Cov khoom siv ceramic

Cov ntaub ntawv ceramic niaj hnub yog ib hom tshiab ntawm ceramics uas yog tsim los ntawm cov tsoos ceramics raws li cov ceramics tshwj xeeb thiab muaj cov yam ntxwv tshwj xeeb uas txawv ntawm cov tsoos ceramics. Nws tau ntev dhau mus dhau lub tswv yim thiab kev ua haujlwm ntawm cov tsoos ceramics. Nws yog ib yam khoom ntawm high thiab tshiab technology. Yog li ntawd, cov ntaub ntawv ceramic yog cov khoom qub thiab cov tub ntxhais hluas.

Cov khoom siv niaj hnub no hu ua cov khoom siv ceramic yog cov khoom siv tsis yog xim hlau. Nws yog ib qho ntawm peb pawg loj ntawm cov ntaub ntawv niaj hnub nrog rau cov hlau thiab cov khoom siv organic. Nws tseem yog qhov kev lees paub dav dav ntawm txhua yam khoom siv tshwj tsis yog cov khoom siv hlau thiab cov khoom siv organic. Lub ntsiab lus ntawm kev sib tham hauv tshooj no yog cov khoom siv niaj hnub ceramic lossis cov khoom siv tsis zoo uas tsis yog hlau niaj hnub.

Cov khoom siv niaj hnub ceramic muaj cov ntsiab lus siab. Piv nrog cov khoom siv tsoos. Nws feem ntau muaj peb yam hauv qab no:

(1) Raws li qhov yuav tsum tau muaj ntawm niaj hnub scientific thiab technology kev loj hlob. Nws yog cov khoom lag luam ntawm kev txhim kho niaj hnub science thiab technology thiab yog cov khoom siv high-tech.

(2) Cov txheej txheem tsim khoom yog qhov nyuaj thiab xav tau kev taw qhia ntawm kev ua tiav kev tshawb fawb thiab thev naus laus zis niaj hnub no. Yog li ntawd, nws yog ib tug technical knowledge-intensive khoom.

(3) Nws muaj cov khoom zoo heev thiab tshwj xeeb thiab tuaj yeem ua tau raws li cov kev cai ntawm kev lag luam thiab kev lag luam tshiab.

Kev faib tawm ntawm cov khoom siv ceramic

Nrog rau kev tsim khoom thiab kev tshawb fawb thiab thev naus laus zis. Cov hom ntawm cov ntaub ntawv ceramic thiab cov khoom lag luam tau nce zuj zus ib hnub. Txhawm rau ua kom yooj yim rau kev nkag siab txog cov yam ntxwv ntawm ntau yam khoom siv lossis cov khoom lag luam, lawv feem ntau yog cais los ntawm cov ces kaum sib txawv.

1. Kev faib tawm los ntawm cov tshuaj muaj pes tsawg leeg

(1) Oxide ceramics. Muaj ntau ntau hom oxide ceramics, uas tuav txoj haujlwm tseem ceeb hauv tsev neeg ceramic. Feem ntau siv oxide ceramics yog Al2O3, SiO2, MgO, ZrO3, CeO2, CaO. Cr2O3, mullite (3Al2O3.2SiO4) thiab spinel (MgAl2O3), thiab lwm yam. Al2O3 thiab SiO2 nyob rau hauv ceramics yog dav siv li hlau thiab txhuas alloys hauv cov ntaub ntawv hlau. Qee cov oxide ceramics tau teev nyob rau hauv Table 11.1. Silicates kuj yog cov oxide series. Zoo li ZrsiO4. Hu tau tos. Kuj tseem muaj cov oxides sib xyaw xws li BaT, CgyiO; etc. kuj poob rau hauv qeb no.

Cov ntaub ntawv ceramic yog cais los ntawm cov tshuaj muaj pes tsawg leeg

(2) Carbide ceramics. Carbide ceramics feem ntau muaj cov ntsiab lus melting ntau dua li oxides. Cov khoom siv feem ntau yog SIC, SC, Phoenix C. TIC thiab lwm yam Carbide ceramics yuav tsum muaj kev tiv thaiv huab cua thaum lub sijhawm npaj.

(3) Amide ceramics. Cov tshuaj chloride siv dav tshaj plaws yog a-ji, uas muaj cov khoom siv zoo heev thiab ua haujlwm kub. Tsis tas li ntawd, cov ntawv thov ntawm TZN, BN, thiab AI nitride ceramics tau dhau los ua ntau dua. C3N4, uas nyuam qhuav tshwm sim tsis ntev los no, xav tias yuav muaj kev ua tau zoo dua Si3O4.

(4) Plaub chemical ceramics. Kev siv ntawm boride ceramics tsis dav heev. Lawv tsuas yog siv los ua cov khoom sib sib zog nqus lossis theem ob ntxiv rau lwm cov ceramic matrices los txhim kho kev ua haujlwm. Feem ntau siv xws li Ti, Zr&, thiab lwm yam.

2. Kev faib tawm los ntawm kev ua tau zoo thiab kev siv

(1) Cov khoom siv ceramics. Structures ceramics yog siv los ua cov khoom siv los tsim cov khoom siv. Feem ntau siv nws cov khoom siv kho tshuab. Txhim kho lub zog, toughness, hardness, modulus, hnav tsis kam, kub tsis kam (siab kub lub zog, thermal shock resistance, ablation resistance), thiab lwm yam. Feem ntau ntawm plaub ceramics cais los ntawm nuclear tshuaj muaj pes tsawg leeg hais los saum toj no yog structural ceramics. Xws li AjZQ pob zeb. 3N4 thiab ZX yog cov neeg sawv cev ntawm cov khoom siv ceramic nrog cov khoom zoo tshaj plaws.

(2) Muaj nuj nqi ceramics. Functional ceramics yog siv los ua cov khoom siv los tsim cov khoom siv ua haujlwm, feem ntau yog siv lawv lub cev xws li cov khoom siv hluav taws xob, cov khoom siv thermal, cov khoom siv kho qhov muag, cov khoom siv roj ntsha, thiab lwm yam. Piv txwv li ferrite. Ferroelectric ceramics feem ntau yog siv rau lawv cov khoom siv hluav taws xob. Nws yog siv los ua electromagnetic Cheebtsam, dielectric ceramics yog siv los ua cov capacitors, thiab piezoelectric ceramics yog siv los ua kev hloov pauv lossis siab sensors. Cov khoom siv electrolyte ceramics tuaj yeem siv los ua cov ntsuas oxygen siv lawv cov khoom hloov pauv ion. Bioceramics yog siv los ua cov pob txha thiab cov hniav cuav. Superconducting cov ntaub ntawv thiab optical fibers kuj yog nyob rau hauv qeb ntawm functional ceramics.

Nws yog tsim nyog hais tias qhov kev faib tawm saum toj no kuj yog txheeb ze. Tsis yog qhov tseeb, qee zaum tsis muaj kev txwv nruj ntawm cov qauv ceramics thiab cov khoom siv ceramics. Rau qee cov ntaub ntawv ceramic, muaj ob qho tib si. Piezoelectric ceramics. Txawm hais tias nws tuaj yeem raug cais raws li kev ua haujlwm ceramics, nws kuj muaj qee qhov kev xav tau rau nws cov khoom siv kho tshuab, xws li lub zog, toughness, hardness, thiab elastic modulus. Ua ntej tshaj plaws, nws yuav tsum muaj lub zog txaus los tiv thaiv kev puas tsuaj thaum tiv thaiv E quab yuam, kom cov yam ntxwv piezoelectric zoo tuaj yeem ua tiav. Tsis tas li ntawd, xws li high-temperature structural ceramics los yog thermal shock-resistant thiab hluav taws-resistant ceramics rau spacecraft tshav kub-pov thawj qhov chaw, txawm hais tias lawv muaj nyob rau hauv qeb ntawm structural ceramics. Txawm li cas los xij, lub thermal expansion kuj tsis yog tsuas yog txiav txim siab los ntawm nws tus kheej lub zog, toughness, thiab modulus, tab sis thermal conductivity thiab thermal expansion coefficient kuj zoo ib yam li cov khoom siv kho tshuab, uas muaj kev cuam tshuam tseem ceeb ntawm thermal shock resistance. Corrosion kuj yog ib qho tseem ceeb ntawm kev ua tau zoo ntawm cov tshuaj ceramics (xws li acid-resistant twj), tab sis nws yuav tsum muaj qee yam khoom siv kom tau raws li qhov yuav tsum tau ua ntawm kev lag luam. Cov khoom siv superconducting yog qhov nyuaj rau ua rau hauv cov xov hlau vim tias lawv muaj roj ntau. Yog li ntawd, nws tseem tsis tuaj yeem nkag mus rau theem kev siv tswv yim. Piv txwv li, txawm hais tias nws yog cov qauv ceramics lossis cov khoom siv ceramics, cov khoom siv kho tshuab yog cov khoom siv yooj yim tshaj plaws ntawm cov khoom siv ceramic. Nws tsuas yog tias kev siv sib txawv muaj cov kev xav tau sib txawv rau cov khoom siv kho tshuab.

Tshooj lus no tham txog cov txheej txheem ceramics.

Qhov zoo ntawm ceramics

1. Kev ua tau zoo ntawm cov khoom siv ceramic

Raws li peb txhua tus paub, cov khoom siv tshuaj lom neeg ntawm cov khoom siv hlau (cov kub ntshiab lossis alloys) feem ntau yog hlau. Lawv yog tsim los ntawm hlau zoo atoms thiab electron huab sau lawv. Hlau bonds tsis muaj directionality. Yog li ntawd, cov hlau muaj zoo yas deformation zog. Raws li rau cov ceramics uas tsis quav ntsej cov tshuaj tsis yog xim hlau, lawv cov khoom siv tshuaj muaj zog ntau dua li kev noj qab haus huv thiab covalent bonds. Cov chemistry no muaj cov kev taw qhia muaj zog thiab ruaj khov zog. Yog li ntawd, nws yog ib qho nyuaj rau cov ntaub ntawv ceramic rau undergo yas deformation. High brittleness thiab muaj zog tawg rhiab heev. Qhov no yog Achilles pob taws ntawm cov khoom siv ceramic. Tab sis nws yog precisely vim hais tias ntawm no tshuaj daim ntawv cog lus hom uas structural ceramics muaj ib tug series ntawm tshwj xeeb cov khoom uas yog superior rau cov ntaub ntawv hlau.

①High hardness txiav txim nws zoo heev hnav tsis kam;

② High nplaim taws. Txiav txim siab tias nws muaj qhov ua tau zoo ntawm cov cua sov;

③ Muaj tshuaj lom neeg ruaj khov. Nws txiav txim siab tias nws muaj kev tiv thaiv corrosion zoo.

Txawm hais tias cov ntaub ntawv ceramic muaj qhov zoo heev. Txawm li cas los xij, nws qhov tsis zoo rau kev tuag - brittleness - txwv nws cov kev ua tau zoo thiab kev siv tswv yim. Yog li ntawd, qhov toughening ntawm ceramics tau dhau los ua lub ntsiab lus tseem ceeb hauv kev tshawb fawb cov ntaub ntawv ceramic uas nyiam thoob ntiaj teb kev saib xyuas (saib qhov toughening ntawm ceramics seem kom paub meej).

2. Kev sib piv ntawm cov niaj hnub (advanced) ceramics thiab tsoos ceramics

Niaj hnub nimno ceramics piv nrog cov tsoos ceramics. Muaj qhov sib txawv tseem ceeb hauv cov khoom siv raw, txheej txheem kev npaj, kev tsim qauv thiab kev ua haujlwm.

Qhov sib txawv ntawm cov tsoos ceramics thiab niaj hnub ceramics