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1、新型光纤材料与器件团队,NOVEL OPTIC FIBERS AND DEVICES TEAM,MCVD,工艺关键技术,光纤的四大制造技术,?,VAD,（轴向汽相沉积）,?,OVD,（外部汽相沉积）,?,MCVD,（改进的化学汽相沉积）,?,PCVD,（等离子体化学汽相沉积）,MCVD,工艺简介,MCVD,工艺步骤,1,Recipe Development,Main variables for each process steps are,following:,?,Gas flows:bubbler carrier gas,O2,He,Cl2,SF6 etc.,?,Preform temper
2、ature,?,Carriage speed,?,Sootbox pressure,?,Ramping of relevant parameters,MCVD,工艺步骤,2,Tube preparation,Typical MCVD production tube is constructed from three quartz tubes,which are welded together prior to MCVD process.,?,inlet tube:low quality quartz,?,substrate tube:high quality synthetic silica,
3、forms final preform,?,exhaust tube:low quality quartz,?,sleeving tube:synthetic silica,MCVD,工艺步骤,3,Fire Polishing/Etching,Purpose:To clean tube outer and inner surface to,improve preform quality.,?,Temperature:1850-2200C,?,Reactant flows:O2+fluorine source for etching,SF6+O2,MCVD,工艺步骤,4,Cladding and
4、 core deposition,Cladding deposition,?,Purpose:deposition of protection barrier for core.,?,Temperature:1900-2100oC,?,Typical reactant flows:SiCl4,?,POCl3,O2,He,Core deposition,?,Purpose:deposition of refractive,?,index difference,?,Temperature:1900-2200oC,?,Typical reactant flows:SiCl4,?,GeCl4,O2,H
5、e,MCVD,工艺反应机理,SiCl,4,+O,2,=SiO,2,+2Cl,2,GeCl,4,+O,2,=GeO,2,+2Cl,2,4POCl,3,+3O,2,=2P,2,O,5,+6Cl,2,4BCl3+3O2=2B2O3+6Cl2,热泳效应,热泳现象,是指在温度梯度不为零的气体或悬浮体中，粒子向较冷区域运动的现象。,热泳速度正比于温度梯度，而与粒径无关。,MCVD,工艺步骤,5,Collapsing,?,Purpose:to produce glass rod for jacketing and,fiber drawing,?,Typically 2 to 5 forward and 1
6、backward steps,?,Temperature:2000-2400oC,?,Chlorine used as a drying agent,MCVD,工艺步骤,5,Preform analysis,?,dimensional and optical parameter evaluation.,?,important process and quality control tool,More preform analysis,?,Preform dimensions,Preform,cladding and core,diameters from different angles,an
7、d longitudinal positions,?,Refractive indices,Substrate tube,cladding and core,from different longitudinal positions,?,Cutoff,MFD,Chromatic dispersion,?,Preform non-circularity,(preform,cladding,core),?,Preform concentricity,(preform,cladding,core),MCVD,工艺步骤,6,Rod in tube sleeving,?,Purpose:enlarge
8、preform size to improve MCVD,productivity,?,Typical final preform size:40 to 80 mm,?,Temperature:2000C,?,Vacuum suction between rod and tube to accelerate joining,process,Fiber,drawing,MCVD,设备系统主要组成,1.Lathe 2.Gas Control System,3.PC/PLC Control System,4.Gas&Water Supply,5.Extract Systems.,SGC MCVD,M
9、CVD Lathe,?,Oxy-hydrogen burner,?,Pyrometer,?,Flame detector,Gas Control and supply System,?,Silicon Tetrachloride(SiCl4)Supply,?,Germanium Tetrachloride(GeCl4)Supply,?,Phosphoryl Chloride(POCl3)Supply,?,Boron trichloride(BCl3)Supply,?,Lathe Hydrogen&Oxygen,Supply,?,Sulphur Hexafluoride(SF6),Supply,
10、?,Chlorine Supply,?,Oxygen Supply,?,Helium Supply,?,Nitrogen Supply,?,Pneumatics Supply,?,Drybox temperature,control,Gas Station,Extract Systems,1.Gas inlet,2.Jet stream column,3.Reduction tank,4.Neutralization tank,5.Absorption column,6.Fresh water feed,7.Chemical feed,8.Waste water discharge,9.Pur
11、e gas outlet,Gas scrubber,Jet stream tank,Over 90%of silica is collected to the,350l jet stream tank.,NaOH and Na2S2O3 solutions are,automatically added to the tank to,keep the pH in the tank between 8 and,8.5 and Redox potential between-50,and+200mV.,The washed gas is directed to Neutralization tan
12、k,through a mist eliminator.,Jet stream tank receives continuous,15-40 l/h overflow from Neutralization tank.,Gas scrubber,Neutralization tank,?,The washed gas from stage 1 is,?,directed to the stage 2 through a set,of dampers and mist eliminator,(chevron type).,?,pH of stage 2 tank is kept between,10 and 11 to ensure efficient,?,neutralization of the HCl gas.,?,HCl+NaOH-NaCl+H2O,?,Cl2+2NaOH-NaCl+NaClO+H2O,新型光纤材料与器件团队,NOVEL OPTIC FIBERS AND DEVICES TEAM,谢谢！,
