Corrosion ntawm tooj liab thiab nws cov alloys: ua rau thiab kev daws teeb meem

2024 Tus sau: Howard Calhoun | [email protected]. Kawg hloov kho: 2023-12-17 10:28

tooj liab thiab tooj liab alloys muaj hluav taws xob thiab thermal conductivity, tuaj yeem ua tshuab, muaj kev tiv thaiv corrosion zoo, yog li lawv tau siv ntau hauv kev lag luam. Tab sis thaum nws nkag mus rau ib puag ncig, corrosion ntawm tooj liab thiab nws cov alloys tseem manifests nws tus kheej. Nws yog dab tsi thiab yuav ua li cas tiv thaiv cov khoom los ntawm kev puas tsuaj, peb yuav xav txog hauv kab lus no.

YDab tsi yog corrosion

Qhov no yog qhov kev puas tsuaj ntawm cov hlau vim qhov raug rau ib puag ncig. Hauv cov tebchaws uas muaj kev lag luam zoo, kev puas tsuaj los ntawm corrosion yog 4-5% ntawm cov nyiaj tau los hauv lub tebchaws. Tsis tsuas yog hlau deteriorates, tab sis kuj mechanisms thiab qhov chaw ua los ntawm lawv, uas ua rau cov nqi siab heev. Corroded pipelines feem ntau xau cov tshuaj phem, ua rau av, dej thiab huab cua. Tag nrho cov no cuam tshuam rau tib neeg txoj kev noj qab haus huv. Corrosion ntawm tooj liab yog nws spontaneous kev puas tsuaj nyob rau hauv tus ntawm ib tug neeg lub ntsiab ntawm tib neeg ib puag ncig. Qhov ua rau kev puas tsuaj rau cov hlau tsis ruaj khovnws mus rau tus kheej cov khoom nyob rau hauv cov huab cua. Qhov kub thiab txias, qhov corrosion ntau dua.

Copper properties

tooj liab yog thawj cov hlau uas tib neeg pib siv. Nws yog xim golden, thiab nyob rau hauv cov huab cua nws yuav npog nrog ib tug oxide zaj duab xis thiab kis tau ib tug liab-daj xim, uas distinguishes nws los ntawm lwm yam hlau uas muaj ib tug grey tint. Nws yog yas heev, muaj thermal conductivity, yog suav tias yog ib tug zoo heev conductor, thib ob tsuas yog nyiaj. Nyob rau hauv tsis muaj zog hydrochloric acid, dej tshiab thiab dej hiav txwv, tooj liab corrosion yog negligible.

Nyob rau hauv qhov qhib huab cua, cov hlau oxidizes nrog tsim cov oxide zaj duab xis uas tiv thaiv cov hlau. Nyob rau tib lub sijhawm, nws darkens thiab ua xim av. Cov txheej uas npog tooj liab hu ua patina. Nws hloov nws cov xim los ntawm brownish mus rau ntsuab thiab txawm dub.

YElectrochemical corrosion

Qhov no yog hom kev puas tsuaj ntau tshaj plaws ntawm cov khoom hlau. Electrochemical corrosion rhuav tshem lub tshuab qhov chaw, ntau yam qauv nyob rau hauv av, dej, cua, lubricating thiab txias kua. Qhov no yog kev puas tsuaj rau saum npoo ntawm cov hlau nyob rau hauv lub zog ntawm cov hluav taws xob tam sim no, thaum, thaum lub sij hawm tshuaj tiv thaiv, electrons raug tso tawm thiab xa tawm ntawm cathodes mus rau anodes. Qhov no yog yooj yim los ntawm heterogeneous tshuaj qauv ntawm hlau. Thaum tooj liab hu rau hlau, galvanic cell tshwm nyob rau hauv cov electrolyte, qhov twg hlau los ua lub anode, thiab tooj liab ua lub cathode, vim hais tias hlau nyob rau hauv lub series ntawm voltages raws li lub sij hawm ntawm lub sij hawm yog nyob rau sab laug ntawm tooj liab thiab yog active.

Nyob hauv ib khub hlau nrog tooj liab, hlau corrosion tshwm sim sai dua tooj liab. Qhov no yog vim hais tias thaum hlau puas lawm, electrons los ntawm nws dhau mus rau tooj liab, uas tseem tiv thaiv kom txog thaum tag nrho cov txheej ntawm hlau puas tag. Cov cuab yeej no feem ntau siv los tiv thaiv qhov chaw thiab cov txheej txheem.

Kev cuam tshuam ntawm impurities ntawm deterioration ntawm hlau

Nws paub tias cov hlau ntshiab siv tau tsis muaj corrode. Tab sis nyob rau hauv kev xyaum, tag nrho cov ntaub ntawv muaj ib co ntawm impurities. Lawv cuam tshuam li cas rau kev nyab xeeb thaum ua haujlwm ntawm cov khoom? Xav tias muaj ib feem ua los ntawm ob hlau. Xav txog yuav ua li cas corrosion ntawm tooj liab nrog aluminium tshwm sim. Thaum raug huab cua, nws saum npoo yog npog nrog ib zaj duab xis nyias ntawm dej. Nws yuav tsum raug sau tseg tias dej decomposes rau hauv hydrogen ions thiab hydroxide ions, thiab carbon dioxide yaj hauv dej tsim carbonic acid. Nws hloov tawm hais tias tooj liab thiab txhuas, immersed nyob rau hauv ib tug tov, tsim ib tug galvanic cell. Ntxiv mus, txhuas yog lub anode, tooj liab yog cathode (txhuas yog nyob rau sab laug ntawm tooj liab nyob rau hauv voltage series).

Aluminium ions nkag mus rau hauv cov tshuaj, thiab cov hluav taws xob ntau dhau mus rau tooj liab, tso tawm hydrogen ions ze ntawm nws qhov chaw. Aluminium ions thiab hydroxide tones sib xyaw ua ke thiab tso nyiaj rau ntawm txhuas qhov chaw ua cov khoom dawb, ua rau corrosion.

Corrosion ntawm tooj liab nyob rau hauv acid ib puag ncig

tooj liab pom zoo tiv thaiv corrosion nyob rau hauv txhua yam kev mob vim nws tsis tshua hloov hydrogen vim nws yog nyob rau hauv electrochemical voltage seriessawv ze ntawm cov hlau muaj nuj nqis. Kev siv tooj liab thoob plaws hauv kev lag luam tshuaj yog vim nws tsis kam mus rau ntau qhov kev tawm tsam organic:

• nitrates thiab sulfides;
• phenolic resins;
• acetic, lactic, citric thiab oxalic acid;
• poov tshuaj thiab sodium hydroxides;
• tsis muaj zog daws ntawm sulfuric thiab hydrochloric acid.

Ntawm qhov tod tes, muaj kev puas tsuaj loj ntawm tooj liab hauv:

• acid daws ntawm chromium ntsev;
• mineral acids - perchloric thiab nitric, thiab corrosion nce nrog nce concentration.
• concentrated sulfuric acid, nce nrog nce kub;
• ammonium hydroxide;
• oxidizing ntsev.

Metal Preservation Methods

Xyaum txhua cov hlau hauv qhov nruab nrab gaseous lossis kua nruab nrab raug puas tsuaj. Txoj hauv kev tseem ceeb los tiv thaiv tooj liab los ntawm kev xeb yog siv cov txheej txheem tiv thaiv rau saum npoo ntawm cov khoom, suav nrog:

• Metal - txheej ntawm cov hlau yog siv rau cov khoom siv tooj liab, uas tiv taus corrosion ntau dua. Piv txwv li, tooj dag, zinc, chromium thiab nickel yog siv raws li nws. Hauv qhov no, kev sib cuag nrog ib puag ncig thiab oxidation yuav tshwm sim nrog cov hlau siv rau txheej. Yog tias cov txheej txheem tiv thaiv ib nrab puas, ces lub hauv paus hlau, tooj liab, raug rhuav tshem.
• Cov khoom tsis yog xim hlau yog cov txheej txheem inorganic uas muaj vitreous loj, cement mortar, lossis organic - xim, kua roj vanish, bitumen.
• tshuajfilms - kev tiv thaiv yog tsim los ntawm ib tug tshuaj txoj kev, tsim cov tebchaw ntawm cov hlau nto uas ntseeg tau los tiv thaiv tooj liab los ntawm corrosion. Ua li no, oxide, phosphate zaj duab xis yog siv los yog nto ntawm cov alloys yog saturated nrog nitrogen, organic tshuaj, los yog kho nrog carbon, cov tebchaw uas ntseeg tau nws.

Ntxiv rau, ib qho kev sib xyaw ua ke yog nkag mus rau hauv cov khoom sib xyaw ntawm tooj liab alloys, uas txhim kho cov khoom tiv thaiv corrosion, los yog cov muaj pes tsawg leeg ntawm ib puag ncig hloov pauv, tshem tawm impurities los ntawm nws thiab qhia cov inhibitors uas ua rau cov tshuaj tiv thaiv qeeb.

Zaj lus

tooj liab tsis yog cov khoom siv tshuaj lom neeg, vim qhov no, nws txoj kev puas tsuaj qeeb heev hauv yuav luag txhua qhov chaw. Yog li ntawd, nws yog dav siv nyob rau hauv ntau sectors ntawm lub teb chaws kev khwv nyiaj txiag. Piv txwv li, hlau yog ruaj khov heev hauv cov dej huv huv thiab dej hiav txwv. Tab sis raws li cov ntsiab lus oxygen nce los yog cov dej ntws nrawm, qhov kev tiv thaiv corrosion txo.