材料加工技術(shù)外文文獻(xiàn)翻譯

材料加工技術(shù)材料加工，將工業(yè)材料從原材料狀態(tài)轉(zhuǎn)換為成品或產(chǎn)品的一系列操作。工業(yè)材料的定義是用于制造“硬”產(chǎn)品的材料，例如為工業(yè)和消費(fèi)者生產(chǎn)的或多或少耐用的機(jī)器和設(shè)備，而與一次性“軟”產(chǎn)品（例如化學(xué)品，食品，藥品和服裝）相反。手工加工的材料與文明一樣古老。機(jī)械化始于18世紀(jì)的工業(yè)革命，并在19世紀(jì)初期，主要在英國(guó)開發(fā)了用于成形，定型和切割的基本機(jī)械。從那時(shí)起，材料加工的方法，技術(shù)和機(jī)械種類和數(shù)量不斷增加。從原材料中提取原材料或從基本化學(xué)物質(zhì)或天然物質(zhì)生產(chǎn)原材料之后，就可以立即開始將材料轉(zhuǎn)換為零件和產(chǎn)品的制造過程循環(huán)。金屬原料通常分兩步生產(chǎn)。首先，對(duì)粗礦石進(jìn)行處理以提高所需金屬的濃度；這稱為選礦。典型的選礦過程包括粉碎，焙燒，磁選，浮選和浸出。第二，使用諸如冶煉和合金化之類的附加工藝來生產(chǎn)金屬，該金屬將被加工成最終組裝成產(chǎn)品的零件。就陶瓷材料而言，將天然粘土與各種硅酸鹽混合并共混以生產(chǎn)原材料。塑料樹脂是通過化學(xué)方法以粉末，顆粒，油灰或液體形式生產(chǎn)的。合成橡膠也通過化學(xué)技術(shù)制造，與天然橡膠一樣，以板，片，縐紗和泡沫的形式生產(chǎn)，以制造成品零件。將原材料轉(zhuǎn)換為成品的過程具有兩個(gè)主要功能中的一個(gè)或兩個(gè)：第一，它們將材料制成所需的形狀；第二，將材料制成所需的形狀。其次，它們改變或改善了材料的性能。成型和成型過程可分為兩種類型：在液態(tài)狀態(tài)下對(duì)材料執(zhí)行的操作和在固態(tài)或塑性狀態(tài)下對(duì)材料執(zhí)行的操作。當(dāng)涉及金屬，玻璃和陶瓷時(shí)，液體形式的材料的加工通常稱為鑄造。當(dāng)應(yīng)用于塑料和其他一些非金屬材料時(shí)，稱為模塑。大多數(shù)鑄造和成型過程涉及四個(gè)主要步驟：（1）制作零件的精確圖案；（2）用該圖案制作模具；（3）將液體引入模具中；（4）從模具中取出硬化的零件模具。有時(shí)需要進(jìn)行精加工。通過施加力或壓力將固態(tài)的材料制成所需的形狀。待處理的材料可以處于相對(duì)堅(jiān)硬且穩(wěn)定的狀態(tài)，并且可以是諸如條，片，粒料或粉末的形式，或者可以是軟的，塑料的或油灰狀的形式。固體材料的形狀可以是熱的或冷的。固態(tài)金屬的加工可以分為兩個(gè)主要階段：首先，通常通過軋制，鍛造或擠壓將大錠或方坯形式的原材料熱加工成較小的形狀和尺寸。其次，通過一個(gè)或多個(gè)較小規(guī)模的熱或冷成型工藝將這些形狀加工成最終零件和產(chǎn)品。材料形成后，通常會(huì)對(duì)其進(jìn)行進(jìn)一步更改。在材料加工中，“去除”過程是消除一塊或一部分材料的部分以獲得所需形狀的過程。盡管去除工藝適用于大多數(shù)類型的材料，但它們最廣泛地用于金屬材料。可以通過機(jī)械或非機(jī)械方式從工件上去除材料。有許多金屬切割工藝。在幾乎所有模具中，機(jī)加工都涉及將切削工具壓在要成型的材料上。該工具比要切割的材料堅(jiān)硬，可以去除切屑形式的不需要的材料。因此，加工的要素是切削裝置，用于固定和定位工件的裝置，通常是潤(rùn)滑劑（或切削油）。有四種基本的非切削去除工藝：（1）在化學(xué)銑削中，通過化學(xué)溶液在金屬上的蝕刻反應(yīng)去除金屬；盡管通常應(yīng)用于金屬，但它也可以用于塑料和玻璃。（2）電化學(xué)加工采用相反的金屬電鍍?cè)?，因?yàn)楣ぜ皇峭ㄟ^電鍍過程堆積的，而是在受控的條件下被消耗掉的。通過電流的作用，（3）放電加工和磨削通過高能火花或放電腐蝕或切割金屬，（4）激光加工用來自激光的強(qiáng)光束切割金屬或耐火材料。另一個(gè)進(jìn)一步的變化可能是“連接”，即永久地（有時(shí)只是臨時(shí)地）將材料彼此粘合或附著的過程。這里使用的術(shù)語包括焊接，釬焊，軟焊以及粘合劑和化學(xué)鍵合。在大多數(shù)連接過程中，通過施加一種或三種能量（熱能，化學(xué)能或機(jī)械能）來產(chǎn)生兩塊材料之間的結(jié)合?？梢允褂没蚩梢圆皇褂门c被連接材料相同或不同的粘結(jié)材料或填充材料。材料的特性可以通過熱處理或冷處理，機(jī)械操作以及暴露于某些形式的輻射來進(jìn)一步改變。通常通過改變材料的微觀結(jié)構(gòu)來實(shí)現(xiàn)性能改變。涉及高于室溫的溫度的熱處理和涉及低于室溫的溫度的冷處理都包括在此類別中。熱處理是其中材料的溫度升高或降低以改變?cè)疾牧系男阅艿倪^程。大多數(shù)熱處理過程都是基于時(shí)間-溫度循環(huán)，包括三個(gè)步驟：加熱，保持溫度和冷卻。盡管某些熱處理適用于大多數(shù)材料系列，但它們?cè)诮饘偕鲜褂米顝V泛。Materialprocessingtechnology出處：EncyclopediaBritannicaContributorsGloriaLotMaterialsprocessing,theseriesofoperationsthattransformsindustrialmaterialsfromaraw-materialstateintofinishedpartsorproducts.Industrialmaterialsaredefinedasthoseusedinthemanufactureof“hard”goods,suchasmoreorlessdurablemachinesandequipmentproducedforindustryandconsumers,ascontrastedwithdisposable“soft”goods,suchaschemicals,foodstuffs,pharmaceuticals,andapparel.Materialsprocessingbyhandasoldascivilization;

mechanization

beganwiththe

IndustrialRevolution

ofthe18thcentury,andintheearly19thcenturythebasicmachinesforforming,shaping,andcuttingweredeveloped,principallyinEngland.Sincethen,materials-processingmethods,techniques,andmachineryhavegrowninvarietyandnumber.Thecycleof

manufacturing

processesthatconvertsmaterialsintopartsandproductsstartsimmediatelyaftertherawmaterialsareeitherextractedfrommineralsorproducedfrombasicchemicalsornaturalsubstances.Metallicrawmaterialsareusuallyproducedintwosteps.First,thecrudeoreisprocessedtoincreasethe

concentration

ofthedesiredmetal;thisiscalledbeneficiation.Typicalbeneficiationprocessesincludecrushing,roasting,magneticseparation,

flotation,andleaching.Second,additionalprocessessuchas

smelting

andalloyingareusedtoproducethe

metal

thatistobefabricatedintopartsthatareeventuallyassembledintoaproduct.Inthecaseofceramicmaterials,naturalclayismixedandblendedwithvarioussilicatestoproducetherawmaterial.Plasticresinsareproducedbychemicalmethodsinpowder,pellet,

putty,orliquidform.

Synthetic

rubberisalsomadebychemicaltechniques,beingproduced,asisnaturalrubber,insuchformsasslabs,sheeting,crepe,andfoamforfabricatingintofinishedparts.Theprocessesusedtoconvertrawmaterialsintofinishedproductsperformoneorbothoftwomajorfunctions:first,theyformthematerialintothedesiredshape;second,theyalterorimprovethepropertiesofthematerial.Formingandshapingprocessesmaybeclassifiedintotwobroadtypes—thoseperformedonthematerialina

liquidstate

andthoseperformedonthematerialinasolidor

plastic

condition.Theprocessingofmaterialsinliquidformiscommonlyknownas

casting

whenitinvolvesmetals,

glass,andceramics;itiscalledmoldingwhenappliedtoplasticsandsomeothernonmetallicmaterials.Mostcastingandmoldingprocessesinvolvefourmajorsteps:(1)makinganaccuratepatternofthepart,(2)makinga

mold

fromthepattern,(3)introducingtheliquidintothemold,and(4)removingthehardenedpartfromthemold.Afinishingoperationissometimesneeded.Materialsintheir

solidstate

areformedintodesiredshapesbytheapplicationofaforceorpressure.Thematerialtobeprocessedcanbeinarelativelyhardandstableconditionandinsuchformsasbar,sheet,pellet,orpowder,oritcanbeinasoft,plastic,orputtylikeform.Solidmaterialscanbeshapedeitherhotorcold.Processingofmetalsinthesolidstatecanbedividedintotwomajorstages:first,therawmaterialintheformoflargeingotsorbilletsishot-worked,usuallyby

rolling,

forging,or

extrusion,intosmallershapesandsizes;second,theseshapesareprocessedintofinalpartsandproductsbyoneormoresmallerscalehotorcoldformingprocesses.Afterthematerialisformed,itisusuallyfurtheraltered.Inmaterialsprocessing,a“removal”processisonethateliminatesportionsofapieceorbodyofmaterialtoachieveadesiredshape.AlthoughremovalprocessesareThereareanumberof

metal-cuttingprocesses.Inalmostallofthem,machininginvolvestheforcingofacuttingtoolagainstthematerialtobeshaped.Thetool,whichisharderthanthematerialtobecut,removestheunwantedmaterialintheformofchips.Thus,theelementsofmachiningareacuttingdevice,ameansforholdingandpositioningtheworkpiece,andusuallyalubricant(orcuttingoil).Shear-basedmaterialremovalprocessessignificantlyinfluencethequalityofworkpiecesurfaceandimplicitlythecomponentfunctionalperformance.Anin-situSEMnano-cuttingenabledthestudyofcrystalflowandlatticerotationoccurringbelowthecuttingedgeinapolycrystallineNickelsuperalloy.Whennano-cuttingwithinsinglegrainsadeformednanolayerappearsthatconsistsofacrystallatticerotatedexclusivelywithinthecuttingplanewhichisdelimitedfromthebulkofthegrainbyhighangleboundary(HAB);thedepthofdeformednanolayerincreaseswiththematerialpile-up(nano-chip)causedbythegrainshearing.Uponnano-cuttingmultiplegrains,nano-recrystallisationattheHABoccurs,accompaniedbythebendingofthegrainboundary(GB)inthecuttingdirection,aphenomenonthatalsosignificantlyinfluencesthedeformationbehaviourofthegrainscutafterpassingtheGB.Clarifyingtheseaspectsatthenanoscaleiscrucialforunderstandingtheformationofworkpiecesurfacedamageaftermaterialremovaloperations.Electricaldischargemachining(EDM)isanon-conventionalprocessthatiswidelyusedforhigh-precisionmachining,complexproductshapes,andhighhardnessmaterials.Therearefourbasicnoncuttingremovalprocesses:(1)in

chemicalmillingthemetalisremovedbytheetchingreactionofchemicalsolutionsonthemetal;althoughusuallyappliedtometals,itcanalsobeusedonplasticsandglass,(2)

electrochemicalmachining

usestheprincipleofmetal

plating

inreverse,astheworkpiece,insteadofbeingbuiltupbytheplatingprocess,iseatenawayinacontrolledmannerbytheactionoftheelectricalcurrent,(3)

electrodischargemachining

andgrindingerodesorcutsthemetalbyhigh-energysparksorelectricaldischarges,(4)

lasermachining

cutsmetallicorrefractorymaterialswithanintensebeamoflightfromalaser.Anotherfurtheralterationmaybe

“joining,”theprocessofpermanently,sometimesonlytemporarily,bondingorattachingmaterialstoeachother.Thetermasusedhereincludes

welding,

brazing,

soldering,and

adhesive

and

chemicalbonding.Inmostjoiningprocesses,abondbetweentwopiecesofmaterialisproducedbyapplicationofoneoracombinationofthreekindsofenergy:thermal,chemical,ormechanical.Abondingorfillermaterial,thesameasordifferentfromthematerialsbeingjoined,mayormaynotbeused.Thepropertiesofmaterialscanbefurtheralteredbyhotorcoldtreatments,bymechanicaloperations,andbyexposuretosomeformsofradiation.Thepropertymodificationisusuallybroughtaboutbyachangeinthemicroscopicstructureofthematerial.Bothheat-treating,involvingtemperaturesaboveroomtemperature,andcold-treating,involvingtemperaturesbelowroomtemperature,areincludedinthiscategory.

Thermaltreatment

isaprocessinwhichthetemperatureofthematerialisraisedorloweredtoalterthepropertiesoftheoriginalmaterial.Mosttherm