人教-八下-Unit7-SectionB-2a-2e-课件(共21张PPT)

第四章铸铁焊接第四章铸铁焊接前言1、优点:成本↓,铸造性能、震性能、耐磨性、切削加工性↑↑,设备简单,废品率较高,机械性能一般,无磁性。C-Fe、Mn、Si、S、P合金元素2.铸铁应用(机制业应用广泛)——50年代QT应用,更广泛1)铸造焊接的应用一般铸件废品率↑,修复可降低成本、完成任务↑2)已损坏(使用过程)的铸铁成品件的焊补(出裂纹使产品报废)节约资金。3)零件的生产(QT件)铸件+钢件(或其它金属件)(异质焊接)§4-1铸铁的种类及性能简介(Wc2%的铁碳合金——铸铁)一、分类按碳在铸铁存在的状态及形式的不同:白口(灰口、可锻、球墨、蠕墨)铸铁1、白口铸铁:C绝大多数以渗碳体(Fe3C)状态存在,进口呈白亮色。(无法机械加工)2、灰口铸铁:石墨以片状存在,性能差异大(石墨存在形式不同)部分存在于珠光体。3、可锻铸铁:石墨以团絮状存在,性能差异大(石墨存在形式不同)部分存在于珠光体。4、球墨铸铁:石墨以圆球状存在,性能差异大(石墨存在形式不同)部分存在于珠光体。5、蠕墨铸铁:石墨以蠕虫状存在,性能差异大(石墨存在形式不同LearningAims1.通过阅读了解更多关于大熊猫的知识。2.通过完成阅读任务，学会运用阅读技巧：skimming（略读）,scanning（扫读）。3.通过制作海报激发学生保护动物的意识。Whostayswiththepandas?Whostayswiththepandas?Pandakeepers熊猫饲养员lookresearchbasecharacterendangeredfavoritefoodwhere...Brainstormingbamboo竹子study濒危的protect研究基地ChengduResearchBaseWhatdoesthisBaseworkon?成都大熊猫繁育研究基地(ChengduResearchBaseofGiantPandaBreeding)位于成都北郊斧头山，距市区10公里，是一个专门从事濒危野生动物研究、繁育、保护教育和教育旅游的非营利性机构。该基地建有一座大熊猫博物馆，存有珍贵的资料和丰富的展品。除大熊猫外，该基地还从事对小熊猫、黑颈鹤等珍稀濒危动物的研究及繁育工作。Skimming:Thismeanslookingquicklythroughapieceofwritingtofindthemainideawithoutreadingeveryword.Scanning:Thismeansmovingyoureyesquicklydownthepagetofindspecificinformation(具体的，详细信息).Reading:SkimmingReadthethewholepassagequicklyanddoExercise1&2.E1:Thepurpose(目的)ofthewriteristoaskusto:E2:Matcheachparagraphwiththemainideas.Paragraph1&2Paragraph3Paragraph4Thewaystosavepandas.Thepandakeeperstakecareofpandas.Thereasonswhypandasareendangered.A.KeeppandasB.Protect/savepandasC.SavethetigersReading:ScanningReadParagraph1,2andanswerthequestions.1.WhatisLinWei’sjob?2.Whatdothepandasdowhentheyseethekeepers?3.WhatcanLinWeidoeveryday?Sheisapandakeeper.Thebabypandasrunovertothemwithexcitementandsomeoftheyoungpandasevenwalkintotheirfriendsandfallover.Hecanwash,feedandplaywithpandaseveryday.跑向激动地，兴奋地;相当于excitedly撞上绊倒，跌倒Reading:ScanningReadParagraph3tofindoutthesenumbers,Underlinethesentenceswithnumbers.10200030012Whatdothesenumbersmean?20003001210Readthesentences,wecaninfer推断pandasnoware____________=ingreatdanger.endangeredTherearefewerthan2,000pandaslivingintheforests.Another300orsoliveinzoosorresearchcentersinChinaorothercountries.Adultpandasspendmorethan12hoursadayeatingabout10kilosofbamboo.大约成年的WhyHumanscutdowntheforestsstartedtoBabypandasdiefromillnessPandasdon’thavemanybabiesReadpara3Carefullyandfindoutthereasonswhythepandasareendangered.死于Reading:detailedreadingReadParagraph4andcompletethechartThewaystosavepandas1.AneducationprograminChengduteacheschildrenabout_______andother____________________________2.TheChinesegovernmentis______________________________3.Scientists____________________tobetterunderstandthehabitsofpandas.HopesWeallhopethatinthefuturetherewillbe_____________pandasthannow.pandasendangeredwildanimalsistryinghardtosavethepandasalotmorearedoingresearchRetellthearticleaccordingtothemindmap.ThepandaiscalledthenationaltreasureofChina.大熊猫被称为中国的“国宝”。Task:Makeapostertogether2017G1:Introducethebasicfactsaboutpandas.G2:Describethereasonswhypandasareendangered.G3-G7:Thinkupmorewaystoprotectpandas.G8:Makesomeslogans(口号)tocallupotherpeopletoprotectpandas.G1:Basicfacts(概况)look，food,character,where,numbers…G8:Slogans（口号）Tips:love,help,save,protect,duty,life,home,friends,environment,beautifulworld…G3-G7:Moreways（保护措施）must/can/should/shouldn’t….G2:Reasons(濒危原因)Nowadayspandasareendangered,because……Therearefewerandfewerpandasintheworld,themainreasonsare……Ourworldissobeautifulwiththeseanimals.1.Retellthepassage2.Chooseyourfavoriteanimal,andmakeapostertoaskmorepeopletoprotectthem.ThankyouThankyou!