Materialwissenschaft und Werkstofftechnik最新文献

After magnetization, the magnetic loss of FeSiAl/SrFe₁₂O₁₉ (SrM) soft magnetic composite is greatly reduced compared with that before magnetization, which has similar effect with FeSiAl magnetic powder core with applied external transverse magnetic field. The experimental results show that the internal bias field provided by SrM ferrite after magnetization increases the average domain size, reduces the number of domain walls and the displacement of domain walls, thereby effectively reducing the hysteresis loss. When the content of SrM ferrite is 8.1 wt.-%, the magnetic loss is reduced by about 50 %, and the overall performance is the best.

The hot compression experiments were performed at a deformation temperature of 720 °C to 870 °C and a strain rate of 0.0005 s⁻¹ to 5 s⁻¹. The strain-compensated Arrhenius constitutive equation and the hot processing map at a strain of 0.6 were established, and the dynamic recrystallization behaviors of the alloy in different power dissipation (η) regions were studied. The results show that the correlation coefficient (R) and average relative errors (AARE) of the established constitutive equations are 0.999 % and 2.523 % in the β phase region, and 0.988 % and 7.709 % in the α+β phase region, respectively. The hot processing map shows that the deformation parameters in the high power dissipation regions range from 810 °C to 870 °C/0.0005 s⁻¹ to 0.005 s⁻¹, accompanied by a power dissipation factor of 0.41 to 0.55. These regions result from a combination of continuous and discontinuous recrystallization mechanisms. With the decrease in the power dissipation value, the appearance of deformation bands (DBs) and localized flow (FL) in the microstructure increased.

Glass dust particles, generated in glass cutting industries as a process waste possess health risk and serious environmental issues. This paper essentially reports on exploring the possibility of using this waste glass dust as particulate filler in two different natural fibers (hemp/flax) reinforced polymer composites. Such composites are prepared by hand lay-up route, varying weight percentages of waste glass dust from 0 to 20. The physical and mechanical characterizations are evaluated experimentally. X-ray diffractogram analysis reveals the degree of crystallinity of the composites and the phases present in the raw filler. With the incorporation of waste glass dust, the flexural strength, inter-laminar shear stress and micro-hardness of the composites are improved up to about 52 %, 44 % and 20 % respectively. On the contrary, tensile and impact strengths tend to decrease about 32 % and 17 % with filler content. Using scanning electron microscopy, the possible mechanisms such as fiber-matrix de-bonding, fiber-pullout, matrix crack and rupture etc. are identified for failures of the composites under tensile, flexural and impact loadings. With low crystallinity and fairly good mechanical properties, these hybrid composites can have potential use in thermal insulations and low-load engineering applications.

For years, coated metal sheets have been used in cookware manufacturing. This paper focuses on employing experimental and numerical analyses to determine the quality and formability of commercially available polytetrafluoroethylene (PTFE)-coated aluminium sheets. For this purpose, examinations of the coating‘s microstructure, hardness, and friction coefficient through nano-indentation and scratch tests, were investigated. Tensile test was performed to obtain some mechanical characteristics of the coated aluminium sheets. Moreover, the forming limit curve for the studied material was established by conducting Nakazima test, covering both negative and positive domains of minor strain. The influence of sheet thickness on formability was investigated since using 2 mm and 1 mm thick sheets in this work. Finally, the limits of deep drawing process using the finite element method with Abaqus software was studied.

Numerous papers have been reported on surface treatment of metallic implant to facilitate positive interaction between the implant and hard tissue interface. In this paper, surface treatment such as chemical etching was done on the biomedical grade cobalt-based alloy prior to hydroxyapatite coating deposition to enhance its biocompatibility. The objective is to investigate which temperature possesses the positive effect in adhesion strength of hydroxyapatite coating without detrimental the surface hardness. Observation showed that acid etched at the highest temperature (80 °C) has successfully roughen the substrate surface from 0.168 μm ±0.1 μm to 1.383 μm ±0.2 μm. Vickers hardness measurement on surface treated at 80 °C exhibit an increment of surface hardness which is about 39 % compared to surface treated at lower temperature. The highest thickness of hydroxyapatite coating layer (~57 μm) was evidently formed on the substrate etched at 80 °C with minimal cracks and no delamination. This phenomenon happened due to chemical reaction were rigorously attack on the substrate surface have provide more micro-pits, pores and deeper craters that trap more efficiently of hydroxyapatite particles for thicker and dense coating formation. It is worth to note that too long acid soaking will also detrimental the material properties.

In this study, the effects of reinforcement ratio, drill bit material, and drilling process parameters on the cutting forces generated during the drilling of glass sphere-reinforced polypropylene composites were investigated experimentally. Test specimens were produced by conventional injection-moulding of glass sphere reinforced polypropylene composite materials at 5 %, 10 % and 20 % wt. ratios. High speed steel, titanium-coated high-speed steel, and carbide drill bits with 4 mm diameter were preferred for drilling. In addition, the drilling process was carried out on a 3-axis computer numeric control milling machine. Three different feed rates of 0.05 mm/rev, 0.10 mm/rev, and 0.15 mm/rev and cutting speeds of 12 m⋅min⁻¹, 16 m⋅min⁻¹, and 20 m⋅min⁻¹ were determined for the drilling process. In addition, Taguchi experimental optimization method, analysis of variance and scanning electron microscopy were used to investigate the morphology of the drilled surface and the wear mechanisms occurring on the drill bit due to the drilling process. The test findings showed that the maximum torque value was 54.64 N⋅mm and the maximum thrust force was 100.43 N. The optimum test parameter for cutting forces was observed as C1D3FR1CS3. Drill parameter had an effect of 40.96 % on thrust force and 36.11 % on torque.

The main aim of this investigation is to fabricate aluminum 6061 composites with three different weight percentages of ferric oxide grade alumino silicate cenosphere (1 wt.%, 3 wt.%, and wt.%) by the stir-casting process. The fabricated cast composite and T6 heat-treated composite is used to obtain a fundamental understanding of various weight percentages of the cenosphere and the influence of heat treatment on the microstructural changes, mechanical characteristics, the mechanism of fracture, and the interface between the aluminum-matrix and ferric oxide grade alumino-silicate cenosphere particulates. Tensile and compressive tests with a constant strain rate (0.5 mm ⋅ min⁻¹) were carried out to study the strength and to find a correlation between the various weight fractions of cenosphere and heat treatment. Investigations of the changes in the microstructure of the aluminum ferric oxide grade alumino silicate cenosphere composite and the fractography of the fracture surface are investigated using optical and scanning electron microscope. X-ray diffraction was utilized to confirm the results obtained from optical and scanning electron microscope analyses for phase characterization validation. A maximum of 30 % increase in hardness value, 20 % increase in tensile strength value, 33 % increase in maximum compressive strength value, and 2 % increase in elongation values are observed in heat-treated composite when compared to cast composite.