Rau Titanium Heat Qws siv los rov ua dua 30% Sodium Thiocyanate Solution Ntawm 80 degree, Thiocyanate Anion Yuav Ua Li Cas Thiaj Tsis Muaj Cov Tshuaj Chloride-Induced Pitting?
Tso lus
Nyob rau hauv 30% sodium thiocyanate (NaSCN) ntawm 80 degree, thiocyanate anions (SCN⁻) adsorb heev rau ntawm titanium nto, tsim ib qho kev tiv thaiv. Thaum muaj cov tshuaj chloride ions, SCN⁻ sib tw rau qhov chaw adsorption nto. Vim tias SCN⁻ muaj qhov adsorption ntau dua li Cl⁻, nws tshem cov tshuaj chloride los ntawm qhov chaw, tiv thaiv chloride-induced pitting. Qhov inhibition efficiency nce nrog SCN⁻ concentration. Ntawm SCN⁻ rau Cl⁻ molar piv saum toj 2, pitting yog kiag li suppressed. Cov yeeb yaj kiab tiv thaiv muaj titanium-thiocyanate complex uas thaiv cov tshuaj chloride nkag mus rau hauv cov hlau.
Lub Mechanism ntawm Competitive Adsorption thiab Pitting Inhibition
Thiocyanate yog lub hauv paus muag muag uas tsim cov ntawv cog lus muaj zog nrog titanium nto atoms. Chloride yog lub hauv paus nyuaj uas tsim cov khoom siv hluav taws xob tsis muaj zog. Hauv cov kev daws teeb meem sib xyaw, SCN⁻ nyiam adsorbs, tuav cov chaw saum npoo uas yuav muaj rau cov tshuaj chloride. Lub adsorbed SCN⁻ txheej kuj hloov cov nqi saum npoo, tiv thaiv chloride ions. Qhov inhibition ua raws li Langmuir isotherm, nrog rau qhov chaw npog θ=(K[SCN⁻])/(1 + K[SCN⁻]), qhov twg K yog qhov sib npaug adsorption tas li.
Quantitative Pitting Inhibition raws li Kev Ua Haujlwm ntawm SCN⁻/Cl⁻ Ratio
Kev tswj xyuas hauv kev daws teeb meem nrog 1,000 ppm Cl⁻ ntawm 80℃thiab sib txawv SCN⁻ ntau tshaj 500 teev tau tsim cov hauv qab no rau Qib 2 titanium. Ntawm SCN⁻/Cl⁻ molar piv ntawm 0 (0 ppm SCN⁻), pitting ceev yog 50-150 pits ib cm², thiab qhov siab tshaj plaws qhov tob yog 200-500 µm. Ntawm qhov sib piv ntawm 0.5 (500 ppm SCN⁻), pitting ceev yog 10-30 pits ib cm², thiab lub qhov tob yog 50-100 µm. Ntawm qhov sib piv ntawm 1.0 (1,000 ppm SCN⁻), pitting ceev yog 2-10 pits ib cm², thiab lub qhov tob yog 10-30 µm. Ntawm qhov sib piv ntawm 2.0 (2,000 ppm SCN⁻), pitting ceev yog 0 pits ib cm², thiab lub qhov tob yog 0 µm (kev tiv thaiv tiav). Ntawm qhov piv ntawm 5.0 (5,000 ppm SCN⁻), pitting ceev yog 0, thiab qhov tob qhov tob yog 0.
Kev cuam tshuam ntawm Kub thiab Chloride Concentration ntawm qhov tseem ceeb piv txwv
Qhov tsawg kawg nkaus SCN⁻ / Cl⁻ piv yuav tsum tau ua kom tiav kev tiv thaiv nce nrog kub. Ntawm 40 degree, qhov piv yog 0.8. Ntawm 60 degree, qhov piv yog 1.2. Ntawm 80 degree, qhov piv yog 2.0. Ntawm 100 degree, qhov piv yog 3.0. Qhov yuav tsum tau ua piv txwv kuj nce nrog chloride concentration; ntawm 500 ppm Cl⁻, qhov piv yog 1.5; ntawm 1,000 ppm Cl⁻, qhov piv yog 2.0; ntawm 5,000 ppm Cl⁻, qhov piv yog 3.0.
Thiocyanate Concentration Guide rau Chloride Pitting Tiv Thaiv
Cov lus hauv qab no muab cov lus pom zoo rau SCN⁻ concentration los tiv thaiv chloride-induced pitting ntawm Qib 2 titanium cua sov ntawm 80℃.
| Chloride Concentration (ppm) | Yam tsawg kawg SCN⁻ rau kev tiv thaiv tiav (ppm) | Pom zoo SCN⁻ (ppm) | SCN⁻/Cl⁻ Molar Ratio |
|---|---|---|---|
| 100 | 200 | 300 | 2.0 |
| 250 | 500 | 750 | 2.0 |
| 500 | 1,000 | 1,500 | 2.0 |
| 1,000 | 2,000 | 3,000 | 2.0 |
| 2,000 | 4,000 | 6,000 | 2.0 |
| 5,000 | 10,000 | 15,000 | 2.0 |
Engineering Tshaj Thiocyanate Concentration Control
Qib titanium cuam tshuam qhov xav tau SCN⁻ concentration. Qib 7 (palladium{2}}stabilized) muaj qhov yuav tsum tau qis dua (SCN⁻/Cl⁻ piv ntawm 1.0–1.5 ntawm 80 degree) vim nws qhov chaw zoo dua. Phab ntsa thickness muab lub qhov nkag mus rau qhov tso cai yog tias inhibition tsis tiav. Cov pH ntawm cov tshuaj cuam tshuam rau SCN⁻ stability; ntawm pH qis dua 4, SCN⁻ hydrolyzes rau HCN thiab poob. Ntawm pH saum toj no 10, SCN⁻ ruaj khov. Lub xub ntiag ntawm oxidizing neeg ua hauj lwm (xws li, Fe³⁺) tuaj yeem oxidize SCN⁻ rau sulfate, txo inhibition.
Ua ib qho kev qhia tshwj xeeb
Rau titanium tshav kub pas nrig nyob rau hauv 30% sodium thiocyanate ntawm 80℃nrog chloride paug, tuav ib tug SCN⁻/Cl⁻ molar piv saum toj 2.0 los tiv thaiv pitting. Yog tias cov tshuaj chloride tsis paub, tswj SCN⁻ ntawm 5,000 ppm (0.5%) raws li cov tshuaj tiv thaiv dav dav. Saib xyuas SCN⁻ concentration txhua lub lim tiam los ntawm titration. Yog tias qhov sib piv poob qis dua 2.0, ntxiv sodium thiocyanate. Rau cov cua sov uas twb muaj lawm nrog pitting, nce SCN⁻ concentration mus rau 10,000 ppm ib ntus kom rov ua dua qhov chaw. Los ntawm kev siv thiocyanate raws li kev sib tw adsorbate, tus kws ua haujlwm tiv thaiv titanium cua sov los ntawm chloride-induced pitting.
