{"id":3316,"date":"2026-05-14T03:36:45","date_gmt":"2026-05-14T03:36:45","guid":{"rendered":"https:\/\/sprocket-chain.net\/?p=3316"},"modified":"2026-05-14T03:36:45","modified_gmt":"2026-05-14T03:36:45","slug":"nickel-plated-and-zinc-plated-roller-chain-what-surface-treatments-actually-protect-against","status":"publish","type":"post","link":"https:\/\/sprocket-chain.net\/cs\/nickel-plated-and-zinc-plated-roller-chain-what-surface-treatments-actually-protect-against\/","title":{"rendered":"Niklovan\u00e9 a pozinkovan\u00e9 v\u00e1le\u010dkov\u00e9 \u0159et\u011bzy: Proti \u010demu povrchov\u00e9 \u00fapravy skute\u010dn\u011b chr\u00e1n\u00ed"},"content":{"rendered":"
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Bezproudov\u00fd nikl<\/div>\n
Chroman zine\u010dnat\u00fd<\/div>\n
vs. nerezov\u00e1 ocel<\/div>\n<\/div>\n

Niklovan\u00e9 a pozinkovan\u00e9 v\u00e1le\u010dkov\u00e9 \u0159et\u011bzy: Proti \u010demu povrchov\u00e9 \u00fapravy skute\u010dn\u011b chr\u00e1n\u00ed<\/h1>\n

\u0158et\u011bz s pokoven\u00edm stoj\u00ed o 20\u201340% v\u00edce ne\u017e standardn\u00ed \u0159et\u011bz z uhl\u00edkov\u00e9 oceli a poskytuje skute\u010dnou ochranu proti korozi \u2013 v prost\u0159ed\u00edch, pro kter\u00e1 byl pokoven\u00ed navr\u017eeno. V prost\u0159ed\u00edch, kter\u00e1 tyto limity p\u0159ekra\u010duj\u00ed, se stejn\u00fd \u0159et\u011bz selh\u00e1v\u00e1 rychleji ne\u017e \u0159et\u011bz z nepokoven\u00e9 uhl\u00edkov\u00e9 oceli, proto\u017ee pokoven\u00ed zakr\u00fdv\u00e1 korozi, dokud nedojde k po\u0161kozen\u00ed konstrukce.<\/p>\n

Ov\u011b\u0159te si spr\u00e1vnou specifikaci protikorozn\u00ed ochrany pro va\u0161i aplikaci<\/a><\/p>\n<\/div>\n<\/div>\n

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Cukr\u00e1\u0159sk\u00fd z\u00e1vod v provincii \u010cchung\u010dchong v roce 2021 modernizoval sv\u00e9 exponovan\u00e9 pohony dopravn\u00edk\u016f ze standardn\u00edho \u0159et\u011bzu z uhl\u00edkov\u00e9 oceli na poniklovan\u00fd \u0159et\u011bz \u2013 spr\u00e1vn\u00e9 rozhodnut\u00ed pro prost\u0159ed\u00ed s ob\u010dasnou kondenzac\u00ed cukrov\u00e9ho prachu a periodickou okoln\u00ed vlhkost\u00ed. Do roku 2023 se na t\u0159ech z osmi modernizovan\u00fdch pozic \u0159et\u011bzu pod niklov\u00fdm pokoven\u00edm na \u010dl\u00e1nkov\u00fdch desk\u00e1ch objevily \u010dervenohn\u011bd\u00e9 skvrny. \u00dadr\u017eb\u00e1\u0159sk\u00fd t\u00fdm se zpo\u010d\u00e1tku domn\u00edval, \u017ee pokoven\u00ed \u201eselh\u00e1v\u00e1\u201c, a po\u017e\u00e1dal dodavatele o st\u00ed\u017enost na kvalitu. Vy\u0161et\u0159ov\u00e1n\u00ed uk\u00e1zalo, \u017ee pokoven\u00ed je neporu\u0161en\u00e9 \u2013 ale \u0159et\u011bz byl veden kolem pasteriza\u010dn\u00ed pece, kde se k vyj\u00edm\u00e1n\u00ed v\u00fdrobk\u016f z formy pou\u017e\u00edvaly parn\u00ed trysky. Lokalizovan\u00e9 vystaven\u00ed p\u00e1\u0159e vytv\u00e1\u0159elo na \u0159et\u011bzu kondenz\u00e1t p\u0159i teplot\u011b 60\u201370 \u00b0C, co\u017e urychlovalo korozi pod pokoven\u00edm v m\u00edst\u011b drobn\u00fdch vad v niklu. Pokoven\u00ed na zb\u00fdvaj\u00edc\u00edch p\u011bti pozic\u00edch \u2013 mimo parn\u00ed z\u00f3nu \u2013 po dvou letech nevykazovalo \u017e\u00e1dnou korozi. Specifikace nebyla chybn\u00e1; hranice pou\u017eit\u00ed nebyly p\u0159i specifikaci modernizace spr\u00e1vn\u011b mapov\u00e1ny.<\/p>\n

V\u00fdb\u011br pokoven\u00e9ho \u0159et\u011bzu vy\u017eaduje t\u0159i informace: p\u0159ed \u010d\u00edm pokoven\u00ed chr\u00e1n\u00ed, p\u0159ed \u010d\u00edm nechr\u00e1n\u00ed a kde se nach\u00e1z\u00ed p\u0159echodov\u00fd bod mezi t\u011bmito dv\u011bma podm\u00ednkami v dan\u00e9 aplikaci. Bez v\u0161ech t\u0159\u00ed \u00fadaj\u016f by v\u00fdb\u011br vedl bu\u010f k zbyte\u010dn\u00fdm n\u00e1klad\u016fm (specifikace nerezov\u00e9 oceli, kdy\u017e by nikl fungoval), nebo k p\u0159ed\u010dasn\u00e9mu selh\u00e1n\u00ed (specifikace niklu v prost\u0159ed\u00ed, kter\u00e9 vy\u017eaduje nerezovou ocel).<\/p>\n

\"v\u00e1le\u010dkov\u00fd<\/p>\n

Co vlastn\u011b d\u011bl\u00e1 pokovov\u00e1n\u00ed \u0159et\u011bz\u016f \u2013 a mechanismus jeho selh\u00e1n\u00ed<\/h2>\n
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\u0158et\u011bzov\u00e9 pokovov\u00e1n\u00ed funguje tak, \u017ee vytv\u00e1\u0159\u00ed fyzickou bari\u00e9ru mezi ocelov\u00fdm substr\u00e1tem a korozivn\u00edm prost\u0159ed\u00edm. Pokovovac\u00ed materi\u00e1l \u2013 nikl, zinek nebo kompozit zinku a chrom\u00e1tu \u2013 v c\u00edlov\u00e9m prost\u0159ed\u00ed nekoroduje, tak\u017ee ocel pod n\u00edm z\u016fst\u00e1v\u00e1 chr\u00e1n\u011bna. Tento bari\u00e9rov\u00fd mechanismus je vysoce \u00fa\u010dinn\u00fd, pokud je pokovov\u00e1n\u00ed kontinu\u00e1ln\u00ed a bez vad. Probl\u00e9m je v tom, \u017ee \u017e\u00e1dn\u00fd galvanicky nebo bezproudov\u011b pokovovan\u00fd \u0159et\u011bz nen\u00ed dokonale kontinu\u00e1ln\u00ed \u2013 proces pokovov\u00e1n\u00ed vytv\u00e1\u0159\u00ed na povrchu mikroskopickou p\u00f3rovitost, zejm\u00e9na na okraj\u00edch plechu, konc\u00edch \u010dep\u016f a v jak\u00e9koli mechanick\u00e9 kontaktn\u00ed z\u00f3n\u011b.<\/p>\n

V m\u00edstech s mal\u00fdmi d\u00edrkami a p\u00f3ry v pokoven\u00ed se korozivn\u00ed prost\u0159ed\u00ed dost\u00e1v\u00e1 p\u0159\u00edmo k ocelov\u00e9mu podkladu. Kdy\u017e k tomu dojde v prost\u0159ed\u00ed, kter\u00e9 je dostate\u010dn\u011b agresivn\u00ed, aby zp\u016fsobilo korozi oceli, koroze se \u0161\u00ed\u0159\u00ed later\u00e1ln\u011b pod povrchem pokoven\u00ed \u2013 tento proces se naz\u00fdv\u00e1 koroze pod pokoven\u00edm nebo nitkov\u00e1 koroze. Pokoven\u00ed se zven\u010d\u00ed jev\u00ed neporu\u0161en\u00e9, zat\u00edmco ocel pod n\u00edm aktivn\u011b koroduje. Toto je mechanismus, kter\u00fd zp\u016fsobuje, \u017ee pokoven\u00fd \u0159et\u011bz je v agresivn\u00edm prost\u0159ed\u00ed hor\u0161\u00ed ne\u017e nepokoven\u00e1 ocel \u2013 alespo\u0148 u nepokoven\u00e9 oceli je koroze viditeln\u00e1 a m\u011b\u0159iteln\u00e1, co\u017e umo\u017e\u0148uje v\u00fdm\u011bnu p\u0159ed struktur\u00e1ln\u00edm selh\u00e1n\u00edm.<\/p>\n<\/div>\n

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Sekvence selh\u00e1n\u00ed pokovov\u00e1n\u00ed<\/div>\n
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F\u00e1ze 1 \u2013 Neporu\u0161en\u00fd<\/div>\n
Pr\u016fb\u011b\u017en\u00e9 pokovov\u00e1n\u00ed. Bez koroze. Pln\u00e1 ochrana. Vizu\u00e1ln\u011b \u010dist\u00e9.<\/div>\n<\/div>\n
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F\u00e1ze 2 \u2013 Vstup d\u00edrkou<\/div>\n
Korozivn\u00ed m\u00e9dium se dost\u00e1v\u00e1 k podkladu v m\u00edstech s vadami. Za\u010d\u00edn\u00e1 koroze pod pokoven\u00edm. Vizu\u00e1ln\u011b \u2013 pouze m\u00edrn\u00e9 skvrny.<\/div>\n<\/div>\n
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F\u00e1ze 3 \u2013 Bo\u010dn\u00ed \u0161\u00ed\u0159en\u00ed<\/div>\n
Koroze se \u0161\u00ed\u0159\u00ed later\u00e1ln\u011b pod plech. Hloubka ocelov\u00e9 j\u00e1my se zv\u011bt\u0161uje. Vn\u011bj\u0161\u00ed vzhled: neporu\u0161en\u00fd se zm\u011bnou barvy na okraj\u00edch.<\/div>\n<\/div>\n
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F\u00e1ze 4 \u2013 Puch\u00fd\u0159e \/ selh\u00e1n\u00ed<\/div>\n
Puch\u00fd\u0159e a v\u00fdr\u016fstky na pokovov\u00e1n\u00ed. Ztr\u00e1ta struktur\u00e1ln\u00edho pr\u016f\u0159ezu v spojovac\u00edm plechu. Nyn\u00ed existuje riziko selh\u00e1n\u00ed. Viditeln\u00e9 pouze v t\u00e9to f\u00e1zi.<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
Protiintuitivn\u00ed: pokoven\u00fd \u0159et\u011bz v prost\u0159ed\u00ed, kter\u00e9 nezvl\u00e1dne, selh\u00e1v\u00e1 rychleji ne\u017e nepokoven\u00fd \u0159et\u011bz ve stejn\u00e9m prost\u0159ed\u00ed.<\/strong> Nepokoven\u00e1 uhl\u00edkov\u00e1 ocel viditeln\u011b koroduje \u2013 \u010derven\u00e1 rez na povrchu \u010dl\u00e1nk\u016f je m\u011b\u0159iteln\u00e1 a poskytuje spolehliv\u00fd indik\u00e1tor pro rozhodnut\u00ed o v\u00fdm\u011bn\u011b. Pokoven\u00fd \u0159et\u011bz v prost\u0159ed\u00ed mimo jeho ochrann\u00fd rozsah koroduje neviditeln\u011b pod pokoven\u00edm. \u00dadr\u017eb\u00e1\u0159sk\u00fd t\u00fdm, kter\u00fd by vym\u011bnil viditeln\u011b zreziv\u011bl\u00fd nepokoven\u00fd \u0159et\u011bz se ztr\u00e1tou profilu 15%, nezjist\u00ed stejnou ztr\u00e1tu profilu pod neporu\u0161en\u00fdm pokoven\u00edm. Koroze pod pokoven\u00edm nab\u00fdv\u00e1 struktur\u00e1ln\u00edho v\u00fdznamu d\u0159\u00edve, ne\u017e se objev\u00ed jak\u00fdkoli viditeln\u00fd indik\u00e1tor. Z tohoto d\u016fvodu je d\u016fle\u017eit\u011bj\u0161\u00ed shoda typu pokoven\u00ed se skute\u010dn\u00fdm korozn\u00edm prost\u0159ed\u00edm ne\u017e pouh\u00e9 \u201especifikov\u00e1n\u00ed pokoven\u00e9ho \u0159et\u011bzu\u201c.<\/div>\n

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Bezproudov\u00e9 niklov\u00e1n\u00ed vs. elektrolytick\u00e9 niklov\u00e1n\u00ed: Pro\u010d je proces d\u016fle\u017eit\u00fd pro \u0159et\u011bzec<\/h2>\n

Pro v\u00e1le\u010dkov\u00e9 \u0159et\u011bzy se pou\u017e\u00edvaj\u00ed dva odli\u0161n\u00e9 procesy niklov\u00e1n\u00ed: elektrolytick\u00e9 niklov\u00e1n\u00ed (konven\u010dn\u00ed galvanick\u00e9 pokovov\u00e1n\u00ed) a bezproudov\u00e9 niklov\u00e1n\u00ed (chemick\u00e9 nan\u00e1\u0161en\u00ed bez elektrick\u00e9ho proudu). Tyto procesy vytv\u00e1\u0159ej\u00ed povlaky s r\u016fzn\u00fdmi vlastnostmi, kter\u00e9 maj\u00ed v\u00fdznamn\u00fd vliv na v\u00fdkon \u0159et\u011bzu.<\/p>\n

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Elektrolytick\u00fd nikl<\/div>\n
Galvanick\u00e9 pokovov\u00e1n\u00ed \u00b7 proudov\u011b \u0159\u00edzen\u00e9 nan\u00e1\u0161en\u00ed<\/div>\n<\/div>\n
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