Peev Casting Paub txog 304 & 316 Stainless Hlau thiab Silica Sol txheej txheem
Hauv kev nqis peev casting, 304 thiab 316 stainless hlau yog cov feem ntau siv austenitic stainless hlau vim lawv cov corrosion kuj zoo heev, zoo mechanical zog, thiab tag nrho cov nqi-effectiveness. Lawv feem ntau yog siv los tsim cov complex-zoo li tus, du -surface precision castings ntawm Silica Sol Plhaub-Tsev txheej txheem nyob rau hauv peev casting, nrhiav cov ntaub ntawv nyob rau hauv tshuaj twj tso kua mis li qub, khoom noj khoom haus machinery, kho mob, thiab architectural hardware.
I. Casting Yam ntxwv ntawm 304 thiab 316 Stainless Hlau
Txawm hais tias ob qho tib si 304 thiab 316 muaj npe nrov rau kev tiv thaiv corrosion zoo heev, lawv qhov sib txawv sib txawv ncaj qha cuam tshuam rau lawv qhov kev ua tau zoo thiab kev siv zaum kawg.
· 304 Stainless Hlau: Nws muaj pes tsawg leeg yog C tsawg dua lossis sib npaug li 0.08%, Cr 18-20%, Ni 8-10.5%. Nws yog tus qauv "nkag-qib" stainless hlau, muab kev tiv thaiv corrosion zoo (tiv thaiv huab cua, dej tshiab, thiab cov organic acids feem ntau) thiab castability. Thaum lub sij hawm casting, nws qhov kub thiab txias ntau yam yog qhov dav, ua rau muaj kev nyiam rau "mushy solidification," uas ua rau nws yooj yim rau interdendritic shrinkage porosity. Yog li ntawd, nws tso siab dua xav tau ntawm cov txheej txheem tsim.
· 316 Stainless Steel: Raws li kev hloov kho rau 304, nws qhov sib txawv tseem ceeb tshaj plaws yog qhov sib ntxiv ntawm 2-3% Molybdenum (Mo). Cov ntsiab lus no ua rau nws muaj peev xwm tiv taus pitting thiab crevice corrosion nyob rau hauv ib puag ncig chloride (xws li dej hiav txwv, brine). Nws muaj pes tsawg leeg yog C tsawg dua lossis sib npaug li 0.08%, Cr 16-18%, Ni 10-14%, Mo 2-3%. Qhov sib ntxiv ntawm molybdenum me ntsis nce yaj viscosity thiab tej zaum yuav exacerbate microsegregation thaum lub sij hawm casting. Txawm li cas los xij, nws qhov kev tiv thaiv corrosion zoo ua rau nws nyiam xaiv rau qhov chaw hnyav.
Common Casting Challenges thiab Countermeasures:
1. Oxidation thiab Slag Inclusions: Chromium hauv cov hlau yaj tau yooj yim oxidizes los ua ib zaj duab xis Cr₂O₃, uas tuaj yeem nkag mus rau hauv cov casting li slag inclusions. Cov kev ntsuas muaj xws li melting sai, argon tiv thaiv, thiab siv cov cuab yeej slag zoo nyob rau hauv lub rooj vag system tsim.
2. Kub Tearing Tendency: Austenitic stainless steels muaj cov thermal conductivity tsis zoo thiab siab linear shrinkage, ua rau lawv raug rau cov kua muag kub ntawm junctions ntawm tuab thiab nyias seem los yog ntawm qhov chaw kub. Qhov no yuav tsum muaj kev sib cav sib cav thiab tsim kev tsim thiab tswj cov cua txias kom txo tau cov kev ntxhov siab thermal.
3. Shrinkage Porosity: Vim muaj qhov sib txawv ntawm qhov kub thiab txias, kev pub mis yog qhov nyuaj. Nws yog ib qho tseem ceeb uas yuav tsum tau ua raws li lub hauv paus ntsiab lus ntawm kev taw qhia solidification, siv chills los yog insulating risers los coj cov hlau solidification sequentially los ntawm cov ntsiab lus furthest ntawm lub casting mus rau riser, kom ntseeg tau tias qhib kev pub noj.
II. Silica Sol Plhaub-Tsim Tsim: Qhov tseem ceeb rau kev ua tiav Precision Surfaces
Cov txheej txheem silica sol tam sim no yog cov pwm tseem ceeb tshaj plaws - ua txoj hauv kev los ua cov khoom zoo - zoo 304/316 stainless hlau castings. Nws cov ntsiab lus nyob hauv kev tsim lub plhaub ceramic nrog lub zog siab, ruaj khov, thiab qhov tseeb rov ua dua.
Cov txheej txheem nthuav dav:
1. Cov qauv sib dhos:
· Cov qauv siv quav ciab, zoo ib yam rau qhov kawg ntawm cov duab, yog txhaj siv txhuas pwm.
· Cov qauv no ces muab sib sau ua ke rau hauv lub hauv paus wax gating system (pob khob, sprue, runners) los ua ib tug "cluster" los yog "ntoo" rau batch ntau lawm.
2. Thawj (Lub ntsej muag) Coat Stuccoing (Qhov tseem ceeb tshaj plaws):
· Silica Sol: Siv los ua cov ntawv khi, nws yog ib qho colloidal ncua kev kawm ntawm nano-Size SiO₂ hais hauv dej los yog hnyav, paub tias tsis yog- tshuaj lom thiab ib puag ncig.
· Cov khoom siv refractory: Lub tsho loj feem ntau siv cov hmoov Zircon zoo heev (ZrSiO₄) lossis Alumina hmoov (Al₂O₃). Cov no muab siab refractoriness, tsis tshua muaj thermal expansion, thiab replicate heev du nto casting.
· Kev khiav hauj lwm: Cov pawg yog immersed rau hauv cov npaj silica sol-zircon hmoov slurry, kom ntseeg tau tag nrho cov kev pab cuam. Tom qab tshem tawm cov slurry tshaj, stuccoing yog tam sim ntawd ua. Thawj lub tsho tiv no feem ntau yog stuccoed nrog nplua -grained Zircon xuab zeb los yog Fused Silica xuab zeb los txhawb cov txheej thiab ua tiav qhov zoo nkauj zoo nkauj.
3. Drying thiab Curing:
· Kev kho ntawm silica sol yog txheej txheem ziab ntawm lub cev. Nyob rau hauv ib puag ncig tswj (piv txwv li, kub 23 ± 2 degree, av noo 40-60%), dej evaporates maj mam thiab uniformly ntawm txheej. Raws li cov dej evaporates, cov nano-SiO₂ hais los ze zog thiab tsim muaj zog siloxane (Si-O-Si) tes hauj lwm los ntawm condensation ntawm silanol pawg (-SiOH), yog li nruj nreem khi cov refractory aggregates. Thawj lub tsho tiv no yuav tsum tau lub sij hawm kom qhuav txaus (feem ntau ob peb teev) kom paub meej thiab tsis muaj kab nrib pleb.
4. Rov qab-up Coat Stuccoing:
· Tom qab thawj lub tsho tiv no tau kho tag nrho, cov txheej txheem dipping thiab stuccoing yog rov ua dua. Cov tsho tiv no tseem siv silica sol ua tus khi tab sis hloov mus rau tus nqi ntau dua -cov khoom siv tau zoo li Mullite lossis Chamotte hmoov thiab xuab zeb. Sand grain size inc
