1.1 本规程涵盖了制备粒度分析用难熔金属粉末及其化合物的去团聚。 1.2 经验表明，这种做法对于元素钨、钼、铼和钽金属粉末以及碳化钨的去团聚是令人满意的。其他金属粉末（例如，元素金属、碳化物和氮化物）可使用本实施规程制备用于粒度分析，但要注意其有效性，直到开发出令人满意的实际经验。 1.3 单位- 除质量值外，使用克（g）单位是长期的行业惯例，以国际单位制表示的值应视为标准值。本标准不包括其他计量单位。 1.4 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。 有关具体预防说明，请参阅 注释2 . 1.5 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 钨和钼等难熔金属粉末通常在高温下通过氢还原产生。 因此，它们通常包含许多大的、烧结牢固的团聚体。使用这些粉末的许多制造过程涉及研磨步骤或一些类似处理，或取决于单个颗粒大小，而不是团聚体大小。 3. 因此，通常需要从这些粉末的粒度分析中了解单个粒度分布，而不是团聚粒度分布。本规程提供了将团聚体分解为其组成颗粒（de）的程序- 结块），单个颗粒没有过度断裂。该程序通常被称为 实验室铣削 或 棒铣削 . 4.2 本指南中规定的实验室研磨条件自1965年起开始使用，最初作为粒度分析测试方法的一部分。本指南于1995年首次作为单独的独立标准发布，因为其适用于制备粉末样品，以便通过其他方法（例如，试验方法）进行分析 B761 和 B822 ). 此处规定的铣削条件的开发和建立信息可在脚注参考中找到。 4. 4.3 本规程中描述的研磨程序不一定只分解团聚体，而不会使单个颗粒破裂；某些粉末中可能会出现一些颗粒破裂。然而，这种做法的使用 做 提供一致的粒度分析结果，这些结果与许多制造过程中的粉末行为密切相关。 4.4 本规程应用于表1所列难熔金属粉末和化合物的去团聚 1.2 ，当需要从随后的粒度分析中评估单个粒度分布时。在以下情况下不得使用: 结块 （按原样或供应）需要尺寸分布。 4.5 本规程可用于制备试验方法用样品 B330型 , B761 , B822 ，以及其他粒度分析方法 B821 ，如果使用。

1.1 This practice covers the de-agglomeration of refractory metal powders and their compounds in preparation for particle size analysis. 1.2 Experience has shown that this practice is satisfactory for the de-agglomeration of elemental tungsten, molybdenum, rhenium, and tantalum metal powders, and tungsten carbide. Other metal powders (for example, elemental metals, carbides, and nitrides) may be prepared for particle size analysis using this practice with caution as to effectiveness until actual satisfactory experience is developed. 1.3 Units— With the exception of the values for mass, for which the use of the gram (g) unit is the long-standing industry practice, the values stated in SI units are to be regarded as standard. No other units of measure are included in this standard. 1.4 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. For specific precautionary statements, see Note 2 . 1.5 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 Refractory metal powders, such as tungsten and molybdenum, are usually produced by hydrogen reduction at high temperatures. Thus, they usually contain numerous large, strongly-sintered agglomerates. Many of the manufacturing processes using these powders involve a milling step or some similar treatment or depend on the individual particulate size, not on the agglomerate size. 3 Thus, a knowledge of the individual particulate size distribution, not the agglomerate size distribution, is usually desired from a particle size analysis of these powders. This practice provides a procedure for breaking down agglomerates into their constituent particles (de-agglomeration), without excessive fracture of the individual particles. The procedure is often referred to as laboratory milling or rod milling . 4.2 The laboratory milling conditions specified in this guide have been in use since 1965, initially as part of a particle size analysis test method. This guide was first published as a separate, stand-alone standard in 1995 because of its applicability in preparing powder samples for analysis by other methods as well (for example, Test Methods B761 and B822 ). Information on the development and establishment of the milling conditions here specified can be found in the footnoted reference. 4 4.3 The milling procedure described in this practice does not necessarily break down only agglomerates without fracturing individual particles; some particle fracture may occur in certain powders. However, use of this practice does provide consistent particle size analysis results that have been found to relate well to powder behavior in numerous manufacturing processes. 4.4 This practice shall be used for the de-agglomeration of the refractory metal powders and compounds listed in 1.2 , when an evaluation of the individual particulate size distribution is required from the subsequent particle size analysis. It shall not be used when the agglomerate (as-is or as-supplied) size distribution is desired. 4.5 This practice may be used in preparing samples for Test Methods B330 , B761 , B822 , and other particle size analysis methods, prior to the dispersion procedure of Guide B821 , if used.