, medicine, life science, chemistry and so on for the domestic and foreign scientific researchers. Neutron powder diffractometer is the largest and most widely used spectrometer in CSNS facilities. Quasi elastic neutron scattering quasi-elastic neutron scattering. QENS) can be obtained by backscattering spectrometer. Qens experiment is a novel experimental method to study the water dynamics in cement samples. There are bound water and confined water in cement samples. Their contents vary with the aging time of cement samples, additives, the mass ratio of water to cement w / c, environmental temperature and other factors. The dynamic characteristics of confined water affect the mechanical properties and durability of cement. Therefore, it is of great significance to study the dynamic behavior of confined water in cement samples. The QENS spectra of 30 days Portland cement samples and 30% calcium silicate hydrate (C-S-H) samples with water to cement mass ratio of 10% to 17% were obtained. By using the energy resolution function of the sum of four Gao Si terms to replace the energy resolution function of a Gao Si term. An improved empirical diffusion model was used to compile the Matlab program. The normalized QENS spectrum data were fitted by nonlinear least square method, and the related physical parameters were derived to describe the water dynamics in cement samples. At the same time, a good fitting curve of QENS spectrum is obtained. These fitting parameters are the constant water coefficient A, the immovable water index BWI, the self-diffusion coefficient DT, and the average residence time 蟿 0 between jumps. The half-maximum width 螕 of QENS spectrum broadening can quantitatively describe the dynamic process of water in cement samples. Thus, a reasonable and practical spectrum analysis method is provided for the application of QENS experiment in the dynamic study of confined water in cement samples.
【学位授予单位】：暨南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ172.1;O571.53

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