Microstructural characterization of plasma sprayed Ln2Zr2O7 thermal barrier coatings by electron microscopy methods

The presented article characterized microstructural aspects of thermal barrier coatings (TBCs) analysis using methods of electron microscopy such as electron backscatter diffraction (EBSD), transmission/scanning electron microscopy (S/TEM), and TEM. The analyzed TBC system is based on gadolinium zirconate deposited by air plasma spraying method, and additionally, it was subjected to an oxidation test for 500 hr at a temperature of 1,100°C. Moreover, the morphological characterization of feedstock powder was showed. EBSD analysis revealed the inhomogeneity of feedstock materials in the form of complex phase composition. In the case of deposited coating, this method was used to characterize the crystallite size of zirconate coating and phase composition of thermally grown oxide zone. S/TEM and TEM analysis showed morphological details of this zone but not revealed such phase as perovskite oxide of GdAlO₃ type.     

Horizontal bottomed semi-cubic parabolic channel and best hydraulic section

This paper presents a new channel section having semi-cubic parabolic sides and horizontal bottom. The formulae for calculating the area, wetted perimeter are presented. The best hydraulic section is derived using three variables (water depth, water surface width and horizontal bottom width). Results show the ratios of the water surface width to depth, bottom width to depth and water surface width to bottom are all constant for the best hydraulic section. Explicit equations of the best hydraulic section for design are also deduced. Examples show these explicit equations are convenient for design. This type of best hydraulic section is compared with the trapezoid and classic semi-cubic parabolic sections. Results indicate that the area and wetted perimeter are less than those of trapezoid and classic semi-cubic parabolic sections for a given flow discharge. It means less lining and excavation cost is required for construction.     

An investigation of epoxy/thermoplastic blends based on addition of a novel copoly(aryl ether nitrile) containing phthalazinone and biphenyl moieties

In this paper, a novel soluble copoly(aryl ether nitrile) containing phthalazinone and biphenyl moieties (PPBEN) was synthesized for the first time to improve the impact resistance of tetraglycidyl 4,4'‐diaminodiphenylmethane epoxy resin cured with 4,4‐diaminodiphenylsulfone. Then a series of blends were prepared via solution blending with different contents of PPBEN. The thermal and mechanical properties and the micromorphology of the cured blends were investigated by differential scanning calorimetry, dynamic mechanical analysis (DMA), parallel plate rheometry, mechanical property tests and SEM analysis, respectively. The results indicated that the incorporation of thermoplastic PPBEN delayed the epoxy curing reaction, and the crosslinking density of epoxies was also reduced. The no‐notch impact strength of the cured blend with 15% PPBEN was up to 16.7 kJ m^?2, higher by about 104% than that of pure epoxy resin without sacrificing the modulus due to a specific sea‐island structure. All the blends showed two‐phase morphology characterized by DMA and SEM. The size of the thermoplastic morphology was only 70?80 nm, much less than that of commonly used thermoplastics, due to the special segment structure of PPBEN. © 2015 Society of Chemical Industry     

Rectangular Section Control Technology for Silicon Steel Rolling

Rectangular section control technology(RSCT)was introduced to achieve high-precision profile control during silicon steel rolling.The RSCT principle and method were designed,and the whole RSCT control strategy was developed.Specifically,RSCT included roll contour design,rolling technology optimization,and control strategy development,aiming at both hot strip mills(HSMs)and cold strip mills(CSMs).Firstly,through the high-performance variable crown(HVC)work roll optimization design in the upper-stream stands and the limited shifting technology for schedule-free rolling in the downstream stands of HSMs,a hot strip with a stable crown and limited wedge,local spot,and single wave was obtained,which was suitable for cold rolling.Secondly,an approximately rectangular section was obtained by edge varying contact(EVC)work roll contour design,edge-drop setting control,and closed loop control in the upper-stream stands of CSMs.Moreover,complex-mode flatness control was realized by coordinating multiple shape-control methods in the downstream stands of CSMs.In addition,the RSCT approach was applied in several silicon-steel production plants,where an outstanding performance and remarkable economic benefits were observed.     

球化率及碳化物形貌对C35E钢精冲质量的影响

通过不同的球化退火工艺获得了不同球化率及碳化物形貌的C35E钢,研究了球化率和碳化物形貌对其精冲质量的影响。C35E钢的最佳球化退火保温温度为720,适当的温度下延长保温时间有助于提高其球化率。球化率越高,碳化物呈细小均匀分布,精冲件的冲裁质量越好。对于球化完全但碳化物呈团块状或带状分布的材料,其冲裁面上依然会出现断裂带。     

Influences of chip serration on micro-topography of machined surface in high-speed cutting

Saw-tooth chip changes from macroscopically continuous ribbon to separated segments with the increase of cutting speed. The aim of this study is to find the correlations between chip morphology and machined surface micro-topography at different chip serration stages encountered in high speed cutting. High strength alloy steel AerMet100 was employed in orthogonal cutting experiments to obtain chips at different serration stages and corresponding machined surfaces. The chips and machined surfaces obtained were then examined with optical microscope (OM), scanning electron microscope (SEM), and white light interferometer (WLI). The result shows that chip serration causes micro-waves on machined surface, which increases machined surface roughness. However, wave amplitudes (surface roughness) at different serration stages are different. The principal factor influencing wave amplitude is the thickness of the sawed segment (tooth) of saw-tooth chip. With cutting parameters in this study, surface roughness contributed by chip serration ranges from 0.39 μm to 1.85 μm. This may bring on serious problems in the case of trying to replace grinding with high-speed cutting in rough machining. Some suggestions have been proposed to control the chip serration-caused surface roughness in high-speed cutting based on the results of the current study.     

Thermally stable cellular poly(vinylidene) ferroelectrets: Optimization of CO2 driven inflation process

Electrically charged cellular ferroelectrets can show excellent thermally stable piezoelectric activity and are therefore progressively used in electrochemical transducers. Given that an optimized cellular structure is a key for improving charge density and the associated piezoelectric properties in this material, we investigated the influence of CO₂ inflation treatment using various gas diffusion expansion or inflation procedures on the piezoelectric d₃₃ coefficient and thermal stability of cellular poly(vinylidene) ferroelectrets and compare with the results (partially) obtained by N₂ inflation as reported in our previous study (Jahan, Mighri, Rodrigue, Ajji, J. Appl. Polym. Sci. 2019, 136, 47540). Samples were prepared using the conventional extrusion–stretching–inflation–corona charging method. Maximum d₃₃ coefficient for CO₂-inflated samples is found to be around 30% higher than that of N₂-inflated samples (327 pC/N compared to 251 pC/N) by stepwise pressure application method. The key parameters addressed in the inflation procedures are the changes in sample thickness, morphology, and the void-height distribution in both gas treatments. The ferroelectrets show excellent thermal stability for up to 4 days at 90, 110, and 120 °C in both treatments with a slightly improved performance in CO₂ gas. The higher activation energy of CO₂-inflated samples (0.52 eV) than the N₂-inflated ones (0.43 eV) further confirms the stability data. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47929.     

Effect of the annealing procedure and the molecular weight on the crystalline phase morphology and thermal properties of polylactide

The thermomechanical properties of poly(lactide) (PLA) are strongly related to its semicrystalline microstructure and morphology. Thermal annealing is a strategy to improve the crystallinity of PLA. However, the different techniques and specimen types needed for each kind of characterization could lead to misleading conclusions. In this work, annealed samples of three PLA grades with different molecular weights were studied by DSC, wide angle X‐ray scattering and polarized optical microscopy (POM) and the results are related to their thermomechanical and impact properties. Special focus is put on the POM results obtained by different approaches and the suitability of each of them to be related to the thermomechanical properties. By annealing medium molecular weight PLA specimens at 140 °C an important increase of the heat distortion temperature was obtained, which was not related to the spherulite size but to the combination of high crystallinity degree together with high α/α′ crystal type ratio. However, the impact properties of annealed PLA decreased with increase in the annealing temperature according to an increment in crystallinity and in the α/α′ crystal ratio. © 2019 Society of Chemical Industry     

Morphology of Flashing Feeds at Critical Fluid Properties in Larger Pipes

Tailored conditioning and control of flashing feeds in industrial applications requires knowledge of the evolving flow morphology and phase fractions along the feed pipe. Design methods obtained from reference systems (e.g. water-air) are hardly applicable for commercial scales and critical fluid properties (e.g. high vapor densities, low surface tension). In this study, the flow morphology of flashing feeds in a novel refrigerant test rig at critical fluid properties was analyzed using wire-mesh sensors at two locations along the feed pipe and experimental data from the water-air system.     

Characteristics of pigments,modification, and their functionalities

Novel treatments of pigments with inorganic materials have tremendous industrial and commercial prospects. Specific treatment of pigment has a marked effect on its behavior during application. The treatment allows a broad modification of the surface characteristics of pigment particles which leads to improved functionalities. Surface modification of pigments is achieved via coating, polymerization with modifying reagent, treatment with derivatives or polymers, which alter either the optical, conductivity or dispersibility during processing and application. These and many other distinguishing factors that affect the characteristics of pigments such as the class, crystal structure, particle morphology, particle size, hiding power, pigment volume concentration, surface character, and surface treatment have been reviewed. Various organic pigments such as those from fungus and bacteria, and the various families of pigment types such as metallic pigment, light interference, and diffractive pigments which presents decorative quality such as leafing, nonleafing, pearlscent, and Fabry‐Perot effects on substrates have also been reviewed in addition to those from inorganic sources with emphasis on the structure and physiochemical modifications using metal and nonmetal Ions.