1.1 这些测试方法涵盖了测量扩散涂层厚度的两个程序。 1.2 测试方法A是确定尺寸变化厚度，定义为涂覆前后零件厚度的差异。（术语微米厚度和零件生长被认为是尺寸变化厚度的同义词。） 1.3 测试方法B是确定总涂层厚度，定义为未受明显影响的基底和涂层外表面之间的距离。这包括所有包含的相、区和层的总和。(术语外壳深度被认为是总涂层厚度的同义词。)总涂层厚度通过对涂层进行横截面、制备冶金支架并在显微镜下测量涂层厚度来确定。1.4 从横截面显微镜下确定的总涂层厚度通常大于或等于由零件生长确定的尺寸变化厚度。当涂层主要通过与基材反应产生时，基材-涂层界面随着基材在反应中被消耗而后退。在这种情况下，总涂层厚度和尺寸变化厚度之间的差是所消耗的基材的厚度。 1.5 扩散涂层通常在高温下形成，用于在高温下使用。这意味着扩散涂层是在高温环境中不断经历变化的动态系统。有必要知道某些相的生长是以牺牲其他相为代价的，并且了解涂层的先前历史以理解涂层厚度数据的重要性。1.6 以SI单位表示的数值应被视为标准。英寸-磅单位仅供参考。 1.7 本标准并不旨在解决与其使用相关的所有安全性问题（如果有）。本标准的使用者有责任在使用前建立适当的安全、健康和环境实践并确定法规限制的适用性。 1.8 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》中确立的国际公认的标准化原则制定的。 ======意义和用途====== 3.1 扩散涂层是通过使一种或多种元素与金属基材的表面反应或扩散到金属基材的表面中或两者，从而化学地改变与该表面相邻的基材而产生的涂层。为了理解涂层厚度测量的重要性，必须理解基材中固溶体区和反应产物如金属间化合物对特定涂层的贡献。

1.1 These test methods cover two procedures for measuring the thickness of diffusion coatings. 1.2 Test Method A is the determination of the dimensional-change thickness, defined as the difference in the thickness of the part before and after coating. (The terms micrometer thickness and part growth are considered synonymous with dimensional change thickness.) 1.3 Test Method B is the determination of total coating thickness, defined as the distance between the observably unaffected substrate and the exterior surface of the coating. This includes the total of all included phases, zones and layers. (The term case depth is considered to be synonymous with total coating thickness.) The total coating thickness is determined by cross-sectioning the coating, preparing a metallurgical mount and microscopically measuring the coating thickness. 1.4 The total coating thickness as determined microscopically from a cross-section will usually be greater than, or equal to, the dimensional change thickness determined by part growth. When the coating is produced primarily by reaction with the substrate, the substrate-coating interface recedes as the substrate is consumed in the reaction. In such cases the difference between the total coating thickness and the dimensional change thickness is the thickness of the substrate consumed. 1.5 Diffusion coatings are usually formed at elevated temperatures for service at elevated temperatures. This means that diffusion coatings are dynamic systems which are continually undergoing changes while in an elevated-temperature environment. It is necessary to know that certain phases are growing at the expense of others and to know the previous history of a coating to understand the significance of coating thickness data. 1.6 Values in SI units are to be regarded as the standard. Inch-pound units are provided for information only. 1.7 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. 1.8 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 ====== 3.1 A diffusion coating is one produced by causing an element or elements to react with or diffuse into, or both, the surface of a metallic substrate, thus chemically altering the substrate adjacent to the surface. To appreciate the significance of coating thickness measurements one must understand the contributions to a particular coating of solid-solution zones in the substrate and reaction products such as intermetallic compounds.