金属粉末 - 在稳态流动条件下 通过测量粉末床的空气渗透性测定包络比表面积

[中文适用范围]： 该文件规定了一种测量金属粉末填充床的透气度和孔隙率并由此得出包络比表面积值的方法。 渗透率是在稳态流动条件下使用接近大气压的空气层流确定的。 本文件不包括通过定容法测量渗透率。 已经提出了几种不同的方法来进行这种测定，并且有几种测试设备可以在商业上获得。 只要遵守本文件中给出的一般说明并且测试参数相同，它们就会给出相似的、可重复的结果。 本文件没有指定特定的商业测试设备和相应的测试程序。 然而，为了方便用户，包含了一个信息性附件（见附件 A），旨在提供有关三种具体方法的一些实用信息： ——Lea 和 Nurse 方法，涉及可内置于实验室（见A.1）； ——张瑞福法，使用类似的测试装置（见A.2）； ——Gooden 和 Smith 方法，涉及可以在实验室中构建的测试设备，但也存在商业测试设备。 （存在两种类型的商业测试设备；其中一种不再可供购买，但仍在使用，参见 A.3。 ）这些方法仅作为示例给出。 各国可用的其他测试设备在本文件的范围内也是可接受的。 该测试方法适用于所有金属粉末，包括直径不超过 1000 µm 的硬质合金粉末，但通常用于直径在 0.2 µm 至 75,0 µm 之间的颗粒。 它不适用于由形状远离等轴的颗粒（即薄片或纤维）组成的粉末，除非有关各方之间特别同意。 本测试方法不适用于不同金属粉末的混合物或含有粘合剂或润滑剂的粉末。 如果粉末含有团聚体，则测量的表面积可能会受到团聚程度的影响。 如果粉末需要进行解聚处理（见附录B），所采用的方法应由有关各方商定。 [外文原描述]： This document specifies a method of measuring the air permeability and the porosity of a packed bed of metal powder, and of deriving therefrom the value of the envelope-specific surface area. The permeability is determined under steady-state flow conditions, using a laminar flow of air at a pressure near atmospheric. This document does not include the measurement of permeability by a constant volume method. Several different methods have been proposed for this determination, and several test devices are available commercially. They give similar, reproducible results, provided that the general instructions given in this document are respected, and the test parameters are identical. This document does not specify a particular commercial test device and corresponding test procedure. However, for the convenience of the user, an informative annex has been included (see Annex A) which is intended to give some practical information on three specific methods: — the Lea and Nurse method, involving a test device which can be built in a laboratory (see A.1); — the Zhang Ruifu method, using a similar test device (see A.2); — the Gooden and Smith method, involving a test device which can be built in a laboratory but for which a commercial test device also exists. (Two types of commercial test device exist; one of these is no longer available for purchase, but is still being used, see A.3.) These methods are given as examples only. Other test devices available in various countries are acceptable within the scope of this document. This testing method is applicable to all metallic powders, including powders for hardmetals, up to 1 000 µm in diameter, but it is generally used for particles having diameters between 0,2 µm and 75,0 µm. It is not intended to be used for powders composed of particles whose shape is far from equiaxial, i.e. flakes or fibres, unless specifically agreed upon between the parties concerned. This testing method is not applicable to mixtures of different metallic powders or powders containing binders or lubricant. If the powder contains agglomerates, the measured surface area can be affected by the degree of agglomeration. If the powder is subjected to a de-agglomeration treatment (see Annex B), the method used is to be agreed upon between the parties concerned.