Microstructure

The oxidation kinetics and microstructure characteristics of oxide scales thermally grown on the surface of developed FeCr alloy were investigated at 900 °C. The influence of difference sintering technique, i.e. spark plasma sintering and hot pressing, to improve nanostructured alloy performance was studied. The La-implantation was also considered in this study. It was found that the SPS sintered sample showed better performance than the HP sintered sample. Moreover, it also found that a combining of La-implantation and nanostructured alloy was most beneficial. While nanostructured alloy reduced the oxidation rate, the La-implantation increased the Cr2O3 scale conductivity.

The effect of α-Al2O3 nanoparticles (up to 5 wt.%) on the physical, mechanical, and thermal properties, as well as on the microstructural evolution of a dense magnesia refractory is studied. Sintering temperatures at 1300, 1500, and 1600 °C are used. The physical properties of interest were bulk density and apparent porosity, which were evaluated by the Archimedes method. Thermal properties were examined by differential scanning calorimetry. The mechanical behavior was studied by cold crushing strength and microhardness tests. Finally, the microstructure and mineralogical qualitative characteristics were studied by scanning electron microscopy and X-ray diffraction, respectively. Increasing the sintering temperature resulted in improved density and reduced apparent porosity. However, as the α-Al2O3 nanoparticle content increased, the density and microhardness decreased. Microstructural observations showed that the presence of α-Al2O3 nanoparticles in the magnesia matrix induced the ...

Spruce wood (picea abis) has been widely used as structural element, from buildings to musical instruments, due to its outstanding mechanical performances. The main stem transverse section exhibits growth rings formed by periodic fringes patterns, which are constituted by lamellae‐tracheid arrangements. In order to improve the understanding of each wood microstructure role, the morphology and crystallinity of earlywood and latewood fibers were examined mainly using scanning electron microscopy, atomic force microscopy, and X‐ray difracction. Moreover, measurements of effective elastic modulus and hardness were obtained by nanoindentation tests using a Berkovich indenter in order to confirmed increase in compactness of the wood microstructures. The results indicate that variations in mechanical properties values can be associated with well defined microstructural performances for each characteristic fiber type, where those that belong to latewood fiber showed the most improved behavi...

The peculiarities in structure formation of interfacial zones at the composite’s boundaries between the molten Fe–C–B–P–Mo matrix and the filler’s solid phases of W2C and WC that have microcrystalline structure were investigated in this work. The structure of the interfaces was studied by methods of metallographic and automatized quantitative analyses. The interfaces of dissolution-and-diffusion type were observed between the matrix and the filler. A dissolution rate of the filler’s microcrystalline phases of W2C and WC was shown to decrease by ~ 1.7–1.8 times as against that of the crystalline phases of the same composition. This result was explained considering the dependence of an average shift of atoms from the equilibrium positions in the lattice on linear size of the phases. Since the average size of the microcrystalline phases is ~ 25 times smaller than that of the crystalline phases, the average shift of microcrystalline phase atoms from the equilibrium positions decreases b...

RESUMEN En este estudio, los efectos de los tratamientos térmicos en el pico de envejecimiento (T6), sobre-envejecimiento (T73) y proceso de regresión y re-envejecimiento (RRA, regresión a 200 °C durante 10 min) sobre la microestructura, resistencia mecánica, corrosión por exfoliación y corrosión intergranular de aleación de aluminio 7075 ha sido investigado mediante microscopia óptica, microscopía electrónica de barrido, ensayos de tracción, ensayos ASTM G110, ensayos ASTM G34, curva de polarización y espectroscopia de impedancia electroquímica (EIS). Los resultados de los ensayos de corrosión intergranular (ASTM G110) y los ensayos de corrosión por exfoliación (ASTM G34), aplicados a los tres tratamientos definen un orden de susceptibilidad a la corrosión dada por: T6 > T73 > RRA. Las tendencias de la resistencia a la corrosión son confirmadas mediante curvas de polarización y ensayos EIS. El tratamiento térmico RRA mejora la resistencia a la corrosión intergranular-exfoliac...

Resistance spot welding is a welding process using electrodes to apply both electrical current and  pressure. Heat is generated by electrical resistance between two or more workpieces. The objective of this research was to investigate the effect of welding time  on AISI 1010 weld characteristic and maximum shear loading. Welding was done on AISI 1010 low carbon steel plates. The thickness of each plates was 0.8 mm. Welding time variation were 0.75, 1.0, and 1.25 seconds at constant voltage of 1.79 V. The material testing was set on tensile-shear test and microstructure. The results shows that the welding time increase make the nugget size enlarged. The largest shear force required  to break the specimen was 4.34 kN and occurred on specimen with welding time 1.25 seconds. That is due to the larger nugget of the two steel plate joint for 1.25 second than for 0.75 and 1.0 second. The microstructure of the weld nugget consists of ferrite and martensite. In the PMZ, the microstructure  c...

AMC (Aluminium Matrix Composite) is material which has a great potential for being developed. This research was done to find effect added of Cu variation for impact strength and microstructure on Al-Si composite. Mass fractions of sand silika is 3% and Cu variation adding is 0, 1, 2, 3 & 4%. Composite manufacture is using stir casting method with stirring 600 rpm during of 5 minutes on semi solid temperature. Speciments were tested using optical microscope and impact charpy testing machine. The value impact of composite without adding Cu is 0,333 J/mm2 after added Cu value down. Until adding Cu 4% the value impact is 0,104 J/mm2. Micro photograph showed the result of porosity and SiO2 unform distribution with the adding of Cu to the composite. From the test results it is known that the strength of the impact decreases with mass fraction addition Cu. This is because the addition of Cu can increase the porosity and formed CuAl2 phase which are brittle.

Pore scale modeling plays a key role in fluid flow through porous media and associated macroscale constitutive relationships. The polyhedral shape and effective local pore size within granular material microstructure are computed in this study by means of the Euclidean Distance Transform (EDT), a local maxima search (non-maximum suppression), and a segmentation process. Various synthetic packed particles are simulated and employed as comparative models during the computation of pore size distribution (PSD). Reconstructed un-sheared and sheared Ottawa 20-30 sand samples are used to compute PSD for non-trivial and non-spherical models.

This article describes the manufacturing of alumina composites with the addition of titanium aluminum carbide Ti3AlC2, known as MAX phases. The composites were obtained by the powder metallurgy technique with three types of mill (horizontal mill, attritor mill, and planetary mill), and were consolidated with the use of the Spark Plasma Sintering method at 1400 °C, with dwelling time 10 min. The influence of the Ti3AlC2 MAX phase addition on the microstructure and mechanical properties of the obtained composites was analyzed. The structure of the MAX phase after the sintering process was also investigated. The chemical composition and phase composition analysis showed that the Ti3AlC2 addition preserved its structure after the sintering process. The increase in fracture toughness for all series of composites has been noted (over 20% compared to reference samples). Detailed stereological analysis of the obtained microstructures also could determine the influence of the applied mill on...

This paper discusses the effects of the environment and temperature of the Ti3C2 (MXene) oxidation process. The MXene powders were annealed at temperatures of 1000, 1200, 1400, 1600, and 1800 °C in argon and vacuum using a Spark Plasma Sintering (SPS) furnace. The purpose of the applied annealing method was to determine the influence of a high heating rate on the MXene degradation scheme. Additionally, to determine the thermal stability of MXene during the sintering of SiC matrix composites, SiC–C–B–Ti3C2 powder mixtures were also annealed. The process parameters were as follows: Temperatures of 1400 and 1600 °C, and pressure of 30 MPa in a vacuum. Observations of the microstructure showed that, due to annealing of the SiC–C–B–Ti3C2 powder mixtures, porous particles are formed consisting of TiC, Ti3C2sym, and amorphous carbon. The formation of porous particles is a transitional stage in the formation of disordered carbon structures.

This paper discusses the influence of Ti3C2 (MXene) addition on silicon nitride and its impact on the microstructure and mechanical properties of the latter. Composites were prepared through powder processing and sintered using the spark plasma sintering (SPS) technic. Relative density, hardness and fracture toughness, were analyzed. The highest fracture toughness at 5.3 MPa·m1/2 and the highest hardness at HV5 2217 were achieved for 0.7 and 2 wt.% Ti3C2, respectively. Moreover, the formation of the Si2N2O phase was observed as a result of both the MXene addition and the preservation of the α-Si3N4→β-Si3N4 phase transformation during the sintering process.

This article presents new findings related to the problem of the introduction of MXene phases into the silicon carbide matrix. The addition of MXene phases, as shown by the latest research, can significantly improve the mechanical properties of silicon carbide, including fracture toughness. Low fracture toughness is one of the main disadvantages that significantly limit its use. As a part of the experiment, two series of composites were produced with the addition of 2D-Ti3C2Tx MXene and 2D-Ti3C2Tx surface-modified MXene with the use of the sol-gel method with a mixture of Y2O3/Al2O3 oxides. The composites were obtained with the powder metallurgy technique and sintered with the Spark Plasma Sintering method at 1900 °C. The effect adding MXene phases had on the mechanical properties and microstructure of the produced sinters was investigated. Moreover, the influence of the performed surface modification on changes in the properties of the produced composites was determined. The analys...

This study presents new findings related to the incorporation of MXene phases into ceramic. Aluminium oxide and synthesised Ti3C2 were utilised as starting materials. Knowing the tendency of MXenes to oxidation and degradation, particularly at higher temperatures, structural modifications were proposed. They consisted of creating the metallic layer on the Ti3C2, by sputtering the titanium or molybdenum. To prepare the composites, powder metallurgy and spark plasma sintering (SPS) techniques were adopted. In order to evaluate the effectiveness of the applied modifications, the emphasis of the research was placed on microstructural analysis. In addition, the mechanical properties of the obtained sinters were examined. Observations revealed significant changes in the MXenes degradation process, from porous areas with TiC particles (for unmodified Ti3C2), to in situ creation of graphitic carbon (in the case of Ti3C2-Ti/Mo). Moreover, the fracture changed from purely intergranular to cra...

Self-lubricating composites are designed to obtain materials that reduce energy consumption, improve heat dissipation between moving bodies, and eliminate the need for external lubricants. The use of a solid lubricant in bulk composite material always involves a significant reduction in its mechanical properties, which is usually not an optimal solution. The growing interest in multilayer graphene (MLG), characterised by interesting properties as a component of composites, encouraged the authors to use it as an alternative solid lubricant in aluminium matrix composites instead of graphite. Aluminium alloy 6061 matrix composite reinforced with 2–15 vol % of MLG were synthesised by the spark plasma sintering process (SPS) and its modification, spark plasma texturing (SPT), involving deformation of the pre-sintered body in a larger diameter matrix. It was found that the application of the SPT method improves the density and hardness of the composites, resulting in improved tribological...

Purpose: The purpose of this study was to evaluate biocompatibility of the binders �€˜ZB58�€™ and the starch powder �€˜ZP15e�€™ used by the Z510 colour printer for printing soft tissue facial prostheses. Materials and Methods: Biocompatibility was investigated by testing four binders and the powder at three concentrations on two cell lines (ROS - osteoblasts and L929 - fibroblasts). The binders and the powder were exposed to the cells for 3, 5 and 7 days, after which the cells were treated with 10% Alamar Blue. Binder and powder toxicity was measured as a comparison against the uninfected media only cell control. Results: The Alamar Blue assays for the ROS and L929 cell line for all days no significant toxic effects were observed at lower binders and powder concentrations. However there was evidence of reduction in all cell vitality at higher concentrations and it appears to be more pronounced at seven days exposure Conclusion: The Alamar Blue assay highlighted the potential toxic e...

In the present work, we report the failed coupling with an airlock in a flour mill aluminium alloy is used to transmit torque from the electric motor to an airlock used on a flour mill production line. The fracture that occurred at the root of the teeth of the coupling was investigated using macro examination, micro and tensile test were employed for this investigation. From the tests carried out, it was observed from the macro However, composition analysis revealed a relatively high weight composition of aluminium (87.5 wt. %) suggesting that the coupling wa alloy. The significant presence of Cu and Zn at 2.77 wt indicates that the alloying elements result revealed that the material has an ultimate tensile strength of 178 N/mm is comparatively lower than most aluminium alloys. This might be as a result of the high Si composition of 7.24 wt The hardness result showed the Brinell hardness of the fractured samples as 76.53 BHN. The microstructure of the coupling at three different sec...

This study evaluated the effect of carbon nanofibers (CNFs) coated by aluminum oxide Al2O3 as a reinforcement on compressive strength, frost resistance, and drying shrinkage of cement mortars. Three weight ratios of 0.125%, 0.25%, and 0.5% of Al2O3/CNFs and bare CNF cement mortars were compared with reference cement mortar samples. The reactive porous and high surface area layer of alumina induced the hydration reaction and promoted the production of well-distributed hydration gel. Derivative thermal analysis–differential thermogravimetric (TGA-DTG) and X-ray powder diffraction (XRD) characterization showed that Al2O3/CNFs reinforcement led to greater hydration gel production than bare CNFs. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were performed to study the coating and microstructure of the cement mortars evaluated in this paper. The results show that the optimum enhancement of the cement mortar properties was obtained at ratios of 0.125% for A...

Purpose This paper aims to investigate the characteristics of ultra-fine lead-free solder joints reinforced with TiO2 nanoparticles in an electronic assembly. Design/methodology/approach This study focused on the microstructure and quality of solder joints. Various percentages of TiO2 nanoparticles were mixed with a lead-free Sn-3.5Ag-0.7Cu solder paste. This new form of nano-reinforced lead-free solder paste was used to assemble a miniature package consisting of an ultra-fine capacitor on a printed circuit board by means of a reflow soldering process. The microstructure and the fillet height were investigated using a focused ion beam, a high-resolution transmission electron microscope system equipped with an energy dispersive X-ray spectrometer (EDS), and a field emission scanning electron microscope coupled with an EDS and X-ray diffraction machine. Findings The experimental results revealed that the intermetallic compound with the lowest thickness was produced by the nano-reinfor...

The effect of substrate surface roughness on the wettability of SAC237 (Sn 99.9%, Ag 0.3%, Cu 0.7%) with difference percentage of CNT on copper substrate was investigated. Solder paste of SAC 237 without CNT, 0.01% and 0.04% of CNT were reflowed at 270°C on different surface roughness of Cu substrate (abrasive number 240, 400, 600, 800). Contact angle of soldered samples measured by Infinite Focus Microscope (IFM). As a result, contact angle value of investigated solders range 7° to 20°. Contact angle obtained decreases with the increasing surface roughness of Cu substrate. This demonstrates that rougher substrate enhance the wettability of the solders. Addition of CNT also effects the wettability of investigated solders. Higher composition of CNT show better wettability.