Vim li cas lub Phab Ntsa Thick (2.0 mm) Titanium muab kev tiv thaiv zoo dua tiv thaiv peroxide-Induced brittle Fracture dua li ib tug nyias (1.0 mm) Phab ntsa?

Piv txwv li, nyob rau hauv cov tshuaj bleaching, tshuaj synthesis, los yog cov txheej txheem kev kho dej khib nyiab, tus txheej txheem engineers khiav lub titanium immersion rhaub nyob rau hauv cov tshuaj uas muaj hydrogen peroxide (H2O2) yuav tsum ntsuas qhov txaus ntshai ntawm peroxide induced brittle fracture raws li ib tug tseem ceeb tsim qauv. Ntawm titanium nto, hydrogen peroxide decomposes muab atomic oxygen thiab, nyob rau hauv tej yam kev mob, atomic hydrogen. Hydrogen diffuses rau hauv titanium lattice thiab tsim titanium hydride brittle (TiHx). Lub phab ntsa tuab (2.0 hli) muaj kev tiv thaiv zoo tshaj plaws tiv thaiv hydride-induced brittle fractured dua li phab ntsa nyias (1.0 mm) los ntawm ob lub tswv yim: ntev diffusion nrug rau hydrogen kom ncav cuag qhov tseem ceeb concentration thiab loj dua phab ntsa thickness tom qab nto hydride ntau lawm. Kev tshawb fawb ntau qhia tau hais tias phab ntsa 2.0 hli yuav tiv taus 4-8 lub sij hawm siab dua hydrogen nqus ua ntej nkig tawg tshwm sim piv rau 1.0 hli phab ntsa, txuas lub neej kev pab cuam los ntawm qhov tseem ceeb ntawm 3-6 hauv kev pab cuam peroxide.

Mechanism ntawm peroxide-induced hydrogen absorption hauv titanium
Titanium surfaces catalyze the exothermic decomposition of hydrogen peroxide . 2H2O2 ->2 H2O + O 2. Qhov kev puas tsuaj no tsim ib qho chaw oxidizing heev uas feem ntau stabilizes TiO2 passive zaj duab xis. Txawm li cas los xij, nyob rau hauv cov cheeb tsam uas muaj peroxide concentration siab los yog kub tshaj 60℃ib theem nrab cov tshuaj tiv thaiv tshwm sim: H2O2 + 2H+ + 2e- → 2H2O (cathodic txo) uas muaj peev xwm yield atomic hydrogen li nruab nrab. Atomic hydrogen yog absorbed rau hauv titanium lattice es tsis recombining li H₂ roj. Thaum nyob rau hauv lub titanium, hydrogen diffuses rau thaj tsam ntawm tensile kev nyuaj siab (feem ntau yog lub sab nrauv thaum lub sij hawm kub cycling). Titanium hydride (TiH2) nag lossis daus tshwm sim thaum lub zos hydrogen concentration tshaj li ntawm 150 feem ntawm ib lab los ntawm qhov hnyav (150 ppmw). Cov hydride platelets yog nkig, thiab ua rau lub ntim nthuav dav ntawm ib ncig ntawm 17%, tsim kev ntxhov siab sab hauv uas ua rau ua rau tawg. Qhov tawg yog sai thiab hnyav, nrog me ntsis ceeb toom.

Quantifying cov nyhuv ntawm phab ntsa thickness ntawm hydride tawg tsis kam
Phab ntsa tuab (mm) Lub Sijhawm kom ua tiav qhov tseem ceeb H concentration (150 ppmw) ntawm qhov chaw (hli) Midwall Critical H Concentration (ppm w) Thaum Nto Mus txog 150 ppmw Lub Sijhawm dhau los ntawm -Wall Hydride Cracking (hli) Lub neej txheeb ze 1.0 3 120 4-5 1.0x 1.2 4 100 6-7 1.5x {{5}x 1.5 6 80 9-11 2.2
Ib phab ntsa 2.0 hli muab yuav luag 4 npaug ntawm lub neej ntawm phab ntsa 1.0 hli hauv tib txoj kev kho peroxide. Nyob rau hauv cov phab ntsa tuab, cov hydrogen yuav siv sij hawm ntev dua rau diffuse mus rau nruab nrab phab ntsa kom ua tiav qhov tseem ceeb concentration thiab ib zaug hydride tsim pib lub phab ntsa tuab kuj muaj ntau yam kev ruaj ntseg.

Ib Daim Ntawv Qhia Raws li Scenario rau Peroxide Service Phab Ntsa Thickness Xaiv
Qhov kub thiab txias ntawm PeroxideRate ntawm H2O2 DecompositionRecommended Phab ntsa Thickness Cia siab rau lub neej tsis ua hauj lwm hom
1-5% H₂O₂, 40℃(bleaching, tsawg txaus ntshai) 1.5 hli <5-8 xyoo Uniform corrosion (non-hydride)
5–15% H₂O₂, 50℃(moderate txaus ntshai) Nruab nrab 1.5–2.0 mm 3–5 xyoo Hydride ntawm weld zones thawj 15–30% H₂O₂, 60℃(muaj kev pheej hmoo siab) Siab 2.0–2.5 mm 1.5–3 xyoo Cracking 1.5–3 xyoos > cracks {14%) H₂O₂,> 60℃Siab heev Tsis pom zoo<1 yearUse Tantalum Equipment or PTFE Lined
Kev sib cuam tshuam (batch txheej txheem) qis qis 1.5 hli 2-4 xyoos Txais tauHydride synergistic + thermal cycling
H2O2 (siab purity, phosphate stabilized) Stabilizer txiav 1.5 hli 4-6 xyoo Stabilizers txo kev tawg thiab hydrogen nqus
Peroxide + chloride (qhov phem tshaj plaws] Synergistic Yam tsawg kawg nkaus 2.5 hli 1-2 xyoos Ua ke chloride pitting + hydride cracking
Engineering Mitigations rau Peroxide Service
Rau kev pab cuam peroxide nrog tuab -walled titanium, ntau cov kauj ruam ntxiv txuas ntxiv mus. Qhov zoo tshaj plaws yog kom txias rau saum npoo ntawm titanium. Tus nqi ntawm hydrogen absorption yog txo los ntawm ib ncig ntawm 40 mus rau 50 feem pua ​​​​rau txhua 10℃txo qis hauv sheath kub. Khiav ntawm 50℃es tsis txhob 70℃nce lub neej 3-4 zaug. Lwm txoj hauv kev yog ntxiv peroxide stabilizers (sodium stannate, sodium pyrophosphate lossis phosphonic acids) rau cov tshuaj. Stabilizers tiv thaiv cov catalytic tawg ntawm H2O2 ntawm qhov chaw ntawm titanium, txo cov evolution ntawm oxygen thiab nqus ntawm hydrogen. Hydrogen uptake tus nqi los ntawm stabilized peroxide daws yog 70-90% qis dua los ntawm unstabilized daws. Ib qho kev ntsuas thib peb yog txhawm rau txhawm rau lub tshuab cua sov titanium ib ntus. Lub tshuab cua sov yog rhuab mus rau 400℃hauv lub tshuab nqus tsev rau 4 teev. Qhov no tsav tawm absorbed hydrogen thiab ductility rov qab. Koj tuaj yeem ua qhov no ib xyoos ib zaug, thiab rov pib dua cov hydrogen concentration kom ze rau xoom.

Kev xaus: 2.0 hli phab ntsa muab 4x Lub Neej v. 1.0 hli hauv Peroxide Service
Lub phab ntsa tuab (2.0 hli) titanium muaj kev tiv thaiv zoo tshaj plaws tiv thaiv peroxide-vim tawg tawg piv rau cov phab ntsa nyias (1.0 hli) vim tias hydrogen yuav tsum tau siv sijhawm ntev dua los cuam tshuam los ntawm ntu tuab thiab ua kom muaj qhov tseem ceeb ntawm lub midwall. 1.0 hli phab ntsa tawg hauv 4-5 hli los ntawm hydride embrittlement nyob rau hauv 10-15% H2O2 ntawm 60 degree, whereas phab ntsa 2.0 hli kav 15-20 lub hlis-ib 4 × lub neej txuas ntxiv. Titanium tsis pom zoo rau ntau dua peroxide ntau dua (tshaj 30%) thiab kub (siab dua 70 degree) tsis hais txog ntawm phab ntsa tuab. Thaum qhia txog lub tshuab cua sov titanium rau ib qho kev pab cuam uas muaj peroxide, qhov peroxide concentration, kub, muaj cov stabilizers, thiab xav kom muaj pes tsawg teev ntawm kev ua haujlwm ib hnub twg yuav tsum tau muab rau tus neeg muag khoom los pab xaiv cov phab ntsa tsim nyog uas sib npaug tus nqi piv rau qhov kwv yees hydride tawg lub neej.