紧固件涂层完整指南：镀锌、热镀锌、达克罗、GEOMET及防腐专用涂层。
涂层基础
涂层保护紧固件免受腐蚀，同时提供可接受的外观和保持机械性能。正确的涂层取决于环境、所需寿命、成本和美观要求。
镀锌和电镀
镀锌是最常见的紧固件涂层：工艺-电化学沉积5-15微米；外观-明亮银色；防腐-室内和温和户外环境良好；成本-经济实惠；限制-不适合恶劣户外或海洋环境。
热镀锌
热镀锌提供卓越的防腐保护：工艺-在450°C熔融锌中浸镀；厚度-40-80微米；防腐-优秀，使用寿命15-25年；非洲应用-推荐用于户外建筑，对沿海地区和采矿环境必不可少。
达克罗和GEOMET涂层
达克罗和GEOMET是片状锌铝涂层：达克罗耐盐雾1000+小时，耐高温达300°C；GEOMET更环保，500-800小时盐雾抵抗；优势-防腐性能优异，尺寸变化最小，适合螺纹紧固件；非洲采矿应用-达克罗涂层紧固件适合地下采矿环境。
专用涂层
尼龙插入涂层-聚合物涂层防松；磷酸盐涂层-好的油漆准备表面；黑色氧化物-最小防腐保护，仅限室内使用；Paint-可涂覆在适当准备的表面上；Xylan(PTFE)-优秀耐化学性和低摩擦，用于化学加工和食品工业应用。
常见问题
See frequently asked questions below.
Which coating is best for African outdoor use?
Hot-dip galvanizing provides the best value for general outdoor use in African climates. For harsh environments (coastal, mining), consider Dacromet or stainless steel.
Can coatings be applied to stainless steel fasteners?
Generally no - stainless steel's corrosion resistance comes from the material itself, not a coating. Coatings on stainless are unnecessary and may cause issues.
What's the difference between zinc plating and zinc flake coatings?
Zinc plating is smooth and thin (5-15μm). Zinc flake (Dacromet/GEOMET) is thicker (8-12μm) with a textured surface providing superior corrosion resistance.
Do coated fasteners affect thread strength?
Coatings add thickness that can affect thread fit. Specify oversize threads or minimum thread engagement where coating thickness is significant.
Can different coated fasteners be used together?
Avoid mixing significantly different metals. Coated carbon steel fasteners are generally compatible with each other.