Yog vim li cas PFA Rhaub nrog Coiled Hlau Cheebtsam yog tiv taus thermal shock dua li lub cam khwb cia-Hauv Kev Tsim?

Thermal shock, xws li ceev ceev ntawm lub rhaub kub rau hauv cov kua txias los yog lub zog ceev ceev, ua rau kub kub gradients hauv PFA sheath. Kev ua raws li cov khoom siv coiled thiab dispersed cua sov tiam muab lub coiled hlau caij cua sov (tsis kam hlau qhov txhab nyob ib ncig ntawm lub mandrel, encapsulated nyob rau hauv PFA) ib tug zoo dua cam khwb cia- nyob rau hauv tsim (hlau cua sov caij cam khwb cia ncaj qha mus rau hauv ib tug thaiv ntawm PFA) nyob rau hauv thermal shock kev ua tau zoo. Cov hlau yog qhov txhab nyob rau hauv ib lub kauj thiab tuaj yeem flex thiab nthuav tawm ntawm nws tus kheej ntawm PFA sheath kom nqus tau qhov sib txawv ntawm kev nthuav dav. Cam khwb cia- nyob rau hauv muaj ib tug nyuaj hlau ntsiab adhered ncaj qha mus rau lub PFA. Cov hlau thiab PFA muaj qhov sib txawv coefficient ntawm thermal expansion (CTE: hlau 14-17 ppm/degree, PFA 110-120 ppm/degree). Kev sib cuag nruj ua rau muaj kev ntxhov siab hauv ib qho chaw thaum kub hloov sai. Delamination lossis cracking tshwm sim. Cov txiaj ntsig tau los ntawm kev ntsuas kev ntsuas cua sov qhia tau tias cov cua sov coiled cua sov tuaj yeem tiv taus 5-10 ntau thermal shock cycles dua li cam khwb cia hauv cov khoom sib npaug.

Nws tiv thaiv Thermal Shock li cas?
Nyob rau hauv ib lub coiled hlau rhaub cov hlau tsis kam yog khi rau PFA. Nws yog embedded nyob rau hauv ib tug ceramic los yog hlau core, uas yog PFA coated. Lub kauj yog pub dawb los nthuav thiab cog lus radially thiab axially nrog kub variations. Cov hlau muaj CTE 6x qis dua lub plhaub, yog li PFA sheath nthuav ntau dua cov hlau tab sis cov coils ntawm cov hlau qhib me ntsis (lub suab nce) los tswj qhov sib txawv. Kev sib cuag ntawm cov xaim thiab PFA ntsib kev nyuaj siab me ntsis, nrog rau PFA tuaj yeem hloov pauv ntawm cov hlau tsis muaj kev txwv.

Ib qho cam khwb cia- hauv kev tsim ua tiav encapsulates cov hlau cua sov (feem ntau yog tus pas nrig ncaj lossis U- zoo li lub raj) hauv PFA. Cov hlau yog khi rau PFA. Nyob rau hauv cov ntaub ntawv ntawm kev hloov kub ceev, PFA nthuav 6 × sai dua hlau. Vim tias cov hlau yog tawv thiab txuas nrog, PFA tsis tuaj yeem nthuav dav dawb do- nws yog ncab ib ncig ntawm cov hlau. Lub zog tensile uas tshwm sim ntawm cov hlau-PFA kev sib cuag tuaj yeem siab li 5-10 MPa rau lub thermal shock ntawm 100℃. PFA muaj lub zog tensile ntawm 12-15 MPa tab sis lub zog khi rau hlau ntawm 2-5 MPa. Nws cais lub interface los tsim qhov sib txawv. Cov dej noo nkag mus rau hauv qhov sib txawv thiab cov cua sov ua ke ua rau PFA tawg.

Thermal Shock Cycles: Quantitative Comparison
Heater Hom Kev Tsim Kho Kub Kub (ΔT) Cycles rau Delamination/Cracking Failure Mode Coiled wire, 2 mm PFA Hlau qhov txhab hla ceramic core 100℃(150℃txog 50 degree) 5,000–10,000 maj mam qaug zog (xaim yuav snap ua ntej)
Wire, PFA, 2 mm, coiled Same 50°C >20,000 Tsawg kawg kev puas tsuaj
Ncaj pas nrig, nrum-inPFA cam khwb cia hlau pas nrig 100℃500–2000Metal-PFA delamination ntawm lub interface
Cam khwb cia-hauv, U- zoo li Bent hlau raj cam khwb cia hauv PTFE 100℃200-1,000Inner vojvoog ntawm khoov tawg
Adhesive txheej cam khwb cia-hauv Hlau + primer + PFA 100℃1,000-3,000 Adhesive tsis ua hauj lwm (primer peels)
Coiled hlau, tuab sheath (3 hli PFA) Thick PFA coiled hlau 100℃8,000-15,000A zoo dua nyias sheath
Hlau core expansion slot Cast-hauv Hlau tub ntxhais nrog qhov sib txawv 100℃2,000-4,000 Txhim kho tab sis tseem tsawg dua coiled
Vim li cas Cam khwb cia-Nyob hauv Designs Fail nyob rau hauv Thermal Shock
Cov cam khwb cia- hauv kev tsim yog raug vim rau thaj tsam loj loj ntawm cov hlau thiab PFA. Rau ib tug 1 m ntev, 10 hli txoj kab uas hla hlau qws cam khwb cia nyob rau hauv PFA, bonded cheeb tsam yog π x 10 x 1, 000=31,400 mm2. Tag nrho qhov tsis sib haum xeeb hauv kev nthuav dav rau 100℃yog ΔL=( _PFA – _metal) × L × ΔT=(110e-6) × 1000 × 100=11 mm. PFA xav kom ntev 11 hli ntau dua li cov hlau. Vim tias lawv txuas nrog, PFA yog elastically stretched thiab ua rau muaj kev ntxhov siab. Lub shear stress ntawm lub interface yog τ=G × ΔL / t, qhov twg G yog shear modulus thiab t yog thickness ntawm PFA. Rau t=5 hli G≈200 MPa τ=200 × 11 / 5=440 MPa ua tsis tau. Hauv qhov tseeb, PFA tshwm sim hauv delamination ntawm lub interface. Lub nro yog concentrated nyob rau hauv qhov kawg ntawm cov hlau pas nrig (qhov twg qhov tsis sib haum yog qhov loj tshaj), thiab cov kab nrib pleb thiab loj hlob sab hauv.

Coiled hlau heaters tsis muaj xws li ib tug loj sib raug zoo interface. Cov xaim hu rau PFA nkaus xwb ntawm cov ntsiab lus hauv cheeb tsam (qhov sab nraud ntawm cov coils). Tag nrho cheeb tsam kev sib cuag yog tsawg (10-20% ntawm cam khwb cia- hauv cheeb tsam). Kev sib cuag tsis yog kev sib txuas (xov hlau tuaj yeem plam). Hlau txav, tsis yog PFA ncab, haum rau kev nthuav dav tsis sib haum.

Cov kev cuam tshuam rau kev xaiv
Rau cov ntawv thov uas thermal cycling nquag (txhua hnub pib / nres, batch txheej txheem los yog thermal shock tu cycles), ib coiled hlau PFA rhaub yuav tsum tau teev. Cam khwb cia- nyob rau hauv cov cua sov yog qhov tsim nyog thiab feem ntau tsis tshua muaj nqi rau kev ruaj khov- cov ntawv thov hauv xeev (kev ua haujlwm tsis tu ncua, tsis muaj kev caij tsheb kauj vab).

Zoo tagnrho rau: Batch reactors, plating kab uas kaw txhua hnub, khov -thaw cycles, thermal shock ntxuav (dipping rhaub rau hauv cov kua txias), portable heaters.

Cam khwb cia- tsim nyog rau: kev ua tshuaj tsis tu ncua, 24/7 dej cua sov, cov khoom siv cua sov, tsis yog- daim ntawv thov caij tsheb kauj vab.

Coiled xaim cua sov feem ntau yog 20-40% kim dua li cam khwb cia-in vim yog kev sib tw winding thiab kev tsim kho. Hwm yog tsim nyog los ntawm kev ncua lub neej nyob rau hauv thermal cycling. Lub tshuab cua sov uas tawg tom qab 500 lub voj voog (6 lub hlis ntawm kev caij tsheb kauj vab txhua hnub) yuav raug hloov 5x hauv 2.5 xyoo; ib co coiled hlau rhaub yuav kav tag nrho lub sij hawm nrog ib tug hloov.

Field Test
The cast-in PFA heaters were utilised in a batch plating process with 10 cycles per day (heat up from 25°C to 85°C, then cool down to 25°C). Heaters delaminated after 3-4 months (ca. 1000 cycles) The plant was converted over to coil wire heaters. The same heaters lasted over 3 years (>10,000 cycles). Ntxiv tus nqi pem hauv ntej (30% tus nqi them) them rov qab hauv 6 lub hlis dhau los ntawm kev hloov pauv qis dua thiab lub sijhawm poob.

Cov ntsiab lus: Coiled hlau yog 5-10 npaug ntau tiv taus thermal shock
Lub tshuab cua sov PFA nrog cov hlau coiled yog qhov ua tau zoo dua rau cov thermal shock dua li cov cam khwb cia- hauv kev tsim vim tias cov hlau coiled tuaj yeem khoov thiab nthuav tawm ntawm PFA sheath kom haum rau qhov sib txawv thermal expansion yam tsis muaj qhov sib txawv ntawm qhov sib txawv. Cov cam khwb cia- hauv kev tsim ua rau cov hlau ua kom nruj rau PFA, uas ua rau delamination thiab tawg nrog kub hloov pauv sai. Rau cov ntawv thov uas muaj qhov kub thiab txias tsis tu ncua (txhua hnub lossis ntau lub voj voog ib hnub) qhia cov xov hlau coiled. Cast-hauv yog OK thiab txo tus nqi rau kev ua haujlwm tas mus li, nyob ruaj khov. Cam khwb cia- nyob rau hauv cov cua sov tau tua los ntawm thermal shock. Hlau coil ciaj sia. Thiab yog tias koj tsis paub meej, qhwv nws. Nws ruaj khov dua.