Materials Science Forum Vol. 1066

Abstract: In this paper, the simulated welding structure at different areas of heat affected zone (HAZ) of austenitic stainless steel are prepared by heating furnace, and the deference of intergranular corrosion resistance of all samples were determined by comparative methods of oxalic acid etching, hot-acid test and electrochemical potentiodynamic reactivation tests (EPR), and the effectiveness of all those methods were analysis and determination at the same time. The result shows that the susceptibility degree at different areas of HAZ increased with the heating temperature increase, but all structures can pass hot-acid test and EPR test, indicating that it could maintain good performance of intergranular corrosion resistance. The hot-acid test results have good consistency with EPR test , but inconsistent with oxalic acid etching test. The results show that the evaluation of oxalic acid etching is too much strict to be used as a judgment method, so that not suitable of use for inspection.

Abstract: The motion of a rigid sphere located at tissue-mimicking material interface in response to a dynamic force of short duration for the purpose of the determination of material viscoelastic properties was investigated in this study. The experiments were performed using a rigid sphere located at tissue-like material (gelatin phantom) interfaces. An electromagnet was used to apply the desired dynamic force to the sphere and a high-speed camera was used to track the movement of the sphere. Using the experimentally measured response of the sphere and the dynamic response of the sphere predicted by a sophisticated analytical model of the sphere located at a medium interface, the shear modulus, density and damping of the tissue-mimicking material were determined. The procedure followed in this study successfully produced the shear modulus, density and viscous damping ratio of the 20% (and 30%) gelation phantom as 1320 Pa, 1040 kg/m³ and 0.12 (and 2580 Pa, 1180 kg/m³ and 0.2), respectively. As the sophisticated theoretical model that is valid for small and large sphere displacements includes many parameters for the system such as the mass and size of the sphere, the inertia force of the medium involved in motion and the radiation damping due to shear waves and the experimental setup is very straightforward, it is believed that the procedure proposed in this study can be widely exploited to identify accurate material viscoelastic properties in practice.

Abstract: This study investigates the effect of the metal matrix composition of the friction material on the pre-sintering process through a simulation experiment on the Sprinkle sintering process. No segregation in the pre-sintered microstructure of the free-deposited friction material powder and no cracks are observed at the interface with the steel plate. In the case of a brass composition containing Zn and trace elements having relatively high vapor pressure, expansion occurs due to the volatilization of the composition elements during pre-sintering. On the contrary, in the case of bronze-based powder, the effect is insignificant. Therefore, when the friction material is manufactured using the sprinkle sintering method, the matrix composition must be selected in consideration of the volatilization effect of the metal matrix element.

Abstract: In previous studies, it has been verified that the magnetic abrasive finishing process using alternating magnetic field can achieve higher finishing efficiency and surface quality, and nanolevel finishing of 5052 aluminum alloy material and SUS304 stainless steel material has been realized. In this study, the feasibility for ultra-precision finishing of polychlorotrifluoroethylene resin by this process was investigated, and the cutting mechanism of particles was discussed. As a result, the cutting depth of the particles is mainly affected by the size of the magnetic particles and abrasive particles. According to the experimental results, under optimized experimental conditions, the surface roughness of the workpiece can be improved from 112.83 nm Ra to 5 nm Ra within 15 minutes.

Abstract: The impact of COVID-19 crisis on global supply chains caused a critical shortage of essential goods like medical devices. Additionally, massive consumption increased mask contamination and waste. 3D printing has become a fast and versatile manufacturing alternative that prevents a single use of masks. However, SARS-CoV-2 virus can persist on plastic surfaces for days. This study proposes the optimization of 3D printed masks, by applying a coating rich in hydrolyzable tannins and copper, in order to diminish the virus presence. Different paints were formulated with copper tannate and applied on thermoplastic polyurethane 3D panels to test bacterial stability. Results showed a significant reduction of colony-forming units on coated polymeric surfaces. Paints pigmented with copper tannates could improve the protection provided by printed masks, even against the COVID-19 virus.

Abstract: Polypropylene (PP) is a promising material for extrusion-based additive manufacturing due to its low cost, chemical resistance, good mechanical properties, versatile, and can be applied in various industrial applications. Recent research has focused on addressing the warpage issue in 3D printing of PP filaments. The effect of environmental conditions and loading of nanoprecipitated calcium carbonate (NPCC) in the pristine polypropylene to decrease warpage using the Fused Deposition Modelling (FDM) printing technology was studied. PP-NPCC composite filaments containing 5, 10, and 15 NPCC (wt%) were prepared using the twin-screw extruder. The printability, physicochemical, and mechanical properties of the PP-NPCC blends were determined. Based on the results, the incorporation of NPCC has contributed to the improvement of 3D printability and warpage in the PP-NPCC composite. At controlled environmental conditions, the filament was printable and the warpage was decreased by 44% at 10% NPCC loading. At the same concentration, there was a 30% increase in compressive strength and 43% increase in elastic modulus of the 3D printed parts.

Abstract: Self-healing capable of storing two or more solutions is proposed to heal cracks by manufacturing capsules with a 3D printer to enable structural design, repeatable fabrication, and strength analysis. The Fusion Deposition Modeling (FDM) method was used to design, analyze, and produce new, widely used self-healing capsules at low cost. However, since the PLA extruded from FDM has low interlayer adhesion energy, the strength varies depending on the load angle applied to the laminated surface and concrete structure, which degrades the performance of the self-healing capsule. Therefore, this paper designed a structure with isotropic strength by controlling the direction and number of solution injection ports of capsules manufactured by the FDM PLA method. In addition, the intensity isotropy of the load applied through the compression test and ANSYS in the x, y, and z directions were verified. As a result, as the arrangement and number of holes were different, the standard deviation of strength according to the direction decreased by 24%.

Abstract: Titanium dioxide (TiO₂) nanoparticles were immobilized on the surface of 14% TIPP/PVP membranes by (1) dip coating the membrane in the powdered nanoparticles and (2) dip coating the membranes in PAN/DMF solution containing the nanoparticles. The composite membranes were then used for the photocatalytic degradation of Allura Red (AR) dye. The effect of the presence of PAN/DMF, the initial dye concentration, and irradiation time was investigated. The extent of photocatalytic degradation was observed by measuring the absorbance of the solution using a UV-Vis spectrophotometer. The presence of PAN/DMF allowed more TiO₂ nanoparticles to adhere to the surface of the membrane. The membrane with PAN/DMF/TiO₂ has greater degradation efficiency across all concentrations used than the membrane without PAN/DMF. In the same membrane, the degradation efficiency increased as the initial dye concentration increased from 0.0008 mg/g AR to 0.004 mg/g AR. However, a further increase to 0.008 mg/g decreased the degradation efficiency. On the other hand, the membrane without PAN/DMF decreased its degradation efficiency as the concentration increased. The degradation efficiency increases with irradiation time but reaches equilibrium after 120 minutes. The experimental data for the membrane with PAN/DMF/TiO₂ followed the Langmuir-Hinshelwood (L-H) rate form with a rate constant of 0.0253 min-1. The membrane can be reused up to 10 times at 0.0008 mg/g dye concentrations but with reduced degradation efficiency values on the extent of membrane photocatalyst reusability.

Abstract: The objective of this work is the valorization of certain local clays by their use in the treatment of waste water. For this, we have improved the surface properties of a natural Algerian Clay from the west of Algeria from the deposit of ghousel (Maghnia). The treatments carried out are the following: physical and chemical. The prepared material (calcined and activated) was characterized by infrared spectroscopy, measurement of the cation exchange capacity, specific surface and by measuring the pH (pzc). Then, the clay used is applied to the adsorption of an industrial dye (yellow bemacid) in aqueous solution. The quantitative analysis of the dye was followed by UV-Visible spectrophotometer, this analysis allows to determine the best conditions that favor the adsorption such as contact time, adsorbate concentration, adsorbent mass, solution pH and temperature.

Abstract: The interaction between small molecules and fullerene C₆₀ has been analyzed using a quantum-mechanics-based DFT calculation. The small molecules are H_2, H₂O, NH₃, O₂, and O₃. Each molecule is put inside and outside C₆₀. Interaction of small molecules with C₆₀ is observed by calculating the inclusion and adsorption energies. We find that C₆₀ with H₂ and H₂O has negative inclusion energies. The inclusion energies of H₂ and H₂O are -0,02 eV and -0,01 eV, respectively, indicating that H₂ and H₂O are stabilized inside the C₆₀. For system outside C_60, interaction between O₂ and O₃ with C₆₀ has negative adsorption energies_. The adsorption energy of O₂ and O₃ are-0,07 eV and-2,10 eV, respectively, indicating that O₂ and O₃ are chemisorbed, which are easily bonded by C₆₀.