Kodi corundum ndi chiyani?

Corundum (Al2O3) ili ndi nkhokwe zambiri zakuthupi, zomwe zimatengera pafupifupi 25% ya kulemera kwa kutumphuka kwa dziko lapansi. Ndi yotsika mtengo ndipo ili ndi zinthu zambiri zabwino kwambiri. Pali makhiristo osiyanasiyana a Al2O3, ndipo pali mitundu yopitilira khumi yamitundu yosiyanasiyana yomwe idanenedwa, koma pali zitatu zazikulu, zomwe ndi α-Al2O3, β-Al2O3, ndi γ-Al2O3.

Tabular corundum

γ-Al2O3 ndi dongosolo la spinel, lomwe limakhala losakhazikika pa kutentha kwakukulu ndipo siligwiritsidwa ntchito kawirikawiri ngati chinthu chimodzi. β-Al2O3 kwenikweni ndi aluminiyumu yokhala ndi zitsulo zamchere kapena zitsulo zamchere zamchere. Kapangidwe kake ka mankhwala kumatha kuyerekezedwa ndi RO · 6Al2O3 ndi R2O · 11Al2O3, latisi ya hexagonal, kachulukidwe 3.30 ~ 3.63g/cm3, 1400 ~ 1500 Imayamba kuwola pa ℃ ndikusintha kukhala α-Al2O3 pa 1600℃. α-Al2O3 ndi mawonekedwe a kutentha kwapamwamba, ndi kutentha kokhazikika pamtunda wosungunuka, ndi kuchuluka kwa 3.96 ~ 4.01g / cm3, zomwe zimagwirizana ndi zonyansa. Selo la unit ndi prism yakuthwa, yomwe ilipo mu mawonekedwe achilengedwe a corundum, ruby ndi safiro. α-Al2O3 ili ndi mawonekedwe ophatikizika, zochita zochepa, magetsi abwino, komanso makina abwino kwambiri. Kuuma kwa Mohs ndi 9. α-Al2O3 ndi ya hexagonal crystal system, corundum structure, a = 4.76, c = 12.99.

Al2O3 ili ndi mphamvu zamakina apamwamba. Kapangidwe kake ka Al2O3 koyera kamakhala kokwera kwambiri. Mphamvu zamakina zitha kugwiritsidwa ntchito kupanga zida zadothi ndi zida zina zamakina. The resistivity Al2O3 ndi yokwera, mphamvu yamagetsi yamagetsi ndi yabwino, resistivity kutentha kutentha ndi 1015Ω · cm, ndipo mphamvu ya dielectric ndi 15kV / mm. Pogwiritsa ntchito kutsekemera kwake ndi mphamvu zake, zimatha kupangidwa kukhala magawo, zitsulo, spark plugs, zipolopolo zozungulira, ndi zina zotero. Al2O3 ili ndi kuuma kwakukulu, kuuma kwa Mohs 9, kuphatikizapo kukana kwambiri kuvala, kotero kumagwiritsidwa ntchito kwambiri popanga zida, mawilo opera, abrasives, kujambula kufa, zimbalangondo, kubala tchire ndi miyala yamtengo wapatali yokumba. Al2O3 ili ndi malo osungunuka kwambiri komanso kukana kwa dzimbiri. Ili ndi malo osungunuka a 2050 ° C. Ili ndi kukana kwabwino pakukokoloka kwa zitsulo zosungunuka monga Be, Sr, Ni, Al, V, Ti, Mn, Fe, CO ndi sodium hydroxide, galasi, ndi slag. Imakhalanso ndi kukana kwakukulu; sichimalumikizana ndi Si, P, Sb, Bi mumlengalenga, kotero chitha kugwiritsidwa ntchito ngati zida zodzitchinjiriza, machubu a ng’anjo, ma crucibles ojambula magalasi, mipira yopanda kanthu, ulusi ndi zotchingira zoteteza thermocouple, ndi zina zambiri.

Al2O3 ali kwambiri kukhazikika kwa mankhwala. Ma sulfides ambiri ovuta, phosphides, arsenides, chlorides, nitrides, bromides, iodides, fluoride youma, sulfuric acid, hydrochloric acid, nitric acid, ndi hydrofluoric acid samayanjana ndi Al2O3. Choncho, zikhoza kupangidwa kukhala zitsulo koyera ndi kristalo kukula crucibles, mafupa a anthu, mafupa yokumba, etc. Al2O3 ali katundu kuwala ndipo akhoza kupangidwa mu kuwala kupatsira zipangizo kupanga Na nthunzi nyali machubu, mayikirowevu fairings, mawindo infuraredi ndi laser. oscillation zigawo zikuluzikulu. Ma ionic conductivity a Al2O3 amagwiritsidwa ntchito ngati zida zama cell a dzuwa ndi mabatire osungira. Al2O3 amagwiritsidwanso ntchito kwambiri mu ceramic pamwamba metallization luso.

Gawo lalikulu la crystalline la alumina-based fused corundum ndi gawo la corundum ndi kukula kwa 1.0-1.5mm ndi makristasi osakanikirana. Zina zonse ndizotsatira za rutile, alumina ndi aluminium titanate, ndipo zili mkati mwa gawo la corundum kapena pakati pa magawo a kristalo. Gawo laling’ono la galasi. Ku China, patatha zaka zoposa khumi zoyesayesa mosalekeza, njira yosungunula ya corundum yopangidwa ndi bauxite yapita patsogolo kwambiri, ndi mphamvu yopanga pachaka yoposa matani 110,000. Bauxite-based fused corundum yakhala ikugwiritsidwa ntchito bwino ngati zopangira njerwa zosiyanasiyana zowotchedwa ndi zida zosapangana zosaoneka. Mwachitsanzo, imatha kusintha pang’ono corundum yowundana mu ng’anjo yoyaka moto, ndipo imagwiritsidwa ntchito ngati matrix ndi zinthu zazing’ono kuti zipangitse kutsika pang’ono. Njerwa zapamwamba za alumina zimagwiritsidwa ntchito m’malo mwa corundum yoyera muzokanira zina za Al2O3-SiO2 pokonzekera zinthu zogwira ntchito kwambiri.

Brown corundum smelting imachokera pa mfundo yakuti aluminiyamu imakhala ndi chiyanjano chachikulu cha mpweya kuposa chitsulo, silicon, titaniyamu, ndi zina zotero. ferrosilicon aloyi. Imalekanitsidwa ndi corundum kusungunuka kuti ipeze corundum ya bulauni yokhala ndi mtundu wa kristalo wokwaniritsa zofunikira ndi zomwe zili mu Al2O3 zazikulu kuposa 94.5%. Fe2O3 imachepetsedwa kuti ipange aloyi ya ferrosilicon ndikuchotsedwa panthawi yosungunuka, koma pang’ono chitsulo okusayidi ndi aluminiyamu opangidwa ndi spinel akadali otsala mu mankhwala. TiO2 imachepetsedwa pang’ono kukhala ferrosilicon alloy panthawi yosungunula, ndipo gawo lalikulu la ilo limakhalabe mu corundum ya bulauni, yomwe ndiyomwe imayambitsa mitundu ya brown corundum. CaO ndi MgO ndizovuta kuchepetsa panthawi yosungunula, ndipo zambiri za CaO ndi MgO zomwe zili muzopangira zilipobe. Ngakhale kuti Na2O ndi K2O zimatha kusinthasintha kutentha kwakukulu panthawi ya smelting, sizingachepetseke ndikukhalabe mu corundum ya bulauni, yomwe imakhudza kwambiri khalidwe.

Brown corundum

Zopangira za brown corundum zimapangidwa ndi njere za α-alumina crystal ndi gawo laling’ono lagalasi, makristasi a α-alumina amapangidwa ndi Al2O3 yankho lolimba lomwe lili ndi Ti2O3, ndipo gawo lagalasi nthawi zambiri limapangidwa ndi titanium dioxide ndi silicon dioxide ndi zina. fufuzani makutidwe ndi okosijeni omwe alipo mu ng’anjo yamagetsi yamagetsi. Ma oxides awa amapanga gawo lagalasi, ndipo amakhala ndi kusungunuka kochepa chabe mumtundu wa kristalo wa njere za alumina. Ti2O3 ndiye oxide yokhayo yomwe Ti imatha kusungunula mu njere za alumina. TiO2 ndiye thermodynamically stable oxide wa Ti. Pakusungunula ndi kuchepetsedwa kwa brown corundum, gawo la TiO2 limachepetsedwa kukhala sub-oxidation ya titaniyamu. (Ti2O3), pamwamba pa 1000 ℃, mpweya ukhoza kufalikira mu njere za Ga-aluminium, oxidize Ti2O3 mu TiO2 yokhazikika ndikuyikulunga mu njere za α-alumina, kotero kuti titaniyamu woipa wambiri ndi α-alumina Njira yolimba ya kristalo. mbewu zilipo.

Kuchulukira kwa TiO2 mu corundum ya bulauni sikungakhalebe mugawo lagalasi, koma imakumana ndi aluminiyamu kupanga titanate ya aluminium (TiO2 · Al2O3). Aluminiyamu titanate ndi gawo lachitatu pa mawonekedwe pakati pa mbewu za α-aluminium ndi gawo la galasi; Kulimba kwa corundum wa bulauni kumawonjezeka ndi kukula kwa TiO2 crystal nuclei. The TiO2 gawo uniformly omwazikana mu α-alumina galasi njere toughens α-alumina particles. Brown corundum olimba yankho Ti2O3 imapangitsa bulauni corundum kuwoneka buluu.

Ti2O3 ndiye oxide yokhayo yomwe Ti imatha kusungunula mu njere za alumina. TiO2 ndiye thermodynamically stable oxide wa Ti. Pakusungunula ndi kuchepetsedwa kwa brown corundum, gawo la TiO2 limachepetsedwa kukhala sub-oxidation ya titaniyamu. (Ti2O3), pamwamba pa 1000 ℃, mpweya ukhoza kufalikira mu njere za Ga-aluminium, oxidize Ti2O3 mu TiO2 yokhazikika ndikuyikulunga mu njere za α-alumina, kotero kuti titaniyamu woipa wambiri ndi α-alumina Njira yolimba ya kristalo. mbewu zilipo. Kuchulukira kwa TiO2 mu corundum ya bulauni sikungakhalebe mugawo lagalasi, koma imakumana ndi aluminiyamu kupanga titanate ya aluminium (TiO2 · Al2O3). Aluminiyamu titanate ndi gawo lachitatu pa mawonekedwe pakati pa mbewu za α-aluminium ndi gawo la galasi; Kulimba kwa corundum wa bulauni kumawonjezeka ndi kukula kwa TiO2 crystal nuclei. The TiO2 gawo uniformly omwazikana mu α-alumina galasi njere toughens α-alumina particles. Brown corundum olimba yankho Ti2O3 imapangitsa bulauni corundum kuwoneka buluu.