Recent advances in efficiency of organic photovoltaics are driven by judicious selection of processing conditions that result in a “desired” morphology. An important theme of morphology research is ...quantifying the effect of processing conditions on morphology and relating it to device efficiency. State‐of‐the‐art morphology quantification methods provide film‐averaged or 2D‐projected features that only indirectly correlate with performance, making causal reasoning nontrivial. Accessing the 3D distribution of material, however, provides a means of directly mapping processing to performance. In this paper, two recently developed techniques are integrated—reconstruction of 3D morphology and subsequent conversion into intuitive morphology descriptors —to comprehensively image and quantify morphology. These techniques are applied on films generated by doctor blading and spin coating, additionally investigating the effect of thermal annealing. It is found that morphology of all samples exhibits very high connectivity to electrodes. Not surprisingly, thermal annealing consistently increases the average domain size in the samples, aiding exciton generation. Furthermore, annealing also improves the balance of interfaces, enhancing exciton dissociation. A comparison of morphology descriptors impacting each stage of photophysics (exciton generation, dissociation, and charge transport) reveals that spin‐annealed sample exhibits superior morphology‐based performance indicators. This suggests substantial room for improvement of blade‐based methods (process optimization) for morphology tuning to enhance performance of large area devices.
For optimizing the performance of organic photovoltaics, it is important to access the 3D distribution of material. This work integrates two recently developed techniques—reconstruction of 3D morphology and its conversion into intuitive morphology descriptors—to comprehensively image and quantify 3D morphology under spin‐coating and doctor‐blading processing conditions. The results suggest substantial room for improvement of blade‐based methods.
The resistance of cast iron to chemical and electrochemical corrosion depends on the exposure conditions, chemical composition and the distribution of alloying elements in the microstructure. The ...article presents an attempt to describe the formation of a corrosion layer under controlled chemical corrosion conditions for SiMo ductile iron. In the experiment, a (HT-HRD) chamber for heating the samples with a controlled atmosphere was used, at the same time providing the possibility of testing the sample surface using the XRD method. The analysis was both qualitative and quantitative. It allowed us to capture the sequence of the oxide layer growth on the tested samples. The beneficial effect of molybdenum on the corrosion resistance of SiMo cast iron has been proven. For all cases under analysis, the phenomenon of an increase in the share of hematite (Fe
O
) and magnetite (Fe
O
) was observed in the subsequent sample heating cycles. It turned out that the addition of molybdenum helps to create a tight oxide coating that inhibits the further growth of corrosion processes. Increasing the share of molybdenum in the alloy also reduces the thickness of the oxide layer.
The microstructure of the in situ TiC-reinforced composite surface layers developed during laser surface alloying of a ductile cast iron substrate with titanium was related to the solidification ...conditions in the molten pool. The solidification conditions were estimated using infrared thermography. It was found that the cooling rates of the melt up to about 700 °C/s enable the complete reaction between carbon and the entire amount of titanium introduced into the molten pool. In turn, the cooling rate of about 280 °C/s for the melt containing 8.0 wt% Ti allows the TiC particles to grow in the dendritic form with well-developed secondary arms and a total size of up to 30 µm. For a constant Ti content, the cooling rate of the melt had no effect on the TiC fraction. The increase in the cooling rate elevated the retained austenite fraction in the matrix material, lowering its hardness.
Ultrasonic inspection of cast austenitic stainless steel (CASS) in the nuclear industry is particularly challenging because of sound field scatter and attenuation caused by the coarse-grained ...microstructure. Modeling and simulation are important tools in ultrasonic testing, as they can be used to help address key aspects of inspections, such as developing new probe designs, predicting inspection reliability, and testing phased-array focal laws. However, developing a useful and reliable CASS model is challenging due to the many grain interfaces and crystalline orientations that must be captured. We demonstrate a method of creating a realistic CASS model that is usable in CIVA, a commercially available modeling and simulation software platform. Using polished and chemically etched sections, we generate models of a coarse-grained equiaxed specimen and a columnar specimen. We also test an alternative method of generating a coarse-grained model using Voronoi regions. We qualitatively compare sound field scatter and quantitatively compare sound field attenuation and beam partitioning in simulated sound fields to those of laboratory-measured sound fields. Results show that the Voronoi models perform as well as or better than the models based on actual grain morphology. Here we also show that model-to-model randomness in Voronoi grain structure can impact the magnitude of a simulated echo response by a factor of two or more. Although CASS models are potentially a good depiction of reality for a given scenario, they should not be considered representative since CASS morphology can change significantly from specimen to specimen or within the same specimen.
The paper investigates and compares the local mechanical properties of microstructure components in grey iron EN GJL -300 and ductile iron EN GJS -500-7. The microstructure of both cast irons is ...analysed by LOM, and then certain microstructure components found and their local mechanical properties are investigated. Finally, the resulting nanohardness and reduced Young modulus of the components are discussed and compared between the two cast irons used. A Hysitron TI -950 gauge with Triboscan software is used to perform experiment measurements.
Hazy images suffer from low visibility since the light gets scattered as it passes through various atmospheric particles. Moreover, such images are prone to color distortion, particularly in real ...weather conditions like sandstorms. In this letter, an effective dehazing technique is proposed using weighted least squares filtering on dark channel prior and color correction that involves automatic detection of color cast images. We show that the spread of the hue in a hazy image can differentiate a color cast image from a non-cast one. We propose a measure using the same for categorizing hazy images as cast and non-cast ones. Our novel color correction is performed by color balancing using a non-linear transformation followed by a cast-adaptive airlight refinement. Subjective and quantitative evaluations show that our method outperforms the state-of-the-art. It removes cast satisfactorily and reduces haze substantially while maintaining the naturalness of the image. Moreover, it produces visually pleasing images without halo artifacts.
•Different mixtures and exposures of CRAC under sulfate attack were investigated.•Degradation of CRAC attributes to chemical attack in fully immersion sulfate exposure.•No evident surface damage ...appeared and chlorides inhibit the deterioration of CRAC.•It suggested the RCA replacement of CRAC less than 50% for the sulfate exposure.•Micro corrosion mechanism of ITZ and RA under sulfate attack were investigated.
With the increase of construction solid waste (CSW) in China's urbanization construction, many ecological and environmental problems have been raised. Recycling and reusing of construction waste is conductive to reducing pollution, carbon emissions and conserving resources. Cast-in-situ concrete structures have been widely used in foundation engineering, application of cast-in-situ recycled aggregate concrete (CRAC) has broad application prospect. This paper investigated the mechanical properties and durability of cast-in-situ recycled aggregate concrete under chemical sulfate attack. Cylinder specimens were casted with four recycled concrete aggregate (RCA) replacements of 0%, 30%, 50% and 100%, and immersed into the exposures of tap water, single sulfate solution and chloride-sulfate mixed solution, respectively. Visual inspection and indicators of sulfate concentration, mass and diameter variation, compressive strength were monitored in the exposure of 52 weeks. The results exhibited that RCA replacement has a significant impact on the mechanical properties and sulfate resistance of CRAC, and the existence of chloride can significantly hinder the sulfate diffusion and delays the deterioration of CRAC. Microscopic evidence also indicated that the dissolving of calcium hydroxide and formation of ettringite resulted in the CRAC degradation. Most importantly, RCA and ITZ can avoid serious chemical attack due to less residual calcium hydroxide existed, while ITZ with a higher porosity can further provide the diffusion path for the sulfate.
•Impact of fatigue strength variation on predicted life of cast iron pipes assessed.•Cast iron pipes are likely to leak before burst under fatigue loading.•Loading early in a cast iron pipe’s life ...need not be included in failure predictions.•For the scenario considered, the predicted pipe fatigue lifetime was 59 ± 9 years.•UK iron pipes are > 50 years old: replacement and prediction accuracy are now critical.
Fatigue cracking is thought to be a critical failure mode for Grey Cast Iron (GCI) water pipes; however, this failure mechanism is poorly understood. Using a novel approach to sourcing GCI pipe material for testing, the variation in fatigue strength between pipes from the same batch was experimentally quantified. These results were used to assess the impact of fatigue strength variation on a hypothetical but realistic GCI water pipe years-to-failure scenario. Full-pipe sections were used during fatigue testing and the observed failure mode gave physical meaning to the years-to-fatigue-failure predictions for the first time. The accumulation of fatigue damage was predicted to represent a terminal and very small part of a GCI pipe’s life, so the loads applied to a GCI pipe early in its life are likely to have a limited impact on its remaining life and so do not need to be included in predictive modelling. For the scenario considered here, the predicted variation in lifetime was an 8.6-year range about an average of 59.4 years. GCI pipes in the UK are all > 50 years old, so this is a significant variation for asset and investment planners to account for as these pipes approach the end of their lives.
Silicon and molybdenum (
SiMo
) alloyed cast irons with spherical graphite are used for exhaust manifolds for service at high temperatures in air and combustion atmospheres containing water vapor. ...Analysis of degraded surfaces of in-service manifolds indicates existence of a combined oxidation and de-carburization (de-
C
) phenomena. Therefore, sequential high-temperature tests in air and combustion atmosphere with recording weight change together with carbon analysis at each time step were utilized to quantify the kinetics of both processes. The recorded weight change was related to weight gain due to oxidation and weight loss due to de-
C
. Carbon analysis was used to de-couple these two processes. SEM measured thicknesses of de-
C
layers were used to verify kinetics obtained from changes in carbon concentration during oxidation. It was shown that the oxidation and de-
C
kinetics have different sensitivities to testing temperature and the type of oxidizing atmospheres. At 700 °C and above, there are several significant mutual effects between scale formation and de-
C
processes which affect the kinetics of these processes and activation energy. The tested experimental methodology for decoupling these processes can be used for alloy optimization.
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