1. Resistance ntawm Monel 400 rau Chloride Pitting Corrosion
Core Resistance Mechanism
In chloride-containing media, Monel 400 forms a dense, adherent passive film composed of nickel oxide and copper oxide on its surface. Cov yeeb yaj kiab no ua haujlwm zoo thaiv cov tshuaj chloride ions los ntawm kev nkag mus rau cov hlau nplaum substrate, muab kev tiv thaiv zoo tiv thaiv pitting pib.
Kev ua tau zoo nyob rau hauv txawv chloride Concentrations
Tsawg-rau- nruab nrab chloride concentrations (tsawg dua lossis sib npaug li 10,000 ppm): Monel 400 ua qauv qhiazoo heev pitting kujntawm chav tsev kub, nrog lub peev xwm pitting ntawm kwv yees li +0.2 V (vs. standard calomel electrode, SCE). Tus nqi corrosion tseem qis dua 0.01 hli / xyoo, ua rau nws tsim nyog rau cov ntawv thov xws li cov kav dej ntawm ntug dej hiav txwv thiab cov dej tuav dej.
High chloride concentrations (>10,000 ppm, piv txwv li, seawater nrog ~ 35,000 ppm Cl⁻): Nyob rau hauv chav tsev kub, cov zaj duab xis passive tseem nyob ruaj khov, thiab pitting tsis tshua muaj tshwm sim nyob rau hauv zoo li qub los yog qis dua - flow condition. Txawm li cas los xij, yog tias qhov nruab nrab muaj oxidizing impurities (piv txwv li, Fe³⁺, O₂, ClO⁻) lossis tus nqi ntws siab (ua rau yaig), cov zaj duab xis passive yuav raug puas tsuaj, ua rau thaj chaw pitting.
Kub cuam tshuam
Thaum qhov kub siab tshaj 60 degree, kev ruaj ntseg ntawm cov yeeb yaj kiab passive poob qis heev. Nyob rau hauv siab - kub, siab - chloride ib puag ncig (xws li, 80℃seawater), pitting tej zaum poob mus rau -0.1 V (vs. SCE), thiab tus nqi corrosion nce mus rau 0.1-0.3 mm / xyoo, nrog pitting yuav ua tau ntau dua.
2. Resistance ntawm Monel 400 rau Chloride Stress Corrosion Cracking (SCC)
SCC Sensitivity Raws li cov xwm txheej
Monel 400 yogCov tshuaj tiv thaiv zoo heev rau chloride SCCNyob rau hauv chav tsev kub, txawm nyob rau hauv nruab nrab tensile kev nyuaj siab (txog 70% ntawm nws yield zog). Tsis zoo li austenitic stainless hlau (xws li, 304/316), nws tsis raug SCC nyob rau hauv chloride- muaj cov xov xwm xws li dej hiav txwv, ntsev tsuag, los yog brine, uas yog ib qho tseem ceeb kom zoo dua ntawm no alloy.
Risk Factors for SCC Initiation
SCC tuaj yeem tshwm sim tsuas yog thaum peb qhov mob hnyav tshwm sim ib txhij:
Elevated temperature (>120 degree)
High chloride concentration (>50,000 ppm)
High tensile stress (>80% ntawm lub zog tawm los, piv txwv li, los ntawm vuam seem kev ntxhov siab lossis kev siv tshuab ntau dhau)
Nyob rau hauv xws li xwm txheej, cov zaj duab xis passive ua tsis tu ncua, thiab cov tshuaj chloride ions nkag mus rau hauv cov ciam teb, ua rau intergranular stress corrosion cracking.
Kev Tiv Thaiv Kev Tiv Thaiv
Txo cov kev ntxhov siab uas nyob ntawm kev tshaj tawm -weld annealing (cua sov rau 620-670℃thiab tuav rau 1-2 teev) tuaj yeem txhim kho cov alloy lub SCC tsis kam nyob rau hauv ib puag ncig hnyav.
3. Kev tsim nyog ntawm Monel 400 rau Seawater Desalination Equipment
Siv tau cov Cheebtsam hauv Desalination Systems
Monel 400 yogzoo- haum rau cov khoom tseem ceebntawm seawater desalination khoom nyob rau hauvchav - mus rau - nruab nrab kub tej yam kev mob (< 60°C), suav nrog:
Tau txais thiab ua ntej- cov kav dej kho mob (tiv taus rau dej hiav txwv yaig thiab pitting)
Lub cev lub cev, lub twj tso kua mis impellers, thiab cov cua kub exchanger raj (hauv qis-kub MED systems)
Fasteners thiab fittings nyob rau hauv ntug dej hiav txwv desalination nroj tsuag (resistant rau ntsev tsuag corrosion)
Nws cov khoom siv zoo heev (yield zog ~ 240 MPa, elongation ~ 35%) kuj ua kom ruaj khov nyob rau hauv ntev - lub sijhawm ua haujlwm loads.
Cov kev txwv nyob rau hauv siab -Tub kub Desalination txheej txheem
Monel 400 yogtsis pom zoo rau siab -kub desalination systems(piv txwv li, MFE systems ua haujlwm ntawm 100–120 degree), rau cov laj thawj hauv qab no:
Cov kub kub txo nws cov pitting thiab SCC tsis kam, ua rau muaj kev pheej hmoo ntawm kev tiv thaiv tsis ua haujlwm.
Tus nqi corrosion accelerates ho, shortening lub neej kev pab cuam ntawm cov cuab yeej thiab nce nqi txij nkawm.
Rau xws li high -kev siv kub, ntau corrosion-cov alloys resistant (xws li, Hastelloy C276, titanium alloys) los yog titanium-clad steel yog lwm txoj kev zoo dua.
Tus nqi -Kev Ua Tau Zoo Zoo
Piv nrog rau titanium alloys thiab Hastelloy, Monel 400 muaj tus nqi zoo dua -kev ua tau zoo piv rau qis- rau- cov khoom siv kub kub desalination, ua rau nws tus nqi- kev xaiv zoo rau ntau qhov kev lag luam desalination project.
