ISO 20998-2:2013 用声学方法测量和描述微粒 第2部分：线性理论指南

标准编号：ISO 20998-2:2013

中文名称：用声学方法测量和描述微粒 第2部分：线性理论指南

英文名称：Measurement and characterization of particles by acoustic methods — Part 2: Guidelines for linear theory

发布日期：2013-08

标准范围

ISO 20998-2:2013描述了超声衰减光谱法，用于测定稀释浓度下分散在液体中的颗粒相的尺寸分布，其中超声衰减光谱是颗粒体积分数的线性函数。在这种情况下，粒子？粒子间的相互作用可以忽略不计。胶体、稀释分散体和乳液在ISO 20998-2:2013的范围内。此类分析的典型粒度范围为10 nm至3 mm，但也成功测量了该范围之外的颗粒。对于悬浮液中的固体颗粒，可在0.1%体积分数至5%体积分数的浓度范围内进行尺寸测量，具体取决于固相和液相之间的密度对比、颗粒尺寸和频率范围。对于乳液，可在更高浓度下进行测量。这些超声波方法可用于监测粒度分布的动态变化。虽然可以根据衰减谱或相速度谱确定粒度分布，但建议仅使用衰减数据。与平均速度相比，由于颗粒尺寸变化而导致的相速度的相对变化很小，因此通常很难高精度地确定相速度，尤其是在环境温度下。同样，不建议结合使用衰减谱和速度谱来确定颗粒大小。振幅和相位谱中存在测量误差（即“噪声”）会增加问题的不适定性，并降低反演的稳定性。

ISO 20998-2:2013 describes ultrasonic attenuation spectroscopy methods for determining the size distributions of a particulate phase dispersed in a liquid at dilute concentrations, where the ultrasonic attenuation spectrum is a linear function of the particle volume fraction. In this regime, particle?particle interactions are negligible. Colloids, dilute dispersions, and emulsions are within the scope of ISO 20998-2:2013. The typical particle size for such analysis ranges from 10 nm to 3 mm, although particles outside this range have also been successfully measured. For solid particles in suspension, size measurements can be made at concentrations typically ranging from 0,1 % volume fraction up to 5 % volume fraction, depending on the density contrast between the solid and liquid phases, the particle size, and the frequency range.For emulsions, measurements may be made at much higher concentrations. These ultrasonic methods can be used to monitor dynamic changes in the size distribution.While it is possible to determine the particle size distribution from either the attenuation spectrum or the phase velocity spectrum, the use of attenuation data alone is recommended. The relative variation in phase velocity due to changing particle size is small compared to the mean velocity, so it is often difficult to determine the phase velocity with a high degree of accuracy, particularly at ambient temperature. Likewise, the combined use of attenuation and velocity spectra to determine the particle size is not recommended. The presence of measurement errors (i.e. "noise") in the magnitude and phase spectra can increase the ill-posed nature of the problem and reduce the stability of the inversion.

标准预览图