With the rapid development of aerospace and rail transit, there is an urgent demand for lightweight materials with good mechanical and damping properties. The use of structural and functional integrated materials to make mechanical parts can achieve weight reduction and vibration reduction, which is conducive to improving the mobility and accuracy of equipment. In addition, some devices are exposed to environments with varying temperatures and frequencies, which require materials that are suitable for a wide range of temperatures and frequencies while having a high vibration damping effect. However, the internal structural features that produce high damping capacity (movable defects) are inverted to the mechanisms that produce good mechanical properties (immovable defects). Therefore, in the traditional damping material design concept, high damping and high strength are often mutually exclusive.
Recently, Professor Li Zhou and Professor Gong Shen from the School of Materials Science and Engineering, Central South University, proposed a dual-scale interpenetrating network design strategy, and developed dual-scale CrMnFeCoNi/polymer interpenetrating phase composites (IPCs). At the macroscopic scale, a composite of carbon nanotubes (CrMnFeCoNi@CNTs) supported with CrMnFeCoNi nanoalloy and polyurethane/epoxy resin interpenetrating polymer network (PU/EP IPN) was infiltrated into the connected pores with Cr20Mn20Fe20Co35Ni5 (at.%) high-entropy shape memory alloy (HESMA) foam with thermoelastic martensitic phase transition and connected pores to form HESMA foam. Polymer interpenetrating network structure. The structure can not only effectively reduce the weight of the damping alloy, but also make up for the shortcomings of low strength and poor dimensional stability of the polymer, and also form a high-density interface between the interpenetrating phases. In addition, the structural integrity and continuity of HESMA and polymers allow them to exert their respective damping mechanisms to achieve high damping capabilities over a wide frequency and temperature range by superimposing multiple dampings. At the microscopic scale, the formation of a high-entropy nanoalloy/CNT/polymer interpenetrating network structure can greatly increase the internal interface of the polymer, improve its stiffness and strength, broaden its damping temperature range, and form a connected thermal conductivity network in the polymer to improve the heat dissipation capacity.
这项研究不仅对减振降噪应用具有吸引力，而且提供了一个新的设计理念和制造方法，可以应用于其他材料体系以提高性能。 相关工作以“Constructing dual-scale high-entropy alloy/polymer interpenetrating networks to develop a lightweight composite with high strength and excellent damping capacity”为题发表在国际著名期刊《Chemical Engineering Journal》上。
Figure 1: Synthesis of biscale CrMnFeCoNi/polymer IPCs
Fig.2 (a) Compressive stress-strain curves at room temperature, (b) energy absorption capacity and efficiency, (c) storage modulus and loss factor at room temperature and in the frequency domain of 0.1~200 Hz, (d) storage modulus and loss factor at 20 to 150°C during heating at 200 Hz and (e) comprehensive performance data of 1-6# sample; Polymer IPCs and other publications have reported (f) loss factors and specific strengths, and (g) damping temperature windows for porous materials and IPCs
Fig.3 (a) DSC curve, (b) SEM image, (c) EDS element map, (d) X-ray microscope image, (e) reconstructed 3D microscopic image, (f) reconstructed 3D pore structure, (g) ball and stick model simulation results of pore network, (h) pore size distribution, (i) throat connection number distribution, (j) throat diameter distribution and (k) throat length distribution
Fig.4 (a) room-temperature XRD spectra, EBSD (b) grain boundary map, (c) IPF map, (d) phase distribution map, (e) TEM image away from the pore and (f-h) pore edge (the inset in g shows the SAED pattern in the contour region), (i) the HRTEM image of the I region (the inset is the FFT pattern), the (j) HRTEM image and (k) the FFT pattern in the J region
Fig. 5 (a) Room temperature XRD spectra of CNTs and CrMnFeCoNi@CNTs, (b) TEM images of CNTs, (c, d) TEM images of CrMnFeCoNi@CNTs, (e-g) HRTEM images, (h) FFT patterns, and (i) HAADF images and EDS element plots
Fig.6 (a) TEM image, (b-d) HRTEM image, (e) SAED pattern and (f) HAADF image and EDS element diagram of the microscale CrMnFeCoNi@CNT/polymer interpenetrating network
Fig.7 (a) Schematic diagram of multiple damping mechanisms at multiple scales in bi-scale CrMnFeCoNi/polymer IPCs, (b) schematic diagram of modeling, (c) stress analysis diagram, (d) experimental and simulated values of loss factors of 1-6# samples (inset is the total area of the interface) ;(e) proportion of strain energy loss of each phase in 1-6# samples, (f) macroscopic scale CrMnFeCoNi/polymer interpenetrating network and (g) in bi-scale CrMnFeCoNi/polymer IPC-2 Decomposition results of micro-scale CrMnFeCoNi@CNT/polymer interpenetrating network with multiple damping mechanisms in the temperature range of 20~150°C
In summary, this study reports dual-scale CrMnFeCoNi/polymer IPCs with high strength and excellent damping ability. Among them, the compressive strength and energy absorption capacity of dual-scale CrMnFeCoNi/polymer IPC-2 are 37.2 MPa and 22.5 MJ·m-3 (ε=65%), respectively, and the density is only 2.528 g·cm-3. In the wide temperature range of 20~150°C, the loss factor is greater than 0.132, and the peak value can reach 0.206. Compared with CrMnFeCoNi foam, its compressive strength, energy absorption capacity and internal friction peak value are increased by 85%, 65% and 156%, respectively, and its excellent mechanical and damping properties are considered to be the result of the design of the dual-scale interpenetrating network structure. Firstly, the complex topology of three-dimensional interconnection and interweaving between the phases is conducive to the internal stress transfer of the composite, increasing the deformation coordination and strengthening effect, and improving the strength and energy absorption capacity of the composite. Secondly, the high-density interface introduced by the dual-scale interpenetrating network structure can effectively increase the interface damping. The results of the three-phase micromechanical model show that the coupling of multi-scale intrinsic damping (CrMnFeCoNi foam, polymer and CrMnFeCoNi@CNTs) and multi-scale interface damping (CrMnFeCoNi foam/polymer and CrMnFeCoNi@CNTs/polymer) gives the composites high ground state damping. In addition, the introduction of CrMnFeCoNi@CNTs broadens the glass transition peaks of the polymer. The superposition of the ε→γ inverse martensitic phase transition peak of CrMnFeCoNi foam and the glass transition peak of the polymer composite matrix makes the composite material have high damping ability in a wide temperature range. This combination of low density, high strength, and excellent damping ability makes the composite a candidate for impact and vibration and weight reduction applications.
Paper Links:
https://doi.org/10.1016/j.cej.2024.151222 Source: Frontiers of Polymer Science