1.1 本试验方法涵盖了测定金和钯涂层孔隙率的设备和方法，尤其是电触点上使用的电镀层和覆层金属。 1.2 该测试方法旨在显示孔隙度水平是否小于或大于用户根据经验认为适用于预期应用的某个值。 1.3 文献中描述了各种其他孔隙度测试方法。 2. , 3. 其他孔隙度测试方法包括 B735型 , B741 , B798 和 B809 . ASTM《电镀层和相关金属涂层孔隙率测试选择指南》可用作指南 B765 . 1.4 以国际单位制表示的数值应视为标准值。 括号中给出的值仅供参考。 1.5 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熟悉所有危险，包括制造商提供的本产品/材料的适当材料安全数据表（MSDS）中确定的危险，建立适当的安全、健康和环境实践，并在使用前确定监管限制的适用性。 有关具体危险，请参阅第节 6. . 1.6 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====== 5.1 金涂层通常用于可分离电连接器和其他设备的触点。电镀层是最常用于触点的金的形式，尽管它也用作镶嵌或覆层金属以及接触表面上的焊接件。金固有的高贵性使其能够抵抗可能干扰可靠接触操作的绝缘氧化膜的形成。 5.2 钯涂层有时被指定为电触点和类似电气部件表面上金的替代品，既可以作为电镀层，也可以作为镶嵌或覆层金属。本试验方法特别适用于测定钯涂层中的孔隙率，因为如果遵循规定的试验条件，所使用的反应性气氛不会侵蚀钯。 相反，钯涂层受到硝酸（HNO）的侵蚀 3. )和其他强氧化剂，使测试方法 B735型 不能用于测定此类涂层中的孔隙率。 5.3 为了使这些涂层按预期发挥作用，暴露基底金属基材和底板的涂层中的孔隙、裂纹和其他缺陷必须最小或不存在，除非在可以将触点用于保护表面免受环境影响的结构中的情况下，或在对沉积物进行防腐表面处理的情况下。涂层中可容忍的孔隙率水平取决于底板或基板环境的严重程度、接触装置的设计因素（如其匹配的力）、电路参数以及需要保持的接触操作的可靠性。 此外，当存在孔隙时，表面上孔隙的位置也很重要。如果气孔数量较少，且位于配合面接触区之外，则通常可以容忍其存在。 5.4 如果能够确定接触表面上的孔的精确位置和数量，则确定接触表面上孔的方法最合适。接触表面的形状通常是弯曲或不规则的，测试方法应适用于它们。此外，孔隙度测定试验的严重性可能因能够检测所有孔隙度的程序和仅检测高孔隙度条件的程序而异。 5.5 本试验方法能够检测几乎所有可能参与与基板或底板腐蚀反应的孔隙或其他缺陷。 该测试快速、简单且价格低廉。此外，它可以用于具有复杂几何形状的触点，例如插脚插座触点（尽管对于深凹槽，最好打开触点结构，以允许二氧化硫与内部有效表面反应）。 5.6 特定测试揭示的孔隙度水平与接触行为的关系必须由这些测试的用户通过实际经验或判断得出。因此，某些应用可能要求涂层中没有孔隙，而接触区中的少量孔隙可能适用于其他应用。 5.7 该试验被认为是破坏性的，因为它通过腐蚀产物污染表面和在孔隙位置或未涂覆区域的边界处咬边涂层来揭示孔隙的存在。 暴露于本试验的任何零件不得投入使用。 5.8 本试验仅用于定量描述孔隙（例如每单位面积或每次接触的孔隙数量），该孔隙密度足够低，以至于腐蚀部位能够很好地分离并易于解决。一般来说，对于高达约100/cm的孔密度，可以实现这一点 2. . 高于该值时，测试有助于定性检测和比较孔隙度。 5.9 为此目的 测量区域 或 有效表面 ，应定义为对零件的可用性或功能至关重要的表面部分，如其接触特性，或可能是干扰零件功能的腐蚀产物或变色膜的来源。 有效表面应在零件图纸上标明，或提供适当标记的样品。

1.1 This test method covers equipment and methods for determining the porosity of gold and palladium coatings, particularly electrodeposits and clad metals used on electrical contacts. 1.2 This test method is designed to show whether the porosity level is less or greater than some value which by experience is considered by the user to be acceptable for the intended application. 1.3 A variety of other porosity testing methods are described in the literature. 2 , 3 Other porosity test methods are B735 , B741 , B798 , and B809 . An ASTM Guide to the selection of porosity tests for electrodeposits and related metallic coatings is available as Guide B765 . 1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only. 1.5 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 become familiar with all hazards including those identified in the appropriate Material Safety Data Sheet (MSDS) for this product/material as provided by the manufacturer, to establish appropriate safety, health, and environmental practices, and determine the applicability of regulatory limitations prior to use. For specific hazards, see Section 6 . 1.6 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 ====== 5.1 Gold coatings are often specified for the contacts of separable electrical connectors and other devices. Electrodeposits are the form of gold that is most used on contacts, although it is also employed as inlay or clad metal and as weldments on the contact surface. The intrinsic nobility of gold enables it to resist the formation of insulating oxide films that could interfere with reliable contact operation. 5.2 Palladium coatings are sometimes specified as alternatives to gold on electrical contacts and similar electrical component surfaces, both as electrodeposits and as inlay or clad metal. This test method is particularly suitable for determining porosity in palladium coatings, since the reactive atmosphere that is used does not attack the palladium if the specified test conditions are followed. In contrast, palladium coatings are attacked by nitric acid (HNO 3 ) and other strong oxidizing agents, so that Test Method B735 cannot be used for determining the porosity in such coatings. 5.3 In order for these coatings to function as intended, porosity, cracks, and other defects in the coating that expose base-metal substrates and underplates must be minimal or absent, except in those cases where it is feasible to use the contacts in structures that shield the surface from the environment or where corrosion inhibiting surface treatments for the deposit are employed. The level of porosity in the coating that may be tolerable depends on the severity of the environment to the underplate or substrate, design factors for the contact device like the force with which it is mated, circuit parameters, and the reliability of contact operation that it is necessary to maintain. Also, when present, the location of pores on the surface is important. If the pores are few in number and are outside of the zone of contact of the mating surfaces, their presence can often be tolerated. 5.4 Methods for determining pores on a contact surface are most suitable if they enable their precise location and numbers to be determined. Contact surfaces are often curved or irregular in shape, and testing methods should be suitable for them. In addition, the severity of porosity-determining tests may vary from procedures capable of detecting all porosity to procedures that detect only highly porous conditions. 5.5 The present test method is capable of detecting virtually all porosity or other defects that could participate in corrosion reactions with the substrate or underplate. The test is rapid, simple, and inexpensive. In addition, it can be used on contacts having complex geometry such as pin-socket contacts (although with deep recesses it is preferred that the contact structures be opened to permit reaction of the sulfur dioxide with the interior significant surfaces). 5.6 The relationship of porosity levels revealed by particular tests to contact behavior must be made by the user of these tests through practical experience or by judgment. Thus, absence of porosity in the coating may be a requirement for some applications, while a few pores in the contact zone may be acceptable for others. 5.7 This test is considered destructive in that it reveals the presence of porosity by contaminating the surface with corrosion products and by undercutting the coating at pore sites or at the boundaries of the unplated areas. Any parts exposed to this test shall not be placed in service. 5.8 This test is intended to be used for quantitative descriptions of porosity (such as number of pores per unit area or per contact) only on coatings that have a pore density sufficiently low that the corrosion sites are well separated and can be readily resolved. As a general guideline this can be achieved for pore densities up to about 100/cm 2 . Above this value the tests are useful for the qualitative detection and comparisons of porosity. 5.9 For these purposes, the measurement area , or significant surface , shall be defined as those portions of the surface that are essential to the serviceability or function of the part, such as its contact properties, or which can be the source of corrosion products or tarnish films that interfere with the function of the part. The significant surfaces shall be indicated on the drawings of the parts, or by the provision of suitably marked samples.