镀锌桥架的耐腐蚀性能源于其表面的锌镀层，核心通过两种机制实现防腐：一是物理隔绝作用，锌镀层紧密覆盖在钢制桥架表面，形成一层连续的 “屏障”，阻止空气中的氧气、水分及腐蚀性介质直接接触钢基材，从根源减少基材氧化生锈的可能；二是牺牲阳极保护作用，锌的电极电位低于铁（锌的标准电极电位约 - 0.76V，铁约 - 0.44V），当桥架表面出现划痕、锌层破损导致钢基材暴露时，锌会优先于铁发生氧化反应（即 “牺牲” 锌自身），通过电子转移抑制铁的腐蚀，直至锌层完全消耗。这种 “双重保护” 让镀锌桥架在多数常规环境中具备优于普通钢制桥架的耐腐能力。
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 优先于 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.
镀锌桥架主要分为热浸镀锌（Hot-Dip Galvanizing）和冷镀锌（Electro-Galvanizing，又称电镀锌）两种工艺，两者的锌层厚度、结合力及耐腐性能差异显著，直接影响桥架的适用场景：
- 热浸镀锌桥架：将钢制桥架浸入熔融锌液（温度约 450℃）中，锌液与钢材发生冶金反应，形成厚度为 65-100μm 的锌铁合金层 + 纯锌层复合结构。该锌层结合力强（不易脱落）、厚度均匀，在中性或弱腐蚀性环境（如室内干燥区域、普通户外无盐雾环境）中，使用寿命可达 15-20 年，甚至更久。例如，小区配电房、非沿海地区的户外桥架多采用此工艺。
- 冷镀锌桥架：通过电解作用在钢材表面沉积锌层，锌层厚度通常仅 10-30μm，且与基材结合力较弱，易因碰撞、摩擦脱落。其耐腐性能远低于热浸镀锌，仅适用于室内干燥、无腐蚀性的轻度环境（如办公楼吊顶内），使用寿命通常为 3-5 年，若用于潮湿或半户外环境，1-2 年内便可能出现锌层剥落、基材生锈。
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.
镀锌桥架的实际耐腐效果并非固定不变，受环境腐蚀性强度、锌层完整性及安装维护方式三大因素影响：
- 环境腐蚀性：在强腐蚀性环境（如海边盐雾区、化工车间、印染厂）中，高浓度的氯离子、酸碱气体能快速侵蚀锌层 —— 例如，海边空气中的氯离子会与锌发生化学反应生成可溶性氯化锌，导致锌层 “溶解”，此时即使是热浸镀锌桥架，使用寿命也可能缩短至 5-8 年；而在干燥、洁净的室内环境（如写字楼机房），锌层消耗缓慢，耐腐寿命可大幅延长。
- 锌层完整性：若桥架在运输、安装过程中出现严重碰撞，导致锌层大面积破损，钢基材直接暴露，会加速局部腐蚀（即 “点蚀”），进而蔓延至整个桥架。此外，桥架焊缝处若未做额外补锌处理（如冷喷锌），也易成为腐蚀 “突破口”。
- 安装维护：若桥架安装在积水区域（如户外低洼处），或长期堆积灰尘、油污且未定期清理，会形成 “局部腐蚀环境”—— 例如，油污吸附水分后会加速锌层氧化，灰尘堆积则会阻碍锌层与空气的正常接触，引发 “缝隙腐蚀”。
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".
若需在中等腐蚀性环境（如潮湿车间、近郊半户外）中使用镀锌桥架，可通过以下措施进一步提升其耐腐能力：
- 增加锌层厚度：选择锌层厚度≥85μm 的加厚热浸镀锌桥架（常规为 65μm），锌层越厚，牺牲阳极保护和物理隔绝的持续时间越长，可将耐腐寿命延长 30%-50%。
- 表面封闭处理：在热浸镀锌层表面喷涂一层环氧富锌漆或聚氯乙烯（PVC）涂层，形成 “锌层 + 封闭层” 的双重防护，既能抵御酸碱气体侵蚀，又能防止锌层氧化变色。例如，在食品加工厂（存在弱酸性蒸汽）中，封闭处理后的镀锌桥架可避免锌层与酸性物质直接反应。
- 定期维护：每半年至一年对户外或潮湿环境中的镀锌桥架进行检查，发现锌层破损处及时用冷喷锌涂料修补；定期清理桥架表面的灰尘、油污，避免堆积物引发局部腐蚀。
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.
综合来看，镀锌桥架（尤其是热浸镀锌类型）具备中等耐腐蚀能力，但并非适用于所有环境：
- 适用场景：室内干燥区域（如办公楼、商场、普通厂房）、非沿海户外区域（如内陆小区户外配电、公路收费站）、无强酸碱的轻度潮湿环境（如地下车库），这些场景中镀锌桥架能以较高的性价比实现长期防腐。
- 不适用场景：强腐蚀性环境（如海边盐雾区、化工园区、电镀车间），此类环境会快速破坏锌层，导致桥架短时间内锈蚀，此时应优先选择玻璃钢（FRP）桥架或衬塑钢制桥架，这类材质的耐腐性能远优于镀锌桥架。
简言之，判断镀锌桥架是否耐腐蚀，需结合具体环境和镀锌工艺 —— 在常规环境中，热浸镀锌桥架是可靠的防腐选择；在强腐蚀环境中，则需更换更耐腐的材质。
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.
