Experimental Study for the Stripping of PTFE Coatings on Al-Mg Substrates Using Dry Abrasive Materials

Recycling of diaper wastes for a triboelectric nanogenerator-based weather station

Escalating concerns over waste management and the need for sustainable energy have prompted innovative solutions at the nexus of resource recycling and self-powered applications. This study presents a novel approach to recycling super-absorbing polymer (SAP) gels from waste diapers and discarded baking sheets to fabricate a diaper waste-based triboelectric nanogenerator (DW-TENG). The DW-TENG, resembling a maraca, demonstrated superior electrical performance with a voltage output of 110 V, a current of 9 μA, and a power of 259.15 μW. It was successfully integrated into a self-powered weather station for real-time monitoring of wind speed, humidity, and temperature. This research underscores the dual benefits of waste management and energy generation, representing a promising step toward a circular and sustainable future.

Method of Stamping the Progression of a Beverage End Rivet of a Thinner Sheet of AW-5182 Alloy

This paper presents a new solution for shaping the rivet progression of a beverage end. The classic method uses three operations to press the cylindrical rivet using 0.208 mm and 0.203 mm thick sheets. The increasing demand for aluminium alloys is prompting measures to make more efficient use of this raw material. One possible solution is to produce packaging from ever thinner sheets. This requires the design of new tooling and the preparation of an appropriate technological process. A method has been developed to stamp a hexagonal-shaped rivet from 0.200 mm thick sheet metal, increasing the number of stamping operations to four. The proposed method was verified through a numerical analysis using the PAM STAMP 2022.0 software package. It was found that for appropriately shaped tools, sheet thicknesses of the stamped component could be achieved that were not less than those for the currently used technology, thus eliminating any possible break in the material structure. Suitable tools and experimental stamping tests were carried out for the developed process. In the simulations, the material Al5182_iso_Xmm was adopted from the programme database, while the experiments were performed on a laboratory press using AW-5182-H48 sheets with a thickness of 0.200 mm. The purpose of the study was to determine the validity for the proposed method of forming the rivet of the beverage end.

Analysis of Wear Phenomena Produced by Erosion with Abrasive Particles against Fluoropolymeric Coatings

To date, PTFE, PFA, and FEP-based fluoropolymer coatings have proven unbeatable in many services due to their excellent chemical inertness, very low wettability, thermal resistance, high non-stick properties, and good applicability. In use, these coatings usually suffer service cycles with consequent deterioration, and it is of great interest to determine the intensity and type of wear caused in addition to the deterioration that occurs in their properties. In this work, the response of three polymeric coatings of interest applied to aluminum substrates, after being subjected to the action of abrasive particles of aluminum corundum, glass, and plastic projected under pressure, has been studied. During the application of a given wear cycle, the hardness, surface roughness, surface texture, and thickness of the coating have been measured, in addition to the slip angle and surface transmittance to analyze the evolution of each type of coating. The results allowed a concise evaluation of the performance of three fluoropolymeric coatings of great interest, differentiating the induced erosive wear phenomena and contributing complete information to facilitate the correct selection for users with practical application purposes and as a basis for future research work focused on advancements in this field.

Fluorinated Ethylene Propylene Coatings Deposited by a Spray Process: Mechanical Properties, Scratch and Wear Behavior

To increase the lifetime of metallic molds and protect their surface from wear, a fluorinated ethylene propylene (FEP) polymer was coated onto a stainless-steel (SS304) substrate, using an air spray process followed by a heat treatment. The microstructural properties of the coating were studied using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) as well as X-ray diffraction. The mechanical properties and adhesion behavior were analyzed via a nanoindentation test and progressive scratching. According to the results, the FEP coating had a smooth and dense microstructure. The mechanical properties of the coatings, i.e., the hardness and Young’s modulus, were 57 ± 2.35 and 1.56 ± 0.07 GPa, respectively. During scratching, successive delamination stages (initiation, expansion, and propagation) were noticed, and the measured critical loads L_C1 (3.36 N), L_C2 (6.2 N), and L_C3 (7.6 N) indicated a high adhesion of the FEP coating to SS304. The detailed wear behavior and related damage mechanisms of the FEP coating were investigated employing a multi-pass scratch test and SEM in various sliding conditions. It was found that the wear volume increased with an increase in applied load and sliding velocity. Moreover, the FEP coating revealed a low friction coefficient (around 0.13) and a low wear coefficient (3.1 × 10⁻⁴ mm³ N m⁻¹). The investigation of the damage mechanisms of the FEP coating showed a viscoelastic plastic deformation related to FEP ductility. Finally, the coating’s resistance to corrosion was examined using electrochemical measurements in a 3.5 wt% NaCl solution. The coating was found to provide satisfactory corrosion protection to the SS304 substrate, as no corrosion was observed after 60 days of immersion.