Rau Titanium Tshav Kub Kub Siv los Melt Paraffin Wax ntawm 80℃nrog Lub Sijhawm Tshaj Tawm mus rau 120 degree, Lub Sijhawm Uas Kub Kub Kub Kub Tseem Ceeb yog dab tsi (teev) Ua ntej cov quav ciab degrades rau Carboxylic Acids Attack Titanium?

Paraffin wax yog yaj ntawm 80℃rau ntau yam kev lag luam xws li tswm ciab ntau lawm, peev casting thiab coatings. Titanium tshav kub rods muaj feem xyuam rau cov kev pab no ntawm ib txwm ua hauj lwm kub. Qee lub sij hawm overheating mus rau 120 C tshwm sim vim tsis ua hauj lwm ntawm lub ntsuas sov los yog cov cua kub tsis zoo uas ua rau thermal deterioration ntawm paraffin wax. Qhov no degradation ua rau cov carboxylic acids, xws li acetic, formic, thiab stearic acids, vim oxidation thiab tawg txheej txheem. Cov kua qaub no tawm tsam cov titanium passive zaj duab xis thiab ua rau pitting thiab uniform corrosion. Lub sijhawm tseem ceeb tshaj plaws ntawm cov cua sov yog 100 teev ntawm 120℃ua ntej cov kua qaub concentration ua nruj. Cov kua qaub concentration yog siab tshaj 500 ppm thiab titanium corrosion tus nqi nce los ntawm qis dua 0.01 hli ib xyoo mus rau 0.1-0.3 hli ib xyoo yog tias qhov pib tshaj.

Lub mechanism ntawm paraffin decomposition thiab acid tsim nyob rau hauv high kub

Paraffin wax yog ruaj khov ntawm 80℃thiab tsis degrade loj. Ntawm 120℃muaj thermal oxidation: paraffin hydrocarbons (C20-C40) hnov ​​​​mob nrog oxygen yaj hauv nws nrog tsim cov cawv, aldehydes thiab thaum kawg carboxylic acids. Cov tshuaj tiv thaiv tshwm sim los ntawm cov txheej txheem dawb radical. Cov kua qaub uas tshwm sim yog corrosive rau titanium txij li thaum lawv ua ke titanium ions thiab ua kom puas cov yeeb yaj kiab passive. Kev sib raug zoo ntawm Arrhenius qhia tau hais tias tus nqi deterioration yog ze li ob npaug rau txhua txhua 10℃nce hauv qhov kub siab tshaj 100 degree. Thaum cov kua qaub tsim tawm lawv nyob hauv cov quav ciab thiab tseem yuav ua rau cov titanium ntog txawm tias qhov kub thiab txias rov qab mus rau 80 degree.

Quantitative Acid Tsim thiab Corrosion Rate Versus Overheating Time

Kev tswj xyuas nrog paraffin wax (melting point 55 degree, roj cov ntsiab lus<1%) at 120°C have indicated the following acid concentrations and Grade 2 titanium corrosion rates. The TAN is below 0.1 mg KOH/g, the titanium corrosion rate is below 0.01 mm per year and the surface is bright at 0 hours of the entire overheating at 120°C (typical operation at 80°C only). After 25 h overheating, the TAN is 0.3-0.6 mg KOH/g, the corrosion rate is 0.01-0.03 mm/yr and little etching is observed on the surface. At 50 h, TAN increases to 0.6–1.2 mg KOH/g, the corrosion rate increases to 0.03–0.08 mm/year and widespread etching may be observed. At 100 hours (critical threshold), the TAN is 1.2-2.5 mg KOH/g , corrosion rate is 0.08-0.15 mm per year and pitting initiates with a pit density of 5-20 pits per cm2 . After 200 h, the TAN is 2.5-5.0 mg KOH/g. The corrosion rate is 0.15-0.30 mm per year and pitting is serious with a pit depth of 0.1-0.3 mm. Corrosion rate >0.3 mm/yr and perforation of 1.2 mm wall at 500 hrs in 2000–4000 hrs. TAN >5 mg KOH/g.

Kev cuam tshuam ntawm wax formulation thiab oxygen muaj nyob rau ntawm tus nqi ntawm acid tsim

Degradation tus nqi yog nyob ntawm seb muaj pes tsawg leeg thiab oxygen muaj. Paraffin wax nrog cov roj ntau dua degrades sai dua . 60 teev mus rau 1.0 mg KOH/g TAN ntawm 120C rau 2% roj cov ntsiab lus vs . 100 teev rau qis- roj ciab. Lub branching molecular qauv ntawm microcrystalline wax ua rau nws qeeb qeeb rau decompose tshaj paraffin wax. Lub sijhawm kub kub tseem ceeb tuaj yeem txuas ntxiv mus rau 200 teev los ntawm cov dawb radical{10}}scavening kev ua ntawm antioxidants xws li butylated hydroxytoluene (BHT) ntawm 500 ppm. Nitrogen daim pam tshem tawm cov pa oxygen yuav tiv thaiv cov kua qaub tag nrho tab sis feem ntau ua tsis tau zoo hauv cov tso tsheb hlau luam yaj. Kev rov ua kom sov dua yog qhov phem tshaj qhov kub dhau mus tas li vim tias thaum lub tank qhib, cov pa oxygen tshiab tau qhia.

Cov lus qhia tseem ceeb ntawm kev ntsuas kub dhau lub sijhawm thiab kev txo qis

Cov lus hauv qab no qhia txog lub sijhawm tseem ceeb ntawm cov cua sov ntawm ntau qhov kub thiab txias rau paraffin wax, thiab pom zoo ntsuas rau Qib 2 titanium rhaub.

Overheating Temperature (degree) Lub Sijhawm Tseem Ceeb Tseem Ceeb rau 1.0 mg KOH / g TAN (teev) Tshaj - cua sov ntawm 80 degree, ua rau corrosion tus nqi (mm / xyoo) Pom Zoo Ua Haujlwm
100 500 0.02-0.05 Txais tau; tshawb xyuas txhua xyoo. 110 200 0.03-0.06 Tau; xyuas peb lub hlis twg. 120 100 0.08-0.15 Hloov cov quav ciab yog tias dhau lawm. 130 50 0.10-0.20 Nruab kev tiv thaiv overheat. 140 25 0.15-0.30Ntxiv cov tshuaj tiv thaiv antioxidant; Qib 7 Titanium 150 10 0.20–0.40 Rov tsim lub rhaub nrog kub txwv Engineering Tshaj Tawm Tshaj Tawm Tshaj Tawm Lub Sij Hawm

Kev tiv thaiv rau acid corrosion yog heev cuam tshuam los ntawm qib ntawm titanium. Tus nqi corrosion nyob rau hauv acidic wax yog qis dua los ntawm qhov zoo ntawm 2-3 rau qib 7 (palladium stabilized) thiab lub sij hawm tseem ceeb tshaj qhov kub yog nce mus rau 250 teev ntawm 120 degree. Phab ntsa tuab muab kev tiv thaiv corrosion: 2.0 hli phab ntsa corroded 0.15 hli ib xyoo los ntawm deteriorated ciab kav rau 13 xyoo. Yog tias TAN ntau dua 1.5 mg KOH / g ces cov quav yuav tsum tau hloov. Qhov sib ntxiv ntawm 0.1% sodium carbonate rau cov quav ciab neutralizes acids thiab zam kev ua phem ntawm titanium, tab sis tuaj yeem ua rau tsis zoo rau cov quav ciab. Tsis muaj overheating. Nws muaj qhov ntsuas kub thiab ceeb toom ntawm 100℃thiab lub tshuab hluav taws xob hloov tawm ntawm 110 degree.

Ua kom paub meej Specification

- titanium tshav kub pas nrig melting paraffin wax ntawm 80℃C nrog lub sij hawm overheating mus rau 120℃C. Tag nrho cov overheating lub sij hawm yuav tsum tsis pub tshaj 100 teev nyob rau hauv lub neej ntawm lub rhaub. Nruab ib lub ntsuas kub nrog cov ntaub ntawv kaw kom kaw tag nrho lub sijhawm dhau 100 degree. Yog tias tag nrho cov sij hawm tshaj 100 teev, hloov cov nqi siv quav ciab thiab xyuas cov cua kub rau pitting. Rau cov ntawv thov uas muaj cua sov tsim- ntau zaus lossis tsis tuaj yeem zam, qhia Qib 7 titanium thiab ntxiv 500 ppm BHT antioxidant rau cov quav ciab. Kev Ua Haujlwm: Ntsuas tag nrho cov kua qaub ntawm cov quav ciab txhua 6 lub hlis. Hloov cov quav ciab yog tias tag nrho cov kua qaub nce mus txog 1.5 mg KOH / g. Tus kws tshaj lij ua kom tag nrho lub sijhawm ntawm kev kub dhau qis dua qhov txwv tsis pub tshaj 100 teev, yog li zam kom tsis txhob muaj cov kab mob paraffin thiab cov kua qaub tom qab ntawm cov cua sov titanium.