Alumina kalsine ak refractories

Sufficient fine grinding of the α-Al2O3 aggregates can destroy their aggregated state and make them non-porous primary crystals, at which time the particle size means close to its grain size. Activated alumina is calcined alumina that has been sufficiently finely ground and has α-Al2O3 with an original crystal size of less than 1 μm as the basic composition (20% to >90 pousan). Nan pwodiksyon an aktive alumina, fò fanm k'ap pile anjeneral obligatwa, tankou sèk fanm k'ap pile nan yon moulen boul seramik-aliyen ak voye boul seramik kòm mwayen an fanm k'ap pile pou plis pase 24 èdtan. Rezon ki fè li rele aktive alumina anjeneral vle di ke li se fasil reyalize pi wo dansite sintering lè sintering, men tanperati a sintering se 100-200 degre pi ba pase sa ki ba-aktivite -Al2O3 poud lan; Li fasil pou reyaji ak sinter ak lòt konpozan nan matris materyèl la, tankou konbine avèk ajil nan matris la pou fòme mullite, reyaji ak siman aluminate kalsyòm pou fòme CA6, reyaji ak MgO pou fòme spinèl, elatriye Dapre teyori sintering la. , gwosè grenn lan anpil afekte pousantaj SINTERING nan etap inisyal la, se sa ki, fòmasyon ak kwasans nan kou a ant grenn yo. Si gwosè grenn lan redwi a 1/10 nan gwosè orijinal la (egzanp soti nan 5 μm a 0.5 μm), sintering pral 1000 fwa a 10000 fwa pi fasil. Sa a eksplike gwo aktivite tèmik alumina aktive.

Pwosesis la fanm k'ap pile konsome yon anpil nan enèji, kidonk pi rafine poud lan, pi chè a li se. Aparans nan Silisyòm mikwo (SiO2 a bwouya pwodwi pandan pwodiksyon an nan carbure Silisyòm oswa metal Silisyòm) te anpil kontribye nan devlopman nan ba-imidite, ba-siman ak ultra-ba siman castables, men sa a SiO2 aktif tou limite castables yo. Tanperati opere. Si pa gen okenn devlopman siksè nan aktive alumina, modèn endistri refractory castable a pa ka devlope tèlman rapid, ak tanperati opere a pa pral depase 1600 degre.

 Generally speaking, powders can be divided into two categories according to the shape of particle size distribution (PSD for short): one type has a unimodal PSD, that is, the particle size distribution curve only surrounds a special particle size (close to but not necessarily Yes D50) peak: the other type is the PSD with multi-peak, that is, there are two or more distribution peaks on the PSD curve. Whether it is unimodal or bimodal, generally the wider the PSD range, the greater the powder bulk density or green body density. The PSD powder with unimodal and narrow range has the lowest bulk density. Of course, activated alumina also has the above two types. The unimodal activated alumina is characterized by a higher percentage (>80 pousan) nan patikil<1μm (≈primary="" crystal="" size),="" and="" thus="" has="" a="" higher="" activity,="" and="" the="" average="" value="" of="" their="" particle="" size="" (≈grain="" size)="" is="" 0.30.="" around="" 5μm.="" the="" density="" of="" this="" activated="" alumina="" green="" body="" is="" low,="" usually="" only="" 54%="" 55%="" of="" the="" theoretical="" density="" of="" α-al2o3="" (3.98g/cm3),="" but="" its="" density="" after="" firing="" at="" 15001600="" ℃="" can="" reach="" 98%="" of="" the="" theoretical="" density,="" or="" even="" higher.="" unimodal="" activated="" alumina="" is="" easily="" and="" completely="" dispersed="" in="" water="" with="" the="" aid="" of="" dispersants="" such="" as="" sodium="" polyphosphate.="" the="" content="" of="" active="" particles="" smaller="" than="" 1="" μm="" in="" the="" multi-bee="" activated="" alumina="" varies="" greatly.="" usually="" between="" 20%="" and="" 7o%.="" the="" ratio="" of="" the="" number="" of="" active="" particles="" to="" the="" number="" of="" larger="" particles="" (="">1 μm) detèmine kapasite pou ranpli vid li yo ak aktivite. Pou alumina multimodal aktive, dyamèt medyàn D50 a ka sèlman reprezante rafineman li yo, olye ke yon paramèt ki karakterize pwopriyete li yo. Dansite vèt nan multimodal aktive alumina ka anjeneral rive nan 62 pousan 68 pousan nan valè a teyorik, ki se evidamman pi wo pase sa yo ki nan alumina unimodal aktive. Dansite sintered ke alumina multimodal aktive ka reyalize depann sou aktivite li yo. Lè alumina multimodal aktivite ki pi wo yo itilize pou peze ak sintering, byenke tanperati sintering li yo se 100-150 degre pi wo pase sa yo ki nan alumina aktive unimodal konplètman densifye, dansite sintered li se sèlman 94 pousan ak 96 pousan nan valè teyorik la. Patikil yo fasil detache soti nan pi gwo patikil yo, kidonk alumina multimodal aktive fasil pou dispèse nan dlo. Ranje nan lajè PSD nan alumina a aktive multimodal pèmèt -Al2O3 micropowder la dwe ranpli nan twou vid ki genyen ant total yo nan brik yo refractory ak castables yo ak vid ki rete yo ant patikil yo gwo poud. Se poutèt sa, lè yo itilize nan castables, pou reyalize menm likidite, kantite dlo ki ajoute a ka redwi pa 4 pousan ak 5 pousan. Nan matris la nan castable a, multimodal alumina aktive aji kòm yon librifyan ant patikil yo gwo, ki ka minimize detachman nan castable a, menm lè sibi entansif melanje oswa ponpe. kenbe separe youn ak lòt.