1.1 本规程描述了粉末涂层用热浸镀锌钢铁表面的制备方法和粉末涂层材料的应用。 1.1.1 粉末涂层是一种干法整理工艺，使用精细研磨的颜料和树脂颗粒，带静电，并喷涂到要涂层的零件上。零件接地，使投射在其上的带电粒子粘附在表面上，并保持在那里，直到熔化并在固化炉中熔合成光滑的涂层。 1.1. 2. 热浸镀锌铁或钢是通过将已制造或未制造的产品浸入熔融锌槽中来生产的，如规范所规定 A123/A123M 或 A153/A153M . 本规程涵盖之前未涂漆或粉末涂层的钢铁产品和五金件的表面处理和热预处理（规程 D6386 ). 镀锌表面可能已经过保护涂层处理，以防止出现湿储存污渍。本规程既不适用于镀锌钢板产品，也不适用于卷材涂层或连续辊涂工艺。 1.2 以国际单位制表示的数值应视为标准。括号中给出的值仅供参考。 1.3 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.4 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 4.1 本规程描述了在应用粉末涂层之前热浸镀锌表面的制备方法。实现粉末涂层和镀锌钢之间适当粘附的关键是表面处理。粉末喷涂前，表面必须完全没有可见的金属氧化物。任何残留在镀锌钢表面的金属氧化物都可能保留空气或水分。在粉末涂覆的固化阶段加热时，氧化物可能释放水蒸气或空气，水蒸气或空气会膨胀并穿透粉末涂层，导致起泡或空洞。 4.2 锌涂层始终处于变化状态。从钢件从镀锌釜中取出时，暴露的锌涂层与环境相互作用，首先形成氧化锌和氢氧化锌，然后形成碳酸锌。 5. 根据当地天气和湿度条件，碳酸锌外层的完全转化过程可能需要暴露在环境中长达两年。 4.3 完全风化后的锌表面非常耐大气腐蚀，因为形成的紧密铜绿（氧化锌、氢氧化锌和碳酸锌）致密而坚韧。 然而，在铜绿发展的形成阶段，氧化物/氢氧化物层粘附不良，必须去除，以使粉末涂层正确粘附在镀锌层上。其次是涂层的针孔/起泡，这会严重限制其潜在性能，尤其是在侵蚀性氯化物环境中。当涂层在高温下固化时，镀锌过程中产生的截留气体通过涂层逸出表面。如果在烘烤粉末之前未通过放气过程去除这些挥发性物质，则可能会发生针孔或起泡。 针孔的存在使氯化物和其他腐蚀剂进入锌基体，从而产生锌腐蚀产物，这些产物可能会通过涂层渗出。虽然这些腐蚀产物的存在可能不会导致涂层的相关分层，但涂层可能会出现难看的白色染色。水泡是指未粘附在表面上的缺陷，在搬运过程中很容易破裂或脱落，从而产生性能和美观问题。正确制备镀锌层表面可以增加克服这些问题所需的附着力和覆盖率，并使粉末涂层和镀锌层的使用寿命达到令人满意的水平。 4.4 表面处理的变化会产生表面粗糙度和锌成分不同的终止条件，因此当随后应用粉末涂层时，它们不一定会产生相同的结果。镀锌层上锌腐蚀产物的年龄决定了要选择的表面处理类型。

1.1 This practice describes methods of preparing surfaces of hot-dip galvanized iron and steel for powder coating and the application of powder coating materials. 1.1.1 Powder coating is a dry finishing process which uses finely ground particles of pigment and resin, electrostatically charged, and sprayed onto a part to be coated. The parts are electrically grounded so that the charged particles projected at them adhere to the surface and are held there until melted and fused into a smooth coating in the curing oven. 1.1.2 Hot-dip galvanized iron or steel is produced by the immersion of fabricated or un-fabricated products in a bath of molten zinc, as specified in Specification A123/A123M or A153/A153M . This practice covers surface preparation and thermal pretreatment of iron and steel products and hardware which have not been painted or powder coated previously (Practice D6386 ). Galvanized surfaces may have been treated with protective coatings to prevent the occurrence of wet storage stain. This practice neither applies to sheet galvanized steel products nor to the coil coating or continuous roller coating processes. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 4.1 This practice describes the methods of preparation of hot-dip galvanized surfaces prior to the application of powder coating. The key to achieving proper adhesion between powder coatings and galvanized steel is surface preparation. The surface must be entirely free from visible metal oxides prior to powder coating. Any metal oxides that remain on the surface of the galvanized steel can potentially retain air or moisture. Upon heating during the curing stages of the powder application, the oxides may release water vapor or air, which can expand and penetrate the powder coating, causing blisters or voids. 4.2 The zinc coating is constantly in a state of change. From the time the steel part is removed from the galvanizing kettle, the exposed zinc coating interacts with the environment to form, first zinc oxides and zinc hydroxides, and then zinc carbonates. 5 The process of complete conversion of the outer layer of zinc carbonates can take up to two years of exposure to the environment, depending on the local weather and moisture conditions. 4.3 The zinc surface after full weathering is very resistant to atmospheric corrosion because the tight patina that is formed (zinc oxide, zinc hydroxide and zinc carbonate) is dense and tenacious. However, during the formative stages of patina development, the oxide/hydroxide layer is poorly adhered and must be removed in order for the powder coating to adhere properly to the galvanized coating. The second is pinholing/blistering of the coating which can severely limit its potential performance, especially in aggressive chloride environments. Entrapped gasses developed during the galvanizing process escape the surface through the coating as it cures at high temperatures. If these volatile materials are not removed through an outgassing process prior to the baking of the powder, then pinholing or blistering can occur. The presence of pinholes gives chlorides and other corrosive agents access to the zinc substrate consequently producing zinc corrosion products which may leach out through the coatings. While the presence of these corrosion products may not result in associated delamination of the coating, unsightly white staining of the coating can occur. Blisters are defects that are not adhered to the surface and may easily be broken into or off during handling, which creates performance and aesthetic issues. The proper preparation of the galvanized coating surface can increase the adhesion and coverage necessary to overcome these problems and results in a satisfactory service life of the powder coating and the galvanized coating together. 4.4 Variations in surface preparation produce end conditions that differ as far as surface roughness and zinc composition, hence they do not necessarily yield identical results when powder coatings are subsequently applied. The age of the zinc corrosion products on the galvanized coating will dictate the type of surface preparation to be selected.