Dab tsi yog qhov txawv ntawm alumina, corundum thiab sapphire?

Muaj ntau incarnations ntawm alumina. Thaum ntau tus phooj ywg hnov ​​lub npe xws li “alumina”, “corundum”, “ruby” thiab “sapphire”, lawv tsis tuaj yeem paub qhov txawv ntawm qhov sib txawv ntawm cov no thiab feem ntau xav tsis meej pem. Tau kawg, qhov xwm txheej no tseem cuam tshuam txog qhov tsis muaj cov qauv niaj hnub no rau ntau yam ntawm alumina. Yuav kom paub qhov txawv ntawm lawv, tus sau yuav muab qee cov ntaub ntawv rau koj los pab koj txheeb xyuas cov ntsiab lus no.

1. Alumina

Alumina, feem ntau hu ua bauxite, muaj qhov ntom ntawm 3.9-4.0g / cm3, melting point ntawm 2050 ° C, boiling point ntawm 2980 ° C, thiab yog insoluble nyob rau hauv dej. Alumina tuaj yeem muab rho tawm los ntawm bauxite hauv kev lag luam. . Ntawm cov Al2O3 variants no, tsuas yog α-Al2O3 ruaj khov, thiab lwm cov ntaub ntawv siv lead ua tsis ruaj khov. Raws li qhov kub thiab txias, cov ntaub ntawv hloov pauv hloov pauv yuav hloov mus rau α-Al2O3.

Nyob rau hauv cov khoom siv lead ua lattice ntawm α-alumina, cov pa oxygen ions tau kaw zoo nyob rau hauv hexagons, thiab Al3 + yog symmetrically faib nyob rau hauv nruab nrab ntawm lub octahedral ligand ncig los ntawm oxygen ions. Lub lattice zog yog loj heev, yog li lub melting point thiab boiling point yog siab heev. Alpha-alumina yog insoluble hauv dej thiab acid. Nws tseem hu ua aluminium oxide nyob rau hauv kev lag luam thiab yog cov khoom siv tseem ceeb rau kev npaj cov hlau txhuas. Tsis tas li ntawd, nws tseem tuaj yeem siv los npaj ntau yam khoom siv refractory, cov ntaub ntawv abrasive, thiab substrates rau kev sib xyaw ua ke. Tsis tas li ntawd, high-purity α-alumina kuj yog cov khoom siv raw rau kev tsim cov khoom siv dag zog corundum, dag rubies thiab sapphires.

γ-hom alumina yog tsim los ntawm lub cev qhuav dej ntawm aluminium hydroxide ntawm qhov kub ntawm 500-600 ° C, thiab tseem hu ua activated alumina hauv kev lag luam. Nyob rau hauv nws cov qauv, cov pa ions yog kwv yees li densely tau ntim rau hauv ntsug dav hlau, thiab Al3 + yog irregularly faib nyob rau hauv lub octahedral thiab tetrahedral voids surrounded los ntawm cov pa ions. Nws tuaj yeem siv ua catalysts, catalyst cab kuj, adsorbents, desiccants, thiab lwm yam hauv kev lag luam. Cov neeg txaus siab rau cov qauv no tuaj yeem tshawb xyuas qhov “Kev Npaj thiab Daim Ntawv Thov ntawm Activated Alumina”.

Hauv luv luv: Alumina tuaj yeem suav hais tias yog ib yam khoom uas muaj Al2O3 (muaj qee yam impurities, feem ntau tsis huv). Cov khoom no muaj cov qauv siv lead ua sib txawv, cov khoom sib txawv purity, thiab cov qauv sib txawv, uas sawv cev rau cov khoom sib txawv. , Siv nyob rau hauv txawv teb.

High alumina pob – lub ntsiab tivthaiv yog alumina

2. Corundum thiab dag corundum

Qhov tshwm sim α-hom alumina crystals yog hu ua corundum, thiab lawv feem ntau pom cov xim sib txawv vim txawv impurities. Corundum feem ntau yog xiav lossis daj grey, nrog iav lossis pob zeb diamond luster, ntom 3.9-4.1g / cm3, hardness 8.8, thib ob tsuas yog pob zeb diamond thiab silicon carbide, thiab tuaj yeem tiv taus qhov kub thiab txias.

Ntuj daj corundum

Feem ntau muaj peb hom corundum hauv qhov xwm txheej: a. High-zoo corundum, feem ntau hu ua gemstone: sapphire muaj titanium, ruby ​​​​muaj chromium, thiab lwm yam; b zoo tib yam corundum: dub los yog brownish liab; c emery: tuaj yeem muab faib ua emerald emery thiab limonite emery, Nws yog ib hom aggregate crystal nrog tsawg hardness. Ntawm cov saum toj no peb hom ntuj corundum, thawj tus yog tsuas yog siv rau cov hniav nyiaj hniav kub, thiab ob lub tom kawg yuav siv tau raws li abrasives los ua sib tsoo log, oilstones, sandpaper, emery ntaub los yog hmoov, abrasive pastes, thiab lwm yam.

Vim tias cov khoom tsim tawm ntawm ntuj corundum tsis txaus, corundum siv hauv kev lag luam feem ntau yog cov khoom siv dag zog corundum es tsis txhob siv cov khoom ntuj corundum.

Muaj alumina yog cov hmoov crystalline xoob nrog cov qauv ntxeem tau thiab xoob, uas tsis tsim nyog rau kev sib cuag ntawm Al2O3 crystals nrog ib leeg thiab yog li tsis zoo rau sintering. Feem ntau tom qab calcination los yog fusion recrystallization, γ-Al2O3 ua α-Al2O3 (corundum) rau sintering thiab densification. Raws li txoj kev tsim khoom, corundum muab faib ua lub teeb hlawv (1350 ~ 1550 ℃) corundum (tseem hu ua lub teeb hlawv α-Al2O3), sintered (1750 ~ 1950 ℃) corundum, thiab fused corundum.

Artificial corundum-dawb corundum xuab zeb

Hauv luv luv: nws yog kev cai hu α-crystal alumina li corundum. Txawm hais tias nws yog ntuj corundum lossis dag corundum, cov khoom tseem ceeb ntawm corundum yog alumina, thiab nws lub ntsiab siv lead ua theem yog α-alumina.

3. Lub pov haum qib corundum thiab dag ruby, sapphire

Qhov zoo tshaj plaws corundum tov nrog ib tug me me ntawm txawv oxide impurities yog lub npe nrov ruby ​​​​thiab sapphire, uas yog cov khoom siv los ua cov hniav nyiaj hniav kub zoo nkauj, thiab nws cov khoom tuaj yeem siv los ua cov bearings ntawm precision instruments thiab watches.

sapphire

Tam sim no, cov synthesis ntawm liab sapphire muaj xws li nplaim hluav taws melting txoj kev (txoj kev melting), flux method, hydrothermal method thiab thiaj li nyob. Ntawm lawv, cov txheej txheem ntawm hydrothermal txoj kev yog siab thiab hnyav, thiab qhov nyuaj yog ntau dua, tab sis

Tam sim no, cov synthesis ntawm liab sapphire muaj xws li nplaim hluav taws melting txoj kev (txoj kev melting), flux method, hydrothermal method thiab thiaj li nyob. Ntawm lawv, txoj kev hydrothermal muaj cov txheej txheem siab thiab cov txheej txheem hnyav. Txawm li cas los xij, kev loj hlob ntawm lub pov haum muaju yog qhov zoo ib yam li cov pob zeb ntuj. Nws tuaj yeem yog qhov cuav tshaj plaws, thiab qhov tseeb thiab qhov cuav yog qhov sib txawv. Cov pob zeb diamonds loj hlob los ntawm txoj kev no suav nrog emeralds, muaju, rubies, thiab lwm yam.

Artificial liab thiab sapphire tsis tsuas yog tib yam li cov khoom ntuj tsim, tab sis kuj nyob rau hauv lub cev thiab tshuaj thiab kho qhov muag, tab sis tus nqi tsuas yog 1/3 rau 1/20 ntawm cov khoom ntuj. Tsuas yog nyob rau hauv lub tshuab tsom iav tuaj yeem pom cov huab cua me me hauv cov khoom siv dag zog kom pom Cov npuas yog puag ncig, thiab cov huab cua npuas hauv cov khoom ntuj yog tiaj tus.

Hauv luv luv: txawm hais tias alumina, corundum, ruby ​​thiab sapphire muaj cov npe sib txawv, lawv cov duab, hardness, zog, thiab kev siv kuj txawv, tab sis lawv cov tshuaj lom neeg tseem ceeb yog alumina. Lub ntsiab siv lead ua ntawm corundum yog α-hom alumina. Corundum yog polycrystalline α-alumina khoom, thiab zoo corundum (jewel-qib corundum) yog ib qho khoom siv lead ua ntawm alumina.

Vim muaj kev txwv ntawm tus sau kev paub, tsab xov xwm piav qhia txog cov lus tsis raug. Kuv kuj nug cov kws paub txog kev lag luam rau cov lus qhia, ua tsaug.