Paraffin wax yog rhuab mus rau 80℃rau melting nyob rau hauv ntau yam kev lag luam xws li tswm ciab, peev casting, thiab coatings. Titanium tshav kub rods yog haum rau cov kev pab no ntawm ib txwm ua hauj lwm kub. Txawm li cas los xij, qee zaus overheating mus rau 120 degree, uas tuaj yeem tshwm sim vim qhov ntsuas kub tsis ua haujlwm lossis hloov pauv tsis zoo, ua rau thermal degradation ntawm paraffin wax. Cov degradation tsim cov carboxylic acids, feem ntau acetic, formic, thiab stearic acids, los ntawm oxidation thiab cracking tshua. Cov kua qaub no tawm tsam cov titanium passive zaj duab xis, ua rau pitting thiab uniform corrosion. Lub sij hawm tseem ceeb tshaj qhov kub kub ua ntej acid concentration nce mus txog 100 teev ntawm 120 degree. Tshaj li qhov pib no, cov kua qaub ntau tshaj 500 ppm, ua rau titanium corrosion tus nqi nce los ntawm qis dua 0.01 hli ib xyoo mus rau 0.1-0.3 hli hauv ib xyoos.

Lub Mechanism ntawm Paraffin Degradation thiab Acid tsim nyob rau hauv siab kub

Ntawm 80 degree, paraffin wax yog ruaj khov thiab tsis degrade loj. Thaum 120 degree, thermal oxidation tshwm sim: paraffin hydrocarbons (C₂₀–C₄₀) hnov ​​​​mob nrog oxygen yaj los ua cawv, aldehydes, thiab thaum kawg carboxylic acids. Cov tshuaj tiv thaiv ua raws li cov txheej txheem dawb radical. Cov kua qaub uas tsim tawm yog corrosive rau titanium, vim lawv tuaj yeem ua rau cov titanium ions nyuaj thiab ua rau cov yeeb yaj kiab tsis muaj zog. Tus nqi degradation ua raws li kev sib raug zoo ntawm Arrhenius, kwv yees li ob npaug rau txhua 10℃nce siab tshaj 100 degree. Thaum cov kua qaub raug tsim, lawv nyob hauv cov quav ciab thiab txuas ntxiv mus tua cov titanium nto txawm tias qhov kub thiab txias rov qab mus rau 80 degree.

Quantitative Acid Tsim thiab Corrosion Rate raws li kev ua haujlwm ntawm lub sijhawm kub dhau

Kev tswj xyuas ntawm paraffin wax (melting point 55 degree, roj cov ntsiab lus<1%) at 120°C has established the following acid concentrations and Grade 2 titanium corrosion rates. At 0 hours of cumulative overheating at 120°C (normal operation at 80°C only), the total acid number (TAN) is below 0.1 mg KOH/g, the titanium corrosion rate is below 0.01 mm per year, and the surface remains bright. At 25 hours of overheating, the TAN reaches 0.3–0.6 mg KOH/g, the corrosion rate is 0.01–0.03 mm per year, and light etching appears on the surface. At 50 hours, the TAN increases to 0.6–1.2 mg KOH/g, the corrosion rate rises to 0.03–0.08 mm per year, and general etching is visible. At 100 hours, the critical threshold, the TAN reaches 1.2–2.5 mg KOH/g, the corrosion rate increases to 0.08–0.15 mm per year, and pitting initiates with a pit density of 5–20 pits per cm². At 200 hours, the TAN is 2.5–5.0 mg KOH/g, the corrosion rate reaches 0.15–0.30 mm per year, and pitting becomes severe with a pit depth of 0.1–0.3 mm. At 500 hours, the TAN exceeds 5 mg KOH/g, the corrosion rate exceeds 0.3 mm per year, and perforation of a 1.2 mm wall occurs within 2,000–4,000 hours.

Kev cuam tshuam ntawm Wax Composition thiab Oxygen Availability ntawm Acid Formation Rate

Tus nqi degradation nyob ntawm qhov muaj pes tsawg leeg thiab cov pa oxygen. Paraffin wax nrog cov roj ntau dua degrades sai dua; ntawm 2% roj cov ntsiab lus, lub sij hawm mus txog 1.0 mg KOH / g TAN yog 60 teev ntawm 120℃piv rau 100 teev rau qis - roj ciab. Microcrystalline wax degrades qeeb dua li paraffin wax vim nws cov qauv molecular branched. Lub xub ntiag ntawm cov tshuaj antioxidants xws li butylated hydroxytoluene (BHT) ntawm 500 ppm txuas ntxiv lub sij hawm tseem ceeb tshaj plaws rau 200 teev los ntawm kev tshem tawm cov dawb radicals. Nitrogen blanketing kom tsis suav oxygen tiv thaiv cov kua qaub tsim tag nrho, tab sis feem ntau ua tsis tau zoo hauv cov tso tsheb hlau luam yaj. Kev rov ua kom sov ntau dua ua rau muaj kev puas tsuaj ntau dua li kev kub ntxhov tas mus li vim tias cov pa tshiab tau qhia txhua zaus lub tank qhib.

Lub Sijhawm Tshaj Tawm Tshaj Tawm Tseem Ceeb thiab Txo Cov Lus Qhia

Cov lus hauv qab no muab lub sijhawm tseem ceeb tshaj qhov kub ntawm ntau qhov kub thiab txias rau paraffin wax, nrog rau kev pom zoo ua rau Qib 2 titanium rhaub.

Engineering Tshaj Tawm Tshaj Tawm Lub Sijhawm Tswjhwm

Qib titanium cuam tshuam rau acid corrosion kuj. Qib 7 (palladium-stabilized) muaj 2-3 zaug qis dua corrosion nyob rau hauv acidic ciab, ncua lub sij hawm overheating tseem ceeb rau 250 teev ntawm 120℃. Phab ntsa thickness muab kev tiv thaiv corrosion; ib lub 2.0 hli phab ntsa nrog 0.15 hli ib xyoo corrosion los ntawm degraded ciab ciaj sia 13 xyoo. Cov wax yuav tsum tau hloov thaum TAN tshaj 1.5 mg KOH / g. Ntxiv 0.1% sodium carbonate rau wax neutralizes acids thiab tiv thaiv titanium nres, tab sis yuav cuam tshuam rau cov khoom siv quav ciab. Lub ntsuas kub ntsuas nrog lub tswb ntsuas ntawm 100℃thiab lub tshuab hluav taws xob txiav-tawm ntawm 110℃tiv thaiv kev kub dhau.

Ua ib qho kev qhia tshwj xeeb

Rau titanium tshav kub pas nrig siv los yaj paraffin wax ntawm 80℃nrog qee zaus overheating rau 120 degree, txwv lub sij hawm overheating mus rau 100 teev dhau lub neej ntawm lub rhaub. Nruab ib lub ntsuas kub nrog cov ntaub ntawv logger los sau lub sijhawm sib sau siab tshaj 100 degree. Yog hais tias lub sij hawm cumulative tshaj 100 teev, hloov tus nqi siv quav ciab thiab tshuaj xyuas lub rhaub dej rau pitting. Rau cov ntawv thov uas overheating yog nquag lossis tsis tuaj yeem, qhia Qib 7 titanium thiab ntxiv 500 ppm ntawm BHT antioxidant rau cov quav ciab. Thaum lub sijhawm ua haujlwm, ntsuas tag nrho cov kua qaub ntawm cov quav ciab txhua 6 lub hlis; Yog tias nws siab tshaj 1.5 mg KOH / g, hloov cov quav ciab. Los ntawm kev tswj hwm lub sijhawm ua kom kub dhau hauv qab qhov tseem ceeb ntawm 100 teev, tus kws tshaj lij tiv thaiv paraffin degradation thiab ua rau acid nres ntawm titanium heaters.