Tempered glass

honggarae 10/04/2022 844

Temperedglass(Reinforcedglass)belongstosafetyglass.Temperedglassisactuallyakindofprestressedglass.Inordertoimprovethestrengthofglass,chemicalorphysicalmethodsareusuallyusedtoformcompressivestressontheglasssurface.Whentheglassissubjectedtoexternalforce,thesurfacestressisfirstoffset,therebyimprovingthebearingcapacityandenhancingtheresistanceoftheglassitself.Windpressure,coldandheat,shock,etc.PayattentiontodistinguishitfromFRP.

Features

Safety

Whentheglassisdamagedbyexternalforce,thefragmentswillbecomehoneycomb-likeobtuse-angledsmallparticles,whicharenoteasytocauseseriousharmtothehumanbody.

Highstrength

Theimpactstrengthoftemperedglassofthesamethicknessis3to5timesthatofordinaryglass,andthebendingstrengthis3to5timesthatofordinaryglass.

Thermalstability

Toughenedglasshasgoodthermalstability,canwithstandatemperaturedifferenceof3timesthatofordinaryglass,andcanwithstandatemperaturedifferenceof300℃.

Advantages

Thefirstisthatthestrengthisseveraltimeshigherthanordinaryglass,anditisresistanttobending.

Thesecondissafeuse,itsload-bearingcapacityisincreasedtoimprovethefragilenature,evenifthetoughenedglassisdamaged,itwillappearassmallfragmentswithoutsharpangles,whichgreatlyreducesthedamagetothehumanbodyNS.Thequenchingandheatingresistanceoftoughenedglassis3to5timeshigherthanthatofordinaryglass,anditcangenerallywithstandtemperaturechangesofmorethan250degrees,whichhasasignificanteffectonpreventingthermalcracking.Itisakindofsafetyglass.Toguaranteethesafetyofqualifiedmaterialsforhigh-risebuildings.

Disadvantages

Disadvantagesoftemperedglass:

1.Thetemperedglasscannolongerbecutandprocessed,andtheglasscanonlybeprocessedbeforetempering.Processedtotherequiredshape,andthentempered.

2.Althoughthestrengthoftemperedglassisstrongerthanthatofordinaryglass,temperedglasshasthepossibilityofself-explosion(breakingbyitself),whileordinaryglassdoesnothavethepossibilityofself-explosion.

3.Therewillbeunevenness(windspots)onthesurfaceofthetemperedglass,andtherewillbeaslightthicknessthinning.Thereasonforthethinningisthataftertheglassismeltedandsoftened,itisrapidlycooledbystrongwind,sothatthecrystalgapinsidetheglassbecomessmallerandthepressurebecomeslarger,sotheglassisthinneraftertemperingthanbefore.Generally,4~6mmglassbecomes0.2~0.8mmthinneraftertempering,and8~20mmglassbecomes0.9~1.8mmthinneraftertempering.Thespecificleveldependsontheequipment,whichiswhytemperedglasscannotbeusedasamirror.

4.Theflatglassusedinconstructionafterpassingthroughthetemperingfurnace(physicaltempering)isgenerallydeformed,andthedegreeofdeformationisdeterminedbytheequipmentandtechnicalpersonnel.Toacertainextent,itaffectsthedecorativeeffect(exceptforspecialneeds).

Preparation

Toughenedglassisobtainedbycuttingordinaryannealedglasstotherequiredsize,thenheatingittoabout700degreesclosetothesofteningpoint,andthenperformingrapidanduniformcooling(usually5-6MMglassisheatedat700degreesforabout240seconds,andthetemperatureisreducedforabout150seconds.8-10MMglassisheatedat700degreesforabout500seconds,andthetemperatureisreducedforabout300seconds.Inshort,accordingtothethicknessoftheglass,choosetheheatingandcoolingmethodThetimeisalsodifferent).Aftertempering,uniformcompressivestressisformedonthesurfaceoftheglass,andtensilestressisformedinside,whichimprovesthebendingandimpactstrengthoftheglass,anditsstrengthisaboutfourtimesthatofordinaryannealedglass.Thetemperedglassthathasbeentemperedcannotbesubjectedtoanycutting,grindingorotherprocessingorbedamaged,otherwiseitwillbe"brokenandbroken"duetothedestructionoftheuniformcompressivestressbalance.

Classification

Accordingtoshape

1.Accordingtotheshape,temperedglassisdividedintoflattemperedglassandcurvedtemperedglass.

Generally,therearetwelvekindsofthicknessofflattemperedglassincluding11,12,15,19mm,andeightkindsofthicknessofcurvedtemperedglass,including11,15,19mm.Thespecificthicknessafterprocessingstilldependsoneachmanufacturer.Equipmentandtechnology.However,curvedsurface(ie,curvedtempered)temperedglasshasamaximumarclimitforeachthickness.Thatis,RRisusuallytheradius.

2.Temperedglassisdividedintoflattemperedandcurvedtemperedaccordingtoitsappearance.

3.Accordingtoitsflatness,toughenedglasscanbedividedintohigh-qualityproductsandqualifiedproducts.High-qualitytemperedglassisusedforautomobilewindshield;qualifiedproductsareusedforarchitecturaldecoration.

Accordingtotheprocess

⒈Physicaltemperedglassisalsocalledtemperedtemperedglass.Whenordinaryflatglassisheatedinaheatingfurnacetoclosetothesofteningtemperatureoftheglass(600℃),theinternalstressiseliminatedthroughitsowndeformation,andthentheglassisremovedfromtheheatingfurnace,andthenamulti-headnozzleisusedtoblowhigh-pressurecoldairontotheglass.Onbothsides,makeitcooltoroomtemperaturequicklyandevenly,andthentemperedglasscanbeobtained.Thiskindofglassisinastressstateofinternaltensionandexternalcompression.Oncelocallydamaged,stresswillbereleased,andtheglasswillbebrokenintocountlesssmallpieces.Thesesmallfragmentshavenosharpedgesandcornersandarenoteasytohurtpeople.

⒉Chemicaltoughenedglassimprovesthestrengthoftheglassbychangingthechemicalcompositionofthesurfaceoftheglass.Generally,itistemperedbytheionexchangemethod.Themethodistoimmersethesilicateglasscontainingalkalimetalionsinthemoltenlithium(Li+)salttoexchangetheNa+orK+ionsonthesurfaceoftheglasswithLi+ions,formingaLi+ionexchangelayeronthesurface.TheexpansioncoefficientissmallerthanNa+andK+ions,sothattheouterlayershrinkslessandtheinnerlayershrinksmoreduringthecoolingprocess.Whencooledtoroomtemperature,theglassisalsoinastateoftensionontheinnerlayerandpressureontheouterlayer.ItseffectSimilartophysicaltemperedglass.

Accordingtothedegreeoftoughening

⒈Temperedglass:Temperingdegree=2~4N/cm,thesurfacestressoftheglasscurtainwalltoughenedglassisα≥95Mpa;

⒉Semi-temperedGlass:Temperingdegree=2N/cm,surfacestressofsemi-temperedglassofglasscurtainwall24Mpa≤α≤69Mpa;

⒊Supertoughenedglass:Temperingdegree>4N/cm.

Productapplication

Flattemperedandbenttemperedglassbelongtosafetyglass.Widelyusedinhigh-risebuildingdoorsandwindows,glasscurtainwalls,indoorpartitionglass,daylightingceilings,sightseeingelevatorchannels,furniture,glassguardrails,etc.Generallytemperedglasscanbeusedinthefollowingindustries:

⒈Construction,buildingtemplate,decorationindustry(forexample:doorsandwindows,curtainwalls,interiordecoration,etc.)

⒉Furnituremanufacturingindustry(glassCoffeetable,furnitureaccessories,etc.)

⒊Homeappliancemanufacturingindustry(TVs,ovens,airconditioners,refrigerators,etc.)

⒋Electronics,instrumentindustry(mobilephones,MP3,MP4,clocks,etc.)Avarietyofdigitalproducts)

Tempered glass

⒌Automotivemanufacturingindustry(automobilewindowglass,etc.)

⒍Dailyproductsindustry(glasscuttingboard,etc.)

⒎SpecialIndustry(MilitaryGlass)

Afterthetoughenedglassisbroken,thefragmentswillbebrokenintouniformsmallparticlesandthereisnocommonglassknife-likesharpcorner,soitiscalledsafetyglassandiswidelyusedinautomobilesandindoors.Inthedecoration,aswellasthewindowsthatopentotheoutsideonthehighfloors.

Emergencymethod

Quality

Toughenedglassistocutordinaryannealedglasstotherequiredsize,thenheatittoaclosesofteningpoint,andthenperformrapidanduniformObtainedbycooling.Aftertempering,uniformcompressivestressisformedonthesurfaceoftheglass,andtensilestressisformedinside,whichgreatlyimprovestheperformanceoftheglass.Thetensilestrengthismorethan3timesthatofthelatter,andtheimpactresistanceismorethan5timesthatofthelatter.

Itispreciselythisfeature.Thestressfeaturehasbecomeanimportantsigntodistinguishtrueandfalsetemperedglass.Layerobservation,youcanseeblackandwhitespots.Thepolarizercanbefoundinthecameralensorglasses.Payattentiontotheadjustmentofthelightsourcewhenobserving,sothatitiseasiertoobserve.

Everypieceoftemperedglasshasa3Ccertificationmark.

Spontaneousexplosiondefect

Theautomaticexplosionoftemperedglasswithoutdirectmechanicalexternalforceiscalledthespontaneousexplosionoftemperedglass.Accordingtoindustryexperience,thespontaneousexplosionrateofordinarytemperedglassis1~3‰about.Self-explosionisoneoftheinherentcharacteristicsoftemperedglass.

Therearemanyreasonsfortheexpansionofself-detonation.Simplysummarizethefollowing:

①Theinfluenceofglassqualitydefects

A.Therearestonesandimpuritiesintheglass,Bubbles:Impuritiesintheglassaretheweakpointsoftemperedglassandstressconcentrationpoints.Especiallyifthestoneisinthetensilestresszoneofthetemperedglass,itisanimportantfactorleadingtotheexplosion.

Stonesexistinglassandhaveadifferentexpansioncoefficientfromtheglassbody.Afterglasstempering,thestressconcentrationinthecrackareaaroundthestoneincreasesexponentially.Whentheexpansioncoefficientofthestoneissmallerthanthatofglass,thetangentialstressaroundthestoneisintension.Thecrackpropagationthataccompaniesthestoneisveryeasytooccur.

B.Theglasscontainsnickelsulfidecrystals

Nickelsulfideinclusionsgenerallyexistassmallcrystallinesphereswithadiameterof0.1-2mm.Theappearanceismetallic,andthesemiscellaneousinclusionsareNi3S2,Ni7S6andNi-XS,whereX=0-0.07.OnlytheNi1-XSphaseisthemaincauseofspontaneousexplosionoftemperedglass.

ThetheoreticalNISisknowntobe379.AtC,thereisaphasetransitionprocess,fromthehigh-temperatureα-NiShexagonalcrystalsystemtothelow-temperatureβ-NiStrigonalcrystalsystem,accompaniedbyavolumeexpansionof2.38%.Thisstructureispreservedatroomtemperature.Iftheglassisheatedinthefuture,theα-βstatetransitionmayoccurquickly.Iftheseimpuritiesareinsidethetemperedglassundertensilestress,thevolumeexpansionwillcausespontaneousexplosion.Ifthereisa-NISatroomtemperature,itwillgraduallychangetotheβstateafterseveralyearsandmonths.Theslowincreaseinvolumeduringthisphasechangedoesnotnecessarilycauseinternalrupture.

C.Theglasssurfacehasdefectssuchasscratches,blasting,anddeepblastingduetoimproperprocessingoroperation,whichmayeasilycausestressconcentrationorcausethetemperedglasstoexplode.

②Thestressdistributionintemperedglassisunevenandoffset

Thetemperaturegradientalongthethicknessdirectionoftheglasswhentheglassisheatedorcooledisunevenandasymmetric.Toughenedproductshaveatendencytoexplode,andsomeproduce"windexplosion"whentheyarechilled.Ifthetensilestresszonedeviatestoacertainsideoftheproductordeviatestothesurface,thetemperedglasswillexplodespontaneously.

③Theinfluenceofthedegreeoftoughening,experimentsshowthatwhenthedegreeoftougheningincreasestolevel1/cm,thenumberofspontaneousexplosionsreaches20%~25%.Itcanbeseenthatthegreaterthestress,thehigherthedegreeoftoughening,andthegreatertheamountofself-detonation.

Historyofdevelopment

Thedevelopmentoftemperedglasscanbetracedbacktothemiddleofthe17thcentury.TherewasasonoftheRhineKingnamedRobertwhooncedidaninterestingexperiment.HemeltedadropTheliquidglassisplacedinice-coldwater,resultinginaveryhardglass.Thiskindofhigh-strengthgranularglassislikeadropofwater,withalongandcurvedtail,called"PrinceRobertPellet".Butwhenthetailofthesmallgrainisbentandbroken,itisstrangethatthewholesmallgraincollapsessuddenlyandevenbecomesafinepowder.Theabovemethodisverysimilartothequenchingofmetal,andthisisthequenchingofglass.Thiskindofquenchingdoesnotcauseanychangeinthecompositionoftheglass,soitisalsocalledphysicaltempered,sotemperedglassiscalledtemperedglass.

ThefirstpatentforglasstemperingwasobtainedbytheFrenchin1874.Thetemperingmethodistoheattheglasstoclosetothesofteningtemperatureandimmediatelyputitintoarelativelylowtemperatureliquidtanktoincreasethesurfacestress.Thismethodistheearlyliquidtemperingmethod.FrederickSiemensofGermanyobtainedapatentin1875,andGeovgeE.RogensofMassachusetts,USAappliedthetemperingmethodtoglasswineglassesandlamppostsin1876.Inthesameyear,HughO’heillofNewJerseyobtainedapatent.

Inthe1930s,Saint-GobaininFrance,TripluxintheUnitedStates,andPilkingtonintheUnitedKingdomallbegantoproducelarge-areaflattemperedglassforwindshield.Japanalsosuccessivelycarriedouttheindustrialproductionoftemperedglassinthe1930s.Fromthenon,theworldbegantheeraofmassproductionoftemperedglass.

After1970,TriplexintheUnitedKingdomusedaliquidmediumtotemperglasswithathicknessof0.75~1.5mmsuccessfully,endingthehistoryofphysicallytemperingthinglassthatcannotbetempered.Thisisamajorbreakthroughintemperedglasstechnology..

ThehistoryofChina'stemperedglassbeganin1955,whenShanghaiYaohuaGlassFactorybegantrialproduction,andQinhuangdaoCityTemperedGlassFactorysucceededintrialproductionin1958.In1965,QinhuangdaoYaohuaGlassFactorybegantoproducetemperedglassformilitaryuse.Inthe1970s,LuoyangGlassFactoryfirstintroducedBelgiantemperingequipment.Atthesametime,ShenyangGlassFactory'schemicaltemperedglasswasputintoproduction.

Sincethe1970s,temperedglasstechnologyhasbeencomprehensivelypromotedandpopularizedworldwide.Temperedglasshasbeguntobeusedinthefieldsofautomobiles,construction,aviation,electronics,etc.,especiallyinconstructionandautomobiles.quick.

Self-explosionsolution

Reducestressvalue

Thestressdistributionintemperedglassisthatthetwosurfacesoftemperedglassarecompressivestress,andthecorelayerisintensilestress.,Thestressdistributioninthethicknessoftheglassissimilartoaparabola.Thecenteroftheglassthicknessistheapexoftheparabola,thatis,thepointwherethetensilestressisthegreatest;thetwosidesclosetothetwosurfacesoftheglassarecompressivestress;thezero-stresssurfaceislocatedatabout1/3ofthethickness.Byanalyzingthephysicalprocessoftemperingandquenching,itcanbeseenthatthesurfacetensionoftemperedglassandthemaximuminternaltensilestressareroughlyproportionalinvalue,thatis,thetensilestressis1/2to1/3ofthecompressivestress.Domesticmanufacturersgenerallysetthesurfacetensionoftemperedglassatabout100MPa,buttheactualsituationmaybehigher.Thetensilestressoftemperedglassitselfisabout32MPa～46MPa,andthetensilestrengthofglassis59MPa～62MPa.Aslongasthetensionproducedbytheexpansionofnickelsulfideis30MPa,itisenoughtocausespontaneousexplosion.Ifthesurfacestressisreduced,theinherenttensilestressofthetemperedglassitselfwillbereducedaccordingly,therebyhelpingtoreducetheoccurrenceofspontaneousexplosion.

AmericanstandardASTMC1048stipulatesthatthesurfacestressrangeoftemperedglassisgreaterthan69MPa;semi-tempered(thermallystrengthened)glassis24MPa～52MPa.CurtainwallglassstandardBG17841stipulatesthatthesemi-temperedstressrangeis24

Uniformstress

Theunevenstressoftemperedglasswillsignificantlyincreasetheself-explosionrate,whichhasreachedalevelthatcannotbeignored.Thespontaneousexplosioncausedbyunevenstresssometimesmanifestsveryconcentratedly.Inparticular,thespontaneousexplosionrateofaspecificbatchofbenttemperedglasscanreachanalarmingseverity,andspontaneousexplosionmayoccurcontinuously.Themainreasonistheunevenlocalstressandthedeviationofthetensionlayerinthethicknessdirection,andthequalityoftheoriginalglassitselfalsohasacertaininfluence.Unevenstresswillgreatlyreducethestrengthoftheglass,whichisequivalenttoincreasingtheinternaltensilestresstoacertainextent,therebyincreasingtherateofspontaneousexplosion.Ifthestressofthetemperedglasscanbeevenlydistributed,thespontaneousexplosionratecanbeeffectivelyreduced.

Hotdiptreatment

Hotdiptreatmentisalsocalledhomogenizationtreatment,commonlyknownas"detonation".Hot-diptreatmentistoheatthetemperedglassto290℃±10℃andkeepitforacertainperiodoftimetopromotetherapidcompletionofthecrystalphasetransformationofnickelsulfideinthetemperedglass,sothatthetemperedglassthatmayexplodeafteruseisartificiallybrokeninadvanceinthefactory.Inthehotdippingfurnace,thespontaneousexplosionofthetemperedglassinuseafterinstallationisreduced.Thismethodgenerallyuseshotairastheheatingmedium.Itiscalled"HeatSoakTest",orHSTforshort,whichisliterallytranslatedashotdiptreatment.

Thedifficultyofhotdipping.Inprinciple,thehotdiptreatmentisneithercomplicatednordifficult.Butinfact,itisverydifficulttoreachthistechnologicalindex.Studieshaveshownthattherearemanyspecificchemicalstructuralformulasofnickelsulfideinglass,suchasNi7S6,NiS,NiS1.01,etc.,notonlytheproportionsofvariouscomponentsaredifferent,butalsootherelementsmaybedoped.Thespeedofthephasechangeishighlydependentonthetemperature.Studieshaveshownthatthephasetransitionrateat280°Cis100timesthatat250°C,soitisnecessarytoensurethateachpieceofglassinthefurnaceexperiencesthesametemperatureregime.Otherwise,ontheonehand,thelowtemperatureglasscannotbecompletelyphasechangedduetotheinsufficientholdingtimeoftheglass,whichweakenstheeffectofhotdipping.Ontheotherhand,whentheglasstemperatureistoohigh,itwillevencausereversephasetransformationofnickelsulfide,causinggreaterhiddendangers.Bothofthesesituationswillcausethehotdiptreatmenttobelaboriousorevencounterproductive.Thetemperatureuniformityofthehotsoakfurnaceissoimportantwhenitisworking,andmostdomestichotsoakfurnaceshaveatemperaturedifferenceofupto60°Cduringhotsoaking,anditisnotuncommonforimportedfurnacestohaveatemperaturedifferenceofabout30°C.Therefore,althoughsometemperedglassishot-dipped,thespontaneousexplosionrateisstillhigh.

Infact,thehotdipprocessandequipmenthavebeenconstantlyimproving.TheGermanstandardDIN18516stipulatedinthe90theditionthattheholdingtimewas8hours,whiletheprEN14179-1:2001(E)standardreducedtheholdingtimeto2hours.Theeffectofthehotdippingprocessunderthenewstandardisverysignificant,andthereareclearstatisticaltechnicalindicators:afterhotdipping,itcanbereducedtoonecaseofspontaneousexplosionper400tonsofglass.Ontheotherhand,thehotdippingfurnaceisconstantlyimprovingitsdesignandstructure,andtheheatinguniformityhasalsobeensignificantlyimproved,whichcanbasicallymeettherequirementsofthehotdippingprocess.Forexample,theself-explosionrateofheat-dippedglassprocessedbytheCSGGrouphasreachedthetechnicalindicatorsofthenewEuropeanstandard,andithasperformedextremelysatisfactorilyinthe120,000-square-meterGuangzhouNewAirportsuperproject.

Althoughhotdippingtreatmentcannotguaranteethattherewillbeabsolutelynoself-detonation,itdoesreducetheoccurrenceofself-detonationandactuallysolvestheself-detonationproblemthatplaguesallpartiesintheproject.Therefore,hotimmersionisthemosteffectivewaytocompletelysolvetheproblemofself-detonationthatisunanimouslyrecognizedintheworld.

Precautionsforpackaging

Productsshouldbepackagedincontainersorwoodenboxes.Eachpieceofglassshouldbepackedinplasticbagsorpaper,andthespacebetweentheglassandthepackingboxshouldbefilledwithlightandsoftmaterialsthatarenoteasytocauseglassscratchesandotherappearancedefects.Specificrequirementsshouldcomplywithrelevantnationalstandards.

Packaginglogo

Thepackaginglogoshouldcomplywiththerelevantnationalstandards,andeachpackageboxshouldbemarkedwith"faceup,handlewithcare,becarefulofbroken,glassthickness,grade,factoryNameortrademark"andotherwords.

Transportation

Varioustypesoftransportationvehiclesandhandlingrulesusedintheproductshouldcomplywithrelevantnationalregulations.

Whentransporting,woodenboxesshouldnotbeplacedflatorinclined,andthelengthdirectionshouldbethesameasthemovingdirectionoftheconveyingvehicle,andmeasuressuchasrainshouldbetaken.

Storage

Theproductshouldbestoredverticallyinadryroom.