Michał Budka

This study presents a manufacturing route for pre-impregnated functional powder coatings (PCs) intended for fibre-reinforced polymer (FRP) composites, including vacuum-infused sandwich structures. PCs comprising powder, thermoplastic nonwoven and twill glass fabric were produced by a two-stage heat-pressing process. Ceramic, mineral and metallic powders were investigated. Uniaxial tensile tests with digital image correlation and three-point bending tests of PC-integrated sandwich composites were supported by finite element analyses of representative volume elements. Powder layers were parametrically generated in CadQuery for F24, F30 and F36 grains with ellipsoidal or sharp-edged geometries. The powder and thermoplastic layers markedly affected tensile stiffness and deformation. Apparent Young’s moduli ranged from 3.8 to 8.1 GPa, compared with 11.7–14.3 GPa for reference specimens. Manufacturing-induced curvature and an atypical transverse response were attributed to the asymmetric layered architecture. All sandwich variants reached similar maximum bending loads of 0.93–0.96 kN, while absorbed energy ranged from 7.2 to 9.1 J. RVE simulations showed that grain size affected local stress, strain and displacement fields. The method enables repeatable manufacture of thin, modular functional layers and their integration with composites without applying loose powder during moulding.

This article presents the manufacturing technology and mechanical properties of innovative pre-impregnated coatings (PCs). The base materials for PC are powders of metal oxides, non-metals, minerals and thermoplastic non-wovens. PC can be used in the manufacture of composites by methods such as vacuum infusion, autoclave curing or hand lamination. This is possible due to the novel PC structure consisting of a functional layer (FL) and a backing layer (BL). PCs are flexible so that they can be used on curved surfaces. In this work, five types of PC were subjected to a uniaxial tensile test. Depending on the powder used, failure force values ranging from 24.61 N to 28.73 N were obtained. In the next step, the pre-impregnated coatings were applied as a coating in “sandwich” composites made by vacuum infusion, which were subjected to three-point bending (3-PB) and adhesion tests. 3-PB tests proved that the coating remained integral with the substrate, even under high flexural deformation, while the adhesion achieved was in the range of 0.95 MPa to 1.57 MPa. PC can be used in many engineering products, e.g., for the coating of façade panels, roof tiles, automotive parts or rail vehicles, etc.

This paper presents the results of laboratory tests for new materials made of a carbon fibre-reinforced polymer (CFRP) composite with a single-sided protective coating. The protective coatings were made of five different powders—Al2O3, aluminium, quartz sand, crystalline silica and copper—laminated in a single process during curing of the prepreg substrate with an epoxy matrix. The specimens were subjected to flame exposure and solid particle erosion tests, followed by uniaxial tensile tests. A digital image correlation (DIC) system was used to observe the damage location and deformation of the specimens. All coatings subjected to solid particle erosion allowed an increase in tensile failure force ranging from 5% to 31% compared to reference specimens made of purely CFRP. When exposed to flame, only three of the five materials tested, Al2O3, aluminium, quartz sand, could be used to protect the surface, which allowed an increase in tensile failure force of 5.6%.