Aspects on early-stage corrosion of different zinc alloys: wet scCO2-induced corrosion

CORROSION ◽  
10.5006/3668 ◽  
2020 ◽  
Author(s):  
Ville Saarimaa ◽  
Aaretti Kaleva ◽  
Erkki Levänen ◽  
Pasi Väisänen ◽  
Antti Markkula
Keyword(s):  
Surface Chemistry ◽  
Corrosion Product ◽  
Early Stage ◽  
Zinc Coating ◽  
Product Formation ◽  
High Ratio ◽  
Al2o3 Layer ◽  
Metal Coatings ◽  
Zinc Alloys ◽  
Initial Reactivity

The surface activity of different zinc alloys was evaluated in wet scCO2. The zinc coating surface chemistry governed the corrosion product formation. On zinc and Zn-Al coatings, the Al2O3 layer prevented growth of corrosion products. A Zn-Al-Mg coating showed high initial reactivity due to active Zn-Mg phases. An electrogalvanized coating was very active due to a high ratio of exposed, less dense planes. In a Zn-Fe coating, several Zn-Fe phases were susceptible to wet scCO2 at the same time, triggering the sacrificial effect of Zn. Wet scCO2 is a convenient medium to assess the early-stage corrosion of metal coatings.

scholarly journals Effect of Weld and Surface Defects on the Corrosion Behavior of Nickel Aluminum Bronze in 3.5% NaCl Solution

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1227
Author(s):  
Xu Zhao ◽  
Yuhong Qi ◽  
Jintao Wang ◽  
Tianxiang Peng ◽  
Zhanping Zhang ◽  
...  
Keyword(s):  
Corrosion Product ◽  
Corrosion Behavior ◽  
Early Stage ◽  
Optical Microscope ◽  
Aluminum Bronze ◽  
Nickel Aluminum ◽  
Nacl Solution ◽  
Corrosion Product Film ◽  
Product Film ◽  
Nickel Aluminum Bronze

To study the effect of weld and defects on the corrosion behavior of nickel aluminum bronze (UNS C95810) in 3.5% NaCl solution, the weight loss, X-ray diffraction, optical microscope, scanning electron microscope and electrochemical test of the specimen with weld and defects were investigated. The results show that the presence of weld and defects increases the corrosion rate of bronze. Weld does not change the structure of the corrosion product film, but defects induce a lack of the protective outermost corrosion product in bronze. Weld makes the corrosion product film in the early stage more porous. Defects always produce an increase in the dissolution rate of the bronze.

Dimensional Changes of Graphite Flakes and Fracture in Tensile Tests of Gray Cast Iron

2018 ◽  
Author(s):  
Naoya Tada ◽  
Takeshi Uemori
Keyword(s):  
Cast Iron ◽  
Tensile Test ◽  
Internal Combustion Engines ◽  
Gray Cast Iron ◽  
Early Stage ◽  
Dimensional Change ◽  
Tensile Tests ◽  
High Ratio ◽  
Gray Cast ◽  
Dimensional Changes

Gray cast iron has been used as a component in various mechanical parts, such as the blocks and heads of automobile and marine engines, cylinder liners for internal combustion engines, and machine tool bases. It is desirable because of its good castability and machinability, damping characteristics, and high ratio of performance to cost. On the other hand, the weak graphite flakes present in gray cast iron act as stress concentrators and negatively affect the strength of this material. It is therefore important to know the relationship between the distribution of graphite flakes and the strength or fracture of gray cast iron. In this study, a tensile test of gray cast iron was carried out using a plate specimen in a scanning electron microscope, and the microscopic deformation was observed on the surface of specimen. Particularly, the change in the size of graphite flakes during the tensile test was examined, and the observed trend was discussed. We found from the experimental results that the dimensional changes in the graphite flakes varied in the observed area, and that the final fracture occurred in an area where a relatively large dimensional change was observed. This suggests that the fracture location or the critical parts of gray cast iron, can be predictable from the dimensional changes of the graphite flakes at an early stage of deformation.

The predictive potential of the spatial signature of lymphocytes in breast cancer patients.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. 530-530
Author(s):  
Nora Balint-Lahat ◽  
Chen Mayer ◽  
Noa Ben-Baruch ◽  
Ady Yosepovich ◽  
Kira Sacks ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Patients ◽  
Early Stage ◽  
Principal Component ◽  
Treatment Decision ◽  
High Ratio ◽  
Luminal Breast Cancer ◽  
Breast Cancers ◽  
Breast Cancer Patients ◽  
Validation Set

530 Background: Tumor-infiltrating lymphocytes in breast cancer have emerged as both a prognostic and a potentially predictive immunotherapy biomarker. Advancements in artificial intelligence can extract pathology-based spatial immune fingerprints for use as treatment decision support tools. Methods: We examined 908 primary breast cancer patients with whole slide images (WSI) available from TCGA database. Digital structuring of WSIs included automated detection of lymphocytes, tumor and tumor adjacent stroma, using deep learning-based semantic segmentation. Prognosis was defined as progression free interval (PFI). A Cox Survival analysis was used to detect prognostic spatial features. We used principal component analysis (PCA) to reduce and decorrelate significant features. The resulting PCA features were used to fit the final model. The model was then validated on an independent database of WSI of breast lumpectomies, from two tertiary hospitals in Israel. Results: The analysis included 908 WSI. The average age was 58.4 years old, with a majority of early stage breast cancer (76.7%, stage I and II). The detection performance for tumor area and lymphocytes reached F1 scores of 99% and 97% respectively, in comparison to human annotation. In the Kaplan Meier (KM) analysis of 414 early stage luminal breast cancers, a high number of lymphocyte clusters (LC) and a high ratio between stromal lymphocyte density and tumor lymphocyte density (LD-S/LD-T) were significantly associated with longer PFI (p = 0.005 and p = 0.038, respectively). Based on these features, two continuous PCA features were added to the multivariate model, and remained significantly associated with PFI after adjusting for age (HR = 1.19, 95% CI 1.05-1.35; HR = 1.26 95% CI 1.03-1.55). The validation set was underpowered (n = 79) and data is still being collected. In a preliminary KM analysis of 37 early stage luminal breast cancer cases from the validation set, LD-S/LD-T was significantly associated with longer PFI (p = 0.046). Conclusions: In our study, LC and LD-S/LD-T, presumably surrogate measures of peritumoral lymphocytes, were found significantly associated with longer PFI.

scholarly journals Durability Improvement of Synthetic Dry Adhesives by Metal Coatings

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
Gyuhe Kim ◽  
Taechang Ahn ◽  
Hui Yun Hwang
Keyword(s):  
Adhesion Strength ◽  
Zinc Coating ◽  
High Hardness ◽  
Metal Coating ◽  
Metal Coatings ◽  
Initial Strength ◽  
Dry Adhesives ◽  
Coating Method ◽  
Strength And Stiffness ◽  
Embedding Methods

Gecko-like synthetic dry adhesives (SDAs) have adhesion comparable to that of a real Gecko’s foot, but with very low durability. To address this problem, self-cleaning or stiff core embedding methods have been proposed. However, the proposed methods require special locomotion or complicated manufacturing. In this study, we suggested a metal coating on synthetic dry adhesives to improve durability. SDAs were fabricated via PDMS. Then, metals such as indium, zinc, and gold were coated on the SDAs. The adhesion tests show that the indium- and zinc-coated microstructures have a higher shear adhesion strength than the noncoated ones. Also, the shear adhesion strength of noncoated SDAs was only 14.5% of the initial strength while that of the zinc-coated ones was 35.6% after 200 times of attachment and detachment. We could find PDMS debris and fractures on noncoated SDAs, which results in weakening of the adhesion strength. On the other hand, a relatively high hardness, strength, and stiffness of the zinc coating layers reduced the wear and fractures of the micropatterns, which led to an improved durability in the SDAs. From these tests, we can conclude that the metal coating method could improve the durability of the SDAs.

scholarly journals Investigation into the effect of water chemistry on corrosion product formation in areas of accelerated flow

2017 ◽  
Vol 493 ◽  
pp. 271-279 ◽  
Author(s):  
John McGrady ◽  
Fabio Scenini ◽  
Jonathan Duff ◽  
Nicholas Stevens ◽  
Stefano Cassineri ◽  
...  
Keyword(s):  
Water Chemistry ◽  
Corrosion Product ◽  
Product Formation ◽  
Effect Of Water ◽  
Accelerated Flow

scholarly journals Simultaneous self-optimisation of yield and purity through successive combination of inline FT-IR spectroscopy and online mass spectrometry in flow reactions

2021 ◽  
Author(s):  
Verena Fath ◽  
Philipp Lau ◽  
Christoph Greve ◽  
Philipp Weller ◽  
Norbert Kockmann ◽  
...  
Keyword(s):  
Real Time ◽  
Process Development ◽  
Early Stage ◽  
High Sensitivity ◽  
Product Formation ◽  
Industrial Applications ◽  
Process Conditions ◽  
Model Free ◽  
Ft Ir ◽  
By Products

AbstractSelf-optimisation constitutes a very helpful tool for chemical process development, both in lab and in industrial applications. However, research on the application of model-free autonomous optimisation strategies (based on experimental investigation) for complex reactions of high industrial significance, which involve considerable intermediate and by-product formation, is still in an early stage. This article describes the development of an enhanced autonomous microfluidic reactor platform for organolithium and epoxide reactions that incorporates a successive combination of inline FT-IR spectrometer and online mass spectrometer. Experimental data is collected in real-time and used as feedback for the optimisation algorithms (modified Simplex algorithm and Design of Experiments) without time delay. An efficient approach to handle intricate optimisation problems is presented, where the inline FT-IR measurements are used to monitor the reaction’s main components, whereas the mass spectrometer’s high sensitivity permits insights into the formation of by-products. To demonstrate the platform’s flexibility, optimal reaction conditions of two organic syntheses are identified. Both pose several challenges, as complex reaction mechanisms are involved, leading to a large number of variable parameters, and a considerable amount of by-products is generated under non-ideal process conditions. Through multidimensional real-time optimisation, the platform supersedes labor- and cost-intensive work-up procedures, while diminishing waste generation, too. Thus, it renders production processes more efficient and contributes to their overall sustainability. Graphical abstract

scholarly journals Corrosion product formation on zinc-coated steel in wet supercritical carbon dioxide

2021 ◽  
pp. 103636
Author(s):  
Ville Saarimaa ◽  
Aaretti Kaleva ◽  
Arnold Ismailov ◽  
Tero Laihinen ◽  
Markus Virtanen ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Corrosion Product ◽  
Product Formation ◽  
Coated Steel ◽  
Zinc Coated Steel ◽  
Supercritical Carbon
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