Rau Titanium Tshav Kub Kub Ua Haujlwm hauv 50% Potassium Carbonate Solution ntawm 110 degree, Yuav Ua Li Cas Cov Qib Oxygen Dissolved (0.5 ppm vs . 5 ppm) Hloov qhov ruaj khov ntawm Titanate Passivation Txheej?
Tso lus
Ib txheej tiv thaiv potassium titanate (K₂TiO₃) txheej yog tsim rau ntawm titanium nto hauv 50% potassium carbonate (K₂CO₃) ntawm 110 degree. Kev tsim titanate yog qhov tseem ceeb nyob ntawm cov pa oxygen (DO). Thaum qis DO (0.5 ppm) titanate txheej yog nyias (0.1-0.5 µm) thiab ntxeem tau thiab muab kev tiv thaiv tsis zoo. Thaum siab DO (5 ppm) cov txheej yog tuab (1-3 teev tsaus ntuj) thiab ntom ntom, txo qhov corrosion ntawm 5-10 zaug. titanate txheej yog tsim los ntawm cov tshuaj tiv thaiv TiO 2 + K 2 O → K 2 TiO 3 qhov twg K 2 O yog tsim los ntawm decomposition ntawm K 2 CO 3 .
Lub Mechanism ntawm Cov nyhuv ntawm Dissolved Oxygen ntawm Tsim Titanate Txheej
Cov pa oxygen yog qhov tseem ceeb los ua kom lub ntsej muag titanium nyob rau hauv qhov mob uas TiO_2 tuaj yeem loj hlob. TiO2 reacts nyob rau hauv muaj K2CO3 thiab tsim K2TiO3. Nrog rau qhov tsis muaj oxygen, TiO2 txheej yog nyias thiab muaj qhov tsis xws luag thiab K2TiO3 txheej tsim tau zoo sib xws. Thaum qis DO cov txheej muaj cov kab nrib pleb thiab qhov pores uas tso cai txuas ntxiv corrosion. Thaum siab DO, txheej txheej nce sib npaug thiab dhau los ua kev tiv thaiv. Nyob rau hauv lub xeev khov kho tus nqi corrosion yog txiav txim los ntawm cov pa oxygen los ntawm titanate txheej.
Quantitative Titanate Layer Properties raws li kev ua haujlwm ntawm cov pa oxygen
110℃hauv 50% K 2 CO 3 rau 1,000 teev tau ua pov thawj hauv qab no hauv kev tswj xyuas qib 2 titanium. Ntawm 0 ppm DO (deaerated) titanate txheej thickness yog 0.05-0.1 µm, tus nqi corrosion ntawm 0.15-0.30 mm / xyoo thiab tsaus nti nto. Ntawm 0.5 ppm DO, lub thickness yog 0.1-0.3 µm, tus nqi corrosion yog 0.08-0.15 mm / xyoo thiab saum npoo yog grey nrog me ntsis porosity. Thickness yog 0.5-1.0 µm. Corrosion tus nqi yog 0.03-0.08 hli ib xyoo. Nto yog lub teeb grey nrog 2 ppm DO. Ntawm 5 ppm DO, lub thickness yog 1.0-2.0 µm, corrosion tus nqi yog 0.01-0.03 hli / xyoo, thiab qhov saum npoo yog ci thiab tiv thaiv. Ntawm 10 ppm DO lub thickness yog 2.0-3.0 µm, tus nqi corrosion yog 0.005-0.015 hli hauv ib xyoos, thiab qhov saum npoo yog ci thiab ruaj khov.
Kev cuam tshuam ntawm qhov kub thiab txias ntawm kev xav tau ntawm cov pa oxygen
Nrog rau qhov kub thiab txias, qhov tsawg kawg nkaus DO yuav tsum tau kom ruaj khov passivation nce. Qhov tsawg kawg nkaus DO ntawm 80℃rau ruaj khov passivation txheej (corrosion tus nqi<0.02 mm per year) is 1 ppm. The minimum is 2ppm at 100°C. At 110°C the minimum is 3ppm. The minimum is at 120 °C (4 ppm). 5 ppm, 130°C. The DO for a safety margin should be 2–3 times the minimum.
Phau Ntawv Qhia Txog Kev Tswj Xyuas Cov Qib Oxygen hauv Potassium Carbonate Heaters
Cov lus pom zoo rau cov qib oxygen yaj hauv 50% K2CO3 ntawm 110℃rau Qib 2 thiab Qib 7 titanium rhaub tau muab rau hauv cov lus hauv qab no.
Measured DO (ppm) Stability of Titanate LayerExpected corrosion rate (mm per annum) Recommended Action: 5 Zoo heev 0.005 txog 0.015None 3-5Good 0.01–0.03 Saib xyuas txhua lub lim tiam 2-3 Marginal 0.03-0.015 Zoo heev 0.005-0.015Sparge air .
0.5 - 1 Tsis ruaj khov 0.15 - 0.30 Rov tsim dua; ntxiv oxidizer<0.5 Very unstable >0.30 Tsis tau
Engineering Beyond DO
Qib Titanium cuam tshuam qhov tsim nyog DO. Qib 7 (palladium stabilized) tsim cov txheej txheem titanate ruaj khov ntawm qis DO theem (1-2 ppm ntawm 110C) vim palladium catalyzed oxygen txo. Qib 12 yog rau kev txhim kho nruab nrab. Phab ntsa thickness muab kev tiv thaiv corrosion; 0.03mm / xyoo corrosion ntawm 2.0mm phab ntsa kav rau 60 xyoo. K2CO3 concentration cuam tshuam rau passivation thiab qis dua DO yog pom ntawm 40% K2CO3. Yuav tsum tau nce 1-2 ppm vim muaj cov chlorides hauv K 2 CO 3 kua (los ntawm impurities).
Ua ib qho kev qhia tshwj xeeb
For titanium heat rod in 50% K₂CO₃ at 110°C, ensure dissolved oxygen >5 ppm los ntawm huab cua sparging lossis oxygen txhaj. Ntxiv DO sojntsuam nrog lub tswb teeb ntawm 4 ppm thiab cuam tshuam ntawm 3 ppm. Rau cov tshuab uas twb muaj lawm nrog DO <3 ppm, nruab ib lub sparger los yog nce tus nqi aeration . Yog tias tsis muaj aeration, dilute K2CO3 mus rau 40% lossis qis dua qhov kub ntawm 100 degree. Tus kws tshaj lij tswj xyuas cov pa oxygen siab tshaj 5 ppm los txhawb kev ruaj khov, tiv thaiv cov poov tshuaj titanate txheej thiab txo qis corrosion.
