1.1 本试验方法涵盖固体试样因液滴或射流的重复离散冲击而被侵蚀或损坏的试验。考虑的附带损伤形式包括窗材料光学性能的退化，以及涂层的渗透、分离或破坏。试验的目的可能是确定受试材料或涂层的抗侵蚀性或其他损伤性，或调查损伤机制和试验变量的影响。由于这些测试的特殊性，以及在许多情况下希望在某种程度上模拟预期的服务环境，标准仪器的规范被认为是不可行的。该测试方法为设置测试提供了指导，并规定了即使在材料、测试设施和测试条件差异很大的情况下也可以遵循的测试和分析程序以及报告要求。 它还提供了适用于金属和其他结构材料的抗侵蚀性数值的标准尺度。在某种程度上，它可以作为液体冲击侵蚀的教程。 1.2 以国际单位制表示的数值应视为标准值。国际单位制后括号中给出的值仅供参考，不被视为标准值。 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====== 5.1 侵蚀环境- 本试验方法可用于评估固体表面受到液滴或射流反复冲击的服务环境中材料的抗侵蚀性。有时，液体冲击试验也用于评估暴露在空化液体环境中的材料。试验方法为 不 用于评估或预测由于固体颗粒冲击、气泡流中的“冲击腐蚀”、液体或泥浆在表面上的“冲洗”或针对表面的连续高速液体射流而导致的材料抗侵蚀性。有关各种形式的侵蚀和侵蚀试验的背景，请参阅参考文献 ( 1. ) 通过 ( 2. ) . 4. 裁判 ( 3. ) 是一篇优秀的综合性论文。 5.2 关于抗侵蚀性的讨论- 从广义上讲，液体冲击侵蚀和空化侵蚀是相似的过程，材料对它们的相对阻力相似。在这两种情况下，损伤都与作用于固体表面的重复、小规模、高强度压力脉冲有关。固体中的精确失效机制因材料以及流固相互作用的详细性质、规模和强度而异( 注1 ). 因此，“抗侵蚀性”不应被视为材料的一种可精确定义的特性，而应被视为一种特性的复合体，其相对重要性可能因刚才提到的变量而异。（尚未成功地将抗侵蚀性与任何可独立测量的材料特性相关联。 )由于这些原因，在不同设施或不同条件下测得的相对抗侵蚀性之间的一致性不是很好。假设20的两种材料之间的差异 % 或者更少可能并不重要:另一项测试可能会显示他们的排名顺序相反。对于大块材料，如金属和结构塑料，抗侵蚀性的范围远大于典型强度特性的范围:在316型不锈钢被赋予统一值的归一化尺度上，最耐磨的材料（一些钨铬钴合金和工具钢）的值可能大于10，最小电阻值（软铝，一些塑料）小于0.1（见参考文献 ( 2. ) 和 ( 4. ) ). 注1: 特别是关于失效机制，请参见参考文献 ( 3. ) 在W。 F、 Adler，J.H.Brunton和M.C.Rochester著的《液滴冲击对固体表面的侵蚀》，C.M.Preece著的《空化侵蚀》。 5.3 侵蚀率随时间变化的意义: 5.3.1 由于液体冲击或气蚀而产生的侵蚀速率并非随时间而恒定，但表现出在本节中更充分讨论的几种“侵蚀速率-时间模式”之一 10.3.3 . 最常见的模式包括一个“潜伏期”，在此期间材料损失轻微或不存在，然后侵蚀率加速到最大值，然后侵蚀率下降，这可能会或可能不会趋于“终端”稳态速率。根据被测试材料的预期服务应用，该历史中各个阶段的重要性可能不同。 然而，在几乎任何情况下，通过简单地对所有材料进行相同时间长度的测试并比较其累积质量损失，都不会得到显著的结果。 5.3.2 对于窗户材料、涂层和其他应用而言，“潜伏期”可能是最重要的测试结果，对于这些应用而言，使用寿命因初始表面损伤而终止，即使质量损失很小。 5.3.3 对于散装材料，本试验方法规定了“标称潜伏期”和“最大侵蚀率”的确定，以及基于每种潜伏期的材料额定值。经验关系如所示 附件A2 通过该公式，可以估计任何液体冲击条件下的标称潜伏期和最大侵蚀率，其中主要冲击变量已知。然而，必须强调的是，由于前面描述的侵蚀率随暴露时间的变化，上述- 上述参数不足以预测长暴露时间的侵蚀。基于最大侵蚀率的外推可能会高估长期累积侵蚀的绝对大小，其系数超过一个数量级。此外，它可能会错误地预测不同材料的长期结果之间的相对差异。 5.3.4 由于这些考虑，一些关注长寿命部件的实验者可能希望材料评级不是基于最大侵蚀率，而是基于较低的“终端侵蚀率”（如果在测试中显示）。这可以在许多方面仍然遵循本试验方法的情况下完成，但应认识到，与最大侵蚀率相比，终端侵蚀率可能更受次要变量的影响，例如试样形状、“重复”与“分布”冲击条件、液滴尺寸分布等。 因此，基于终端侵蚀率的结果在实验室之间的可变性可能更差，并且所需的测试时间将更大。 5.4 该试验方法适用于大约60 m/s至600 m/s的冲击速度；不应假设在该范围内获得的结果在更高或更低的速度下有效。在非常低的冲击速度下，腐蚀效应变得越来越重要。在极高的速度下，材料去除过程会发生显著变化，试样温度也可能成为一个重要因素；然后，应以与服务环境相对应的速度进行测试。 5.5 相关试验方法- 由于材料对液体冲击侵蚀和空化侵蚀的阻力已被视为相关特性，因此空化侵蚀试验方法 G32 和 G134页 对于某些应用，可将其视为本试验方法的替代试验。对于金属，试验方法的相关结果 G32 或 G134页 应与液体冲击试验的结果相似，但不一定完全相同（参见 5.2 ). 任一测试方法 G32 或 G134页 可能比冲击试验便宜，并提供了标准化的试样和试验条件，但可能与要模拟的冲击环境的特征不匹配。液体冲击试验的优点是可以选择液滴或射流的尺寸和冲击速度，并且可以更接近地模拟特定的液体冲击环境。对于尺寸效应可能非常重要的弹性体、涂层和脆性材料，应首选设计良好的液体冲击试验。

1.1 This test method covers tests in which solid specimens are eroded or otherwise damaged by repeated discrete impacts of liquid drops or jets. Among the collateral forms of damage considered are degradation of optical properties of window materials, and penetration, separation, or destruction of coatings. The objective of the tests may be to determine the resistance to erosion or other damage of the materials or coatings under test, or to investigate the damage mechanisms and the effect of test variables. Because of the specialized nature of these tests and the desire in many cases to simulate to some degree the expected service environment, the specification of a standard apparatus is not deemed practicable. This test method gives guidance in setting up a test, and specifies test and analysis procedures and reporting requirements that can be followed even with quite widely differing materials, test facilities, and test conditions. It also provides a standardized scale of erosion resistance numbers applicable to metals and other structural materials. It serves, to some degree, as a tutorial on liquid impingement erosion. 1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard. 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 ====== 5.1 Erosion Environments— This test method may be used for evaluating the erosion resistance of materials for service environments where solid surfaces are subjected to repeated impacts by liquid drops or jets. Occasionally, liquid impact tests have also been used to evaluate materials exposed to a cavitating liquid environment. The test method is not intended nor applicable for evaluating or predicting the resistance of materials against erosion due to solid particle impingement, due to “impingement corrosion” in bubbly flows, due to liquids or slurries “washing” over a surface, or due to continuous high-velocity liquid jets aimed at a surface. For background on various forms of erosion and erosion tests, see Refs ( 1 ) through ( 2 ) . 4 Ref ( 3 ) is an excellent comprehensive treatise. 5.2 Discussion of Erosion Resistance— Liquid impingement erosion and cavitation erosion are, broadly speaking, similar processes and the relative resistance of materials to them is similar. In both, the damage is associated with repeated, small-scale, high-intensity pressure pulses acting on the solid surface. The precise failure mechanisms in the solid have been shown to differ depending on the material, and on the detailed nature, scale, and intensity of the fluid-solid interactions ( Note 1 ). Thus, “erosion resistance” should not be regarded as one precisely-definable property of a material, but rather as a complex of properties whose relative importance may differ depending on the variables just mentioned. (It has not yet been possible to successfully correlate erosion resistance with any independently measurable material property.) For these reasons, the consistency between relative erosion resistance as measured in different facilities or under different conditions is not very good. Differences between two materials of say 20 % or less are probably not significant: another test might well show them ranked in reverse order. For bulk materials such as metals and structural plastics, the range of erosion resistances is much greater than that of typical strength properties: On a normalized scale on which Type 316 stainless steel is given a value of unity, the most resistant materials (some Stellites and tool steels) may have values greater than 10, and the least resistant (soft aluminum, some plastics) values less than 0.1 (see Refs ( 2 ) and ( 4 ) ). Note 1: On failure mechanisms in particular, see in Ref ( 3 ) under “The Mechanics of Liquid Impact” by W. F. Adler, “Erosion of Solid Surfaces by the Impact of Liquid Drops” by J. H. Brunton and M. C. Rochester, and “Cavitation Erosion” by C. M. Preece. 5.3 Significance of the Variation of Erosion Rate with Time: 5.3.1 The rate of erosion due to liquid impact or cavitation is not constant with time, but exhibits one of several “erosion rate-time patterns” discussed more fully in 10.3.3 . The most common pattern consists of an “incubation period” during which material loss is slight or absent, followed by an acceleration of erosion rate to a maximum value, in turn followed by a declining erosion rate which may or may not tend to a “terminal” steady-state rate. The significance of the various stages in this history can differ according to the intended service applications of the materials being tested. In almost no case, however, are significant results obtained by simply testing all materials for the same length of time and comparing their cumulative mass loss. 5.3.2 The “incubation period” may be the most significant test result for window materials, coatings, and other applications for which the useful service life is terminated by initial surface damage even though mass loss is slight. 5.3.3 For bulk materials, this test method provides for determination of the “nominal incubation period” as well as the “maximum erosion rate,” and material ratings based on each. Empirical relationships are given in Annex A2 by which the nominal incubation period and the maximum erosion rate can then be estimated for any liquid impingement conditions in which the principal impingement variables are known. It must be emphasized, however, that because of the previously described variation of erosion rate with exposure time, the above-mentioned parameters do not suffice to predict erosion for long exposure durations. Extrapolation based on the maximum erosion rate could overestimate the absolute magnitude of long-term cumulative erosion by a factor exceeding an order of magnitude. In addition, it could incorrectly predict the relative difference between long-term results for different materials. 5.3.4 Because of these considerations, some experimenters concerned with long-life components may wish to base material ratings not on the maximum erosion rate, but on the lower “terminal erosion rate” if such is exhibited in the tests. This can be done while still following this test method in many respects, but it should be recognized that the terminal erosion rate is probably more strongly affected by secondary variables such as test specimen shape, “repetitive” versus “distributed” impact conditions, drop size distributions, and so forth, than is the maximum erosion rate. Thus, between-laboratories variability may be even poorer for results based on terminal erosion rate, and the test time required will be much greater. 5.4 This test method is applicable for impact velocities ranging roughly from 60 m/s to 600 m/s; it should not be assumed that results obtained in that range are valid at much higher or lower velocities. At very low impact velocities, corrosion effects become increasingly important. At very high velocities the material removal processes can change markedly, and specimen temperature may also become a significant factor; testing should then be done at the velocities corresponding to the service environment. 5.5 Related Test Methods— Since the resistances of materials to liquid impingement erosion and to cavitation erosion have been considered related properties, cavitation erosion Test Methods G32 and G134 may be considered as alternative tests to this test method for some applications. For metals, the relative results from Test Method G32 or G134 should be similar but not necessarily identical to those from a liquid impact test (see 5.2 ). Either Test Method G32 or G134 may be less expensive than an impingement test, and provides for standardized specimens and test conditions, but may not match the characteristics of the impingement environment to be simulated. The advantages of a liquid impingement test are that droplet or jet sizes and impact velocities can be selected and it can simulate more closely a specific liquid impingement environment. A well-designed liquid impingement test is to be preferred for elastomers, coatings, and brittle materials, for which size effects may be quite important.