Cov txheej txheem sintering thiab sintering silicon carbide ceramic tsis muaj siab

Kev sib xyaw ua ke ntawm cov tshuaj tiv thaiv

Kev sib xyaw ua ke ntawm cov tshuaj reactionsilicon carbide ceramicsCov txheej txheem ntau lawm suav nrog kev sib xyaw ua ke ntawm cov khoom siv ceramic, kev sib xyaw ua ke ntawm cov khoom siv flux infiltration agent, kev npaj cov khoom siv ceramic sintering, kev npaj cov khoom siv ceramic ntoo silicon carbide thiab lwm cov kauj ruam.

Cov tshuaj tiv thaiv sintering silicon carbide nozzle

Ua ntej, 80-90% ntawm cov hmoov av ceramic (muaj ib lossis ob lub hmoov ntawmsilicon carbide hmoovthiab hmoov boron carbide), 3-15% ntawm cov hmoov carbon (muaj ib lossis ob hom carbon dub thiab phenolic resin) thiab 5-15% ntawm cov neeg sawv cev molding (phenolic resin, polyethylene glycol, hydroxymethyl cellulose lossis paraffin) raug sib xyaw kom sib npaug siv lub tshuab zeb pob kom tau txais cov hmoov sib xyaw, uas yog tshuaj tsuag ziab thiab granulated, thiab tom qab ntawd nias rau hauv pwm kom tau txais cov khoom siv ceramic compact nrog ntau yam duab tshwj xeeb.
Qhov thib ob, 60-80% hmoov silicon, 3-10% hmoov silicon carbide thiab 37-10% hmoov boron nitride raug sib xyaw kom sib npaug, thiab nias rau hauv pwm kom tau txais cov khoom siv sintering flux infiltration agent compact.
Cov khoom siv ceramic compact thiab cov khoom siv sintered infiltrant compact ces muab sib dhos ua ke, thiab qhov kub thiab txias raug tsa mus rau 1450-1750 ℃ ​​hauv lub tshuab cua sov uas muaj qhov nqus tsev tsawg kawg 5 × 10-1 Pa rau sintering thiab khaws cia cua sov rau 1-3 teev kom tau txais cov khoom siv ceramic sintered. Cov khoom seem infiltrant ntawm qhov chaw ntawm cov khoom siv ceramic sintered raug tshem tawm los ntawm kev tapping kom tau txais daim ntawv ceramic ntom ntom, thiab cov duab qub ntawm cov khoom siv compact raug khaws cia.
Thaum kawg, cov txheej txheem sintering tshuaj tiv thaiv tau txais yuav, uas yog, kua silicon lossis silicon alloy nrog kev ua haujlwm tshuaj tiv thaiv ntawm qhov kub siab nkag mus rau hauv cov khoom siv ceramic porous uas muaj cov pa roj carbon nyob rau hauv qhov kev ua ntawm capillary force, thiab reacts nrog cov pa roj carbon nyob rau hauv los tsim silicon carbide, uas yuav nthuav dav hauv qhov ntim, thiab cov qhov seem seem yog puv nrog cov silicon elemental. Cov khoom siv ceramic porous tuaj yeem yog cov pa roj carbon ntshiab lossis silicon carbide / carbon-based composite khoom. Tus thawj yog tau los ntawm catalytic kho thiab pyrolyzing ib qho organic resin, ib qho pore former thiab ib qho solvent. Tus tom kawg yog tau los ntawm pyrolyzing silicon carbide particles / resin-based composite khoom kom tau txais silicon carbide / carbon-based composite khoom, lossis los ntawm kev siv α-SiC thiab carbon hmoov ua cov khoom pib thiab siv cov txheej txheem nias lossis txhaj tshuaj molding kom tau txais cov khoom sib xyaw.

Kev sintering tsis muaj siab

Cov txheej txheem sintering tsis muaj siab ntawm silicon carbide tuaj yeem muab faib ua cov khoom sintering thiab cov kua theem sintering. Nyob rau hauv xyoo tas los no, kev tshawb fawb txogsilicon carbide ceramicsnyob hauv tsev thiab txawv teb chaws tau tsom mus rau kev ua kua dej sintering. Cov txheej txheem npaj cov khoom siv ceramic yog: sib xyaw cov khoom siv pob milling–> tsuag granulation–> qhuav nias–> ntsuab lub cev solidification–> nqus tsev sintering.

Cov khoom siv silicon carbide sintered uas tsis muaj siab

Ntxiv 96-99 feem ntawm silicon carbide ultrafine hmoov (50-500nm), 1-2 feem ntawm boron carbide ultrafine hmoov (50-500nm), 0.2-1 feem ntawm nano-titanium boride (30-80nm), 10-20 feem ntawm cov dej-soluble phenolic resin, thiab 0.1-0.5 feem ntawm high-efficiency dispersant rau hauv lub tshuab zeb pob rau pob milling thiab sib tov rau 24 teev, thiab muab cov slurry sib tov rau hauv lub thoob sib tov rau do rau 2 teev kom tshem tawm cov npuas hauv cov slurry.
Cov khoom sib tov saum toj no raug txau rau hauv lub pej thuam granulation, thiab cov hmoov granulation nrog cov qauv zoo ntawm cov khoom me me, cov kua dej zoo, qhov faib tawm ntawm cov khoom me me thiab cov dej noo nruab nrab tau txais los ntawm kev tswj lub siab tsuag, qhov kub ntawm huab cua nkag, qhov kub ntawm huab cua tawm thiab qhov loj ntawm cov ntawv tsuag. Lub zaus hloov pauv centrifugal yog 26-32, qhov kub ntawm huab cua nkag yog 250-280 ℃, qhov kub ntawm huab cua tawm yog 100-120 ℃, thiab lub siab ntawm slurry nkag yog 40-60.
Cov hmoov granulation saum toj no tau muab tso rau hauv cov pwm cemented carbide rau kev nias kom tau txais lub cev ntsuab. Txoj kev nias yog bidirectional siab, thiab lub tshuab cuab yeej siab tonnage yog 150-200 tons.
Lub cev ntsuab uas nias lawm muab tso rau hauv qhov cub kom qhuav thiab kho kom tau lub cev ntsuab nrog lub zog ntsuab zoo.
Lub cev ntsuab kho saum toj no muab tso rau hauvgraphite cruciblethiab teeb tsa kom zoo thiab zoo nkauj, thiab tom qab ntawd lub graphite crucible nrog lub cev ntsuab raug muab tso rau hauv lub tshuab nqus tsev kub siab rau kev hlawv. Qhov kub hlawv yog 2200-2250 ℃, thiab lub sijhawm rwb thaiv tsev yog 1-2 teev. Thaum kawg, cov khoom siv sintered silicon carbide uas ua haujlwm siab tau txais.

Kev sib xyaw ua ke ntawm cov khoom khov kho

Cov txheej txheem sintering tsis muaj siab ntawm silicon carbide tuaj yeem muab faib ua cov khoom sintering thiab cov kua theem sintering. Cov kua theem sintering xav tau ntxiv cov khoom ntxiv sintering, xws li Y2O3 binary thiab ternary additives, kom ua rau SiC thiab nws cov ntaub ntawv sib xyaw ua kua theem sintering thiab ua tiav qhov ntom ntawm qhov kub qis dua. Txoj kev npaj ntawm cov khoom sintered silicon carbide ceramics suav nrog kev sib xyaw ntawm cov khoom siv raw, tshuaj tsuag granulation, molding, thiab nqus tsev sintering. Cov txheej txheem tsim khoom tshwj xeeb yog raws li nram no:
70-90% ntawm submicron α silicon carbide (200-500nm), 0.1-5% ntawm boron carbide, 4-20% ntawm resin, thiab 5-20% ntawm cov organic binder raug muab tso rau hauv lub tshuab sib tov thiab ntxiv nrog dej ntshiab rau kev sib tov ntub. Tom qab 6-48 teev, cov slurry sib xyaw raug dhau los ntawm 60-120 mesh sieve;
Cov slurry sieve yog tshuaj tsuag granulated los ntawm lub tshuab tsuag granulation. Qhov kub nkag ntawm lub tshuab tsuag granulation yog 180-260 ℃, thiab qhov kub tawm yog 60-120 ℃; qhov ceev ntawm cov khoom granulated yog 0.85-0.92g / cm3, fluidity yog 8-11s / 30g; cov khoom granulated yog sieve los ntawm 60-120 mesh sieve rau tom qab siv;
Xaiv ib lub pwm raws li cov khoom xav tau, thauj cov khoom granulated rau hauv lub pwm qhov, thiab ua qhov kub thiab txias compression molding ntawm lub siab ntawm 50-200MPa kom tau txais lub cev ntsuab; lossis muab lub cev ntsuab tom qab compression molding rau hauv lub cuab yeej nias isostatic, ua isostatic nias ntawm lub siab ntawm 200-300MPa, thiab tau txais lub cev ntsuab tom qab nias thib ob;
Muab lub cev ntsuab uas tau npaj tseg rau hauv cov kauj ruam saum toj no rau hauv lub tshuab nqus tsev sintering rau sintering, thiab qhov tsim nyog yog cov silicon carbide bulletproof ceramic tiav lawm; hauv cov txheej txheem sintering saum toj no, ua ntej tshem tawm lub tshuab sintering, thiab thaum qib nqus tsev ncav cuag 3-5 × 10-2 Tom qab Pa, cov roj inert raug xa mus rau hauv lub tshuab sintering rau qhov siab ib txwm thiab tom qab ntawd cua sov. Kev sib raug zoo ntawm qhov kub thiab txias thiab lub sijhawm yog: chav tsev kub txog 800 ℃, 5-8 teev, khaws cia cua sov rau 0.5-1 teev, ntawm 800 ℃ txog 2000-2300 ℃, 6-9 teev, khaws cia cua sov rau 1 txog 2 teev, thiab tom qab ntawd txias nrog lub tshuab cua sov thiab poob rau hauv chav tsev kub.

Microstructure thiab ciam teb ntawm silicon carbide sintered ntawm qhov siab ib txwm muaj

Hauv ntej, cov khoom siv ceramic uas tsim los ntawm cov txheej txheem kub nias sintering muaj kev ua tau zoo dua, tab sis tus nqi tsim khoom kuj nce siab heev; cov khoom siv ceramic uas npaj los ntawm kev kub siab sintering muaj cov khoom siv raw ntau dua, qhov kub sintering siab, kev hloov pauv loj ntawm cov khoom, cov txheej txheem nyuaj thiab kev ua tau zoo tsawg; cov khoom siv ceramic uas tsim los ntawm cov txheej txheem sintering tshuaj tiv thaiv muaj qhov ceev siab, kev ua tau zoo tiv thaiv ballistic, thiab tus nqi npaj qis dua. Ntau yam txheej txheem npaj sintering ntawm silicon carbide ceramics muaj lawv tus kheej qhov zoo thiab qhov tsis zoo, thiab cov xwm txheej thov kuj yuav txawv. Nws yog txoj cai zoo tshaj plaws los xaiv txoj kev npaj zoo raws li cov khoom thiab nrhiav kev sib npaug ntawm tus nqi qis thiab kev ua tau zoo.