Lub luag hauj lwm dab tsi ua Heated Platens Ua Si hauv Kev Kub Siab ntawm Kev Siv Ceramics?

Koj tsis tsuas yog yaj thiab nrum ib tug tub rog cov khoom, mos txwv -cov ntaub ntawv pov thawj ceramic armor phaj, los yog pob tshab, ultra-dome hard dome rau missile's infrared seeker. Nws yog tsim los ntawm kub nias: nyias, xoob ceramic hmoov tau ntim rau hauv qhov tuag thiab nyem hauv qab lub siab zoo ntawm qhov kub thiab txias, sib sib zog nqus hauv lub tshuab nqus tsev. Thiab cov platens uas xa cov crushing no, hlawv lub zog tsis yog hlau, uas yuav sag thiab yaj. These are blocks of dense graphite or refractory metal, orange with heat, and they are the sculptors of the world's hardest and most advanced materials.

Kub nias ntawm technical ceramics
Technical ceramics, such as silicon carbide (SiC), aluminium oxide (Al₂O₃), boron carbide (B₄C) and silicon nitride (Si₃N₄), are characterised by excellent hardness, high-temperature strength, wear resistance and chemical inertness. However, they cannot be melted and cast like metals, because their melting points are very high (typically >2000 degree) thiab molten ceramics tawg lossis tsim cov theem tsis xav tau. Hloov chaw lawv tau tsim los ntawm cov txheej txheem hmoov hlau metallurgy, kub nias yog ib qho ntawm cov txheej txheem ua tau zoo tshaj plaws los muab ze rau - theoretical ntom ntom thiab cov yam ntxwv zoo heev.

Ua tib zoo ntsuas tus nqi ntawm cov hmoov ceramic yog thauj mus rau hauv qhov tuag kab noj hniav, feem ntau graphite, hauv kev ua haujlwm kub kub. Cov tuag yog nyob nruab nrab ntawm ob loj, tiaj tus kub platens. Tag nrho cov sib dhos yog muab tso rau hauv lub tshuab nqus tsev chamber los yog lub cub tawg uas muaj roj inert (argon los yog nitrogen). Cov platens yog rhuab, feem ntau yog muab cov hluav taws xob siab heev ncaj qha los ntawm lawv (cov cua sov ua haujlwm) lossis los ntawm cov cua kub inductive, kom kub ntawm 1500 degree. thiab tshaj 2000 degree. Nyob rau tib lub sij hawm hydraulic ram exerts uniaxial siab (feem ntau 20-100 MPa) ntawm platens mus rau hmoov. Cov yas deformation ntawm cov khoom ceramic nyob rau hauv qhov kub thiab txias thiab siab thiab cov nplej ciam diffusion thiab creep ua rau densification. Porosity raug txo qis thiab ua kom muaj kev ua haujlwm siab ntawm cov khoom siv ceramic.

Cov kub kub graphite platens yog cov kub, tsis muaj kev hlub tshua uas nyem lub neej mus rau hauv ib lub pob ntawm cov hmoov thiab forge ib daim ntawm yuav luag indestructible pottery.

Vim li cas Heated Platens tseem ceeb heev rau cov txheej txheem
Cov txheej txheem thev naus laus zis ceramic kub xovxwm nrog cov cua sov platens tsis yog tsuas yog cov chaw muab cua sov thiab quab yuam, tab sis lub hauv paus khoom txiav txim siab qhov zoo ntawm cov khoom tiav tiav. Cov platens muaj ntau lub luag haujlwm tseem ceeb:

1. Uniform, kub kub cua sov
Cov platens yuav tsum uniformly cua sov cov tuag thiab cov hmoov tshaj tag nrho cov nias nto. Txhua qhov kub sib txawv ua rau qhov tsis sib xws, nrog rau qhov kub kub dhau - ntom ntom thiab tejzaum nws pom kev loj hlob ntawm cov nplej thaum cov seem txias tseem ntxeem tau thiab tsis muaj zog. Cov platens yog li txiav mus rau ib qho kev tiaj tus (feem ntau zoo dua 0.01 hli) thiab ua kom sov siv ntau- cheeb tsam fais fab los yog cov khoom siv hluav taws xob kom zoo. Ntawm 2000℃uas yog qhov zoo tshaj plaws engineering feat, qhov kub thiab txias homogeneity raws lub ntsej muag ntawm platen feem ntau yog khaws cia nyob rau hauv ± 5 degree.

2. Txawm tias Kev Tshaj Tawm Siab
Lub hydraulic ram exerts ib tug quab yuam tab sis nws yog cov platens uas faib uas quab yuam uniformly tshaj tag nrho cov hla ntu ntawm qhov tuag. Yog hais tias lub platen nto tsis yog theem thiab sib npaug, qhov kev faib tawm siab tsis yog -uniform. Qhov no txhais tau hais tias cov khoom yog thicker ntawm ib sab thiab thinner rau lwm yam los yog hais tias lawv muaj qhov ntom ntom gradients. Txawm nyob rau qhov kub siab (tshaj 1500 degree) graphite pib nkag mus. Cov platens yuav tsum yog tuab txaus thiab siab purity nplua grained graphite uas yuav tsis distort nyob rau hauv strain. Qee qhov kev tshaj lij tshaj lij siv cov tawv graphite platens txhawb los ntawm softer, ua raws li graphite xav lossis hydraulic multi-piston system kom ntxiv dag zog sib npaug.

3. Resistance rau siab thermal thiab mechanical stress
Cov platens ib txhij muaj zog compressive load thiab kub hnyav. Hlau yuav mos thiab ntws ntawm 1000 degree, zoo ua ntej qhov xav tau 1500-2000℃ntau yam. Cov khoom siv ib txwm yog tuab, siab -lub zog graphite (isotropic lossis nplua nplej). Graphite muaj kev tiv thaiv zoo rau thermal poob siab (sai cua sov thiab txias tsis tawg), yog cov tshuaj sib xyaw nrog feem ntau cov hmoov ceramic, thiab khaws nws lub zog compressive ntawm 2500 degree. Hauv qee cov ntawv thov tshwj xeeb uas yuav tsum muaj purity siab heev lossis tsis yog - carbon cua yuav tsum tau, cov hlau refractory zoo li tungsten lossis molybdenum yog siv rau cov platens, txawm tias cov no kim dua thiab tsawg dua oxidation-resistant.

4. Muab qhov huv, Reactive - Ib puag ncig dawb
Technical ceramics yuav luag txhua zaus kub nias hauv lub tshuab nqus tsev (feem ntau yog 10-2 txog 10-}4 mbar) lossis inert gas cua (argon, nitrogen). Qhov no inhibits oxidation ntawm ceramic hmoov thiab graphite platens. Oxygen ntawm qhov kub thiab txias yuav kub hnyiab tau graphite sai thiab ua puas feem ntau uas tsis yog-oxide ceramics. Cov tuag lossis cov ceramic yuav tsum tsis txhob hnov ​​​​qab nrog cov platens nws tus kheej. Vim tias qhov inertness ntawm high-purity graphite rau carbides, nitrides thiab oxides ntawm cov txheej txheem kub, nws yog cov khoom zoo tshaj plaws platen.

Tsim thiab Npaj Graphite Heated Platen
Graphite platens tsis yog carved los ntawm graphite block. Lawv yog precision tsim Cheebtsam. Tej yam parameter yog:

Khoom siv: zoo- nplej (<10 μm), high bulk density (>1.8 g / cm³), graphite, isostatic lossis kev co pwm. Lub siab ceev txhim khu cov cua sov conductivity, txhua yam muaj zog thiab yaig kuj.

Flatness: Nto flatness ntawm tag nrho lub ntsej muag platen Tsawg dua lossis sib npaug li 0.01 hli. Qhov no feem ntau ua tiav los ntawm pob zeb diamond sib tsoo tom qab kub kub ntxhov siab annealing.

Parallelness: Lub ntsej muag ntawm sab sauv thiab qis platens yog hauv av sib npaug li tsawg dua lossis sib npaug li 0.02mm.

Cov txheej txheej saum npoo (yeem): Qee cov platens yog coated nrog ib txheej nyias ntawm pyrolytic graphite los yog refractory carbide (xws li TaC, NbC) kom txo tau hnav, tsis txhob lo ntawm qhov tuag, thiab ua kom lub neej ntev.

Cov kab cua txias (kev sib xyaw): Thaum cov platens yuav tsum tau txias sai sai tom qab lub voj voog nias, cov kab sab hauv yog tshuab rau hauv cov graphite blocks uas muaj cov roj inert (xws li helium lossis argon) yog pumped. Txawm li cas los xij yuav tsum tau saib xyuas hauv qhov txias kom tsis txhob muaj kev poob siab thermal.

Cov graphite platens tshiab feem ntau yog 'ci tawm' ua ntej siv thawj zaug ntawm qhov kub thiab txias hauv lub tshuab nqus tsev kom tshem tawm cov khoom nqus dej los yog cov kab mob tsis zoo. Cov txheej txheem outgassing no lub hom phiaj los tiv thaiv kev sib kis ntawm cov ceramic.

Cov txheej txheem ceeb toom: Tswj Cooldown kom tsis txhob muaj cua sov
Ceramic feem tsim ntawm 1500-2000℃yuav tsum tau txias rau chav sov. Qhov txias - theem qis no tseem ceeb npaum li qhov nias nws tus kheej. Cov txheej txheem ceramics tshwj xeeb tshaj yog tsis yog -oxides (silicon carbide, boron carbide) yog nkig thiab muaj cov thermal conductivity tsawg. Yog tias qhov txias txias yog nrawm los yog tsis sib xws, cov thermal tensions sab hauv tau teeb tsa uas tuaj yeem ua rau qhov tawg ntawm qhov tsis sib xws - feem ntau ua nruj ua tsiv - raws li nws tawm hauv xovxwm.

Yog li ntawd, thaum kawg ntawm lub voj voog nias, lub zog muab rau cov cua sov platens maj mam txo qis tom qab qhov programd txias -down profile. Ib qho profile feem ntau yuav poob qhov kub ntawm 2000℃mus rau 800℃hauv 2-4 teev thiab tom qab ntawd cia nws txias nyob rau hauv qhov chaw tsis zoo. Cov platens lawv tus kheej yuav tsum txias tusyees. Graphite pab nrog nws cov thermal conductivity (kwv yees . 50-100} W / mk ntawm qhov kub thiab txias, nyob ntawm qib), tab sis tus nqi uas nws txias yog tseem txwv los ntawm qhov zoo ntawm cov ceramic. Qee cov xovxwm kub muaj lub tshuab ua kom txias txias uas tso cov roj inert los ntawm cov platen raws tab sis tus nqi ntws tau ua tib zoo tswj kom tsis txhob muaj cua sov gradient hla lub ntsej muag platen.

Txawv ceramics, txawv phaj tsim
Cov xwm txheej kub nias yog hloov pauv rau cov txheej txheem sib txawv ceramics. Raws li, cov rhuab platens tau yoog raws:

ceramic|Hom kub nias kub|Platen Khoom|Kev txiav txim siab tshwj xeeb
Silicon carbide (SiC) 1800-2100℃Graphite Kub kub heev purity graphite xav tau Feem ntau pyrolytic graphite txheej siv los tiv thaiv kev cuam tshuam nrog SiC vapors
Alumina (Al2O3) 1400-1600℃Graphite los yog molybdenum tuaj yeem nias hauv lub tshuab nqus tsev lossis roj inert. Molybdenum thaum cov pa roj carbon monoxide yuav tsum zam
Boron carbide (B₄C) 2000-2200℃Graphite Kub heev; tshwj xeeb siab - ntom, nplua -grained graphite yuav tsum tau; qeeb heev - cia
Silicon nitride (Si3N4) 1700-1850℃Graphite Feem ntau yog cov hmoov txaj lossis ntawv ci (xws li BN tso txheej) yog siv los tiv thaiv kev sib txuas ntawm cov khoom siv rau cov platen lossis tuag.
Zirconium diboride (ZrB 2) 1900-2100℃Graphite (them nrog TaC) Reactive heev, yuav tsum muaj kev tiv thaiv carbide txheej ntawm lub platen
Yog vim li cas kub nias zoo dua lwm yam Ceramic txoj kev?
Piv rau pressureless sintering los yog kub isostatic nias (HIP), kub nias nrog rhuab platens muab:

Higher Density: Hot pressing gives you >99.5% theoretical ceev, thiab nyob rau hauv tsawg lub sij hawm.

Fine grain loj. Sintering nyob rau hauv siab tso cai rau sintering ntawm qhov kub thiab txias tshaj li qhov tsis muaj zog sintering, ua rau cov nplej me me thiab txhim kho cov yam ntxwv zoo.

Nyob ze -net zoo: Cov khoom siv ceramic yog tsim ncaj qha rau hauv qhov tuag kom tsawg machining tom qab nias yuav tsum tau (uas yog qhov nyuaj thiab kim rau cov ceramics nyuaj).

Cov khoom sib xws: Kev sib xyaw ua ke ntawm uniaxial siab thiab cov cua kub sib xws ua rau hauv isotropic lossis ze rau -isotropic zog, nyob ntawm cov khoom siv thiab cov xwm txheej nias.

Tab sis kub nias yog txwv tsis pub sib piv cov ntaub ntawv yooj yim (cylinders, blocks, daim hlau) thiab yog kim dua nyob rau hauv cov cuab yeej siv nyiaj ntau dua pressureless sintering. Rau cov duab zoo nkauj dua, qee qhov txheej txheem yuav tsum tau ua, piv txwv li kev txhaj tshuaj molding thiab tom qab ntawd sintering.

Kev nyab xeeb thiab kev xav txog kev ua haujlwm
Thaum ua haujlwm nrog cov cua sov platens ntawm 2000℃hauv lub tshuab nqus tsev, kev ntsuas kev nyab xeeb yuav tsum tau ua:

Oxidation ntawm graphite: Yog hais tias lub hoover poob los yog inert gas mov tsis ua hauj lwm, kub graphite yuav ignite nyob rau hauv cov huab cua ntawm kub tshaj 400 degree, kub ceev thiab muab tawm kub heev. Yog tias oxygen nkag mus rau hauv, tsis siv neeg interlocks tua lub hwj chim thiab yaug lub chamber nrog cov roj inert.

Thermal hluav taws xob. Cov blazing platens radiate heev nyob rau hauv infra-liab. Cov ntxaij lim dej tiv thaiv yog mounted nyob rau hauv lub viewports. Cov neeg ua haujlwm tsis txhob saib ncaj qha rau thaj chaw kub yam tsis muaj qhov muag tiv thaiv.

Thermal shock of graphite Cracking of graphite platens with quick cooling Large platens muaj qis txias -down tus nqi qis dua los yog sib npaug li 50℃/ feeb thiab feem ntau qeeb qeeb.

Kev phom sij ntawm kev tuag thiab hmoov: Qee cov hmoov ceramic (xws li beryllium oxide, thorium oxide) yog tshuaj lom. Qhov kub nias ntawm cov ntaub ntawv no yog ua tiav hauv hnab looj tes-box enclosures. Graphite plua plav, txawm tias "inert," tuaj yeem ua rau muaj hluav taws xob txaus ntshai thaum nws tsim.

NYEEM NTXIV: Qib Siab Tshaj, Tshaj Lij Tshaj Plaws, Kub Tshaj Plaws
Lub rhuab platen yog qhov siab tshaj plaws nyob rau hauv siab -kub forging cov cuab yeej, tig ib tug xoob, grey hmoov rau hauv lub neej tshaj plaws - txuag ceramic Cheebtsam ntawm lub ntiaj teb. Lawv muaj xws li los ntawm armor daim hlau uas nres phom phom, mus rau txiav cov cuab yeej uas tshuab superalloys, mus rau missile domes uas ciaj sia nyob supersonic ya davhlau, rau bearing npas uas khiav tsis muaj lubrication-txhua tus yug los ntawm kub tshaj plaws, muaj zog tshaj plaws, thiab flattest ntawm qhov chaw- lub glowing graphite platens ntawm lub qhov cub kub kub. Cov txheej txheem yuav tsum tau kub siab heev (> 1500 C ), txawm siab, thiab lub tshuab nqus tsev huv si los yog inert cua. 2) Kev tsim ntawm txhua lub ntsiab ntawm cov cua sov platen system, los ntawm kev nplua -grained graphite qib mus rau micron -theem flatness mus rau qhov txias txias -down profile, yog optimized, {1 kev ua tau zoo ceramic. Thaum soj ntsuam nrog cov ntaub ntawv sophisticated, cov khoom nyuaj tshaj plaws yog tsim los ntawm cov khoom siv nyuaj tshaj plaws, kub tshaj plaws - cov rhuab platens ntawm cov xovxwm kub.