哈尔滨工业大学本科生毕业论文

LiF-KF-MgF2-NaF/膨胀石墨复合相变蓄热材料的制备及性能研究陈梓尧院（系）：材料科学与工程学院专业：材料科学与工程学号：1111900137指导教师：李明伟研究员2015年7月毕业设计（论文）题目：LiF-KF-MgF2-NaF/膨胀石墨复合相变蓄热材料的制备及性能研究专业材料科学与工程学生陈梓尧学号1111900137指导教师李明伟研究员答辩日期2015.7.02哈尔滨工业大学教务处制哈尔滨工业大学本科毕业设计（论文）I摘要高超声速飞行器在政治、经济及军事方面具有重要的战略意义，是21世纪世界航空航天事业发展的热点。航天飞行器的热防护的特点是超高温，热防护的方法主要有两种：隔热与蓄热。蓄热的作用是将在短时间内将通过隔热层的热量，以相变材料的相变吸热的原理储存。膨胀石墨凭借其吸附性强和导热性良好等特点，被广泛用作相变材料的吸附基质，制备出大量具有良好储热性能的定形复合相变。而飞行器内部的机件安全使用温度在500°C以下，因此开发500°C以下的高性能膨胀石墨基复合高温相变储能材料对于实现保护飞行器有巨大的实际应用价值。本文选取膨胀石墨作为吸附基质，相变温度为449°C的LiF-KF-MgF2-NaF共晶盐为相变材料，以多孔吸附法制备了LiF-KF-MgF2-NaF/膨胀石墨复合相变蓄热材料，利用SEM、XRD、红外光谱分析、DSC等手段对复合相变材料的微观形貌和热特性进行了表征。对一次成型与二次成型两种制备方法，不同复合温度，不同LiF-KF-MgF2-NaF共晶盐含量的制备的LiF-KF-MgF2-NaF/膨胀石墨复合相变蓄热材料的性能进行研究。通过对共晶盐、膨胀石墨及其复合材料的XRD衍射图谱发现，LiF-KF-MgF2-NaF共晶盐与膨胀石墨只是物理结合。通过扫描电镜照片观察和多次DSC差示扫描分析二次成型制备的样品的LiF-KF-MgF2-NaF共晶盐均匀性比一次成型好。通过DSC差示扫描分析，在LiF-KF-MgF2-NaF共晶盐质量分数一定情况下，在450°C-500°C范围内，复合温度与相变潜热不完全呈现正线性关系；复合温度一定的情况下，LiF-KF-MgF2-NaF共晶盐质量分数与最终复合材料的相变潜热也不完全呈现正线性关系。本实验以二次成型，复合温度为490°C制备了LiF-KF-MgF2-NaF共晶盐质量分数为90%的LiF-KF-MgF2-NaF/膨胀石墨复合相变蓄热材料的相变潜热能达到最大值。获得了具备高储能密度，使用温度高的LiF-KF-MgF2-NaF/膨胀石墨复合相变储能材料。关键词：高温蓄热；复合相变材料；膨胀石墨；LiF-KF-MgF2-NaF共晶盐；相变潜热哈尔滨工业大学本科毕业设计（论文）IIAbstractHypersonicvehiclehasimportantstrategicsignificanceinthepolitical,economicandmilitaryaspects,anditisahotspotinthedevelopmentoftheworldaviationindustryintwenty-firstCentury.Thethermalprotectionofhypersonicvehicleischaracterizedbyhightemperature.,therearetwomainmethods:heatinsulationandheatstorage.Thefunctionofheatstorageistostoretheheatoftheheatintheshorttime,andtostoretheheatenergyofthephasechangematerial.Withthecharacteristicsofstrongadsorptionandgoodthermalconductivity,expandedgraphiteiswidelyusedasthematrixofthephasechangematerials,andmakeoutalargenumberofshapecompositephasetransformationwithgoodthermalstorageproperties.Andinsidethevehiclepartssafeusetemperatureisbelow500°C,sothedevelopmentbelow500°Chighperformanceexpansivegraphitebasecompositehightemperaturephasechangeenergystoragematerialfortherealizationofanaircraftprotectionhasgreatpracticalvalue.Thispaperselectstheexpandedgraphitewasusedasthesubstrateofadsorption,LiF-KF-MgF2-NaFcrystalsaltthatphasetransitiontemperatureis449°Cwasusedasasphasechangematerials,to,maeoutLiF-KF-MgF2-NaF/expandedgraphitecompositephasechangethermalstoragematerial,usingSEM,XRD,IRandDSCtocharacterizecompositephasechangematerialmicrostructureandthermalproperties.ThispaperstudyLiF-KF-MgF2-NaF/expansiongraphitecompositephasechangeregenerativematerialpropertiesontwokindsofpreparationmethodsforonetimeformingandtwotimesforminganddifferentcompositetemperatureanddifferentLiF-KF-MgF2-NaFicrystalsaltcontentofthepreparation.ThroughtheXRDdiffractionpatternsofeutecticsalt,expandedgraphiteanditscompositematerials,LiF-KF-MgF2-NaFeutecticsaltandexpandedgraphiteareonlyphysicalcombination.ThroughtheDSCdifferentialscanninganalysis,theLiF-KF-MgF2-NaFeutecticsaltuniformityofthesamplepreparedbymultiplemoldingisbetterthanonetime.InLiF-KF-MgF2-NaFeutecticsaltmassfractionundercertaincircumstancesandin450~C-500C,compositetemperatureandlatentheatofnotfullyshowedpositivelinearrelationship.InCompositetemperatureundercertaincircumstances,哈尔滨工业大学本科毕业设计（论文）IIILiF-KF-MgF2-NaFcrystalsaltmassfractionandthefinalcompositephasechangelatentheatnorfullyrenderedpositivelinearrelationship.Inthisexperiment,LiF-KF-MgF2-NaF/expansiongraphitecompositephasechangeregenerativematerial,whichtheLiF-KF-MgF2-NaFeutecticsaltmassfractionis90%waspreparedbysecondmoldingand490°Ccompositing.LiF-KF-MgF2-NaF/expandedgraphitecompositephasechangeenergystoragematerialswithhighenergystoragedensityandhightemperaturewereobtained.KeyWord:Hightemperatureheatstorage,Compositephasechangematerials,Expandedgraphite,LiF-KF-MgF2-NaFeutecticsalt,Latentheatofphasechange哈尔滨工业大学本科毕业设计（论文）IV目录摘要................................................................................................................................IAbstract...........................................................................................................................II第1章绪论.....................................................................................................................11.1课题背景及研究的目的和意义........................................................................11.2膨胀石墨的研究现状........................................................................................21.2.1膨胀石墨的制备.....................................................................................21.2.2膨胀石墨的结构与性能.........................................................................41.3相变材料的发展概况........................................................................................51.3.1相变材料的分类.....................................................................................51.3.2固-液相变材料........................................................................................61.3.3复合相变材料.........................................................................................71.4氟化盐.........................................................................................