Investigation of the Structural Coating Homogeneity in Open‐Porous Nickel/Polyurethane Hybrid Foams Produced by Flow‐Controlled Electrodeposition

Novel cellular materials promise a combination of high strength and low specific weight for sustainable and energy‐efficient material design. Inhomogenieties of the materials such as varying coating thickness are inherent to the production process but require advanced characterization in order to better understand mechanical properties. In this work, we studied global and local acoustic analysis for nondestructive characterization of local coating thickness on an open‐porous hybrid metal foam system. Experiments and numerical simulations were carried out to evaluate vibration behavior stimulated by a low energy impact. The novelty of our work is the use of local excitation and analysis of decay times to determine coating thickness gradients. This qualitative measurement can inform and speed up the material development process due to its simplicity, speed and low cost. Furthermore, it provides a basis quality control when scaling up the technology of metal hybrid foams for industrial applications.This article is protected by copyright. All rights reserved.

Evaluation of a Local Acoustic Resonance Method for Coating Thickness Determination on Stochastic Metal Hybrid Foams

Kollmannsperger,

Kunz,

Becker

et al. 2024

Remanent Magnetic Field Scanning of Coating‐Graded Hybrid Foams

Kunz,

Ibrahim,

Becker

et al. 2024

The manufacturing of hybrid materials such as nickel/polyurethane (Ni/PU) hybrid foams and 3D printed hybrid materials with the aid of electrochemical coating of lightweight structures leads to new materials, which can be used as crash absorbers, but also for lightweight design applications. Optimizing the coating quality of the developed hybrid materials necessitates a characterisation on different scales regarding the coating thickness distribution. The ferromagnetic properties of the nickel coating enable a remanent magnetization of the produced hybrid foams and a subsequent measurement of resulting magnetic fields, so that the time‐consumption of a coating distribution determination could be enormously reduced by automating the quantification method. Previous studies have shown, that the local strength of these fields correlate with the deposited mass thus the coating thickness. The here presented automated measurement gives useful information about the homogeneity and the local coating thickness distribution according to an appropriate calibration. In order to optimise the coating quality of the newly developed hybrid materials, improved deposition conditions as well as semi‐automated characterization methods are studied to establish a large‐scale industrial production and a higher applicability of hybrid materials in the near future.This article is protected by copyright. All rights reserved.

Influence of Heat Treatment on Microstructure Evolution and Yield Surfaces of Ni/PU Hybrid Foams

Fries,

Schäfer,

Janka

et al. 2024

Metal foams are characterized by low weight, high resource efficiency, high relative stiffness and exceptional energy absorption capacity under compressive load. Nickel/polyurethane (Ni/PU) hybrid foams consist of an open‐cell polyurethane foam coated with a layer of nickel produced by electrochemical deposition. The coating of the polyurethane foams takes place in a flow reactor, in which the electrolyte is pumped through the foam at a defined flow velocity. The macromechanical properties of foam‐like structures depend on the structure of the skeleton, the inherent material properties and, in the case of Ni/PU hybrid foams, the properties of the electrochemically generated nickel layer. To influence their mechanical properties, the Ni/PU hybrid foams are subjected to heat treatment. In the given experimental setup, the parameters flow velocity, temperature and duration of the heat treatment are each investigated at two different levels. Thus, interactions between the initial microstructure and the type of heat treatment are evaluated by means of X‐ray diffraction (XRD) and electron backscatter diffraction (EBSD) measurements. Interactions between initial mechanical properties and heat treatment are investigated by uniaxial compression tests and superimposed compression‐torsion tests. The knowledge gained is used to control the macromechanical properties of the hybrid foam.This article is protected by copyright. All rights reserved.