柠檬酸钠对半水石膏不同晶面结晶习性及力学性能的影响  

Effect of Sodium Citrate on Crystal Habit and Mechanical Properties of Different Crystal Surfaces of Hemihydrate Gypsum

作　　者：刘冬梅[1,2] 张典 彭艳周[1,2] 张亚利 姚惠芹[1,2] LIU Dongmei;ZHANG Dian;PENG Yanzhou;ZHANG Yali;YAO Huiqin(Hubei Key Laboratory of Disaster Prevention and Mitigation,China Three Gorges University,Yichang 443002,China;School of Civil Engineering and Architecture,China Three Gorges University,Yichang 443002,China)

机构地区：[1]三峡大学,防灾减灾湖北省重点实验室,宜昌443002 [2]三峡大学土木与建筑学院,宜昌443002

出　　处：《材料导报》2021年第18期18052-18058,共7页Materials Reports

基　　金：国家自然科学基金(51379111);湖北省自然科学基金(2018CFB642)。

摘　　要：本工作采用X射线衍射(XRD)分析方法,研究了在不同柠檬酸钠掺量下半水石膏在蒸压时不同晶面的结晶习性。运用Materials Studio 2017软件进行分子动力学模拟,研究了柠檬酸钠吸附在半水石膏晶体不同晶面的结晶习性。基于等温等容系统(NVT)对柠檬酸钠吸附于半水石膏晶体不同晶面的最低能运动轨迹进行模拟,研究了半水石膏晶体不同晶面的力学性能。XRD分析结果表明:柠檬酸钠的掺量为0.06%(质量分数,下同)时,半水石膏晶体的(200)晶面、(020)晶面和(400)晶面衍射峰强度最高,即晶面发育较好。分子动力学模拟结果表明:从柠檬酸根离子与半水石膏晶面距离来看,(200)晶面和(400)晶面是柠檬酸根离子与Ca^(2+)的主要结合位点;相互作用能从小到大的顺序为ΔE_((400))<ΔE_((200))<ΔE_((111))<ΔE_((204))<ΔE_((020)),则柠檬酸钠更易于与半水石膏晶体的(200)晶面、(400)晶面作用,从而抑制半水石膏晶体在C轴方向上生长;从弹性模量(E)、体模量(K)和剪切模量(G)等力学性能的参数可知,柠檬酸根离子与(200)晶面和(111)晶面上钙离子之间主要有较强的结合力,即柠檬酸根离子易于吸附在C轴方向的晶面上。柠檬酸根离子使半水石膏晶体在垂直于C轴方向上的尺寸变大,对半水石膏晶体在C轴方向上的强度的影响显著。试验所得的晶面分析结果与模型研究的结果具有互证性。Using X-ray diffraction(XRD)analysis method,and the crystallization habits of different crystal faces of hemihydrate gypsum under different sodium citrate content were studied.Using Materials Studio 2017 software for molecular dynamics simulation,the crystallization habits of sodium citrate adsorbed on different crystal faces of hemihydrate gypsum crystals were studied.Based on the isothermal isovolumetric system(NVT),the minimum energy trajectories of sodium citrate adsorbed on different crystal faces of hemihydrate gypsum crystal was simulated,and the mechanical properties of different crystal planes of hemihydrate gypsum crystals were studied.X-ray diffraction(XRD)analysis results show that,when the mass content of sodium citrate is 0.06%,the diffraction peaks of(200)crystal plane,(020)crystal plane and(400)crystal plane of hemihydrate gypsum crystals reaches the maximum,that is,the above planes developed well.The molecular dynamics simulation results show that:(200)and(400)planes are the main binding sites of citrate ions and Ca^(2+)from the distance between citrate ion and hemihydrate gypsum.The order of interaction energy from small to large isΔE(400)<ΔE(200)<ΔE(111)<ΔE(204)<ΔE(020),then sodium citrate is more likely to interact with(200)and(400)planes of hemihydrate gypsum crystal,thus inhibiting the growth of hemihydrate gypsum crystal in the C axis direction.According to the mechanical properties such as elastic modulus(E),bulk modulus(K)and shear modulus(G),there is a strong binding force between citrate ions and calcium ions on(200)and(111)crystal planes,that is,citrate ions are easy to adsorb on the crystal planes along the C axis.The size of hemihydrate gypsum crystal in the direction perpendicular to the C axis is enlarged by citrate ion,which has a significant effect on the strength of hemihydrate gypsum crystal in the direction of C axis.The crystal plane analysis results obtained from the experiment are mutually corroborative with the model research results.

关 键 词：半水石膏 分子动力学模拟 晶面 吸附 相互作用能 力学性能 

分 类 号：TB321[一般工业技术—材料科学与工程]