鍍鋅橋架的耐腐蝕性能源于其表面的鋅鍍層，核心通過兩種機制實現(xiàn)防腐：一是物理隔絕作用，鋅鍍層緊密覆蓋在鋼制橋架表面，形成一層連續(xù)的 “屏障”，阻止空氣中的氧氣、水分及腐蝕性介質(zhì)直接接觸鋼基材，從根源減少基材氧化生銹的可能；二是犧牲陽極保護作用，鋅的電極電位低于鐵（鋅的標準電極電位約 - 0.76V，鐵約 - 0.44V），當橋架表面出現(xiàn)劃痕、鋅層破損導致鋼基材暴露時，鋅會優(yōu)先于鐵發(fā)生氧化反應（即 “犧牲” 鋅自身），通過電子轉(zhuǎn)移抑制鐵的腐蝕，直至鋅層完全消耗。這種 “雙重保護” 讓鍍鋅橋架在多數(shù)常規(guī)環(huán)境中具備優(yōu)于普通鋼制橋架的耐腐能力。
The corrosion resistance of galvanized cable trays stems from the zinc coating on their surface, which achieves anti-corrosion through two core mechanisms: first, the physical isolation effect — the zinc coating tightly covers the surface of the steel cable tray, forming a continuous "barrier" that prevents oxygen, moisture, and corrosive media in the air from directly contacting the steel substrate, fundamentally reducing the possibility of oxidative rusting of the substrate; second, the sacrificial anode protection effect — the electrode potential of zinc is lower than that of iron (the standard electrode potential of zinc is about -0.76V, and that of iron is about -0.44V). When scratches appear on the tray surface or the zinc coating is damaged, exposing the steel substrate, zinc will undergo an oxidation reaction 優(yōu)先于 iron (i.e., "sacrificing" itself), and inhibit the corrosion of iron through electron transfer until the zinc coating is completely consumed. This "dual protection" enables galvanized cable trays to have better corrosion resistance than ordinary steel cable trays in most conventional environments.
鍍鋅橋架主要分為熱浸鍍鋅（Hot-Dip Galvanizing）和冷鍍鋅（Electro-Galvanizing，又稱電鍍鋅）兩種工藝，兩者的鋅層厚度、結(jié)合力及耐腐性能差異顯著，直接影響橋架的適用場景：
- 熱浸鍍鋅橋架：將鋼制橋架浸入熔融鋅液（溫度約 450℃）中，鋅液與鋼材發(fā)生冶金反應，形成厚度為 65-100μm 的鋅鐵合金層 + 純鋅層復合結(jié)構(gòu)。該鋅層結(jié)合力強（不易脫落）、厚度均勻，在中性或弱腐蝕性環(huán)境（如室內(nèi)干燥區(qū)域、普通戶外無鹽霧環(huán)境）中，使用壽命可達 15-20 年，甚至更久。例如，小區(qū)配電房、非沿海地區(qū)的戶外橋架多采用此工藝。
- 冷鍍鋅橋架：通過電解作用在鋼材表面沉積鋅層，鋅層厚度通常僅 10-30μm，且與基材結(jié)合力較弱，易因碰撞、摩擦脫落。其耐腐性能遠低于熱浸鍍鋅，僅適用于室內(nèi)干燥、無腐蝕性的輕度環(huán)境（如辦公樓吊頂內(nèi)），使用壽命通常為 3-5 年，若用于潮濕或半戶外環(huán)境，1-2 年內(nèi)便可能出現(xiàn)鋅層剝落、基材生銹。
Galvanized cable trays are mainly divided into two processes: hot-dip galvanizing and electro-galvanizing (also known as cold galvanizing). The two differ significantly in zinc coating thickness, adhesion, and corrosion resistance, which directly affect the applicable scenarios of the tray:
- Hot-dip galvanized cable trays: The steel cable tray is immersed in molten zinc liquid (temperature about 450℃), and a metallurgical reaction occurs between the zinc liquid and the steel, forming a composite structure of zinc-iron alloy layer + pure zinc layer with a thickness of 65-100μm. This zinc layer has strong adhesion (not easy to fall off) and uniform thickness. In neutral or weakly corrosive environments (such as indoor dry areas, ordinary outdoor environments without salt spray), its service life can reach 15-20 years or even longer. For example, hot-dip galvanized trays are mostly used in community power distribution rooms and outdoor cable trays in non-coastal areas.
- Electro-galvanized cable trays: A zinc layer is deposited on the steel surface through electrolysis. The zinc layer thickness is usually only 10-30μm, and its adhesion to the substrate is weak, so it is easy to fall off due to collision or friction. Its corrosion resistance is much lower than that of hot-dip galvanizing, and it is only suitable for mild indoor dry and non-corrosive environments (such as inside the ceiling of office buildings). Its service life is usually 3-5 years. If used in humid or semi-outdoor environments, the zinc layer may peel off and the substrate may rust within 1-2 years.
鍍鋅橋架的實際耐腐效果并非固定不變，受環(huán)境腐蝕性強度、鋅層完整性及安裝維護方式三大因素影響：
- 環(huán)境腐蝕性：在強腐蝕性環(huán)境（如海邊鹽霧區(qū)、化工車間、印染廠）中，高濃度的氯離子、酸堿氣體能快速侵蝕鋅層 —— 例如，海邊空氣中的氯離子會與鋅發(fā)生化學反應生成可溶性氯化鋅，導致鋅層 “溶解”，此時即使是熱浸鍍鋅橋架，使用壽命也可能縮短至 5-8 年；而在干燥、潔凈的室內(nèi)環(huán)境（如寫字樓機房），鋅層消耗緩慢，耐腐壽命可大幅延長。
- 鋅層完整性：若橋架在運輸、安裝過程中出現(xiàn)嚴重碰撞，導致鋅層大面積破損，鋼基材直接暴露，會加速局部腐蝕（即 “點蝕”），進而蔓延至整個橋架。此外，橋架焊縫處若未做額外補鋅處理（如冷噴鋅），也易成為腐蝕 “突破口”。
- 安裝維護：若橋架安裝在積水區(qū)域（如戶外低洼處），或長期堆積灰塵、油污且未定期清理，會形成 “局部腐蝕環(huán)境”—— 例如，油污吸附水分后會加速鋅層氧化，灰塵堆積則會阻礙鋅層與空氣的正常接觸，引發(fā) “縫隙腐蝕”。
The actual corrosion resistance effect of galvanized cable trays is not fixed, and is affected by three key factors: environmental corrosion intensity, zinc coating integrity, and installation and maintenance methods:
- Environmental corrosion: In highly corrosive environments (such as coastal salt spray areas, chemical workshops, printing and dyeing factories), high concentrations of chloride ions and acid-base gases can quickly erode the zinc coating. For example, chloride ions in coastal air will react chemically with zinc to form soluble zinc chloride, causing the zinc coating to "dissolve". Even hot-dip galvanized cable trays may have their service life shortened to 5-8 years in such environments; while in dry and clean indoor environments (such as office building computer rooms), the zinc coating is consumed slowly, and the corrosion-resistant service life can be significantly extended.
- Zinc coating integrity: If the cable tray is severely collided during transportation and installation, resulting in large-area damage to the zinc coating and direct exposure of the steel substrate, local corrosion (i.e., "pitting corrosion") will be accelerated, which will then spread to the entire tray. In addition, if the welds of the tray are not treated with additional zinc supplementation (such as cold zinc spraying), they are also likely to become a "breakthrough" for corrosion.
- Installation and maintenance: If the cable tray is installed in a water-accumulating area (such as a low-lying outdoor area), or accumulates dust and oil for a long time without regular cleaning, a "local corrosion environment" will be formed. For example, oil will accelerate the oxidation of the zinc coating after absorbing moisture, and dust accumulation will hinder the normal contact between the zinc coating and air, causing "crevice corrosion".
若需在中等腐蝕性環(huán)境（如潮濕車間、近郊半戶外）中使用鍍鋅橋架，可通過以下措施進一步提升其耐腐能力：
- 增加鋅層厚度：選擇鋅層厚度≥85μm 的加厚熱浸鍍鋅橋架（常規(guī)為 65μm），鋅層越厚，犧牲陽極保護和物理隔絕的持續(xù)時間越長，可將耐腐壽命延長 30%-50%。
- 表面封閉處理：在熱浸鍍鋅層表面噴涂一層環(huán)氧富鋅漆或聚氯乙烯（PVC）涂層，形成 “鋅層 + 封閉層” 的雙重防護，既能抵御酸堿氣體侵蝕，又能防止鋅層氧化變色。例如，在食品加工廠（存在弱酸性蒸汽）中，封閉處理后的鍍鋅橋架可避免鋅層與酸性物質(zhì)直接反應。
- 定期維護：每半年至一年對戶外或潮濕環(huán)境中的鍍鋅橋架進行檢查，發(fā)現(xiàn)鋅層破損處及時用冷噴鋅涂料修補；定期清理橋架表面的灰塵、油污，避免堆積物引發(fā)局部腐蝕。
If galvanized cable trays need to be used in moderately corrosive environments (such as humid workshops, suburban semi-outdoor areas), their corrosion resistance can be further improved through the following measures:
- Increase the zinc coating thickness: Choose thickened hot-dip galvanized cable trays with a zinc coating thickness of ≥85μm (conventional is 65μm). The thicker the zinc coating, the longer the duration of sacrificial anode protection and physical isolation, which can extend the corrosion-resistant service life by 30%-50%.
- Surface sealing treatment: Spray a layer of epoxy zinc-rich paint or polyvinyl chloride (PVC) coating on the surface of the hot-dip galvanized layer to form a dual protection of "zinc layer + sealing layer", which can not only resist the erosion of acid-base gases but also prevent the zinc layer from oxidative discoloration. For example, in food processing plants (with weak acid steam), galvanized cable trays after sealing treatment can avoid direct reaction between the zinc layer and acidic substances.
- Regular maintenance: Inspect the galvanized cable trays in outdoor or humid environments every six months to one year, and promptly repair the damaged zinc layer with cold zinc spray paint when found; regularly clean the dust and oil on the surface of the tray to avoid local corrosion caused by accumulated substances.
綜合來看，鍍鋅橋架（尤其是熱浸鍍鋅類型）具備中等耐腐蝕能力，但并非適用于所有環(huán)境：
- 適用場景：室內(nèi)干燥區(qū)域（如辦公樓、商場、普通廠房）、非沿海戶外區(qū)域（如內(nèi)陸小區(qū)戶外配電、公路收費站）、無強酸堿的輕度潮濕環(huán)境（如地下車庫），這些場景中鍍鋅橋架能以較高的性價比實現(xiàn)長期防腐。
- 不適用場景：強腐蝕性環(huán)境（如海邊鹽霧區(qū)、化工園區(qū)、電鍍車間），此類環(huán)境會快速破壞鋅層，導致橋架短時間內(nèi)銹蝕，此時應優(yōu)先選擇玻璃鋼（FRP）橋架或襯塑鋼制橋架，這類材質(zhì)的耐腐性能遠優(yōu)于鍍鋅橋架。
簡言之，判斷鍍鋅橋架是否耐腐蝕，需結(jié)合具體環(huán)境和鍍鋅工藝 —— 在常規(guī)環(huán)境中，熱浸鍍鋅橋架是可靠的防腐選擇；在強腐蝕環(huán)境中，則需更換更耐腐的材質(zhì)。
In summary, galvanized cable trays (especially hot-dip galvanized ones) have moderate corrosion resistance, but they are not suitable for all environments:
- Applicable scenarios: Indoor dry areas (such as office buildings, shopping malls, ordinary factories), non-coastal outdoor areas (such as outdoor power distribution in inland communities, highway toll stations), and slightly humid environments without strong acid and alkali (such as underground garages). In these scenarios, galvanized cable trays can achieve long-term corrosion protection with high cost-effectiveness.
- Inapplicable scenarios: Highly corrosive environments (such as coastal salt spray areas, chemical parks, electroplating workshops). Such environments will quickly damage the zinc coating, leading to rusting of the tray in a short time. In this case, fiberglass reinforced plastic (FRP) cable trays or plastic-lined steel cable trays should be preferred, as their corrosion resistance is far better than that of galvanized cable trays.
In short, to judge whether a galvanized cable tray is corrosion-resistant, it is necessary to consider the specific environment and galvanizing process — in conventional environments, hot-dip galvanized cable trays are a reliable anti-corrosion choice; in highly corrosive environments, more corrosion-resistant materials need to be used instead.
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