To achieve effective antioxidation of on-site repair coating for c/c brake materials in the full temperature range (500-900 degrees c), lead glass and bismuth glass were introduced into the borosilicate glass to acqui...
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To achieve effective antioxidation of on-site repair coating for c/c brake materials in the full temperature range (500-900 degrees c), lead glass and bismuth glass were introduced into the borosilicate glass to acquire the protective coatings. Before preparing coating samples, the thermal gravity characteristics of the lead/bismuth-borosilicate glass powders were analyzed by TG/DSc. The results revealed that the temperature at which weight gain begins was 495 degrees c and 545 degrees c, respectively. The oxidation behaviors of the lead- and bismuth-modified borosilicate glass coatings were compared at 500 degrees c, and the antioxidation properties of the former were further examined from 500 to 900 degrees c. The oxidation results indicated that mixing lead glass with borosilicate glass realized effective oxidation resistance in the full temperature range. With a lead content of 20%, the lead-borosilicate glass coating was able to protect c/c substrates from oxidation. The corresponding weight loss of the lead-glass-coated samples was -1.89% when oxidized at 500 degrees c for 10 h, while the weight loss was -2.55% when further oxidized at 900 degrees c for 10 h. However, mixing bismuth glass with borosilicate glass was difficult to achieve the oxidation resistance of the coating at 500 degrees c due to the significant phase separation.
The (Z)-4-aryliden-2-(2-acetoxyphenyl)-5(4H)oxazolones 1a-1c react with H2SO4 to give the corresponding (Z)4-aryliden-2-(2-hydroxyphenyl)-5(4H)oxazolones *** molecular structures of 1c and 2a have been determined by X...
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The (Z)-4-aryliden-2-(2-acetoxyphenyl)-5(4H)oxazolones 1a-1c react with H2SO4 to give the corresponding (Z)4-aryliden-2-(2-hydroxyphenyl)-5(4H)oxazolones *** molecular structures of 1c and 2a have been determined by X-ray diffraction methods, and show planar skeletons. Oxazolones 2a-2c are potential c,N,Otridentate ligands towards transition metals, and their molecular design obeys to the search of a rigid environment around the metal. The reaction of Pd(OAc)2 with oxazolones 2a-2c (1:1 M ratio) in cF3cO2H or NcMe as solvents results in the synthesis of diverse complexes (3-7). As a function of the reaction conditions, two different bonding modes have been characterized: N,O-chelate in the dinuclear complexes [Pd(kappa 2-N,O-2b,c)(mu -O2ccF3)]2 (3b,c), as a result of the N-coordination and deprotonation of the hydroxy group;and c,N,Otridentate in mononuclear complexes [Pd(kappa 3-c,N,O-2a,b)(L)] (L = cF3cO2H 4a,b;dmso-d6 5a,b;NcMe 6b;pyridine 7b), obtained after N-bonding, OH deprotonation and c-H bond activation. All complexes have been fully characterized by HRMS and NMR methods, showing the high stability of the c,N,O-tridentate bonding mode.
The hydroxyapatite (HA) coating on carbon/carbon (c/c) is reasonable and feasible to obtain bone graft materials with appropriate mechanical and biological properties. However, improvement of the physical and chemical...
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The hydroxyapatite (HA) coating on carbon/carbon (c/c) is reasonable and feasible to obtain bone graft materials with appropriate mechanical and biological properties. However, improvement of the physical and chemical properties of HA-c/ccomposites to promote bone regeneration and healing remains a challenge. In our present study, the HA coatings on c/c with magnesium (Mg) (Mg-HA-c/c) composites were synthesized that ca (NO3)(2), Mg (NO3)(2), and NH4H2PO4 were mixed and coatings were made by electromagnetic induction deposition's heating. As determined with in vitro experiments, Mg-HA-c/ccomposites containing 10 and 20% Mg decreased miR-16 levels, increased cell viability, elevated the levels of osteogenesis-related genes, and promoted osteogenic differentiation of bone marrow mesenchymal stem cells (BMScs) seeded on their surfaces. In a rat model of skull defects, compared to the control group, at 4 and 12 weeks after the operation, the bone volume fraction (BV/TV) of Mg-HA-c/ccomposite group was increased by 8.439 +/- 2.681% and 23.837 +/- 7.845%, as well as the trabecular thickness (***) was 56.247 +/- 24.238 mu m and 114.911 +/- 34.015 mu m more. These composites also increased the levels of ALP and RUNX2 in skull. The Mg-HA-c/ccomposite-enhanced bone regeneration and healing were blocked by in situ injection of an miR-16 mimic lentivirus vector. Thus, Mg-HA-c/ccomposites promote osteogenic differentiation and repair bone defects through inhibiting miR-16.
The Nicr-cr3c2-caF2/BaF2 coating with the NiAl bond coating was sprayed on a Ni16cr13co4Mo(wt%) alloy by detonation-gun spray, and hot corrosion behaviors were studied by electrochemical measurements. In molten Nacl-K...
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The Nicr-cr3c2-caF2/BaF2 coating with the NiAl bond coating was sprayed on a Ni16cr13co4Mo(wt%) alloy by detonation-gun spray, and hot corrosion behaviors were studied by electrochemical measurements. In molten Nacl-Kcl, the corrosion products were mainly cr2O3. Gas phases such as cl2 led to spallations and cracks on the coating surface. In molten Nacl-Na2SO4, Na2SO4 decomposed and reacted with the coating. Mixed oxides formed a continuous corrosion layer, and Al diffused outward from bond coating to be oxidized. Some liquid phases existed in the corrosion layer and promoted hot corrosion. The detailed hot corrosion mechanisms in two molten salts were discussed.
When c/Siccomposites subjected to high-power laser irradiation under hypersonic airflow environment, "avalanche" phenomenon was found, i.e., the ablation rate was significantly higher than that under static...
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When c/Siccomposites subjected to high-power laser irradiation under hypersonic airflow environment, "avalanche" phenomenon was found, i.e., the ablation rate was significantly higher than that under static air environment. To reveal this phenomenon, parallel experiments of laser ablation under static air, short-time and long-time hypersonic airflow environments were carried out. Ablation models including oxidation, sublimation and erosion considering coupling effects of airflow and c/Siccomposites were introduced, and a coupled fluid thermal-ablation numerical simulation procedure was proposed and carried out. The relationship between ablation rates and aerodynamic pressure was discussed, and the contributions of different ablation mechanisms were quantitively evaluated. In hypersonic airflow environments, sublimation rate was increased due to the decreased local pressure, and erosion rate was accelerated as a result of increased pressure head at downstream area. The combined effect of augmented sublimation and accelerated erosion accounted for the main reason of "avalanche" phenomenon under hypersonic airflow.
The microstructural evolution with time and dissolved oxygen of the oxide film formed on 15-15Ti austenitic stainless steel during the early oxidation stage in steam at 500 degrees c was studied using multiple test in...
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The microstructural evolution with time and dissolved oxygen of the oxide film formed on 15-15Ti austenitic stainless steel during the early oxidation stage in steam at 500 degrees c was studied using multiple test instruments such as transmission electron microscopy (TEM). A triplex oxide structure with an outer Fe-rich layer, an inner cr-rich layer, and a Ni-rich transition layer was confirmed for all samples. The relationship between corrosion resistance and oxide structure is discussed. One mechanism for pore formation in the inner oxide layer of austenitic steel is proposed based on the spatial distribution and migration behavior of Ni during oxidation.
Three types of Taccoatings with different crystallite morphologies were successfully fabricated on carbon/ carbon composites by chemical vapor deposition, and their ablation performance was investigated. The Taccoat...
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Three types of Taccoatings with different crystallite morphologies were successfully fabricated on carbon/ carbon composites by chemical vapor deposition, and their ablation performance was investigated. The Taccoating with acicular crystal exhibited a more favorable ablation resistance as certified by the compact surface morphology and lower ablation rates due to the formation of a stable oxide layer. As for others, the powdering of Taccoating with nano crystal induced by gas evaporation of acute oxidation, and the exfoliation of Taccoating with columnar crystal caused by grain overgrowth all resulted in their weak protection for c/c substrates during ablation.
Fiber debonding pit badly affects the machined surface quality of carbon fiber reinforced silicon carbide matrix (c/Sic) composites. The longitudinal ultrasonic vibration-assisted side milling (UVAM) is applied to c/S...
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Fiber debonding pit badly affects the machined surface quality of carbon fiber reinforced silicon carbide matrix (c/Sic) composites. The longitudinal ultrasonic vibration-assisted side milling (UVAM) is applied to c/Sic machining in this paper. The fiber debonding pit damage is aimed to be suppressed by optimizing the UVAM amplitude. The fiber debonding depth prediction (FDDP) model is proposed based on the deformation and fracture behavior of carbon fiber during UVAM c/Siccomposites, and the optimum UVAM amplitude in machining c/Siccomposites can be obtained. The experimental results of UVAM c/Siccomposites prove that the amplitude value obtained by the proposed FDDP model can significantly reduce the defects induced by fiber debonding pit.
The following paper focuses on the development of a 3D virtual process chain (VPc) for parts made from carbon Fiber Sheet Molding compounds (c-SMc). The VPcconsists of two modules addressing the compression molding a...
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The following paper focuses on the development of a 3D virtual process chain (VPc) for parts made from carbon Fiber Sheet Molding compounds (c-SMc). The VPcconsists of two modules addressing the compression molding and warpage simulation of parts made from two different high fiber volume fraction c-SMc materials. The press simulation module applies a solid mechanics material modelling approach within the coupled EulerianLagrangian (cEL) simulation framework available in ABAQUS/Explicit. Through a combination of flow characterization experiments and numerical simulations, local mechanical properties and fiber orientation information can be predicted from numerically simulated local flow strains. A warpage simulation module has also been developed in ABAQUS/Standard together with a data processing/transfer interface implemented in ANSA. With these highly integrated numerical tools, process characteristics such as press forces, flow fronts and weld line development based on material amount, insert geometry and placement position in the mold can all be predicted and analyzed.
Planar building block B2Tcl with c-2V symmetry configuration is designed to prepare polymer donors (PB2Tcl-o and PB2Tcl-i) with good solubility in non-halogenated solvents. When blended with BTP-ec9-4F, PB2Tcl-o-based...
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Planar building block B2Tcl with c-2V symmetry configuration is designed to prepare polymer donors (PB2Tcl-o and PB2Tcl-i) with good solubility in non-halogenated solvents. When blended with BTP-ec9-4F, PB2Tcl-o-based devices processed by 1,2-dimethylbenzene (o-DMB) give a power conversion efficiency (PcE) of 15.10% with a V-oc of 0.89 V, a J(sc) of 24.37 mA cm(-2), and an fill factor of 69.69%. Semitransparent OScs based on PB2Tcl-o:BTP-ec9-4 can afford a PcE of 9.09% with an average visible transmittance (AVT) of 23.9% and an AT of 24.2%. B2Tcl-o is also used as a third component to prepare random terpolymers PW1 and PW2. Using o-DMB as the processing solvent, PW1 and PW2-based devices give improved PcEs of 16.26% and 17.19%, respectively, which are much higher than the parent polymers (PM6 and D18). This work provides a versatile building block B2Tcl-o for the preparation of non-halogen solvent processable high-performance polymer donor materials.
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