Lub hauv paus ntsiab lus ntawm kev tiv thaiv hluav taws xob thiab kev tawg ntawm ceramic PTC cua sov hauv tsheb cua txias

PTC yog ib hom semiconductor thermosensitive ceramic, abbreviated li zoo kub coefficient thermosensitive ceramic, uas belongs rau ib yam tshiab ntawm cov khoom uas tsis tshua muaj neeg siv. Los ntawm kev siv lub nonlinear tsis kam kub ntawm PTC ceramic, nws tuaj yeem tsim thiab siv rau ntau qhov chaw. Piv txwv li, kev siv cov ceramic PTC corrugated heaters hauv cov cua txias tau dhau los ua ntau dua. Ib qho ntawm nws cov yam ntxwv tseem ceeb yog nws txoj kev nyab xeeb. Thaum lub kiv cua ua haujlwm tsis zoo thiab tsis ua haujlwm, lub zog ntawm PTC lub rhaub yuav cia li poob qis vim tsis txaus cua sov. Lub sijhawm no, qhov kub thiab txias ntawm lub tshuab cua sov yog khaws cia nyob ib ncig ntawm Curie kub (feem ntau yog nyob ib ncig ntawm 250 degree), thiaj li tsis tsim cov phenomenon ntawm "redness" nyob rau saum npoo ntawm hluav taws xob cua sov tube rhaub.

2 PTC nyhuv

Muaj ntau cov qauv theoretical los piav qhia PTC cov nyhuv ntawm BaTiO3 semiconducting ceramics, ntawm cov qauv txheej txheem txheej txheem los ntawm Heywang thiab barium vacancy qauv npaj los ntawm Daniels li al. yog cov paub tab ntau dua thiab lees paub los ntawm cov kws tshawb fawb feem ntau.

Yog vim li cas rau cov nyhuv PTC tuaj yeem raug ntaus nqi los ntawm qhov muaj peev xwm thaiv txheej uas tshwm sim los ntawm qhov chaw txais qhov chaw ntawm lub lis piam ciam ntawm cov khoom siv polycrystalline BaTiO3 semiconductor. Cov khoom siv lub zog yog tsim los ntawm ob qhov chaw: grain lub cev tsis kam thiab grain nto lub xeev barrier. Raws li qhov kub thiab txias, cov khoom tiv thaiv yuav hloov los ntawm ntau qhov kev txiav txim ntawm qhov loj.

Ceramic PTC thermistor yog tsim los ntawm barium titanate thiab doped nrog lwm cov ntaub ntawv polycrystalline ceramic, nrog qis tsis kam thiab semiconductive zog. Los ntawm lub hom phiaj doping ib yam khoom uas muaj tshuaj valence siab dua li cov lattice keeb ntawm cov siv lead ua, ib feem ntawm barium ions los yog titanate ions nyob rau hauv lub lattice yog hloov los ntawm ntau dua valence ions, uas ua rau ib tug tej yam dawb electrons uas tsim conductivity. Yog vim li cas rau PTC thermistor nyhuv, uas yog cov kauj ruam nce nyob rau hauv tus nqi kuj, yog hais tias cov khoom qauv yog tsim los ntawm ntau me me microcrystals, uas tsim muaj peev xwm barrier ntawm lub grain ciam teb (grain ciam teb), inhibiting electrons hla ciam teb thiab nkag mus cov cheeb tsam uas nyob ib sab, ua rau muaj kev tiv thaiv siab. Cov nyhuv no raug tshem tawm ntawm qhov kub tsis tshua muaj: qhov siab dielectric tas li thiab lub zog ntawm lub cev polarization ntawm cov ciam teb cuam tshuam rau kev tsim cov teeb meem uas muaj peev xwm thiab tso cai rau cov hluav taws xob ntws los ntawm qhov kub thiab txias. Thaum qhov kub thiab txias, qhov cuam tshuam no txo ​​qis qhov dielectric qhov tsis tu ncua thiab polarization siv, ua rau muaj kev cuam tshuam loj thiab muaj peev xwm ua rau muaj zog, ua rau muaj zog PTC nyhuv.

Cov yam ntxwv kub tsis kam (RT yam ntxwv) ntawm ceramic PTC

Cov yam ntxwv kub tsis kam, feem ntau hu ua qhov ntsuas kub tsis kam, yog hais txog kev sib raug zoo ntawm xoom fais fab tsis kam ntawm PTC thermistor thiab qhov ntsuas kub ntawm lub cev resistor ntawm qhov ntsuas hluav taws xob. Vim qhov hloov pauv sai thiab hnyav hauv qhov kub thiab txias ntawm PTC thermistors tom qab lub hwj chim, nws feem ntau nyuaj rau ntsuas qhov ntsuas kub ntawm cov yam ntxwv nkhaus hauv lub zog. Qhov ntsuas kub ntawm cov yam ntxwv nkhaus feem ntau yog muab los ntawm kev tso cov ceramic PTC chips uas tsis txuas nrog rau hauv qhov cub, kho qhov kub thiab txias kom ruaj khov thiab ntsuas tus nqi sib xws ntawm qhov kub thiab txias, thiab thaum kawg kos qhov ntsuas kub ntawm cov yam ntxwv nkhaus.

R c hloov tsis kam

R p siab tshaj plaws ua haujlwm tsis kam

R max qhov siab tshaj plaws kuj

Rim yam tsawg kawg nkaus kuj

T c Curie kub

T p siab tshaj kev khiav hauj lwm kub

T max qhov kub thiab txias

T min yam tsawg kawg nkaus kub

Qhov tseem ceeb parameter uas characterizes cov yam ntxwv ntawm qhov kub thiab txias yog qhov kub coefficient, uas qhia txog qhov steepness ntawm qhov kub tsis kam ntawm cov yam ntxwv nkhaus. Qhov kub coefficient PTC thermistor yog rhiab heev rau qhov kub thiab txias hloov, uas yog, qhov tseem ceeb ntawm PTC nyhuv, qhov ua tau zoo ntawm nws cov khoom siv PTC thermistor, thiab nws lub neej ua haujlwm ntev dua. Qhov kub coefficient ntawm PTC thermistor yog txhais raws li tus txheeb ze hloov hauv qhov tsis kam los ntawm kev hloov kub. =(lgR2-lgR1)/(T2-T1), feem ntau, T1 siv Tc+15 degree, thiab T2 siv Tc+25 degree los xam qhov kub coefficient.

Cov yam ntxwv Volt Ampere (VI Yam ntxwv) ntawm Ceramic PTC

Cov yam ntxwv tam sim no, luv luv li volt ampere yam ntxwv, qhia txog kev sib cuam tshuam ntawm qhov hluav taws xob thiab tam sim no hauv PTC thermistors thaum raug hluav taws xob thauj khoom kom ua tiav cov thermal tshuav. Thaum lub ceramic PTC thermistor yog powered, tam sim no sai sai nrog rau qhov nce ntawm voltage. Thaum qhov kub ntawm Curie mus txog, qhov tam sim no nce mus txog qhov siab tshaj plaws, thiab PTC thermistor nkag mus rau thaj tsam PTC. Cov yam ntxwv ntawm volt ampere ntawm PTC thermistor tuaj yeem faib ua peb thaj tsam:

Cov cheeb tsam nruab nrab ntawm 0-Vk yog hu ua thaj tsam linear, thiab kev sib raug zoo ntawm qhov hluav taws xob thiab tam sim no hauv cheeb tsam no yeej ua raws li Ohm txoj cai, tsis muaj kev hloov pauv tseem ceeb, tseem hu ua cheeb tsam tsis ua haujlwm.

Qhov chaw nruab nrab ntawm Vk thiab Vmax yog hu ua dhia zone. Nyob rau lub sijhawm no, vim nws tus kheej cua sov ntawm PTC thermistor, tus nqi tiv thaiv tau dhia, thiab tam sim no txo ​​qis nrog qhov nce ntawm qhov voltage. Yog li ntawd, thaj chaw no tseem hu ua thaj chaw ua haujlwm. Cov khoom seem ntawm cov khoom tam sim no thiab qhov hluav taws xob nyob rau hauv cheeb tsam no tseem nyob tas li, qhia txog lub zog tsis tu ncua. Vim tias qhov dav ntawm qhov hluav taws xob hauv cheeb tsam tsis tu ncua, txawm tias qhov hluav taws xob hloov pauv, PTC thermistor tseem tswj tau qhov kub thiab txias.

Thaj chaw saum toj no VD hu ua thaj chaw tawg. Lub sijhawm no, qhov tam sim no nce nrog qhov nce ntawm qhov hluav taws xob, thiab qhov tsis kam ntawm PTC thermistor txo qis exponentially. Yog li ntawd, qhov siab dua qhov hluav taws xob thiab tam sim no, qhov kub ntawm PTC thermistor ntau dua, thiab qhov ua haujlwm qis dua. Qhov no sai sai ua rau lub thermal tawg ntawm PTC thermistor.

Lub mechanism ntawm PTC Cheebtsam tawg

Kev tawg ntawm ceramic PTC Cheebtsam yog feem ntau muab faib ua grain ciam tawg thiab thermal tawg.

5.1 Grain boundary breakdown: Qhov kev puas tsuaj tshwm sim los ntawm kev siv hluav taws xob ntau dhau los siv rau qee qhov ciam teb vim qhov kev loj hlob txawv txav lossis tsis sib xws ntawm cov nplej yog hu ua grain ciam tawg.

1963 G Goodman tau taw qhia tias ib leeg siv lead ua BaTiO3 ib qho semiconductor doping tsis pom cov nyhuv PTC, thaum polycrystalline BaTiO3 ceramic doping nthuav tawm cov nyhuv PTC. Txij thaum ntawd los, PTC feem ntau tau muab faib ua ib thaj tsam ntawm thaj tsam thoob ntiaj teb. Nyob rau hauv PTC Cheebtsam, nplej muaj nyob rau hauv semiconductors, thiab grain ciam teb yog nyob rau hauv insulating txheej, uas yog lub peev xwm barrier. Sab nraud hluav taws xob teb yog tsuas yog siv rau cov lis ciam txheej. Qhov me me ntawm cov qoob loo, ntau thaj tsam ntawm cov qoob loo muaj nyob rau hauv ib chav tsev tuab, thiab qhov me me ntawm qhov muaj txiaj ntsig zoo faib rau txhua tus ciam teb, ua rau txo qis hauv cov nyhuv piezoresistive thiab nce voltage kuj. Yog hais tias cov nplej loj tsis sib xws, nws muaj peev xwm muaj qee qhov loj lossis txawv txav hauv cov ceramic, uas tsim cov kab nrog qis qis thiab txo qhov tsis kam. Ntxiv qee cov tshuaj ntxiv kom raug thiab txhim kho cov cua sov ntawm cov txheej txheem sintering hauv cov khoom siv tiag tiag tuaj yeem tiv thaiv cov tiam ntawm cov nplej tsis zoo. Hauv kev tsim khoom tiag tiag, PTC cov nplooj ntawv ceramic nrog cov nplej tsis zoo tuaj yeem kuaj pom los ntawm 600V interpole withstand voltage test.

Thermal breakdowns: Lub point ua hauj lwm ntawm PTC Cheebtsam hla lub siab tshaj plaws point ntawm kuj kub yam ntxwv thiab nkag mus rau hauv lub NTC theem, ua rau ib tug ntse nce nyob rau hauv kub thiab ua rau thermal tawg. Cov yam ntxwv uas cuam tshuam rau thermal tawg yog feem ntau cuam tshuam nrog qhov cuam tshuam ntawm qhov hluav taws xob, kev ua haujlwm kub, ib puag ncig huab cua, thiab interpole tiv thaiv qhov ntsuas hluav taws xob.

Qhov ntsuas kub ntawm cov yam ntxwv nkhaus ntawm PTC tau pom nyob rau hauv nkhaus A hauv daim duab, uas qhia tau hais tias thaum qhov kub thiab txias nce, tus nqi kuj nce ib kauj ruam. PTC nrog Curie point ntawm 250 degree nce mus txog nws tus nqi siab tshaj plaws nyob ib ncig ntawm 320 degree (lub npe hu ua inflection point temperature), uas yog hais txog ntau pua kiloohms lossis ntau dua. Yog hais tias qhov kub thiab txias nce ntxiv tom qab ncav cuag qhov inflection point, RT cov yam ntxwv ntawm cov khoom pov thawj NTC cov yam ntxwv, uas yog, raws li qhov kub thiab txias, qhov tsis kam yuav txo.

Qhov nkhaus saum toj no tau ntsuas los ntawm PTC nyob rau hauv xoom lub zog, uas yog, qhov ntsuas tam sim no tsawg dua 2mA (qhov tam sim no yuav tsis ua rau PTC cua sov), uas yog RT tus yam ntxwv zoo li qub. Qhov tseeb, thaum PTC yog loaded nrog voltage, lub amplitude ntawm kuj hloov nrog kub (nce mus rau kuj piv) yuav ho txo, thiab cov kuj kub yam ntxwv nkhaus yuav zoo li yuav tiaj tus, raws li qhia nyob rau hauv nkhaus B nyob rau hauv daim duab. Qhov ntawd yog qhov hu ua voltage effect. Qhov siab dua qhov hluav taws xob, qhov ntau tshaj tawm qhov hluav taws xob ntawm PTC. Yog li thaum lub sij hawm 500V tiv thaiv cov txheej txheem ntsuas hluav taws xob, PTC ceramic nplooj ntawv nrog kev ua haujlwm tsis zoo yog qhov ua rau tawg, thiab qhov siab dua qhov ntsuas hluav taws xob, qhov ntau dua qhov tshwm sim ntawm kev tawg. Raws li cov qauv kev lag luam PTC tam sim no, qhov ntsuas hluav taws xob tiv thaiv rau kev kuaj xyuas lub Hoobkas yog ua los ntawm qhov hluav taws xob ntawm 500V.

Tom qab siv qee qhov hluav taws xob rau PTC, cov cua sov uas tsim los ntawm nws tus kheej mus txog qhov sib npaug nrog cov khoom siv hluav taws xob sab nraud, thiab qhov kub thiab txias hauv lub xeev sib npaug yog hu ua qhov kub ua haujlwm. Cov yam ntxwv uas cuam tshuam rau kev ua haujlwm kub yog cuam tshuam nrog kev siv hluav taws xob thiab cov cua kub dissipation. Noj cov ceramic PTC nrog Curie point ntawm 250 degree ua piv txwv thaum kuaj nyob rau hauv qee qhov cua qhov cua, thaum siv 220V voltage, qhov kub ntawm lub ceramic PTC yog 258 degree. Raws li qhov voltage nce, nws ua hauj lwm kub kuj nce. Thaum siv qhov hluav taws xob 500V, qhov ua haujlwm kub ntawm cov ceramic PTC yog 281 degree, uas yog ze rau qhov ntsuas kub ntawm 320 degree. Ceramic PTC yog yooj yim tawg. Nyob rau hauv qhov tsis muaj qhov cua, qhov cua kub dissipation tej yam kev mob ntawm ceramic PTC rhaub ua phem. Nyob rau lub sijhawm no, kev ntsuas siab dua qhov ntsuas hluav taws xob ntau dua tuaj yeem mus rau qhov kev hloov pauv, ua rau muaj kev nce ntxiv ntawm qhov sib piv ntawm kev tawg tsis ua haujlwm. Yog li ntawd, rau ceramic PTC rhaub nrog ib tug ntsuas voltage ntawm 220V thiab ib tug Curie point ntawm 250 degree, qhov ntsuas voltage yog kuaj nyob rau hauv 500V withstand voltage yam tsis muaj qhov cua, yog li qhov ntsuas voltage yog 500V. Kev xaiv ntawm PTC ceramic los xij nrog 220V thiab Curie point ntawm 250 degree, thiab cov kev xaiv raug xaiv rau chav sov R25 resistors

Cov cua kub dissipation muaj xws li qhov luaj li cas ntawm cov kav dej txhuas thiab cov strips, qhov sib nrug ntawm cov phaj corrugated, qhov chaw teeb tsa ntawm PTC hluav taws xob cua sov hauv lub tshuab cua txias, thiab seb lub tshuab cua puas tsim nyog. Qhov loj dua qhov loj ntawm aluminium raj thiab txhuas sawb, qhov zoo dua qhov kub dissipation tej yam kev mob. Qhov tsim nyog txo qhov sib nrug ntawm daim hlau corrugated tuaj yeem ua rau thaj tsam ntawm daim hlau corrugated, uas txhim kho cov cua sov dissipation. Lub kaum sab xis ntawm lub tshuab hluav taws xob PTC hluav taws xob hauv lub tshuab cua txias yog qhov tsim nyog rau cov cua ntws los ntawm cov phaj corrugated, uas txhim kho cov cua sov dissipation. Qhov ntau conducive lub cua duct tsim ntawm lub tshuab cua txias yog rau cov kev khiav ntawm airflow, qhov zoo dua cov cua kub dissipation tej yam kev mob ntawm lub PTC.

Tsis tas li ntawd, kev xaiv lub hwj chim kuj yog ib qho tseem ceeb cuam tshuam rau cov cua kub dissipation tej yam kev mob. Txhawm rau txhim kho lub zog cua sov ntawm lub tshuab cua sov, kev siv cov khoom siv PTC nce ntxiv, ua rau txhua yam tsis tuaj yeem siv tag nrho nws lub zog cua sov thiab nce hauv kev ua haujlwm kub. Qhov laj thawj tseem ceeb yog tias tom qab qhov loj ntawm PTC lub tshuab rhaub hluav taws xob tsim tau txiav txim siab, nws qhov chaw tshav kub kub kuj tau txiav txim siab. Raws li tus naj npawb ntawm PTC Cheebtsam nce, qhov nruab nrab kub dissipation cheeb tsam ntawm ib chav tsev ntawm PTC Cheebtsam txo, ua rau kom ib tug nce nyob rau hauv thermal ntom ntawm PTC ceramic los xij. Piv txwv li, lub tshuab hluav taws xob PTC nrog qhov loj ntawm XX * 580 siv 32 * 12 * 2.4mm ceramic phaj. Lub zog ntawm 14 daim hlau tuaj yeem ncav cuag 900W, tab sis lub zog ntawm 20 daim hlau tuaj yeem ncav cuag 1000W xwb. Cov ntaub ntawv qhia tias lub zog ntawm 14 daim hlau yog 64W, thaum lub zog ntawm 20 daim hlau yog 50W. Qhov no qhia tau hais tias chav tsev kub dissipation cheeb tsam txo qis nrog qhov nce ntawm cov phaj ceramic, uas ua rau muaj cua sov ceev thiab ib puag ncig ua haujlwm hnyav, uas tuaj yeem ua rau muaj qhov tshwm sim ntawm kev tawg yooj yim.

Cov qauv sab hauv ntawm PTC yog tsim los ntawm cov nplej thiab cov ciam teb. Qhov kev tiv thaiv ntawm PTC kuj tseem muaj cov nplej thiab nplej ciam teb tsis kam. Qhov tsis kam ntawm PTC ntawm chav tsev kub yog txiav txim siab los ntawm cov nplej, thiab qhov tsis kam yog tsawg heev. Cov ciam teb ntawm grain yog conductive. Thaum qhov kub siab tshaj qhov kub ntawm Curie, cov qoob loo ciam teb kuj nce siab, nce mus txog ntau pua kiloohms lossis txawm megaohms. Qhov no yog vim hais tias thaum lub sij hawm sintering thiab txias txheej txheem ntawm PTC, lub grain ciam teb absorbs txaus oxygen atoms nyob rau hauv ib tug oxygen cua, ua rau kom qhov siab ntawm lub barrier txheej ntawm grain ciam teb thiab ua rau cov zoo heev PTC yam ntxwv. Thaum siv, yog tias cov pa ib nrab siab nyob rau hauv ib puag ncig uas PTC nyob qis, qhov siab ntawm oxygen atoms ntawm cov ciam teb yuav maj mam diffuse thiab dhau mus rau qhov tsis tshua muaj siab sab nraud, ua rau cov nplej ciam teb tsis kam ntawm PTC kom txo, nqa mus rau luag piv kom txo qis, thiab cov yam ntxwv ntawm PTC yuav hnyav zuj zus, thaum kawg ua rau tsis muaj zog tsis zoo thiab PTC tawg.

Qhov zoo ntawm cov ntawv Ceramic PTC yog qhov tseem ceeb hauv kev txiav txim siab qhov hluav taws xob tsis kam thiab tawg. Cov neeg muab kev ntseeg siab yuav tsum raug xaiv, thiab kev soj ntsuam nruj ntawm cov ntawv Ceramic PTC yuav tsum tau ua los xaiv PTC cov ntawv uas muaj hluav taws xob tsis zoo thiab kub coefficient.

Txhawm rau txo qhov kev sib cuag ntawm PTC cov cua sov thiab txo cov cua sov thaum lub sij hawm cua sov, muaj ib txoj hauv kev los txo qhov diffusion ntawm oxygen atoms thiab txhim kho lub zog compressive los ntawm txheej txheej ntawm PTC ceramic nplooj ntawv nrog nplaum.

⑶ Tsim PTC hluav taws xob cua sov lub zog