La/Bi co-doped NaTaO3 nanomaterials for photocatalytic applications have been successfully synthesized by hydrothermal method at low temperature. The obtained materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and UV-Vis molecular absorption spectroscopy. The results showed that the particle sizes of La/Bi co-doped NaTaO3 were smaller than that of the pure NaTaO3. La/Bi co-doping has extended optical absorption in the visible light region and then successfully increased photocatalytic activity of the La/Bi-codoped NaTaO3 that were evaluated by degradation of methylene blue (MB).
The effect of Mn content on the microstructure and properties of a newly-designed CoCrCu0.1Fe0.15Mo1.5MnxNi (where x is atomic ratio, x = 0.05, 0.12 and 0.3) near equiatomic alloys are investigated in this study. Typical dendrites and interdendritic structures are observed. According to EDS, the primary dendrites are enriched with Co and Mo, while at the interdendritic region Cr-rich and (Co, Fe, Ni)-rich structures are obtained. The X-ray diffraction patterns of the CoCrCu0.1Fe0.15Mo1.5MnxNi alloys indicate that all the alloys exhibit simple BCC, FCC solid solution phase and μ phase. The volume fraction of FCC phase increases when Mn element was added, confirming that Mn is a FCC-forming element. Notely, the hardness of the alloys dropped from HV 715 to HV 392 when the Mn content changed from 0.05 to 0.3. The wear resistance declines as the Mn content increases. The optimal wear resistance was obtained in CoCrCu0.1Fe0.15Mo1.5Mn0.05Ni near equi-atomic alloys.
Fe84−xCrxB10Zr5Gd1 (x = 0, 2, 4, 6, 8) ribbons were fabricated and their magnetocaloric effect was studied. The microstructure of the ribbons was found to change from crystalline to amorphous with the addition of Cr. The Curie temperature (TC) undergoes an almost linear reduction (from 410 K to 300 K) and the peak magnetic entropy change, |Δ SMpeak| (measured under a field of 1.5 T), first increases to a maximum value (from 0.70 J/kg K to 0.91 J/kg K) and then decreases to 0.66 J/kg K with increasing Cr content. The results further show that Fe80Cr4B10Zr5Gd1 ribbon demonstrates good refrigerant capacity as large as 110 J/kg under a field of 1.5 T. With its TC being close to room temperature and having a good refrigerant capacity, the Fe-based amorphous ribbon is a potential magnetocaloric material, although further work is needed to further improve the refrigerant capacity for industrial applications.
Titanium-based composite coating reinforced by in situ synthesized TiN and TiB particles was successfully fabricated on Ti-3Al-2V alloy by laser cladding with Ti/c-BN powder mixture. The microstructures of in situ synthesized TiB and TiN were compared with needle platelet and dendrite. TiB tends to nucleate and grow on the surface of TiN and grain boundary. In the rapid solidification process, phases crystallization follow the five steps: primary TiN → peritectic structure TiN+α-Ti → primary TiB; → binary eutectic β-Ti+TiB → solid transformation from β-Ti to α-Ti.
During the bending and straightening process of low carbon microalloyed steel, high-temperature microstructure (HTM) governs the slab corner transverse cracking susceptibility. In this paper, the stiffness was used to characterize the resistance ability of HTM to elastic deflection, and a model describing the relationship between the stiffness and characteristics of HTM was established. The criterion was created based on the HTM features for the slab corner transverse cracking susceptibility. The results are mainly manifested in two aspects: 1) the stiffness was used to characterize the resistance of HTM against the elastic deformation, and it can also indirectly reflect the relationship between prior austenite grain and film-like ferrite, second-phase precipitate. 2) The critical equivalent diameter of the prior austenite generating the slab surface transverse cracks was found to be 0.68 mm. If the equivalent diameter of the prior austenite (DγP) became >0.85 mm, the index of the traverse crack on the surface of slab increased sharply, indicating strong susceptibility of transverse corner cracks.
The fatigue behavior of a nickel-base superalloy was investigated under total strain-controlled mode at high temperature. The fatigue life, cyclic stress response behavior and hysteresis loop of the superalloy were investigated under isothermal low cycle fatigue (LCF) conditions. The superalloy exhibited cyclic hardening and softening behaviors during the process of fatigue loading. The hysteresis loop shifted downwards slightly with the increase of the number of cycles. The fatigue life under different strain amplitudes reflects the interactions of dislocations and γ′ precipitates at elevated temperature. Three life prediction models to evaluate the fatigue life of the superalloy were evaluated for the LCF tests. The prediction values obtained by Manson-Coffin relationship agree well with the experimental results. The mechanisms of LCF were revealed through the observation of the microstructures by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The main deformation mechanism of the superalloy is the different interactions between dislocations and γ′ precipitates.
According to the microstructure characteristics of sandwich (AFS) panels, two-dimensional random models of AFS panels with different porosities were created by C++ and ANSYS/LS-DYNA software in this paper. The main purpose of the current paper is investigating and analyzing the effects of porosity on the compression behaviors and energy absorption capacities of AFS panels under the same compressive loading on base of established random models. It was found that there were obvious three stages in the stress-strain curves of AFS panels, namely elastic region, collapse region and densification region. In addition, the results also confirmed that porosity had apparent effect on the compressive capacities and energy absorption capacities of AFS panels. Furthermore, through comparison and analysis, the simulation results in this work were basically consistent with the previous theoretical results and experimental results.
By using the mechanical property tester, conductivity tester, DSC and optical microscope, the effects of the solid solution temperature, water temperature, transfer time and delay time of quenching on the mechanical properties and conductivity of 7475 alloy were investigated, respectively. The results showed that all properties are satisfied at the solid solution temperature of 460°C–480°C while the over-burning may occur above 490°C. The tensile strength, yield strength and elongation are changed about −6.5 MPa, −6.2 MPa and 0.17% when the water temperature is increased by 10°C, but the conductivity always remains about 37.6%IACS from 30°C to 60°C. The strengths and conductivity will drop while the elongation will gradually rise against the transfer time. With the extension of delay time, the strengths decrease and then increase while the elongation and conductivity has a reverse change. When the delay time is 8 h, the tensile strength and yield strength achieve the minimum of 512 MPa and 450 MPa, and the elongation and conductivity reaches the maximum of 17.8% and 37.4%IACS. The optimal quench parameters are that the solid solution is 470°C, water temperature is below 60°C, transfer time is below 30 s, and delay time is below 4 h or above 24 h.
A synthesis process of spinel Li4Ti5O12 (LTO) nanomaterials was investigated using Li+-exchanged titanate nanotubes obtained via hydrothermal synthesis and subsequent reflux treatment. The substituted amount of Li+ ions can be controlled by the temperature and time during the reflux treatment in a LiOH aqueous solution, which is the key for the synthesis of single-phase LTO. The rate capability of nanosized LTO as an active material for Li-ion batteries is significantly higher than that of microsized LTO obtained via conventional solid-state synthesis. By changing the intercalated ions during the reflux treatment, this synthesis process can also be applied to the synthesis of other titanate nanomaterials, which are promising active materials for future battery systems.
The isobaric heat capacities, Cp,m°, for BaMoO4 at 2–300 K were measured by the relaxation method. The third law entropy, Sm°, was determined via the Debye-Einstein function into which the Debye temperature, ΘD, as physico-chemical constant and a thermal expansion term were incorporated. ΘD was determined from Cp,m° at very low temperatures. The obtained thermodynamic properties were: Sm° (BaMoO4(cr), 298.15 K)/J K−1 mol−1 = 152.69 ± 1.53; ΘD(BaMoO4(cr))/K = 295 ± 3. The phase stability of BaMoO4 was discussed on the basis of its standard Gibbs energy of formation, Δ fGm°. It was derived by combining Sm° determined in this study with the reference data of the standard enthalpy of formation, Δ fHm°. The thermodynamic properties obtained in the present study can be used for evaluating the hierarchy for formation of the yellow phase related-substances in nuclear waste glasses.
Distribution of the corrosion depth around a surface scratch of epoxy-coated High Tensile (HT) Strength steel (0.7Ni-0.6Cr–0.3Mo–Fe) was measured by using a laser microscope after a wet and dry cyclic corrosion test and compared with that of epoxy-coated carbon (SM) steel. The Gumbel distribution analysis was applied to the corrosion depth profile as a function of distance far from the scratch. In the analysis, the mode (λ) and distribution parameter (α) of the coated HT steel displayed much smaller values than those of coated carbon (SM) steel. The smaller values indicate that the coated HT steel has higher corrosion resistance than that of the coated SM steel. The SEM (Scanning Electron Microscope)-EDS (Energy dispersive X-ray spectrometry) analysis showed that Cr and Mo were enriched in the inner rust layer and Ni distributed in all rust layer around the scratched area of the coated HT steel after the corrosion test. The TEM (Transmission Electron Microscope)-EELS (Electron Energy Loss Spectroscopy) analysis confirmed the presence of nanoscale Fe oxides containing Cr, Ni and Mo in the rust of the HT steel, and these nanostructures of the rust was assumed to enhance the corrosion resistance of the coated HT steel.
During the continuous casting of high-aluminum steel, important components of the mold flux can be easily reduced by the aluminum in the molten steel. Consequently, the mold flux performance is deteriorated, impeding the smooth running of the continuous casting and affecting the quality of the cast slab. To solve this problem, thermodynamic calculations and laboratorial crucible experiments were performed to investigate the reduction of different mold fluxes by the aluminum in molten steel. Plant trials based on the laboratory studies were performed. It was found that SiO2, MnO, Na2O and B2O3 reacted with the aluminum in molten steel, while CaO, CaF2, MgO, Li2O and BaO did not. Since the composition contents of in CaO-Al2O3-based mold flux were changed only slightly after steel/slag interfacial reactions, a stable CaO-Al2O3-based mold flux was tested in industry production. The application effect of this stable mold flux was very good.
It is necessary to understand behaviors of the material in worked sheet to reduce troubles of punch fracturing in the punching of slanted fine holes in austenitic stainless-steel SUS304 sheets. The behavior of the material is estimated as the follows by the map of Vickers hardness in the cross-section of worked sheet. The material flow changes the complexity of what as a result of the influence of work hardening or transformation to strain-induced martensite. Then, the direction and magnitude of the pressure applied to the punch also change such inn a complex manner. However, the worked material almost flows into the die hole. Then, the punch is carried into the hole by this material flow.
In this investigation, rare earth metal oxide films were synthesized from metal complexes of ethylenediaminetetraacetic acid (metal-EDTA) by utilizing a flame spray technique. Two raw metal-EDTA powders were prepared as starting materials in order to synthesize (Y,Er)2O3 films on stainless steel (SUS) substrates by a reaction that is promoted by the combustion of gaseous H2-O2. Molecularly mixed EDTA·(Y,Er)·H and mechanically mixed EDTA·Y·H + EDTA·Er·H complexes were subsequently prepared. The existence of Y2O3 and Er2O3 crystalline phases was confirmed for the EDTA·Y·H + EDTA·Er·H mixtures. Lamellar structures were formed on the film with a porosity of 9.5%. Alternatively, a homogenous, (Y,Er)2O3 film was obtained from the EDTA·(Y,Er)·H complex, with a film porosity of 31.8%. These results indicate that uniform (Y,Er)2O3 films were synthesized on SUS substrates from molecularly mixed EDTA·(Y,Er)·H powders.
TiO2 particles with stacked flat sheets are synthesized via thermal oxidation of TiO powder in an oxygen atmosphere. The flat sheets are formed under specific synthesis conditions of 1000°C and 6.5 × 104 Pa. The x-ray diffraction pattern demonstrates that the sheets are TiO2 with a rutile crystallographic structure. The characteristic peaks of the anatase crystal structure of TiO2 are not detected. From the scanning electron microscopy, the thickness of the sheets is in the range from 80 to 200 nm and the lateral dimensions of the sheets are several tens of µm × several tens of µm, which indicates that the sheets have significant surface area-to-volume ratio when compared with those of other nanostructures. Furthermore, most sheets are aligned parallel to each other.
This study investigated the effect of heat treatment on the tensile and fatigue properties of Al 3527 K alloy manufactured by the strip casting process. Al 3527 K alloy (as strip cast material, F) produced by twin roll strip casting and heat treated (480°C/6 h., H) alloy were examined and compared. Microstructure observation results revealed that both alloys (F and H) featured rapid solidification microstructures. In addition, both alloys were identified to be composed of Al, Al6(Mn, Fe) and AlFeMnSi phases. As heat treatment was applied, H alloy formed a more even phase distribution than F alloy. Tensile results showed F alloy to have a yield strength of 135.0 MPa, tensile strength of 194.7 MPa and elongation of 14.3%, while H alloy had a yield strength of 147.9 MPa, tensile strength of 235.2 MPa and elongation of 10.9%. The tensile properties showed that heat treatment resulted in an increase of strength and decrease of elongation. In tensile fracture surface observation, both alloys showed typical ductile fracture modes. The F alloy was measured to have a dimple size of 6.8 µm on average, and the H alloy measured 4.2 µm in tensile fracture surfaces. High-cycle fatigue results showed the F alloy to have a fatigue limit of 120 MPa, and the H alloy to have that of 145 MPa. Al 3527 K-F alloy featured a larger deviation in fatigue life in all identical stress conditions compared to the H alloy. This study also discussed the tensile and fatigue deformation behaviors of Al 3527 K alloy manufactured by strip casting through the abovementioned mechanical properties as well as the fractographies.