Zoumba
Alumina ceramic ndi mtundu wa zinthu zosavala, zosagwira dzimbiri komanso zamphamvu kwambiri za ceramic. Imagwiritsidwa ntchito kwambiri ndipo pakadali pano ndi gulu lomwe limagwiritsidwa ntchito kwambiri pazida zadothi zotentha kwambiri. Kuti apange kupanga misa ndikukwaniritsa zofunikira za mawonekedwe anthawi zonse, kugaya pang'ono komanso kupukuta kosavuta, ndikofunikira kwambiri kusankha njira yopangira makina owuma. Kuponderezana kumafuna kuti chopanda kanthu ndi ufa wokhala ndi gradation inayake, yokhala ndi chinyezi chochepa komanso binder.Chifukwa chake, slurry wa batch pambuyo pa mphero ndi kuphwanyidwa kwabwino kuyenera kuuma ndi kupukuta ufa ndi granulated bwino. Utsi wowumitsa granulation wakhala njira yofunikira yopangira zitsulo zomangira ndi ceramics zatsopano.Ufa wokonzedwa ndi njirayi uli ndi madzi abwino, gawo lina la tinthu tating'onoting'ono tating'onoting'ono tating'onoting'ono tating'onoting'ono, ndi kachulukidwe kabwino kameneka.
Kuyanika kwautsi ndi njira yomwe zida zamadzimadzi (kuphatikiza slurry) zimasinthidwa kukhala zida zouma zowuma pamalo otentha. Zipangizozi zimakhala ndi ma atomu ozungulira kwambiri, chifukwa cha fogdrops ndi zabwino kwambiri ndipo chiŵerengero cha pamwamba pa voliyumu ndi chachikulu kwambiri, chinyezi chimasanduka nthunzi, ndipo kuyanika ndi granulation kumatsirizika nthawi yomweyo. The tinthu kukula, okhutira ndi chochuluka kachulukidwe zipangizo akhoza lizilamulira ndi kusintha kuyanika ntchito magawo. ufa ozungulira ndi yunifolomu khalidwe ndi repeatability wabwino akhoza kupangidwa ndi kutengera kutsitsi kuyanika luso, motero kufupikitsa ndondomeko yopanga ufa, kutsogoza zodziwikiratu ndi mosalekeza kupanga, ndi kukhala njira yothandiza kwambiri yokonzekera bwino alumina ceramic youma zipangizo ufa.
2.1.1 Kukonzekera kwa Slurry
Woyamba kalasi mafakitale aluminiyamu ndi chiyero cha 99% anawonjezera ndi pafupifupi 5% ya zina kukonzekera 95% zadothi zadothi, ndi mpira mphero ikuchitika molingana ndi chiŵerengero cha zinthu: mpira: madzi = 1: 2: 1, ndi binder, deflocculant ndi yoyenera kuchuluka kwa madzi amawonjezedwa kukonzekera khola kuyimitsidwa ndi slurry wokhazikika woyezedwa ndi slurry wokhazikika woyezedwa ndi slurry. zili, mtundu ndi mlingo wa deflocculant.
2.1.2 Njira yowumitsa utsi
Zigawo zazikulu zowongolera pakuwumitsa utsi ndi: a). The kubwereketsa kutentha kwa dryer.Kawirikawiri ankalamulira pa 110 ℃.b). M'mimba mwake wa nozzle. Gwiritsani ntchito 0.16mm kapena 0. 8mm orifice mbale. c), kusiyana kwa kuthamanga kwa Cyclone Separator, kuwongolera pa 220Pa.
2.1.3 Kuyang'ana Kachitidwe ka Ufa Pambuyo Poyanika
Chinyezi kutsimikiza kudzachitika molingana ndi wamba ceramic chinyezi kutsimikiza method.The tinthumorphology ndi kukula kwa tinthu kunawonedwa ndi microscope.The fluidity ndi kuchulukana kwa ufa kumayesedwa molingana ndi miyezo yoyesera ya ASTM ya fluidity ndi kuchulukana kwa ufa wachitsulo. Njirayi ndi: pansi pa kugwedezeka kosagwedezeka, 50g ufa (wolondola mpaka 0. 01g) umadutsa pakhosi la galasi la galasi ndi m'mimba mwake 6mm ndi kutalika kwa 3mm chifukwa cha madzi ake;Pansi pa kugwedezeka kosasunthika, ufawo umadutsa muzitsulo zamagalasi zomwezo ndikugwera mu chidebe cha 25mm pamwamba kuchokera ku galasi lomwelo. Kachulukidwe wosagwedera ndi kachulukidwe kakatundu wotayirira.
3.1.1 Kukonzekera kwa slurry
Pogwiritsa ntchito njira yowumitsa granulation, kukonzekera kwa slurry ndikofunikira kwambiri. Olimba okhutira, fineness ndi fluidity wa matope mwachindunji zimakhudza linanena bungwe ndi tinthu kukula youma ufa.
Chifukwa ufa wa mtundu uwu wa aluminiyado zadothi ndi wosabala, m'pofunika kuwonjezera mlingo woyenera wa binder kuti apititse patsogolo kupanga ntchito ya blank.Awiri ntchito organic zinthu monga dextrin, polyvinyl mowa, carboxymethylcellulose, polystyrene, etc.Polyvinyl mowa (PVA), ndi madzi sungunuka binder, anasankhidwa mu kuyesera ndi kusintha kwa chilengedwe chinyontho kwambiri, tcheru kusintha kwa humbity. zimakhudza katundu wa ufa wouma.
Mowa wa polyvinyl uli ndi mitundu yambiri yosiyanasiyana, madigiri osiyanasiyana a hydrolysis ndi digiri ya polymerization, zomwe zingakhudze njira yowumitsa kutsitsi. Digiri yake yonse ya hydrolysis ndi digiri ya polymerization ikhudza kuyanika kwa utsi. Mlingo wake nthawi zambiri ndi 014 - 015wt% .Kuwonjezera kwambiri kumapangitsa kuti granulation powder ikhale yowuma kwambiri kuti iteteze particles ku deforming panthawi ya pressing.Ngati zizindikiro za tinthu sizingathetsedwe panthawi ya kukanikiza, zolakwikazi zidzasungidwa mu thupi lobiriwira ndipo sizingathetsedwe pambuyo powombera, zomwe zidzakhudza ubwino wa mankhwala omaliza. Binder Kuwonjezera mphamvu zochepa zobiriwira zidzawonjezera kuwonongeka kwa ntchito. Kuyesera kumasonyeza kuti pamene kuchuluka koyenera kwa binder kuwonjezeredwa, gawo la billet lobiriwira limawonedwa pansi pa microscope. Zitha kuwoneka kuti pamene kupanikizika kumawonjezeka kuchokera ku 3Mpa kupita ku 6Mpa, gawolo likuwonjezeka bwino, ndipo pali tinthu tating'onoting'ono tozungulira. Pamene kuthamanga ndi 9Mpa, gawo ndi yosalala, ndipo kwenikweni palibe particles ozungulira, koma kuthamanga kwambiri kudzatsogolera ku stratification wa billet.PVA wobiriwira imatsegulidwa pafupifupi 200 ℃.
Yambani kuwotcha, ndi kukhetsa pafupifupi 360 ℃. Kuti kupasuka organic binder ndi kunyowetsa billet particles, pangani madzi interlayer pakati particles, kusintha plasticity wa billet, kuchepetsa kukangana pakati pa particles ndi kukangana pakati pa zipangizo ndi nkhungu, kulimbikitsa kachulukidwe kuchuluka kwa mbamuikha billet ndi kugawa pulasitiki wamba ndi kugawa koyenera, kugawa pulasitiki wamba ndi kugawa wamba ndi kugawa kwa pulasitiki. Zomwe zimagwiritsidwa ntchito ndi glycerin, ethyl oxalic acid, etc.
Chifukwa binder ndi organic macromolecular polima, njira yowonjezera binder mu slurry ndi yofunika kwambiri.Ndi bwino kuwonjezera binder okonzeka mu matope yunifolomu ndi zofunika olimba okhutira.Mwa njira iyi, undissolved ndi undispersed zinthu organic akhoza kupeŵa kubweretsedwa mu slurry, ndi zofooka zotheka kuchepetsedwa. mpira mphero kapena kugwedeza. Mpweya wokulungidwa mu droplet umakhala mu ufa wouma, womwe umapangitsa kuti tinthu tating'ono touma tisakhale ndi dzenje ndikuchepetsa kuchuluka kwa voliyumu. Pofuna kuthetsa vutoli, defoamers akhoza kuwonjezeredwa.
Chifukwa cha zofunikira zachuma ndi zaumisiri, zolimba zapamwamba zimafunikira.Monga mphamvu yopangira chowumitsira imatanthawuza madzi otuluka pa ola limodzi, slurry yokhala ndi zinthu zolimba kwambiri idzawonjezera kwambiri ufa wouma. Zolimba zikakwera kuchokera pa 50% mpaka 75%, zotulutsa zowumitsa zimawonjezeka kawiri.
Kutsika olimba okhutira ndi chifukwa chachikulu mapangidwe dzenje particles.Mu njira kuyanika, madzi amasamukira pamwamba pa dontho ndi kunyamula particles olimba, amene amapangitsa mbali yamkati ya droplet dzenje; ngati otsika permeability zotanuka filimu aumbike padziko droplet, chifukwa cha otsika evaporation liwiro, kutentha kwa droplet ukuwonjezeka, ndi madzi amasanduka nthunzi kuchokera mkati mbali, zomwe zimapangitsa droplet bulge. Muzochitika zonsezi, mawonekedwe a mpira wa particles adzawonongedwa, ndi dzenje annular kapena apulo zooneka kapena peyala zooneka particles zidzapangidwa, zomwe zidzachepetsa kusungunuka kwa madzi olimba. zokhutira zimatha kuchepetsa
Mwachidule kuyanika ndondomeko kuchepetsa kuyanika kungachepetse kuchuluka kwa zomatira anasamutsidwa kwa tinthu pamwamba pamodzi ndi madzi, pofuna kupewa kuti binder ndende pa tinthu pamwamba ndi wamkulu kuposa pakati, kuti particles kukhala pamwamba olimba, ndi particles musati deform ndi kuphwanya mu ndondomeko kukanikiza ndi kupanga, kuti kuchepetsa thupi la billet. Choncho, kuti mupeze ufa wowuma wapamwamba kwambiri, zolimba za slurry ziyenera kuwonjezeka.
Ngati kukhuthala kwa slurry kumachepetsedwa poyambitsa madzi ochulukirapo, osati kugwiritsira ntchito mphamvu zowumitsa kumawonjezeka, komanso kuchepetsedwa kwakukulu kwa mankhwala kumachepetsedwa. akhoza kuonedwa ngati colloidal dispersion system.Lingaliro la kukhazikika kwa colloidal limasonyeza kuti pali mphamvu ziwiri zomwe zikugwira ntchito pazigawo zoyimitsidwa: van der Waals force (Coulomb force) ndi electrostatic repulsion force. Ngati mphamvu makamaka yokoka, agglomeration ndi flocculation will happen.The okwana kuthekera mphamvu (VT) wa mogwirizana pakati particles ndi zokhudzana ndi mtunda wawo, pamene VT pa nthawi ina ndi chiŵerengero cha mphamvu yokoka VA ndi zonyansa mphamvu VR.Pamene VT pakati particles amapereka pazipita zabwino mphamvu mphamvu, ndi dongosolo ena a depoly ndi depoly VA. dongosolo ndi ntchito zimene kulamulira VR: pamwamba mlandu wa particles ndi makulidwe awiri magetsi layers.The makulidwe a bilayer ndi inversely proportional kuti lalikulu muzu wa valence chomangira ndi ndende ya equilibrium ion.Double wosanjikiza psinjika akhoza kuchepetsa kuthekera chotchinga cha flocculation, kotero chomangira valence ndi ndende ya ndende ya equilibrium ntchito ndi otsika decor. HCI, HNO3, NaOH, (CH) 3noh (quaternary amine), GA, etc.
Chifukwa madzi opangidwa ndi slurry wa 95 alumina ceramic ufa ndi ndale ndi alkalescent, coagulants ambiri amene ali ndi zotsatira zabwino diluting pa ena ceramic slurry kutaya ntchito.Chotero, n'kovuta kwambiri kukonzekera slurry ndi mkulu olimba okhutira ndi fluidity wabwino.The wosabala aluminiyamu slurry, amene ali amphoteric okusayidi, ali ndi njira zosiyana za disociation kapena dissociation njira zosiyanasiyana za asidi dissociation. kapangidwe ka micelle ndi kapangidwe. Phindu la pH la slurry lidzakhudza mwachindunji kuchuluka kwa dissociation ndi adsorption, zomwe zimabweretsa kusintha kwa ζ kuthekera ndi flocculation kapena dissociation.
Alumina slurry ali ndi phindu lalikulu la zabwino ndi zoipa ζ kuthekera mu asidi kapena zamchere sing'anga.Panthawiyi, mamasukidwe akayendedwe a slurry ndi otsika mtengo wa de coagulation, pamene slurry ali mu ndale chikhalidwe, mamasukidwe ake kukhuthala kumawonjezeka, ndipo flocculation zimachitika. imachepetsedwa powonjezera demulsifier yoyenera, kotero kuti mtengo wake wa viscosity uli pafupi ndi madzi. Madzi amadzimadzi omwe amayezedwa ndi viscometer yosavuta ndi 3 masekondi / 100 ml, ndipo fluidity ya slurry ndi 4 masekondi / 100 ml. kukhuthala kwa slurry kumachepetsedwa, kotero kuti zolimba zomwe zili mu slurry ziwonjezeke mpaka 60%, ndipo kunyamula kokhazikika kumatha kupangidwa.Monga mphamvu yopangira chowumitsira imatanthawuza kutuluka kwa madzi pa ola limodzi, kotero kuyimitsidwa.
3.1.2 Kuwongolera magawo akuluakulu pakuyanika kwautsi
Mchitidwe wa mpweya mu nsanja yowumitsa umakhudza nthawi yowumitsa, nthawi yosungiramo, madzi otsalira ndi kumamatira khoma kwa madontho. countercurrent, ndipo dontho likafika pamwamba pa sitiroko, limakhala kutsika kwamtsinje ndikupopera mu mawonekedwe a conical.Mwamsanga pamene dontho limalowa mu nsanja yowumitsa, posachedwapa lidzafika pamtunda wowuma mofulumira ndikulowa mu siteji yowumitsa nthawi zonse. Kutalika kwa siteji yowumitsa nthawi zonse kumadalira chinyezi cha dontho, kukhuthala kwamatope, kutentha ndi chinyezi cha mpweya wouma. Malire a C kuchokera kumalo owumitsa nthawi zonse mpaka kumalo owuma mofulumira amatchedwa mfundo yovuta. Panthawiyi, pamwamba pa dontho silingathe kukhalabe ndi malo odzaza ndi kusamuka kwa madzi, ndi kuchepa kwa evaporation, kutentha kwa madontho kumawonjezeka, ndipo pamwamba pa madontho pa D ndi odzaza, kupanga chipolopolo cholimba. Mpweya umapita mkati, ndipo kuyanika kumapitirira kuchepa. Kuchotsanso kwina kwa madzi kumakhudzana ndi kutsekemera kwa chinyezi cha chipolopolo cholimba.Choncho, m'pofunika kulamulira magawo oyenerera ogwirira ntchito.
Chinyezi cha ufa wowuma chimatsimikiziridwa ndi kutentha kwa mpweya wa sprayer.Chinyezichi chimakhudza kachulukidwe wochuluka ndi fluidity ya ufa wouma, ndipo zimatsimikizira mtundu wa mbande blank.PVA ndi tcheru ndi chinyezi. Pansi pazikhalidwe zosiyanasiyana za chinyezi, kuchuluka komweko kwa PVA kungayambitse kuuma kosiyana kwa pamwamba pa tinthu tating'ono ta ufa, zomwe zimapangitsa kutsimikiza kwa kupanikizika kusinthasintha komanso kupanga kusakhazikika panthawi yokakamiza. Choncho, kutentha kubwereketsa ayenera mosamalitsa ankalamulira kuonetsetsa chinyezi zili youma ufa. Nthawi zambiri, kutentha kwa kutuluka kumayenera kuyendetsedwa pa 110 ℃, ndipo kutentha kwa malowa kuyenera kusinthidwa moyenera.Kutentha kwa malowa sikupitirira 400 ℃, kawirikawiri kumayendetsedwa pafupifupi 380 ℃. Pamene nkhungu imatsika pamwamba kwambiri ndikukumana ndi mpweya wotentha kwambiri, chifukwa cha ufa wa ceramic womwe uli ndi binder, zotsatira za binder zidzachepetsedwa, ndipo pamapeto pake ntchito yowonongeka ya ufa wowuma idzakhudzidwa. zimatsimikiziridwa, kutentha komwe kumatulukako kumathanso kusinthidwa ndi kukakamiza kwa mpope wa chakudya, kusiyana kwamphamvu kwa olekanitsa chimphepo, zolimba za slurry ndi zinthu zina.
Kuthamanga kusiyana kwa cyclone separator.Kusiyana kwa kuthamanga kwa olekanitsa mphepo yamkuntho ndi kwakukulu, zomwe zidzawonjezera kutentha kwa kutuluka, kuonjezera kusonkhanitsa particles zabwino ndi kuchepetsa zokolola za chowumitsira.
3.1.3 Makhalidwe a ufa wowuma wopopera
Kuchulukana kwamadzimadzi ndi kulongedza kwa alumina ceramic ufa wokonzedwa ndi njira yowumitsa utsi nthawi zambiri kumakhala kwabwinoko kuposa komwe kumakonzedwa mwachizolowezi. Ufa wa granulation pamanja sungathe kudutsa mu chipangizo chozindikira popanda kugwedezeka, ndipo ufa wa granulation ukhoza kuchita izi kwathunthu. Potengera muyeso wa ASTM woyesa kuchuluka kwa ufa wachitsulo ndi kachulukidwe kachulukidwe, kachulukidwe kachulukidwe komanso kuchuluka kwa tinthu tating'onoting'ono tomwe timapeza poyanika kutsitsi pansi pamikhalidwe yosiyanasiyana yamadzi adayesedwa. Onani Table 1.
Table 1 lotayirira kachulukidwe ndi fluidity wa kutsitsi zouma ufa
Table 1 Kachulukidwe ka ufa ndi kuchuluka kwake
| Chinyezi (%) | 1.0 | 1.6 | 2.0 | 2.2 | 4.0 |
| Kuchulukirachulukira (g/cm3) | 1.15 | 1.14 | 1.16 | 1.18 | 1.15 |
| Liquidity (s) | 5.3 | 4.7 | 4.6 | 4.9 | 4.5 |
Chinyezi cha ufa wowuma wopopera nthawi zambiri chimayendetsedwa pa 1 - 3%. Panthawi imeneyi, madzi a ufa ndi abwino, omwe amatha kukwaniritsa zofunikira za kukanikiza akamaumba.
DG1 ndi kachulukidwe ka ufa wopangidwa ndi manja, ndipo DG2 ndi kuchuluka kwa ufa wa granulation.
Pamanja granulated ufa amakonzedwa ndi mpira mphero, kuyanika, sieving ndi granulation.
Table 2 kachulukidwe wa ufa woponderezedwa wopangidwa ndi granulation pamanja ndi kutsitsi granulation
Table 2 Kuchulukana kwa Green Body
| Pressure (MPA) | 4 | 6 | 8 | 10 | 12 | 14 |
| DG1 (g/cm3) | 2.32 | 2.32 | 2.32 | 2.33 | 2.36 | 2.4 |
| DG2 (g/cm3) | 2.36 | 2.46 | 2.53 | 2.56 | 2.59 | 2.59 |
The tinthu kukula ndi morphology wa ufa ankaona ndi maikulosikopu.Zitha kuona kuti particles kwenikweni olimba ozungulira, ndi mawonekedwe omveka ndi pamwamba yosalala. Tinthu tating'onoting'ono tomwe timapangidwa ndi ma apulo, mawonekedwe a peyala kapena bridged, zomwe zimawerengera 3% yazonse. The tinthu kukula kugawa ndi motere: pazipita tinthu kukula ndi 200 μ m (< 1%), osachepera tinthu kukula ndi 20 μ m (munthu), ambiri particles ndi za 100 μ m (50%), ndipo ambiri particles ndi za 50 μ m (20%). The ufa opangidwa ndi utsi kuyanika ndi sintered ndi 3750 digiri density0 ndi 31cm density0 31cm / 16cm3.
(1) 95 alumina slurry ndi 60% okhutira olimba akhoza analandira pogwiritsa ntchito PVA monga binder, kuwonjezera coagulant yoyenera ndi lubricant.
(2) kuwongolera koyenera kwa magawo opangira kuyanika kutsitsi atha kupeza ufa wabwino wowuma.
(3) potengera kuyanika kutsitsi, 95 aluminiyamu ufa, amene ali oyenera chochuluka youma kukanikiza ndondomeko, akhoza kupangidwa. Kachulukidwe kake ndi pafupifupi 1. 1g/cm3ndi kachulukidwe sintering ndi 3170g/cm3.
