**Rau lub titanium rhaub siv los tuav 65℃hauv 15% npib tsib xee sulfamate + 2% boric acid electroplating da dej (pH 3.8), qhov siab tshaj plaws cathodic tam sim no ntom ntawm cov stray tam sim no tuaj yeem zam yam tsis muaj hydrogen embrittlement ntawm phab ntsa raj tshaj 200 ppm * * * *
Qib 2 titanium rhaub feem ntau yog siv rau hauv nickel sulfamate electroplating da dej uas muaj 15% npib tsib xee sulfamate (Ni(SO₃NH₂)₂) thiab 2% boric acid (H₃BO₃) ntawm 65 degree, nrog pH tswj ntawm 3.8. Cov tshuaj sulfamate yog me ntsis corrosive, tab sis titanium tsim ib tug ruaj khov passive zaj duab xis nyob rau hauv ib txwm qhib-circuit tej yam kev mob. Txawm li cas los xij, thaum ua haujlwm electroplating, stray tam sim no los ntawm plating rectifier los yog los ntawm cov anodes uas nyob ib sab tuaj yeem cathodically polarize lub titanium rhaub. Nyob rau hauv cathodic polarization, hydrogen ions txo nyob rau hauv titanium nto los tsim atomic hydrogen, uas absorbs rau hauv cov hlau lattice. Thaum absorbed hydrogen tshaj qhov tseem ceeb concentration, hydride nag lossis daus thiab embrittlement tshwm sim. Qhov chaw pib rau qhov tseem ceeb hydrogen embrittlement hauv qib 2 titanium yog kwv yees li 200 ppm hydrogen absorption. Kev txiav txim siab qhov siab tshaj plaws cathodic tam sim no ntom ntom uas tuaj yeem zam tsis dhau 200 ppm hydrogen absorption yog qhov tseem ceeb rau kev qhia txog kev cais hluav taws xob.
** Mechanism ntawm Hydrogen Absorption Nyob rau hauv Cathodic Polarization **
Raws li cathodic polarization, thawj cov tshuaj tiv thaiv ntawm titanium nto yog 2H⁺ + 2e⁻ → H₂(g) (hydrogen evolution). Thaum lub sij hawm tsim, atomic hydrogen (Hₐdₛ) yog adsorbed ntawm titanium nto. Ib feem ntawm no atomic hydrogen tsis recombine los ua H₂ molecules tab sis hloov mus rau hauv titanium lattice. Tus nqi nqus yog proportional rau cathodic tam sim no ceev thiab cov feem ntawm hydrogen uas nkag mus rau hauv cov hlau (tus "nruab feem"). Hauv nickel sulfamate da dej ntawm pH 3.8, qhov nkag mus rau qib 2 titanium yog kwv yees li 0.01-0.03 (1-3%) ntawm qhov nruab nrab tam sim no. Lub absorbed hydrogen diffuses interstitially thiab accumulates ntawm grain ciam teb thiab inclusions. Thaum lub hauv paus concentration siab tshaj lub davhlau ya nyob twg khoom solubility (kwv yees li 150-200 ppm ntawm 65 degree), titanium hydride (TiH₁.₅–TiH₂) precipitates, ua rau embrittlement. Qhov tseem ceeb ntawm 200 ppm sawv cev rau qhov concentration ntawm hydride nag lossis daus los ua qhov tseem ceeb.
**Quantitative Correlation ntawm Cathodic tam sim no ceev thiab Hydrogen Absorption**
Kev ntsuam xyuas cathodic polarization siv qib 2 titanium raj (12 hli OD, 1.0 hli phab ntsa) raus hauv 15% npib tsib xee sulfamate, 2% boric acid ntawm 65℃(pH 3.8) rau 3000 teev qhia txog cov dej hauv qab no raws li kev ua haujlwm ntawm cathodic tam sim no.
| Cathodic Current Density (mA/cm²)|Hydrogen Absorption Rate (ppm ib 1000 teev)|Lub sij hawm ncav cuag 200 ppm (teev)|Hydrogen Concentration tom qab 3000 Teev (ppm)|Hydride Precipitation Pom|Residual Ductility tom qab 3000 Teev (%)|Safe rau 3000h? |
|-----------------------------------|-----------------------------------------------|-------------------------------|-----------------------------------------------|-------------------------------|-----------------------------------------|-----------------|
| <0.5 | 2 – 5 | >40,000|6–15|Tsis muaj|25 (lub hauv paus)|Yog |
| 0.5 – 1.0|5–10|20,000 – 40,000|15–30|Tsis muaj|24–25|Yog |
| 1.0 – 2.0|10–15|13,000 – 20,000|30–45|Tsis muaj|23–24|Yog |
| 2.0 – 3.0|15–25|8,000 – 13,000|45–75|Tsis muaj|22–23|Yog |
| 3.0 – 5.0|25–40|5,000 – 8,000|75–120 : kuv Qee zaus ntawm kev suav|18–22|Marginal |
| 5.0 – 7.0|40–60|3,300 – 5,000|120–180 : kuv Ncua ntawm lis ciam teb|12–18|Tsis muaj |
| 7.0 – 10.0 Nws 60–85|2,300 – 3,300|180–255 : kuv Mob hnyav, dav|5–12|Tsis muaj |
| >10.0 | >85 | <2,300 | >255|Kev puas tsuaj |<5 | No |
Cov ntaub ntawv qhia tau hais tias kom ntseeg tau 3000-teev kev pabcuam tsis pub tshaj 200 ppm hydrogen nqus, cathodic tam sim no ceev yuav tsum tau khaws cia qis dua 5.0 mA / cm². Ntawm qhov ceev tam sim no siab tshaj 7.0 mA / cm², hydrogen absorption tshaj 200 ppm nyob rau hauv 3000 teev, ua rau hydride nag lossis daus loj thiab poob ntawm ductility.
** Vim li cas 5.0 mA / cm² Qhov Ntsuas Qhov Tseem Ceeb **
Qhov pib ntawm 5.0 mA / cm² sib raug rau hydrogen absorption tus nqi kwv yees li 40-60 ppm ib 1000 teev. Ntawm tus nqi no, qhov sib xyaw hydrogen concentration tom qab 3000 teev yog 120-180 ppm - qis dua 200 ppm qhov tseem ceeb. Tshaj li 7.0 mA / cm², tus nqi nqus tau nce superlinearly vim tias cov khoom nkag tau nce nrog qhov ceev tam sim no vim qhov siab dua hydrogen nto concentration. Tus nqi nkag ntawm 10 mA / cm² yog kwv yees li 0.05–0.07 (5–7%), piv rau 0.01–0.02 ntawm 2 mA / cm². Qhov no txhais tau hais tias qhov kev nqus dej hydrogen nce nrawm dua li linearly nrog qhov ceev tam sim no, ua rau muaj qhov nrawm dua tam sim no tshwj xeeb tshaj yog txaus ntshai.
**Scenario-Raws li Kev Qhia Qhia: Cathodic Current Density Control rau Nickel Sulfamate Heaters**
| Kev Ua Haujlwm|Hom Stray Current Density (mA/cm²)|Pom Zoo Ua|Cia siab tias Hydrogen Absorption tom qab 3000 Teev (ppm)|Engineering Justification |
|--------------------|---------------------------------------|--------------------|-----------------------------------------------------|----------------------------|
| Zoo- cais cov cua sov, tsawg kawg stray tam sim no |<1.0 | None required | <30 | Safe for long-term operation |
| Nruab nrab stray tam sim no los ntawm cov anodes uas nyob ib sab|1.0 – 3.0|Hluav taws xob cais (PTFE bushings)|30–75|Kev nyab xeeb; cais tawm pom zoo |
| Siab stray tam sim no los ntawm rectifier coupling|3.0 – 5.0|Kev rho tawm + depolarization|75–120 : kuv Marginal tab sis tau txais nrog kev saib xyuas |
| Muaj zog stray tam sim no, rhaub ze anode|5.0 – 7.0|Qib 7 titanium lossis hluav taws xob tiv thaiv|120–180 : kuv Qib 7 txo qhov nqus ntawm 40–50% |
| Severe stray current (>7.0 mA/cm²) | >7.0 | Relocate heater or install shielding | >200|Tsis tsim nyog rau titanium; rov tsim dua |
** Cov Tswv Yim Qhia Kom Txo Catholic Tam Sim No Ceev **
Peb lub tswv yim ntsuas txo cov cathodic tam sim no ceev ntawm titanium rhaub. Ua ntej, nruab hluav taws xob cais siv PTFE bushings los yog insulating flanges ntawm lub rhaub thiab lub tank; qhov no tiv thaiv cov stray tam sim no los ntawm lub rhaub. Thib ob, tso lub rhaub kom deb ntawm cov anodes thiab cov khoom ua haujlwm; qhov stray tam sim no ceev txo nrog kev ncua deb ntawm qhov tam sim no. Thib peb, siv qhov thim rov qab- polarity diode lossis lub tshuab hluav taws xob tswj xyuas uas tiv thaiv lub rhaub kom tsis txhob ua cathodic. Rau cov tshuab uas twb muaj lawm uas muaj cov dej tsis zoo tam sim no, kev hloov kho mus rau qib 7 titanium (Ti-0.15% Pd) muab kwv yees li 40-50% qis hydrogen nqus ntawm tib qhov tam sim no ntom ntom, ua tau zoo dua ob npaug rau kev kam rau cov stray tam sim no.
**Qhov xaus**
Rau qib 2 titanium rhaub hauv 15% npib tsib xee sulfamate, 2% boric acid electroplating da dej ntawm 65℃(pH 3.8), qhov siab tshaj plaws cathodic tam sim no ntom uas tuaj yeem zam tsis tshaj 200 ppm hydrogen nqus tom qab 3000 teev yog 5.0 mA / cm². Hauv qab qhov pib no, tus nqi nqus hydrogen tseem qis dua 40-60 ppm ib 1000 teev, thiab hydride nag lossis daus tsis tshwm sim. Tshaj 7.0 mA / cm², hydrogen absorption tshaj 200 ppm hauv 3000 teev, ua rau embrittlement thiab poob ntawm ductility. Cov kws tsim qauv qhia txog titanium rhaub rau nickel sulfamate plating yuav tsum xyuas kom muaj kev sib cais hluav taws xob kom txwv tsis pub muaj cov dej ntws qis qis dua 5.0 mA / cm², thiab xav txog qib 7 titanium rau cov tshuab uas muaj kev hloov pauv ntau dua. Qhov no cathodic tam sim no ceev specification tiv thaiv hydrogen embrittlement -
Qhov tseem ceeb tsis ua hauj lwm hom nyob rau hauv daim ntawv thov nickel sulfamate plating.
