Rau Titanium Immersion rhaub nyob rau hauv 2% Sodium Dodecyl Sulfate Surfactant Solution ntawm 70 degree, Yuav Ua Li Cas Qhov Tseem Ceeb Micelle Concentration (CMC) Hloov Cov Qauv Wetting Thiab Cov Qauv Hauv Ib Cheeb Tsam?
Tso lus
Sodium dodecyl sulfate (SDS) yog ib qho anionic surfactant siv hauv kev tu thiab kev lag luam. Ntawm 70 degree, nws qhov tseem ceeb micelle concentration (CMC) yog kwv yees li 0.05-0.1 wt% (500-1,000 ppm). Hauv qab CMC, surfactant molecules muaj nyob ua monomers thiab adsorb rau ntawm titanium nto, hloov tus cwj pwm wetting thiab txhawb kev ntub dej. Saum toj no CMC, micelles daim ntawv, thiab saum npoo ua hydrophobic, ua rau dewetting thiab tsim ntawm localized electrolyte droplets. Cov tee dej no tsim cov kab sib txawv aeration, ua rau pitting ntawm cov npoo npoo. Cov qauv corrosion hloov los ntawm cov me me etching hauv qab CMC mus rau qhov hnyav hauv zos pitting saum CMC.
Lub tshuab ntawm CMC-Nyob rau Wetting thiab Corrosion
Surfactants adsorb rau ntawm titanium nto nrog lawv cov tails hydrophobic taw qhia deb ntawm cov hlau. Ntawm qhov tsis tshua muaj siab (hauv qab CMC), txheej txheej adsorbed tsis tiav, thiab qhov chaw tseem nyob hauv hydrophilic, tso cai rau kev sib cuag ntawm electrolyte. Ntawm qhov siab tshaj CMC, ib daim ntawv ua tiav bilayer, ua rau saum npoo hydrophobic. Cov tee dej hlaws rau ntawm qhov chaw es tsis kis mus. Oxygen diffusion yog nrawm dua los ntawm cov npoo nyias ntawm cov tee dua li ntawm qhov chaw, tsim cov hlwb sib txawv. Qhov chaw nruab nrab ua anodic thiab pits, thaum cov npoo yog cathodic.
Quantitative Corrosion Pattern raws li Kev Ua Haujlwm ntawm SDS Concentration
Kev tswj xyuas hauv 2% SDS ntawm 70℃(zoo saum CMC) nrog ntau yam dilutions tshaj 500 teev tau tsim cov kev coj cwj pwm hauv qab no rau qib 2 titanium. Ntawm SDS concentration ntawm 0.02% (hauv qab CMC), qhov saum npoo tseem hydrophilic, tus nqi corrosion yog 0.02-0.05 hli ib xyoo, pitting ceev yog 0-5 pits ib cm², thiab etching yog uniform. Ntawm 0.05-0.08% (ntawm CMC), qhov chaw hloov mus rau hydrophobic, tus nqi corrosion nce mus rau 0.05-0.10 hli hauv ib xyoos, pitting ceev nce mus txog 5-20 pits ib cm², thiab droplet - zoo li pits tshwm. Ntawm 0.1-0.5% (saum CMC), qhov saum npoo yog tag nrho hydrophobic, tus nqi corrosion yog 0.08-0.15 hli ib xyoo, pitting ceev yog 20-80 pits ib cm², thiab pits yog ncig nrog tsa sawv. Ntawm 1-2% (ib txwm siv concentration), tus nqi corrosion yog 0.10-0.20 hli hauv ib xyoos, pitting ceev tshaj 80 pits ib cm², thiab cov kua dej loj heev -pitting tshwm sim. Ntawm 5% SDS, tus nqi corrosion yog 0.15-0.30 hli ib xyoo, thiab perforation ntawm 1.2 hli phab ntsa tshwm sim nyob rau hauv 4,000-8,000 teev.
Kev cuam tshuam ntawm Kub thiab Surfactant Hom ntawm CMC thiab Corrosion
CMC txo qis nrog nce kub rau SDS. Ntawm 30 degree, CMC yog 0.08-0.12%, thiab tus nqi corrosion saum CMC yog 0.05-0.10 hli ib xyoo. Ntawm 50 degree, CMC yog 0.06-0.10%, thiab tus nqi yog 0.08-0.15 hli ib xyoo. Ntawm 70 degree, CMC yog 0.05-0.08%, thiab tus nqi yog 0.10-0.20 hli ib xyoo. Ntawm 90 degree, CMC yog 0.04-0.07%, thiab tus nqi yog 0.15-0.30 hli ib xyoo. Nonionic surfactants (piv txwv li, Triton X-100) tsis ua rau tib lub hydrophobic hloov thiab tsis txhob ua rau cov tee dej pitting. Cationic surfactants (xws li, CTAB) tuaj yeem ua rau pitting hnyav dua.
Surfactant Concentration Management Guide rau Titanium rhaub
Cov lus hauv qab no muab cov lus pom zoo rau SDS concentration txheeb ze rau CMC kom txo qis pitting ntawm Qib 2 titanium cua sov ntawm 70 degree.
| SDS Concentration | Tus txheeb ze rau CMC | Nto Wettability | Corrosion Rate (mm / xyoo) | Pitting Qauv | Kev pom zoo |
|---|---|---|---|---|---|
| <0.02% | <0.5× CMC | Hydrophilic | 0.02–0.05 | Hnav khaub ncaws | Muaj kev nyab xeeb |
| 0.02–0.05% | 0.5-1 × CMC | Hloov pauv | 0.05–0.10 | Mixed | Txais tau |
| 0.05–0.1% | 1-2 × CMC | Hydrophobic | 0.08–0.15 | Droplet pitting | Saib xyuas |
| 0.1–0.5% | 2-10 × CMC | Heev hydrophobic | 0.10–0.20 | Pitting hnyav | Siv qib 7 |
| >0.5% | >10 × CMC | Heev hydrophobic | 0.15–0.30 | Pitting heev | Tsis pom zoo |
Engineering Beyond Concentration Control
Qib titanium cuam tshuam rau pitting kuj. Qib 7 (palladium-stabilized) muaj 2-3 zaug siab dua rau cov tee dej pitting, tso cai rau kev ua haujlwm ntawm 2–3 × CMC nrog rau cov nqi corrosion. Qib 12 muaj kev txhim kho nruab nrab. Phab ntsa thickness muab lub qhov nkag nkag; ib lub 2.0 hli phab ntsa nrog 0.15 hli ib xyoo pitting kav 13 xyoo. Kev taw qhia ntawm lub tshuab cua sov tseem ceeb; ntsug tso cua sov tso cov tee dej kom zoo dua li cov cua sov kab rov tav, txo qhov mob hnyav. Ntxiv tus neeg sawv cev ntub dej (piv txwv li, ib qho me me ntawm nonionic surfactant) tuaj yeem kho tus cwj pwm hydrophilic txawm nyob rau qhov siab SDS ntau.
Ua ib qho kev qhia tshwj xeeb
Rau titanium immersion rhaub hauv 2% SDS ntawm 70℃(kwv yees li 20–40 × CMC), qhia Qib 7 titanium thiab lees txais pitting corrosion tus nqi ntawm 0.08–0.15 hli ib xyoo. Rau Qib 2, txo qhov SDS concentration kom qis dua 0.1% (1–2 × CMC) los ntawm dilution los yog siv lwm cov surfactant. Rau cov cua sov uas twb muaj lawm nrog cov tee dej pitting, ntxiv 0.1% ntawm cov khoom siv nonionic surfactant (xws li Triton X-100) los sib tw nrog SDS adsorption thiab rov ua kom cov dej ntub dej. Thaum lub sijhawm ua haujlwm, tshuaj xyuas lub rhaub rau cov yam ntxwv ntawm lub voj voog nrog cov npoo; yog tias pitting tshaj 0.2 hli qhov tob, hloov lub rhaub. Los ntawm kev nkag siab yuav ua li cas CMC hloov tus cwj pwm wetting, tus engineer xaiv cov qib titanium tsim nyog los yog kho cov surfactant concentrations los tiv thaiv pitting hauv zos.
