1.1 该试验方法涵盖了一项可用于比较固体材料抗气蚀性能的试验。从喷嘴发出的浸没空化射流撞击放置在其路径上的试样，使空腔在其上塌陷，从而导致侵蚀。试验在规定的条件下，在规定的液体（通常是水）中进行。该试验方法也可用于比较各种液体的空化侵蚀能力。 1.2 本试验方法规定了喷嘴和喷嘴支架的形状和尺寸、试样尺寸及其安装方法以及最小试验室尺寸。介绍了选择支座距离的程序和几种标准试验条件之一。在适当的情况下，如果有适当的文件记录，允许偏离其中一些条件。提供了关于设置合适仪器、测试和报告程序以及应采取的预防措施的指导。 规定了标准参考材料；这些必须用于验证设施的运行，并确定其他材料的标准化抗侵蚀性。 1.3 包括两种类型的测试，一种使用可以被浪费的测试液体，例如自来水，另一种使用必须再循环的液体，例如试剂水或各种油。每种类型需要略微不同的测试电路。 1.4 此测试方法提供了测试方法的替代方法 G32 在该方法中，空化是通过以指定振幅以高频（20kHz）振动浸没的试样而引起的。在本方法中，空化是在流动系统中产生的，因此射流速度和下游压力（导致气泡坍塌）都可以独立变化。 1.5 以国际单位制表示的数值应视为标准。本标准中不包括其他计量单位。 1.6 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者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。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《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====== 5.1 该试验方法可用于估计材料对气蚀的相对阻力，例如在泵、水轮机、阀门、液压测功机和联轴器、轴承、柴油发动机缸套、船舶螺旋桨、水翼、内部流道以及柴油发动机的流体动力系统或燃料系统的各种部件中可能会遇到这种情况。 它还可用于比较不同液体在试验模拟条件下产生的侵蚀。其一般应用与试验方法类似 G32 。 5.2 在这种试验方法中，流动系统中会产生气穴现象。导致空腔形成的流速和空腔坍塌的腔室压力都可以很容易地独立地改变，因此可以单独研究各种参数的影响。空化条件可以容易而精确地控制。此外，如果在恒定空化数（σ）下进行试验，则可以通过适当改变压力来加速或减缓试验过程（参见 11.2 和 图A2.2 )。 5.3 此测试方法 标准条件 不应用于对电化学腐蚀或固体颗粒冲击起主要作用的应用的材料进行分级。 然而，如果使用适当的液体和空化数（适用于相关的使用条件），则可以对其进行调整，以评估侵蚀腐蚀效应（参见 11.1 )。 5.4 对于金属材料，如果使用实践 G73 这是不可行的。然而，不建议将其用于弹性体涂层、复合材料或其他非金属航空航天材料。 5.5 空化侵蚀和液体冲击侵蚀的机制尚未完全理解，并且可能会有所不同，这取决于液体/固体相互作用的详细性质、规模和强度。因此，耐侵蚀性可能由多种性质而非单一性质产生，并且尚未与其他独立可测量的材料性质成功相关。 因此，不同测试方法（例如振动、旋转圆盘或空化射流）之间或不同实验条件下的结果一致性不是很好。两种材料之间的微小差异可能并不显著，它们的相对排名很可能在另一次测试中逆转。 5.6 由于空化侵蚀中侵蚀时间曲线的非线性性质，在进行比较和得出结论时必须考虑该曲线的形状。简单地比较所有材料在相同累积试验时间下的累积质量损失不会给出可靠的比较。

1.1 This test method covers a test that can be used to compare the cavitation erosion resistance of solid materials. A submerged cavitating jet, issuing from a nozzle, impinges on a test specimen placed in its path so that cavities collapse on it, thereby causing erosion. The test is carried out under specified conditions in a specified liquid, usually water. This test method can also be used to compare the cavitation erosion capability of various liquids. 1.2 This test method specifies the nozzle and nozzle holder shape and size, the specimen size and its method of mounting, and the minimum test chamber size. Procedures are described for selecting the standoff distance and one of several standard test conditions. Deviation from some of these conditions is permitted where appropriate and if properly documented. Guidance is given on setting up a suitable apparatus, test and reporting procedures, and the precautions to be taken. Standard reference materials are specified; these must be used to verify the operation of the facility and to define the normalized erosion resistance of other materials. 1.3 Two types of tests are encompassed, one using test liquids which can be run to waste, for example, tap water, and the other using liquids which must be recirculated, for example, reagent water or various oils. Slightly different test circuits are required for each type. 1.4 This test method provides an alternative to Test Method G32 . In that method, cavitation is induced by vibrating a submerged specimen at high frequency (20 kHz) with a specified amplitude. In the present method, cavitation is generated in a flowing system so that both the jet velocity and the downstream pressure (which causes the bubble collapse) can be varied independently. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 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. 1.7 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 This test method may be used to estimate the relative resistances of materials to cavitation erosion, as may be encountered for instance in pumps, hydraulic turbines, valves, hydraulic dynamometers and couplings, bearings, diesel engine cylinder liners, ship propellers, hydrofoils, internal flow passages, and various components of fluid power systems or fuel systems of diesel engines. It can also be used to compare erosion produced by different liquids under the conditions simulated by the test. Its general applications are similar to those of Test Method G32 . 5.2 In this test method cavitation is generated in a flowing system. Both the velocity of flow which causes the formation of cavities and the chamber pressure in which they collapse can be changed easily and independently, so it is possible to study the effects of various parameters separately. Cavitation conditions can be controlled easily and precisely. Furthermore, if tests are performed at constant cavitation number (σ), it is possible, by suitably altering the pressures, to accelerate or slow down the testing process (see 11.2 and Fig. A2.2 ). 5.3 This test method with standard conditions should not be used to rank materials for applications where electrochemical corrosion or solid particle impingement plays a major role. However, it could be adapted to evaluate erosion-corrosion effects if the appropriate liquid and cavitation number, for the service conditions of interest, are used (see 11.1 ). 5.4 For metallic materials, this test method could also be used as a screening test for applications subjected to high-speed liquid drop impingement, if the use of Practice G73 is not feasible. However, this is not recommended for elastomeric coatings, composites, or other nonmetallic aerospace materials. 5.5 The mechanisms of cavitation erosion and liquid impingement erosion are not fully understood and may vary, depending on the detailed nature, scale, and intensity of the liquid/solid interactions. Erosion resistance may, therefore, arise from a mix of properties rather than a single property, and has not yet been successfully correlated with other independently measurable material properties. For this reason, the consistency of results between different test methods (for example, vibratory, rotating disk, or cavitating jet) or under different experimental conditions is not very good. Small differences between two materials are probably not significant, and their relative ranking could well be reversed in another test. 5.6 Because of the nonlinear nature of the erosion-time curve in cavitation erosion, the shape of that curve must be considered in making comparisons and drawing conclusions. Simply comparing the cumulative mass loss at the same cumulative test time for all materials will not give a reliable comparison.