Alumina

xabagta Aluminum dhacdaa deegaanka dabiiciga ah ee foomka of alumina caadiga ah, ay formula kiimikada - AL2O3. In noocan oo kale ah kiristaalo lama isagoo midabo in ay yihiin heerkulka a of 2044 ° C bilaabi dhalaali, iyo marka heerka 3530 ° C kasoobaxa.

Meelo dabiiciga ah oo kaliya walax-habeynta deggan yahay xabagta aluminium isagoo cufnaanta ah 3,99 g / cm3. Tani waa muunad ah oo aad u adag ay leeyihiin heerka sagaalaad ee horyaalka Mohs. Qiimaha index ka Refractive waa sida soo socota, waayo, ray caadiga ah - 1.765 iyo 1.759 for caadi ah. Meelo dabiiciga ah alumina inta badan ka kooban oxides biraha kala duwan, si kastaba ha ahaatee, corundum macdanta heli karaan midabo kala duwan ee midabka. Tusaale ahaan, waa safayr kuwa, luulka iyo dhagaxyo kale oo qaali ah. Sida oo kale, alumina waxaa laga yaabaa in loo diyaar garoobo iyo habka shaybaar-kiimikada. Waayo, kanu Ujeedada, foomka metastable A12O3 iyo thermally baaliyoobay. Sidoo kale, sida isha habka shaybaarka loo isticmaalo xabagta aluminium , hydroxide aluminium.

xarunta-habeynta Standard waa daaqaddii tetragonicheskuyu ay ku jiraan in ay ka kooban oo ku saabsan 1-2% biyaha. waxaa laga heli karaa amorphous in qaab-dhismeedka alumina - gel alumina, oo gelevidny xal of AL (OH) 3 waxaa dewatered si aad u hesho wax iska furan mass hufan.

xabagta Aluminum gebi ahaanba beelaya biyo, laakiin in si wanaagsan loo kala diri karaa cryolite, kululaynta si heer kulka sare. walax Amphoteric. Characteristically hantida a of alumina ku dhexsameeysmo jirka sida ku tiirsanaanta bedelka ee heerkulka formation iyo waxqabad kiimikada sida. Sida aan dabiici ahayn (i.e., helay at heerkul ka badan 1200 ° C) iyo corundum dabiiciga ah ee lagu soo bandhigid deegaanka caadiga ah shiidaa boqolkiiba boqol dhamaystiran inertness kiimikada iyo la'aanta hygroscopicity.

Oxide kiimikaad aluminium uu bilaabo inuu si firfircoon jimicsi marka heerkulku 1000 ° C, marka uu bilaabo inuu si degdeg ah ula falgalaan walxaha sida carbonates kala duwan alkali biraha alkali. Marka aluminates dhexgalka this loo sameeyay. xarunta ayaa gaabis ah uga jawaabo la SiO2, iyo sidoo kale noocyo kala duwan oo slags acidic. Sidaas darteed of isdhexgalka kuwan waxaa aluminosilicates helay.

gel Alumina iyo alumina oo waxaa loo diyaariyey by calcination of hydroxides aluminium at mid ka mid ah ugu yaraan 550 ° C, waxay leeyihiin hygroscopicity aad u dheer, u fiican galaan falgalka kiimikada iyo si firfircoon ula falgalaan xal acidic iyo alkaline.

Sida caadiga ah, sida qalab dihin oo soo saara xabagta aluminium waxaa loo isticmaalaa bauxite, alunite iyo nepheline. Marka content oo ah walaxda in su'aasha iyaga in ka badan 6-7% wax soo saarka waa habka ugu muhiimsan - by Bayer, iyo content a hoose ee habka sintering ore adeegsiga maandooriyaha la shiday ama soda. habka Bayer waa dhagax weyn processing burburiyo in a ku daqiijin jireen kubada, raaceen bauxite waxaa lagu daaweeyaa xal cawaaqib xumadoodu waxay heerkulka a of 225-250 ° C. Halabuurka The sidaas helay waxaa qasi jiray xal sodium aluminate aqueous iyo sifeeyo. In geeddi-socodka of dabaqii slurry ka kooban alumina ah, kuwaas oo guryaha u dhigma heerka, waxaa giirte in centrifuges. technology noocan oo kale ah oo u ogolaanaya in la helo dhalidda 50% oo ah walaxda. Intaas waxaa sii dheer, isticmaalka habkan waxay suuro gelineysaa in ay sii khamriga hooyada loo isticmaalo hawlgallada xiga by leaching ah bauxite.

Guud ahaan, taasoo keentay habka dardaro xabagta aluminium waxaa loo isticmaalaa sida wax dhexe diyaarinta aluminium saafi ah. In warshadaha, waxaa loo adeegsanayaa qalab sida xawliga ah u soo saara qalabka madax adkaadeen, hadal haynta dhoobada iyo jarida qalabka. technology Modern si firfircoon uga codsan kiristaalo hal of xabagta aluminium in saacadaha soo saarka, PCB, dahabka.