Iyini i-corundum?

I-Corundum (Al2O3) inenqwaba yezinto ezigciniwe zezinto ezingavuthiwe, ezibalelwa ku-25% wesisindo soqweqwe lomhlaba. Ayibizi futhi inezinto eziningi ezinhle kakhulu. Kunamakristalu amaningi ahlukene e-Al2O3, futhi kunezinhlobo ezingaphezu kweshumi zokuhlukahluka okubikiwe, kodwa kukhona ezintathu eziyinhloko, okuyi-α-Al2O3, β-Al2O3, kanye ne-γ-Al2O3.

I-tabular corundum

I-γ-Al2O3 iyisakhiwo se-spinel, esingazinzile emazingeni okushisa aphezulu futhi asivamile ukusetshenziswa njengento eyodwa. I-β-Al2O3 empeleni iyi-aluminate equkethe izinsimbi ze-alkali noma izinsimbi zomhlaba ezine-alkali. Ukwakheka kwayo kwamakhemikhali kungalinganiswa ngokuthi i-RO·6Al2O3 kanye ne-R2O · 11Al2O3, i-lattice ene-hexagonal, ukuminyana 3.30~3.63g/cm3, 1400~1500 Iqala ukubola ku-℃ futhi iguqulele ku-α-Al2O3 ku-1600℃. I-α-Al2O3 ifomu lezinga lokushisa eliphezulu, elinezinga lokushisa elizinzile liphakeme njengephuzu lokuncibilika, kanye nokuminyana kwe-3.96 ~ 4.01g/cm3, okuhlobene nokuqukethwe kokungcola. I-unit cell iyi-prism ebukhali, ekhona ngesimo se-corundum yemvelo, i-ruby nesafire ngokwemvelo. I-α-Al2O3 inesakhiwo esihlangene, umsebenzi ophansi, izakhiwo zikagesi ezinhle, kanye nezakhiwo ezinhle kakhulu zemishini. Ubulukhuni be-Mohs bungu-9. I-α-Al2O3 ingeye-hexagonal crystal system, isakhiwo se-corundum, a=4.76, c=12.99.

I-Al2O3 inamandla amakhulu emishini. Ukuhlanzeka kokwakheka kwe-Al2O3, kuyanda amandla. Amandla emishini angasetshenziswa ukwenza i-porcelain yedivayisi nezinye izakhi zemishini. I-resistivity ye-Al2O3 iphakeme, ukusebenza kokufakwa kukagesi kuhle, ukumelana nezinga lokushisa legumbi ngu-1015Ω·cm, futhi amandla e-dielectric ngu-15kV/mm. Isebenzisa ukufakwa kwayo nokuqina kwayo, ingenziwa ibe ngama-substrates, amasokhethi, ama-spark plugs, amagobolondo wesekethe, njll. I-Al2O3 inobunzima obuphezulu, ubulukhuni be-Mohs obungu-9, kanye nokumelana nokugqoka okuhle kakhulu, ngakho-ke isetshenziswa kabanzi ukwenza amathuluzi, amasondo okugaya, ama-abrasives, umdwebo uyafa, ama-bearings, izihlahla ezithwalayo namagugu okwenziwa. I-Al2O3 inephuzu eliphezulu lokuncibilika kanye nokumelana nokugqwala. Inephuzu lokuncibilika elingu-2050°C. Inokumelana kahle nokuguguleka kwezinsimbi ezincibilikisiwe njenge-Be, Sr, Ni, Al, V, Ti, Mn, Fe, CO kanye ne-sodium hydroxide, ingilazi, ne-slag. Iphinde ibe nokumelana okuphezulu; ayihlangani no-Si, P, Sb, Bi endaweni engasebenzi, ngakho-ke ingasetshenziswa njengezinto eziphikisayo, amashubhu esithandweni somlilo, ama-crucible okudweba ingilazi, amabhola angenalutho, imicu kanye nesembozo sokuzivikela se-thermocouple, njll.

I-Al2O3 inokuqina okuhle kwamakhemikhali. Ama-sulfide amaningi ayinkimbinkimbi, ama-phosphides, ama-arsenides, ama-chlorides, ama-nitrides, ama-bromide, ama-iodides, ama-fluoride awomile, i-sulfuric acid, i-hydrochloric acid, i-nitric acid, ne-hydrofluoric acid ayihlanganisi ne-Al2O3. Ngakho-ke, ingenziwa ibe yinsimbi ehlanzekile kanye nezinsimbi zokukhula kwekristalu eyodwa, amalunga omuntu, amathambo okwenziwa, njll. I-Al2O3 inezinto ezibonakalayo futhi ingenziwa ibe izinto ezidlulisa ukukhanya ukuze yenze amashubhu e-Na vapor lamp, ama-microwave fairing, amafasitela e-infrared ne-laser. izingxenye ze-oscillation. I-ionic conductivity ye-Al2O3 isetshenziswa njengempahla yamaseli elanga namabhethri okugcina. I-Al2O3 iphinde isetshenziswe kubuchwepheshe be-ceramic surface metallization.

Isigaba esiyinhloko se-crystalline se-alumina-based fused corundum yisigaba se-corundum esinosayizi we-1.0-1.5mm namakristalu ahlanganisiwe. Okusele kungamanani omkhondo we-rutile, i-alumina ne-aluminium titanate, futhi atholakala ngaphakathi kwesigaba se-corundum noma phakathi kwezigaba zekristalu. Inani elincane lesigaba sengilazi. E-China, ngemva kweminyaka engaphezu kweshumi yemizamo engapheli, inqubo yokuncibilika kwe-bauxite-based fused corundum ibe nenqubekelaphambili enkulu, ngomthamo wonyaka wokukhiqiza wamathani angaphezu kuka-110,000. I-Bauxite-based fused corundum isetshenziswe ngempumelelo njengempahla eluhlaza yezitini ezihlukahlukene ezibasiwe kanye nezinto eziphikisayo ezingabunjiwe. Isibonelo, ingafaka ingxenye ye-corundum eminyene ezitsheni zomlilo eziqhumayo, futhi isetshenziswe njengempahla ye-matrix nezinto eziyimbudumbudu ukuze kukhiqizwe ukukhasa okuphansi. Izitini eziphakeme ze-alumina zisetshenziselwa ukufaka esikhundleni se-corundum emhlophe kwezinye i-Al2O3-SiO2 refractories ukuze kulungiswe imikhiqizo esebenza kahle kakhulu.

Ukuncibilikiswa kwe-brown corundum kusekelwe esimisweni esiyisisekelo sokuthi i-aluminium inokuhlangana okukhulu komoyampilo kune-iron, i-silicon, i-titanium, njll. Ngokulawula inani le-ejenti yokunciphisa, ukungcola okuyinhloko ku-bauxite kuyancipha ngokuncibilika kokuncibilika, futhi ukungcola okuncishisiwe kwenza ifomu. ama-alloys e-ferrosilicon. Ihlukaniswe ne-corundum melt ukuze kutholwe i-corundum ensundu enekhwalithi yekristalu ehlangabezana nezidingo kanye nokuqukethwe kwe-Al2O3 okukhulu kuno-94.5%. I-Fe2O3 incishisiwe ukuze ikhiqize i-ferrosilicon alloy futhi isuswe ngesikhathi sokuncibilika, kodwa inani elincane le-iron oxide ne-alumina ekhiqizwa i-spinel lisasele emkhiqizweni. I-TiO2 incishiswe ngokwengxenye ibe ingxubevange ye-ferrosilicon phakathi nenqubo yokuncibilikisa, futhi ingxenye enkulu yayo isala ku-corundum ensundu, okuyisici esiyinhloko ekubaleni umbala kwe-corundum ensundu. I-CaO ne-MgO kunzima ukunciphisa ngesikhathi sokuncibilikiswa, futhi iningi le-CaO ne-MgO ezintweni ezingavuthiwe zisekhona emkhiqizweni. Nakuba i-Na2O ne-K2O zingashintshashintsha ekushiseni okuphezulu ngesikhathi sokuncibilika, azikwazi ukuncishiswa futhi zihlale ku-corundum ensundu, enomthelela omkhulu kwikhwalithi.

I-brown corundum

Impahla eluhlaza ye-brown corundum yenziwe ngezinhlamvu zekristalu ze-α-alumina kanye nenani elincane lesigaba sengilazi, amakristalu e-α-alumina akhiwa i-Al2O3 isisombululo esiqinile esiqukethe i-Ti2O3, futhi isigaba sengilazi sakhiwe kakhulu yi-titanium dioxide ne-silicon dioxide nezinye. landelela i-oxidation ekhona esithandweni se-arc sikagesi.物组合。 Ukwakheka kwezinto. Lawa ma-oxides akha isigaba sengilazi, futhi anokuncibilika okuphansi kuphela esakhiweni sekristalu sezinhlamvu ze-alumina. I-Ti2O3 ukuphela kwe-oxide i-Ti engancibilika kuzinhlamvu ze-alumina. I-TiO2 iyi-oxide eqinile ye-thermodynamically ye-Ti. Ngesikhathi sokuncibilika nokuncishiswa kwe-corundum ensundu, ingxenye ye-TiO2 iyancipha ibe yi-sub-oxidation ye-titanium. (Ti2O3), ngaphezu kuka-1000℃, umoya-mpilo ungasakazekela kuzinhlamvu ze-Ga-alumina, wenze i-Ti2O3 ikhiphe i-TiO2 ezinzile bese isonga ngezinhlamvu ze-α-alumina, ngakho-ke iningi le-titanium dioxide i-α-alumina Isixazululo esiqinile sekristalu. okusanhlamvu kukhona.

I-TiO2 eyeqile ku-corundum ensundu ayikwazi ukuhlala esigabeni sengilazi, kodwa ihlangana ne-alumina ukuze yakhe i-aluminium titanate (TiO2 · Al2O3). I-aluminiyamu titanate yisigaba sesithathu esibonakalayo phakathi kwezinhlamvu ze-α-alumina kanye nesigaba sengilazi; Ukuqina kwe-brown corundum kukhula ngokukhula kwe-TiO2 crystal nuclei. Isigaba se-TiO2 esihlakazwe ngokufanayo kuzinhlamvu zekristalu ye-α-alumina siqinisa izinhlayiya ze-α-alumina. Isixazululo esiqinile se-corundum esinsundu i-Ti2O3 ibangela ukuthi i-corundum ensundu ibonakale iluhlaza okwesibhakabhaka.

I-Ti2O3 ukuphela kwe-oxide i-Ti engancibilika kuzinhlamvu ze-alumina. I-TiO2 iyi-oxide eqinile ye-thermodynamically ye-Ti. Ngesikhathi sokuncibilika nokuncishiswa kwe-corundum ensundu, ingxenye ye-TiO2 iyancipha ibe yi-sub-oxidation ye-titanium. (Ti2O3), ngaphezu kuka-1000℃, umoya-mpilo ungasakazekela kuzinhlamvu ze-Ga-alumina, wenze i-Ti2O3 ikhiphe i-TiO2 ezinzile bese isonga ngezinhlamvu ze-α-alumina, ngakho-ke iningi le-titanium dioxide i-α-alumina Isixazululo esiqinile sekristalu. okusanhlamvu kukhona. I-TiO2 eyeqile ku-corundum ensundu ayikwazi ukuhlala esigabeni sengilazi, kodwa ihlangana ne-alumina ukuze yakhe i-aluminium titanate (TiO2 · Al2O3). I-aluminiyamu titanate yisigaba sesithathu esibonakalayo phakathi kwezinhlamvu ze-α-alumina kanye nesigaba sengilazi; Ukuqina kwe-brown corundum kukhula ngokukhula kwe-TiO2 crystal nuclei. Isigaba se-TiO2 esihlakazwe ngokufanayo kuzinhlamvu zekristalu ye-α-alumina siqinisa izinhlayiya ze-α-alumina. Isixazululo esiqinile se-corundum esinsundu i-Ti2O3 ibangela ukuthi i-corundum ensundu ibonakale iluhlaza okwesibhakabhaka.