Colloidal Analysis of Particles Extracted from Microalloyed Steels

Abstract

Different colloidal particle characterization methods are examined for their suitability to determine the particle size distribution of particles extracted from steels. Microalloyed steels are dissolved to extract niobium and titanium carbonitride particles that are important for the mechanical properties of these steels. Such particles have sizes ranging from several nanometers to hundreds of nanometers depending on the precipitation stage during the thermomechanically controlled rolling process. The size distribution of the particles is analyzed by dynamic light scattering (DLS), analytical ultracentrifugation (AUC), and hollow fiber flow field‐flow fractionation (HF5) and compared to data obtained for reference particles as well as data from electron microscopy, the standard sizing technique used in metallurgy today. AUC and HF5 provide high‐quality size distributions, average over large particle numbers that enables statistical analysis, and yield useful insights for alloy design; however, DLS fails due to a lack of resolution. Important aspects in the conversion and comparison of size distributions obtained for broadly distributed particle systems with different measurement principles and the role of surfactants used in sample preparation are discussed.

PEG-Lipids: Quantitative Study of Unimers and Aggregates Thereof by the Methods of Molecular Hydrodynamics

“…Together with the definition of [ s ] (eq ), we obtain the following expression for hydrodynamic diameters, d h , from sedimentation velocity experiments in AUC d normalh = 3 2 [ s ] υ false( f / f sph false) 3 / 2 For an ideal solid sphere, f / f sph values are obsolete in eq (i.e., f / f sph = 1) and d h values are those of a spherical particle sedimenting at the same speed as the objects under observation . In the literature, those are referred to as a sedimentation-equivalent hydrodynamic diameter since altered translational friction properties, due to hydration and/or shape anisotropy, are neglected. ,, …”

“… 26 In the literature, those are referred to as a sedimentation-equivalent hydrodynamic diameter since altered translational friction properties, due to hydration and/or shape anisotropy, are neglected. 26 , 41 , 42 …”

“…26 In the literature, those are referred to as a sedimentation-equivalent hydrodynamic diameter since altered translational friction properties, due to hydration and/or shape anisotropy, are neglected. 26,41,42 Hydration. At this point, it is worthwhile to take a closer look at f/f sph values, which are often referred to describe shape anisotropy, i.e., by the classical Perrin friction factor, P. 43 However, regarding the interpretation of f/f sph from sedimentation−diffusion analysis, one must consider hydration, δ AUC , of the objects under investigation 10,44…”