Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology真空物理与技术真空物理与技术第7章 高真空技术Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology高真空技术高真空技术l真空材料选择l真空清洗技术l真空密封技术l真空系统检漏l真空系统计算Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology真空清洗技术真空清洗技术l真空清洗u清除表面可见污垢u去除粘附在表面的物理污染物（油、脂、灰尘）u去除表面化学污染物（氧化物、硫化物）l清洗工艺u表面层去除n机械或化学方法除去（磨料喷洁、刷、酸洗、浸蚀）u油脂去除n动植物油：水解在脂肪酸中，碱性溶液清洗n矿物油：溶解于有机溶剂中u机械清洗-酸洗-去垢清洗-去油脱脂Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology金属清洗金属清洗l酸洗u酸洗液-彻底冲洗-碱浴中和-热风吹干金属酸洗液金属酸洗液AlNaOH(10%)用NaCl饱和15-50s后浸入10%HClSS13%HNO3+25%HCl 65C7%H2SO4+3%HCl 65CCuHNO3:H2SO4:HCl:H2O(25:60:2:13)500mlHNO3、500mlH2SO4、10mlHCl+5g碳黑Mo蒸馏水 100ml+CrO3 12g +H2SO4 3ml室温15sFe50%HCl溶液515H2SO4溶液W50mlHNO330mlH2SO4溶于20ml蒸馏水沸腾H2O2Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology玻璃清洗玻璃清洗l清洗液u铬酸n 1L浓硫酸+50ml饱和重铬酸钾，加热n褐红色时有效，绿色时失效u5% HF+33%HNO3+60%H2O 冷用u有机溶剂n去除油脂，二氯乙烯、煤油n酒精（石英必须用酒精）n乙醚、丙酮Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology清洗技术清洗技术l陶瓷清洗u8001000焙烧u碱清洗液清洗，稀HNO3浸渍l橡胶清洗u降低出气率 70C 20%KOH清洗，漂洗后吹干u70C真空出气45小时尽可能使用尽可能使用“新鲜新鲜”处理的材料处理的材料Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology真空密封技术真空密封技术l真空系统u各种组件和材料的组合u更换零件、开关容器l真空密封的基本要求u保证零件连接，又要防止通过接头漏气u真空气密性：必须不漏气，但不一定是气密的u允许电流的传输，材料传递l真空密封分类u永久密封u可拆密封u电引入密封u材料传输密封Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology真空密封技术真空密封技术l永久密封u金属n熔焊：利用温度或压力使金属局部熔化（气焊、弧焊）n钎焊：用第三种熔点较低的金属焊接两种金属（低温）u玻璃n熔融：将玻璃加热到软的足以加工的温度n退火点：软玻璃400C，硬玻璃500Cn热膨胀系数、残余应力u玻璃金属n直接粘附：可以达到真空密封，但不结实n中间加氧化层：一系列分层氧化物u陶瓷金属n玻璃作为中间材料Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology真空密封技术真空密封技术l半永久可拆密封u石蜡（粘附剂）n暂时连接零件或泄漏接缝u环氧树脂胶u氯化银封接l磨口封接u平面磨口：用于不需要轴向移动零件u锥形磨口：相同锥度的内外两部分装配u球形磨口：小口径密封u涂脂Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology真空密封技术真空密封技术l液体密封u用液体材料密封连接部件的空隙u水银、油l垫圈密封u表面光洁度非常好的法兰紧压，会留下微米大小的通道Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology电线引入电线引入l基本要求u与管壳绝缘，密封连接到真空系统l永久引线u基于玻璃金属、陶瓷金属封接l可拆引线u引入线和真空系统分开u垫圈密封或者石蜡密封Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology物质传递物质传递l气体传递：活拴或者阀门u改变气流方向，调节流量大小，切断或接通管路Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology真空系统零件真空系统零件l阀门u玻璃活栓n带孔的芯子n转动芯子控制气体通路n用封脂密封 n小口径u隔膜阀n手轮带动阀杆上下移动n隔膜离开或压紧阀座Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology真空系统零件真空系统零件l阀门u球阀n两个环状弹性体紧压于一个金属球表面 n金属球上有一个大穿孔 n手柄转动金属球使穿孔改变方向nO形密封圈密封 u蝶阀n阀板的边缘上嵌有O形密封圈 n阀杆带动阀板转动n密封圈与阀体紧密接触关闭，900 n体积小。结构简单 Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology真空系统零件真空系统零件l阀门u电磁阀n磁力驱动 n电磁线圈接通电流，磁力吸引衔铁，带动阀盖，将阀门打开n电磁真空带充气阀 l机械泵入口专用阀门l自动放气Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology真空系统零件真空系统零件l阀门u针阀n微调阀 n阀塞为针形，主要用作调节气流量 u超高真空阀门n能承受高温(400450)多次烘烤n放气量小，气密性好n重复性好n流导大 n无氧铜阀盖，不锈钢阀体 Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology真空系统检漏真空系统检漏l真空检漏的重要意义u抽气过程u极限压强dP/dt=0时 Pu=Q/Sen漏气与放气总和Q对有效抽速Se的比值n物理过程：一边抽气，一边不断的漏气，动态平衡n要得到低的极限压强：提高有效抽速、减低漏气量u漏气形成原因n系统微小裂缝：玻璃、金属、金属-玻璃封接、引线封接n肉眼不能直接观察，必须予以找出并修复（更换）Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology真空系统漏气的判断真空系统漏气的判断l抽不到预定的极限真空u材料放气u泵工作不正常u漏气l判断u测量系统压强变化na: 压强保持P0不变。 既不漏气，也没有放气，泵不正常nb: 开始上升较快，然后饱和。放气nc: 直线上升。漏气，漏气量正比大气压（常数）nd:开始上升很快，后来变慢，漏气、放气Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology漏孔大小漏孔大小l漏孔本质u漏气：在压强差作用下气体流动u气体流动：流量（单位时间流过的气体量）u用通过漏孔的流量表示漏孔大小u漏率定义：在漏孔一端为标准大气压，另一端低于大气压，大气露点低于25C（干燥空气），温度23C，空气通过漏孔的流量u只要漏孔漏率相同，就可以认为完全相同u同一漏孔，对不同气体漏率不同n分子态 He漏率为空气的Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology漏率大漏率大=危害大？危害大？l不确切u漏入一定气体量u引起的压强增长与容器体积大小有关u漏孔的危害是相对的n泵抽速大小n容器体积Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology容许漏率容许漏率l极限压强u抽气、漏气（忽略放气）动态平衡u绝对不漏：不可能、不必要u漏孔的漏气足够小，平衡压强小于工作压强u容许漏率：真空系统正常工作所允许的最大漏气量考虑到材料放气（消耗抽速） 抽速越大、压强越高，容许漏率高Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology常见真空设备容许漏率常见真空设备容许漏率漏率（Torr.L/s)真 空 设 备10210110-110-210-310-410-510-610-710-810-910-1010-11简单减压装置、真空过滤减压干燥、真空浸渍减压蒸馏、真空干燥真空蒸馏、真空干燥真空蒸馏、冷冻干燥分子蒸馏、真空反应器连续抽气的汞弧整流器放射性元素容器、保温瓶真空冶炼设备回旋加速器一般高真空抽气装置宇宙空间模拟设备、半导体真空设备超高真空设备（连续抽气）封闭电真空器件（微波管、电子束管等）Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology检漏基本原理检漏基本原理l检漏目的u确定真空系统是否存在漏气u找出漏孔位置（修复或更换）u估计漏孔大小（必要时）l方法u压强差u示漏气体Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology利用压强差利用压强差l原理u漏孔两端存在压强差，就有气体流动u利用气体流动引起的效果，探测漏孔位置nP1P2l气体由内向外流动nP1P2，管道流导为F，泵口抽速为S，经过管道后的有效抽速为Se，U为泵在单位时间内抽除的气体量。1. 试写出真空系统基本方程；2. 讨论气导F在真空系统中的作用；3. 如果容器内材料放气率为6x10-4，要想扩散泵口的压强为10-8Pa，那么扩散泵的抽速至少要多少？要想容器中的工作压强为1x10-4Pa，那么连接容器和扩散泵的管道流导应为多少？ S=Q/P2=6x104L/s F=Q/(P1-P2)=Q/P1=6L/s Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and TechnologyVacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology Vacuum Science and Technology非稳定流动计算非稳定流动计算一蒸发台V=55L，机械泵抽至2x10-2Torr需要多长时间？管道20cm长，直径4cm，泵2X4型，抽速4L/s，极限压强5x10-4Torr