This study aimed to modulate the magnetic properties of selective laser melting NiFeMo alloy. This was achieved via the controlled addition of Mo elemental in-situ alloying content to change the ...tissue morphology and crystal structure of SLM-formed (NiFeMo)100−xMox alloy (x = 0 wt%, 0.25 wt%, 0.5 wt%, 0.75 wt%, 1.0 wt%, 1.25 wt%, 1.5 wt%, 2.0 wt%). The results of scanning electron microscopy (SEM), X-ray diffraction, electron backscatter diffraction (EBSD), DC B-H hysteresis tester, and transmission electron microscopy (Titan-G2) indicate that all samples are predominantly face-centered-cubic (FCC) γ- (Ni, Fe) solid solutions and typical soft-magnetic hysteresis line features. However, the lattice parameter a of γ- (Ni, Fe) decreased and then increased with increasing Mo content. When the added Mo content is 0–1.25 wt%, the Mo particles inside the (NiFeMo)100−xMox alloy become nucleation sites, creating a diffusive metallurgical behavior with the Ni and Fe elements, and preventing the growth of columnar crystals, leading to the reduction of LAGBs density and the enhancement of the {111} texture orientation in the easy magnetization direction, increasing Bs and the decrease of Hc of the NiFeMo alloy. At the Mo content of 1.25 wt%, the soft magnetic properties were optimal, with Bs and Hc being 0.704 T and 17.31 A/m, respectively. Conversely, when the added Mo content was 1.5–2.0 wt%, the solubility of Mo elements in the γ- (Ni, Fe) solid solution was limited, which resulted in the occurrence of metallurgical defects within the organization such as unfused Mo particles, unfused areas, and porosity. Moreover, when the added Mo content increased to 2.0 wt%, the {111} lattice spacing in the easy magnetization direction increased by 0.2261 nm compared to the NiFeMo alloy, and the average lattice distortion Δε increased to 0.16%, causing a decrease in the soft magnetic performance of the (NiFeMo)98Mo2 alloy, with Bs reducing to 0.6666 T and Hc increasing to 23.44 A/m.
•The microstructure evolution of NiFeMo alloy formed by in-situ alloy-SLM was analyzed and described in detail.•The crystallographic relationship of NiFeMo alloy with Mo element was analyzed on an atomic scale by HETEM.•Analyzed the changes in soft magnetic properties of NiFeMo alloy with different Mo additions.•Clarified the influencing mechanism of Mo element in-situ alloying on the magnetic properties of NiFeMo alloy.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Metallurgical defects significantly affect the performance of materials fabricated by selective laser melting (SLM), becoming a bottleneck problem in the application of laser 3D printing technology. ...To investigate the effect of metallurgical defects on the magnetic properties of SLM NiFeMo permalloy. An in-depth characterization of the microstructure and phase composition of SLM-fabricated NiFeMo permalloy samples were carried out. Soft magnetic DC BH hysteresis loop tester was used to assess the magnetic properties. Defect voxel data of as-built samples were obtained using X-ray microcomputed tomography (XCT). The results show that the micro-defects of SLM NiFeMo alloy are mainly composed of lack of fusion, pores, etc., and the phase composition of NiFeMo is mainly γ- (Ni, Fe) solid solution. With the increase of laser volume energy density, the Bs and μm of the material increase, while the Hc and Pu decreases. The equivalent diameter of the defects shows a positive correlation with the coercivity (Hc) and a negative correlation with the saturation magnetic induction (Bs) of NiFeMo permalloy.
•The microstructural features, the evolution of defect size and morphology were analyzed and described in detail.•Defect data information in SLM-fabricated permalloy was extracted and quantified using XCT.•Permalloy samples with relatively good magnetic properties were obtained by adjusting the process conditions.•Constructed and validated an approximate relational model describing the correlation of defects and magnetic properties.
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IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
High temperature corrosion poses a great threat to boiler water wall safe operation. To investigate the corrosion root cause, a 300 MW level boiler water wall high temperature H2S corrosion case was ...reported. The typical hydrogen sulfide H2S corrosion feature was large amounts of sulfur which could be found in the cut down sample tube corrosion layer, with a thickness of 482 μm. In addition, huge amounts of lead (Pb) could be found in the corrosion layer, which resulted from the lead sulfide (PbS) deposition when the high temperature flue gas condensed at the water wall tubes. Meanwhile, the sulfur in the corrosion layer was closely related to the H2S concentration in the water wall ambience. The related ambience test showed that the H2S could achieve up to 1000 ppm when the boiler was in operation, far larger than the suggested reference value of 100 ppm. Hence, the overlarge H2S concentration was a vital factor for the tube corrosion. To further investigate the reason why the H2S was kept in such high concentration in the boiler long term operation, and the reasons for the over-high sulfur content in the coal and the over-large diameter of the imaginary circle of primary air (DICPA), two factors were obtained. The peak sulfur content reached 2.5% and the suggested sulfur content was below 1%. The DICPA was so large (1580 mm) that the pulverized coal easily scoured the water wall tubes, which would boost the thinning process of the tubes. To relieve the high temperature corrosion, improve the coal qualities, decrease the DICPA, adjust the operation diameter and adopt a coating technology four measures were suggested.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
A gel system has been widely used in many mature oilfields for water shut-off treatment. In the present study, the hydrophobically associating polymer (HAP) was cross-linked with the polyethylenimine ...(PEI) to form a HAP/PEI gel system which contains 0.35 wt % HAP and 0.60 wt % PEI. Gelation behaviors of the HAP/PEI gel formed in bottle and in core were studied, respectively. Results show that the gelation behaviors of the gel system were greatly affected by the concentration of HAP and that of PEI. The addition of the sodium chloride or calcium chloride generally resulted in a decrease of the apparent viscosity and an extension of the gelation time. However, a low concentration of sodium chloride led to a slight increase of the gel viscosity in bottle due to the intensification of the hydrophobic association. The rock skeleton of the core had a great effect on the gelation behavior. Compared with the results obtained in bottle, the apparent viscosity of the HAP/PEI gel system in core was obviously reduced, and the gelation time in core was extended two times or even longer. Both the gelation times achieved in bottle and in core decreased with the increase of temperature following the relationship of Arrhenius-type. The activation energy of the HAP/PEI gel system was 41.57 kJ/mol in bottle but increased to 60.95 kJ/mol in core. Data collected from the core flowing tests present a favorable shut-off performance and a strong wash-out resistance of the HAP/PEI gel system. In addition, the in-depth flow diversion and water permeability reduction were two main mechanisms of this gel system for water shut-off treatment.
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IJS, KILJ, NUK, PNG, UL, UM
To investigate the pollutants emissions during the retired wind turbine blade (RWTB) recycle process by thermal chemistry method, three ambiences (N2, O2 and CO2) and four temperatures (400, 600, 800 ...and 1000 °C) conditions were tested. Results show that either enhancing temperature or adding CO2 can both pronouncedly boost the HCN and NO formation and restrain the HCl formation. At 1000 °C, the nitrogen release in the form of HCN exceeds 44%, 94% of the total nitrogen in N2, CO2 ambience, respectively. The oxygen atom of NO mainly comes from the RWTB itself rather than the external oxygen, which means the traditional NOx reducing technology such as staged air or staged fuel technology is infeasible for NOx reduction. In addition, by comparing the RWTB and coals pyrolysis products, the nitrogen structure differences were deduced. The nitrogen in the coal is located in the aromatic rings while that is in the aliphatic chains in RWTB, which is more prone to be broken for the C-N bond. For the chlorine in RWTB, it is organic chlorine locating at the aliphatic chains which is easy to be released in the form of HCl at low temperature (400 °C).
•The major gaseous pollutants were well investigated during the retired wind turbine blade thermal conversion process.•The HCN, NO, HCl are the major pollutants.•CO2 can pronouncedly boost the HCN and NO formation whereas restrain the HCl formation.•The oxygen atom of NO mainly comes from the RWTB itself rather than the external oxygen.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
CO2-responsive smart fluids have been widely investigated in the past decade. In this article, we reported a CO2-responsive smart fluid based on supramolecular assembly structures varying from ...vesicles to wormlike micelles. Firstly, oleic acid and 3-dimethylaminopropylamine reacted to form a single-chain weak cationic surfactant with a tertiary amine head group, N-3-(dimethylamino)propyloleamide (NDPO). Then, 1,3-dibromopropane was used as the spacer to react with NDPO to form a gemini cationic surfactant, trimethylene α,ω-bis(oleate amide propyl dimethyl ammonium bromide) (GCS). By controlling the feed ratio of 1,3-dibromopropane and NDPO, we found that the mixtures of GCS and NDPO with the molar ratio of 7 : 3 approximately could form vesicles in aqueous solution by supramolecular self-assembly. After bubbling CO2, the tertiary amine of NDPO was protonated. The packing parameter of the mixed surfactants reduced accordingly, accompanied by the transition of aggregates from vesicles to wormlike micelles. As a result, the zero-shear viscosity of the solution increased by more than four orders in magnitude. When the solid content of GCS/NPDO mixtures was higher than 5 wt% in solution, the sample treated by CO2 behaved as a gel over a wide frequency range with shear-thinning and self-healing properties. In addition, the sol–gel transition could be repeatedly and reversibly switched by cyclically bubbling CO2 and N2. Our effort may provide a new strategy for the design of CO2-responsive smart fluids, fostering their use in a range of applications such as in enhanced oil recovery.
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IJS, KILJ, NUK, UL, UM, UPUK
Aimed at the disadvantages of secondary damage to oil layers caused by the conventional bull-heading water control technique, a thermo-sensitive temporary plugging agent for water control was ...synthesized by water solution polymerization and applied in the field with a new secondary temporary plugging technique. The optimization and performance evaluation of thermo-sensitive temporary plugging agent were carried out through laboratory experiments. The optimized formula is as follows: (6% − 8%) acrylamide + (0.08% − 0.12%) ammonium persulfate + (1.5% − 2.0%) sepiolite + (0.5% − 0.8%) polyethylene glycol diacrylate. The thermo-sensitive temporary plugging agent is suitable for formation temperatures of 70−90 °C, it has high temporary plugging strength (5−40 kPa), controllable degradation time (1−15 d), the apparent viscosity after degradation of less than 100 mPa(S and the permeability recovery value of simulated cores of more than 95%. Based on the research results, secondary temporary plugging technique was used in a horizontal well in the Jidong Oilfield. After treament, the well saw a drop of water cut to 27%, and now it has a water cut of 67%, its daily increased oil production was 4.8 t, and the cumulative oil increment was 750 t, demonstrating that the technique worked well in controlling water production and increasing oil production.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Medium-temperature (850 ~ 1000°C) preheating technology has proven to burn coal gasification fine slag (CGFS) steadily. However, the potential of further de-NO
x
and improving burnout at high ...preheating temperature (>1000°C) has not been reported. Likewise, the feasibility of preheating treatment at low temperature (<800°C) has also not been verified. Aiming to better understand the influence of preheating treatment on disposing CGFS, the preheating technology with a wider range of preheating temperature (600 ~ 1400°C) was tested on a two-stage drop-tube furnace system in this study. The effects of preheating temperature (T
p
), O
2
concentration at the outlet of system (O
2outlet
) and the excess air ratio in preheating zone (λ
1
) on NO emission and burnout were investigated. Our results showed that by increasing T
p
above 1000°C and maintaining O
2outlet
concentration above 4%, the combustion of CGFS could achieve both low NO emission and high combustion efficiency. A critical preheating temperature of CGFS was obtained to be 600°C. Under this condition, the conversion ratios of C and N were extremely low in the preheating process, and the final NO emission hardly changed with λ
1
. Under pyrolysis condition (λ
1
= 0), T
p
should increase to 1400°C for achieving satisfying reduction of NO emission. λ
1
had a positive effect on the reduction of NO emission as T
p
was above 800°C. By controlling T
p
to 1200°C and λ
1
to 0.6, 39.2% of fuel nitrogen could be converted to gaseous nitrogen, in which the portion of N
2
was 56.1%. Compared with coal, N-containing species in syngas of CGFS were mainly composed of NO, NO
2
and N
2
. Finally, application prospect in the combustion of CGFS using a burner based on the idea of preheating is provided.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
Injectable self‐healing hydrogels have found broad applications in drug delivery, tissue engineering and controlled 3D cell culture. In this article, the coordination interaction between ...polymer‐bearing imidazole groups and Mg2+ ions “trapped” in Laponite, has been employed to develop an injectable self‐healing nanocomposite hydrogel. The properties and gelation mechanism of the hydrogel have been characterized and demonstrated by rheology, TEM, XRD, SEM, and NMR in particular. The hydrogel exhibits swift self‐healing performance without waiting for long time or elevated temperature. In particular, the present hydrogel can be applied in harsh alkaline environments, exhibiting a great advantage over traditional metal ion crosslinked hydrogels. The injectable self‐healing hydrogels based on the coordination interaction between Laponite and polymer have been rarely reported. Our research may make contributions not only to the design but also to the potential application of the hydrogels in a range of harsh alkaline environments, especially in enhanced oil recovery (EOR).
Injectable self‐healable hydrogels was obtained by mixing imidazole group containing polyacrylamide solution with the Laponite clay dispersion. Due to the coordination interaction of Mg2+ ions trapped in CNS with imidazole groups in poly(AAm‐NVI), the hydrogel exhibits shear‐thinning and rapid self‐healing ability even in harsh alkaline environment.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In search of robust polymers for enhanced oil recovery (EOR) application in reservoirs with harsh conditions, a water-soluble biopolymer was thoroughly investigated in this work to evaluate its ...applicability in such reservoirs. The experimental data revealed that compared to the commonly used EOR polymer, HPAM, the biopolymer was more efficient in thickening a brine solution as a result of its peculiar conformation. The presence of an electrolyte has almost no effect on the rheology of the biopolymer solution, even at an extremely high salt concentration (20 wt% NaCl). The relation between viscosity and the concentration curve was well fitted to the power-law model. Moreover, the rigid polymer chains rendered the polymer solution superior tolerance to elevated temperatures and salinity, but also led to considerable retention within tight porous media. The adsorption behavior was characterized by the average thickness of the hydrodynamic adsorbed layer on sand grains. The mechanical degradation was assessed by forcing the polymer solutions to flow through an abrupt geometry at ultra-high shear rates. The slight viscosity loss compared to HPAM proved the high mechanical stability of this polymer. These properties made it a promising alternative to HPAM in polymer flooding in the near future for high permeability oil reservoirs with harsh conditions.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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