Fluidized Bed Spray Coating for Improved Mechanical Properties of Particles

Abstract

When designing crash absorber particles for application as a filling material in the double-hull of ships, the main goal is to achieve an optimal mechanical performance, in combination with a low-density particle structure, while fulfilling several additional requirements regarding, for example, non-toxic and hydrophobic behavior. In this study, a fluidized bed was used to coat Poraver® glass particles with Candelilla wax and silicone to attain these specifications. A uniform coating was achieved with wax, but the process turned out to be far more challenging when using silicone. To evaluate the suitability of coated particles as a granular filling material, and to compare their performances with that of untreated Poraver® particles, several mechanical tests, as well as structural investigations, were conducted. While no notable improvement in mechanical behavior was observed on the single-particle level, bulk tests showed promising results regarding compressibility and abrasion resistance of coated particles compared to untreated ones.

Simulation of the mechanical behaviour of coated particles using DEM‐BPM

“…where 𝑓 exp and 𝑓 sim are vectors containing the function values from experiments and simulation at similar displacement values, respectively. The optimisation is done on experimental results from uniaxial single particle compression test found in [4]. Due to computational costs, the optimisation is done on a single particle.…”

“…The addition of an environmentally friendly coating on Poraver R increases complexity. Although it does improve the energy absorption capabilities of the particles to an extent, the scattering of results still remains [4]. Figure 1 highlights the microstructure of a wax coated Poraver R particle.…”

“…Once the optimisation is done on a single particle, the next step is to test the optimised numerical model in a multi particle compression test setting to determine its suitability in simulating the actual goal of simulating the compression of a ship double hull. The setup for the test is similar to experiments [4]. The results of compression of wax-coated Poraver R particles are depicted in Figure 8.…”

“…Consequently, the whole structure works like a sandwich plate. To further optimise the energy absorption and particle breakage under dynamic loads, a coating layer made of environmentally friendly material properties was added and the mechanical behaviour of coated and uncoated particles was compared [4]. The results show differences in breakage behaviour and energy absorbed depending on the type of coating.…”

Numerical investigation of multi‐particle interactions using the discrete element method

“…The idea of filling the double hull of a ship with granular material to increase collision safety has already been investigated in several papers [1][2][3][4]. Nevertheless, there are a number of open questions regarding the numerical simulation of the filling material and its behaviour during a compression.…”