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Inconel 625 superalloy coatings were prepared on 12CrMoV steel plates by CMT process and MIG process respectively. The microstructures, the mechanical properties and oxidation resistance of the coatings were tested and analyzed. The results show that the heat input of CMT process is obviously lower than that of MIG process, and the forming quality of the coating is better, with smooth surface, no splash, no internal porosity and no other defects. The average weld penetration depth of CMT process coating is 0.51 mm and the dilution ratio is 6.8 %, which are much lower than that of the MIG process. Both coatings are mainly composed of coarse columnar crystals, however, the dendrites in the CMT process coating are finer and have better alignment consistency. The microstructure of two process coatings shows significant differences, and a large amount of Laves phase presents in the coating of the MIG process. The presence of Laves phase was not found in the coating of CMT process, but was replaced by element segregation region. In terms of mechanical properties, the CMT process coating has a higher hardness of about 221 HV and it is higher than the MIG process coating which is about 204 HV. Oxidation resistance testing of the coatings shows that the outer Cr2O3 film plays key role to the oxidation resistance. More compact and stable outer oxide film is formed in the oxidation process of the coating prepared by CMT process, which resulted in a better oxidation resistance.

The preparation of high-performance electro-optical materials is one of the key factors determining the application of optoelectronic communication technology such as 5G communication, radar detection, terahertz, and electro-optic modulators. Organic electro-optic materials have the advantage of a high electro-optic coefficient (~1000 pm/V) and could allow the utilization of photonic devices for the chip-scale integration of electronics and photonics, as compared to inorganic electro-optic materials. However, the application of organic nonlinear optical materials to commercial electro-optic modulators and other fields is also facing technical bottlenecks. Obtaining an organic electro-optic chromophore with a large electro-optic coefficient (r33 value), thermal stability, and long-term stability is still a difficulty in the industry. This brief review summarizes recent great progress and the strategies to obtain high-performance OEO materials with a high electro-optic coefficient and/or strong long-term stability. The configuration of D-π-A structure, the types of materials, and the effects of molecular engineering on the electro-optical coefficient and glass transition temperature of chromophores were summarized in detail. The difficulties and future development trends in the practical application of organic electro-optic materials was also discussed.

In this paper, arc oscillation is applied in the fabrication of 2319 aluminum alloy samples by cold metal transition wire arc additive manufacturing process (CMT-WAAM). The porosity, microstructure and mechanical properties of 2319 aluminum alloy under different arc oscillation patterns were discussed. The results showed that the stirring of arc oscillation can influence the molten pool shape and improve the fluidity, change the thermal distribution and the growth direction of columnar crystal. Arc oscillation has a obvious effect on reducing the grain size and proportion of pores. After using the spiral arc oscillation pattern and asymmetrical trapezoid arc oscillation pattern, the volume fraction of pores reduced from 2.64% to 1.09% and 1.22%, and the size of pores was mainly smaller than 40 μm, respectively. The tensile strength in vertical direction and plasticity were improved with arc oscillation, but its effect on the horizontal tensile strength was not noticeable. After solid solution-aging treatment, the tensile strength of the sample with spiral arc oscillation pattern increased to 277 MPa, with a cross-section reduction of 3.6%.

Abstract The development of electro‐optical materials with high chromophore loading levels that possess ultrahigh electro‐optic coefficients and high long term alignment stability is a challenging topic. Anthracene‐maleimide Diels–Alder (DA) reaction and π–π interaction of Anthracene‐pentafluorobenzene and benzene‐pentafluorobenzene are developed for making highly efficient binary cross‐linkable/self‐assembled dendritic chromophores FZL1‐FZL4. A covalently or non‐covalently cross‐linked network is formed by DA reaction or π–π interaction after electric field poling orientation, which greatly improves the long‐term alignment stability of the materials. An electro‐optic coefficient up to 266 pm V−1 and glass transition temperature as high as 178 °C are achieved in cross‐linked film FZL1/FZL2, and 272–308 pm V−1 is achieved for self‐assembled films FZL1/FZL4 and FZL3/FZL4 due to high chromophore density (3.09–4.02 × 1020 molecules cm−3). Long‐term alignment stability tests show that after heating at 85 °C for over 500 h, 99.73% of the initial r33 value is maintained for poled crosslinked electro‐optic films 1:1 FZL1/FZL2. The poled self‐assembled electro‐optic films 1:1 FZL1/FZL4 and 1:1 FZL3/FZL4 can still maintain more than 97.11% and 98.23%, respectively, of the original electro‐optic coefficient after being placed at room temperature for 500 h. The excellent electro‐optic coefficient and stability of the material indicate the practical application prospects of organic electro‐optic materials.

Laser cladding repair technology is valued for its ability to repair of damaged parts with high performance. However, there are so many parameters affect the repair quality that it takes a lot of work to determine the optimal parameters. In this article, a variety of parameters were combined as dimensionless heat input (Q∗), and the effect of Q∗ on the microstructure and mechanical properties of 300M steel repaired samples were studied. Results showed that with the increase of Q∗, microstructure of heat affected zone transformed from tempered martensite to tempered martensite and low bainite. The microstructure of the repaired zone transformed from untempered martensite to untempered martensite and a small amount of retained austenite. With increasing of Q∗, residence time above the austenitizing temperature was extended, and more uniform microstructure were obtained in the repaired zone. What's more, at Q∗ = 5.1, the repair efficiency increases twice than Q∗ = 1. The tensile strength of the repaired samples reached 1017.6 MPa and the elongation reached 6.9%, which were far lower than that of forged samples. The heat treatment was carried out on the repaired parts, which eliminated the microstructure difference due to different Q∗. Compared with the repaired samples without heat treatment, the tensile strength increased by 75% to 1783.8 MPa and the elongation increased by 86% to 10.4%.

Development of polymer-based flooding technology to improve oil recovery efficiency, water dispersion copolymerization of acrylamide, cationic monomer methacryloxyethyltrimethyl ammonium chloride (METAC), and anionic monomer acrylic acid (AA) were carried out in aqueous ammonium sulfate solution with polyvinyl pyrrolidone (PVP) as the stabilizer. The copolymers were characterized by 1H-NMR, FT-IR, TG, and SEM to confirm that they were prepared successfully and exhibited excellent salt-resistant property. Moreover, the effect of the aqueous solution of ammonium sulfate (AS) concentration, stabilizer concentration, and initiator concentration on the viscosity and size were systematically investigated. To further improve the thermal endurance properties of copolymer, hydrophobic monomers with different alkyl chain lengths were added to the above system. The acrylamide-based quadripolymer possessed prominent thermal and salt endurance properties by utilizing the advantages of zwitterionic structure and hydrophobic monomer. With the temperature rising, the viscosity retention could reach 70.2% in the water and 63.8% in the saline. This work had expected to provide a new strategy to design polymers with excellent salinity tolerance and thermal-resistance performances.

In this study, the effect of Al addition on the microstructure and microhardness of Inconel 718 superalloy fabricated by laser additive manufacturing (LAM) was studied. The addition of Al had little effect on the grain morphology and orientation, but the segregation of Nb element intensified with the increase of Al content, which promoted the formation of Laves phase in the inter-dendritic region. After HSDA (Homogenization + Solution + Double aging) heat treatment, the precipitation of δ phase at grain boundaries changed from cross needle-like to the rod-like, and at the same time, the more content of Al was added, the more rod-like δ phase formed inside the grains. Besides, the addition of Al can promote the precipitation of γ′ phase, and inhibit the precipitation of γ'' phase through promoting the segregation of Nb element. When 5% wt.% Al was added, only γ′ phase was precipitated in the matrix. With the increase of Al content, the microhardness of as-deposited LAMed Inconel 718 increased and reached 325 HV when 5% wt.% Al was added. For microhardness of heat-treated samples, it showed the similar evolution trend with the increase of Al content.

With the wide application of titanium alloys in the aerospace industry, the burn resistance properties and surface strengthening processes of titanium alloys have been received increasing attention. In this study, Ti40 burn-resistant titanium alloy was cladded on the surface of TC4 by electron beam cladding, and the surface layer of the nanostructure was prepared by ultrasonic impact treatment (UIT). The nanostructure layer was examined by pulse laser ablation. The results showed that when the moving speed was 16 mm/s, the maximum thickness of the plastic deformation zone of the UIT Ti40 cladding layer reached 150 μm. The highest hardness value was 531 HV, which was approximately 43.5% higher than the original microstructure of the Ti40 cladding layer without UIT. Moreover, the surface microstructure of the Ti40 burn resistant titanium alloy cladding layer was nanocrystalline with uniform distribution and random orientation, and the average grain size was 50 nm. The UIT process can effectively increase the relative content of burn-resistant alloy elements on the surface of the Ti40 cladding layer and increase the content of dense oxidation protective films after laser ablation, which hinders the diffusion and migration of oxygen elements to the matrix alloy in the process of ablation and then improves the burn resistance of the Ti40 cladding layer.

Plain strain deformation trials were carried out on samples of pipeline steels at 1473 K, 1673 K and 1723 K, respectively. The deformation of inclusions in the solid steel at different temperatures and in the semi-solid steel was studied. The composition of inclusions changed from 60.62%Al2O3–16.10%CaO–10.27%MgO–13.01%CaS before deformation to 60.59%Al2O3–13.03%CaO–12.74%MgO–13.63%CaS, 59.69%Al2O3–7.04%CaO–11.51%MgO–21.76%CaS, and 68.26%Al2O3–22.56%CaO–6.68%MgO–2.5%CaS with corresponding deforming temperatures of 1473 K, 1673 K and 1723 K. While the average aspect ratio of inclusions increased from 1.28 to 2.23, 1.32, and 1.35, respectively. Thermodynamic calculations performed by FactSage 7.0 verified the composition transformation from CaO to CaS during the solidification and cooling process of the steel. A kinetic model was used to calculate the dynamic transformation of the inclusion composition at compression temperatures. The inclusion transformation ratio from CaO to CaS increased from 38.28% at 1473 K to 50.50% at 1673 K. For the deformation in the solid steel at the temperature below 1673 K, the thickness of the hard phase CaS increased with the soaking temperature, while the hardness of the steel matrix decreased. The larger hardness difference between inclusions and the steel matrix led to a higher aspect ratio of inclusions after deformation. For the deformation in the semi-solid steel, the small difference of hardness between the soft inclusion phase and the soft steel matrix resulted in a low aspect ratio of inclusions in the semi-solid steel after deformation.

Laser remelting can be used not only to improve the metal surface structure, but also to repair metal surface defects. 34CrNiMo6 belongs to European standard high strength alloy structural steel. It has been widely used in the manufacture of large-size shaft parts which are prone to defects such as cracks and wear during service. This study proposed a repair method for these defects by laser remelting the filled block and then performed heat treatment. The microstructure, m9icrohardness and tensile strength of the repaired sample and heat-treated sample were analyzed using scanning electron microscope (SEM), Vickers hardness tester and universal tensile tester. The final results showed that the metallurgical bonding between the substrate and the filler was good. The microstructure of repaired sample could be divided into three regions: I, II, and III. The main microstructure in region I and II was tempered martensite, and in region III was bainite and martensite. Different regions of repaired sample presented uneven hardness distribution, and the fracture mode was quasi-cleavage fracture. However, after heat treatment, the microstructure of the sample was tempered martensite. Its hardness became uniform, and the fracture mode of the heat-treated sample was ductile fracture. The average hardness value of the heat-treated sample was 296.4HV0.2, which was slightly higher than the substrate. The tensile strength value of the heat-treated sample reached 972.91MPa, which was about 99.3 % of substrate, and its elongation δ was 14.25 %. Overall, the mechanical properties were close to those of the forging.

In order to achieve the microstructure homogeneity at a lower temperature and improve the mechanical properties, a novel post heat treatment was introduced to Inconel 718 fabricated by laser direct energy deposition (LDED), by means of δ aging treatment + solution treatment. The microstructure analysis shows that the fully precipitation of δ phase in LDED Inconel 718 superalloy can “cut” the long strip Laves phase into small pieces. According with the δ phase solution treated at 1020 °C for 30 min, only tiny particle Laves phase was remained. The equilibrium volume fraction of Laves phase after δ phase solution treatment is about 1%, which is much lower than that of the as-deposited sample or the sample only solution treated at 1020 °C. Due to the solution strengthening and precipitation of γ″ phase during aging treatment, the tensile strength of δ aging + δ solution + double aging treated samples was 10.27% higher than that of directed solution + double aging treated samples, as well as a 31.38% and 52.71% increases in elongation and the reduction of area during tensile tests.

Six nonlinear, optical chromophores, Z1–Z6, based on the bis(N,N-diethyl)aniline-derived donor and thiolated isophorone bridge, were designed and synthesized. The bis(N,N-diethyl)aniline-derived donor was applied in a chromophore with thiolated isophorone as an electron bridge for the first time. In particular, the bridge parts of chromophores Z2–Z6 were modified with different functional groups, including tert-butyltrimethylsilane and tert-butyl(methyl)diphenylsilane derivative: 1,3-bis(trifluoromethyl)benzene and alkylaniline cyanoacetate, respectively. Density functional theory calculations suggested this series of chromophores show much greater hyperpolarizability than traditional, nonlinear, optical chromophores due to strong electron donor ability. These chromophores, Z1–Z6, showed very high poling efficiencies due to the large steric hindrance and hyperpolarizability of the chromophores. A large poling efficiency (2.04 ± 0.08 nm2/V2) and r33 value (193 pm/V) were achieved for polymeric thin films doped with 25 wt% chromophore Z6 at 1310 nm.

In the present work, the flow field in a slab continuous casting mold with thicknesses of 180 and 250 mm are compared using high temperature quantitative measurement and numerical simulation. The results of the numerical simulation are in agreement with those of the high temperature quantitative measurement, which verifies the accuracy and reliability of the numerical simulation. Under the same working conditions, the velocities near the mold surface with the thickness of 180 mm were slightly higher than those of the mold with the thickness of 250 mm. The flow pattern in the 180 mm thick mold maintains DRF more easily than that in 250 mm thick mold. The kinetic energy of the jet dissipates faster in the 250 mm thick mold than in the 180 mm mold. For double-roll flow (DRF), as the argon gas bubbles can be flushed into the deeper region under the influence of strong jets on both sides, the argon bubbles distribute widely in the mold. For single-roll flow (SRF), as the argon bubbles float up quickly after leaving the side holes, the bubble distribution is more concentrated in the width direction, which may cause violent interface fluctuation and slag entrainment. The fluctuation at the steel-slag interface in the mold with 180 mm thickness is greater than that in the mold with 250 mm thickness but less than 5 mm. The increase of mold thickness may lead to a decrease of the symmetry of the flow field in the thickness direction and uniformity of mold powder layer thickness. In summary, the steel throughput should be increased in the 250 mm thick mold compared with that in the 180 mm thick mold.

The analysis of dried drop patterns has various applications in research fields like archeology, medical practice, printing, and so on. In this paper, we studied the evaporation and pattern formation of polytetrafluoroethylene (PTFE) colloid droplets on smooth substrate and rough substrates with different roughness. We found that the evaporation of droplets shows remarkable coffee-ring effect on smooth substrate and that the cross-section of the ring is wedge-shaped with its thickness decreasing from the edge to the center. However, with increasing roughness, the effect strengthened, with the section of the coffee-ring changing from wedge- to hill-shaped. The contact angle decreased with increasing roughness, leading to an increase in evaporation rate. Moreover, wicking led to additional evaporation, which also enhanced capillary flow, moving more particles to the edge. In addition, the rough structure of the substrate inhibited the back-flow of the capillary flow, preventing the particles’ move to the center. The formation of radial wrinkles on the edge also led to particle retention, preventing them from moving to the center. All these factors contribute to the decreased width and increased height of the coffee-ring pattern after evaporation on rough surfaces. It is an effective method to regulate the deposition pattern of evaporating droplet by changing the substrate roughness.

Three series of high-performance nonlinear optical chromophores, B-TCF, B-3F, B-5F, N-TCF, N-TCF, S-TCF, and S-3F-S-5F, were synthesized using triphenylamine and N,N-bis-(4-methoxyphenyl)arylamine as donors, tetraene and thiophene as bridges, and tricyanofuran (TCF), perfluorophenyl-tricyanofuran (5F-TCF) and phenyltrifluoromethyl-tricyanofuran (3F-TCF) as acceptors. We conducted a comprehensive analysis of these three series of chromophores to elucidate the structure-performance relationship from various perspectives. By employing DFT calculations and electro-optical coefficient tests, we observed significant influences of different electron donors, p-conjugated bridges, and acceptors on the performance of the chromophores. Polymeric thin films doped with chromophores N-3F and N-5F of 25 wt% with the N,N-bis-(4-methoxyphenyl)aryl-amino donor have been poled to afford large r33 values of 198 and 171 pm V-1 at 1.31 mm, respectively, which surpassed those obtained with other chromophores. [ABSTRACT FROM AUTHOR]

In some rural areas of northern China, brucellosis is an endemic zoonotic infection caused by a bacteria of the genus Brucella. As a result of brucellosis, osteoarticular involvement is the most common complication. Here, we report the case of a 50-year-old male who presented with severe swelling and pain in the right knee in players. Brucella arthritis was diagnosed based on his contact history, clinical manifestations, and results of serological tests, synovial fluid cultures, and radiological imaging. As part of the treatment plan, surgery including an arthrotomy, debridement, and irrigation of the joint cavity was carried out. In the weeks following surgery, the patient reported significant improvement in his right knee joint's function and a significant reduction in the intensity of his joint pain in players. [ABSTRACT FROM AUTHOR]