In battery cycling, mechanical effects introduced by electrochemical reactions are commonly observed. In return, the mechanical deformations also have a large impact on the electrochemical process. However, such a coupling effect of electrochemical reaction and mechanical deformation has a complicated interplay on the atomic scale and an explicit elucidation is still challenging. Herein, we used in situ transmission electron microscopy to directly visualize the coupling process during the lithiation of two-dimension Van der Waals MoS 2 layered electrodes. A self-sustained cracking mechanism was identified; the first crack was created by the accumulation of the linear defects originated from the strain in lithiation. The formed defects including dislocations and antiphase boundaries, in turn accelerated the Li-ion diffusion, promoting the electrochemical reaction and cooperatively gave rise to the formation of a second and following cracks that resembled the “avalanche effect”. Meanwhile, it is observed that a threshold crystal size exists, under which the lithiation stress is not sufficient to initiate the first crack, and thus the serial cracking process could be avoided. The present work provides an atomistic insight into a cooperation from the mechanical and electrochemical effects toward the formation of the arrayed cracks. It also sheds light on the enhancement of mechanical properties of layered electrode materials for rechargeable batteries.
{"title":"Serial Cracking in 2D Van der Waals Layered Electrodes Mediated by Electrochemical Reaction and Mechanical Deformation","authors":"Fanjie Xia, Hao-yang Peng, Qihao Liang, Xin Peng, Congli Sun, Jinsong Wu","doi":"10.2139/ssrn.3906937","DOIUrl":"https://doi.org/10.2139/ssrn.3906937","url":null,"abstract":"In battery cycling, mechanical effects introduced by electrochemical reactions are commonly observed. In return, the mechanical deformations also have a large impact on the electrochemical process. However, such a coupling effect of electrochemical reaction and mechanical deformation has a complicated interplay on the atomic scale and an explicit elucidation is still challenging. Herein, we used in situ transmission electron microscopy to directly visualize the coupling process during the lithiation of two-dimension Van der Waals MoS 2 layered electrodes. A self-sustained cracking mechanism was identified; the first crack was created by the accumulation of the linear defects originated from the strain in lithiation. The formed defects including dislocations and antiphase boundaries, in turn accelerated the Li-ion diffusion, promoting the electrochemical reaction and cooperatively gave rise to the formation of a second and following cracks that resembled the “avalanche effect”. Meanwhile, it is observed that a threshold crystal size exists, under which the lithiation stress is not sufficient to initiate the first crack, and thus the serial cracking process could be avoided. The present work provides an atomistic insight into a cooperation from the mechanical and electrochemical effects toward the formation of the arrayed cracks. It also sheds light on the enhancement of mechanical properties of layered electrode materials for rechargeable batteries.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81309716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Vaara, Miikka Väntänen, J. Laine, J. Kemppainen, T. Frondelius
Nowadays, casting simulations can predict local properties, such as matrix ferrite-pearlite ratio and nodule count. Thus, there is a need for a model capable of using these to predict the fatigue of nodular cast irons. In this paper, we derive the necessary methods for predicting the fatigue of nodular cast irons, where graphites act as crack initiating defects. The graphite and ferrite size distributions were derived based on elementary inputs using stochastic processes to emulate the microstructure patterns. The √area model was used to check crack arrest at the ferrite-pearlite interface of mixed grades, with respective microhardness. We address ferrite and graphite clustering by stochastic processes that have not been addressed before properly. Furthermore, we provide a solution to an important problem that has not been raised in the literature: the largest ferrite defect containing a crack initiating graphite. We propose a model to take into account changes in ferrite hardness by solid solution strengthening. The model predictions were compared to a large amount of literature data with various parameters. Finally, an in-depth analysis of the mechanisms was performed to provide a clear overview of the problem. The method was compared to some of the other methods proposed in the literature.
{"title":"Prediction of the Fatigue Strength Defining Mechanism of Nodular Cast Iron Based on Statistical Microstructural Features","authors":"J. Vaara, Miikka Väntänen, J. Laine, J. Kemppainen, T. Frondelius","doi":"10.2139/ssrn.3862296","DOIUrl":"https://doi.org/10.2139/ssrn.3862296","url":null,"abstract":"Nowadays, casting simulations can predict local properties, such as matrix ferrite-pearlite ratio and nodule count. Thus, there is a need for a model capable of using these to predict the fatigue of nodular cast irons. In this paper, we derive the necessary methods for predicting the fatigue of nodular cast irons, where graphites act as crack initiating defects. The graphite and ferrite size distributions were derived based on elementary inputs using stochastic processes to emulate the microstructure patterns. The √area model was used to check crack arrest at the ferrite-pearlite interface of mixed grades, with respective microhardness. We address ferrite and graphite clustering by stochastic processes that have not been addressed before properly. Furthermore, we provide a solution to an important problem that has not been raised in the literature: the largest ferrite defect containing a crack initiating graphite. We propose a model to take into account changes in ferrite hardness by solid solution strengthening. The model predictions were compared to a large amount of literature data with various parameters. Finally, an in-depth analysis of the mechanisms was performed to provide a clear overview of the problem. The method was compared to some of the other methods proposed in the literature.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":"79 9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87958264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Drey, Eric C. O’Quinn, S. Finkeldei, J. Neuefeind, M. Lang
Pyrochlore complex oxides (A2B2O7) are an important class of fluorite-derivative ceramics with exceptional chemical and structural versatility which make them ideal model systems for studying disordering mechanisms over a range of spatial scales. Neutron total scattering methods were used to analyze the structural behavior in the non-stoichiometric series NdxZr1-xO2-0.5x (0.5 ≤ x ≤ 0.23) as a function of Nd content, x. Characterization of the structure functions using Rietveld refinement and the pair distribution functions with small-box refinement reveal complex disordering pathways; the average, long-range phase changes over a very narrow compositional range from pyrochlore (Fd m) to defect fluorite (Fm m) through full randomization of the cation and anion sublattices at x ~ 0.31, while the local, short-range structure continuously adopts a weberite-type atomic arrangement (C2221). Comparison to a previously studied Ho2Ti2-xZrxO7 solid solution series reveals how changes in chemical composition and stoichiometry modify defect formation and determine how disordering progresses across different length scales in pyrochlore oxides.
{"title":"Local Ordering in Disordered Nd xZr 1-xO 2-0.5x Pyrochlore as Observed Using Neutron Total Scattering","authors":"D. Drey, Eric C. O’Quinn, S. Finkeldei, J. Neuefeind, M. Lang","doi":"10.2139/ssrn.3890348","DOIUrl":"https://doi.org/10.2139/ssrn.3890348","url":null,"abstract":"Pyrochlore complex oxides (A2B2O7) are an important class of fluorite-derivative ceramics with exceptional chemical and structural versatility which make them ideal model systems for studying disordering mechanisms over a range of spatial scales. Neutron total scattering methods were used to analyze the structural behavior in the non-stoichiometric series NdxZr1-xO2-0.5x (0.5 ≤ x ≤ 0.23) as a function of Nd content, x. Characterization of the structure functions using Rietveld refinement and the pair distribution functions with small-box refinement reveal complex disordering pathways; the average, long-range phase changes over a very narrow compositional range from pyrochlore (Fd m) to defect fluorite (Fm m) through full randomization of the cation and anion sublattices at x ~ 0.31, while the local, short-range structure continuously adopts a weberite-type atomic arrangement (C2221). Comparison to a previously studied Ho2Ti2-xZrxO7 solid solution series reveals how changes in chemical composition and stoichiometry modify defect formation and determine how disordering progresses across different length scales in pyrochlore oxides.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":"53 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86761032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jianwen Liu, Kai Zhang, Yi Yang, Hao Wang, Yuman Zhu, A. Huang
Investigation into the precipitation and coarsening behavior of grain boundary α-phase (GB-α) in Ti6Al4V (Ti-64) manufactured by selective laser melting (SLM) were carried out and compared with that in as-cast Ti64 in this study. It was found that in SLM Ti64, the GB-α tends to precipitate first at the triple junctions (TJs) of the β-phase grain boundaries during the further annealing heat treatments in the α+β phase regime. With 750 ℃ annealings, the coarsening process of GB-α was controlled by the bulk diffusion mechanism with a small coarsening coefficient, different from as-cast Ti64. The interface reaction which has a large coarsening coefficient was dominant for the GB-α coarsening at 850℃ and 950 ℃ annealings. Such a difference in coarsening behavior at different annealing temperatures in SLM Ti64 was found to be related to the different curvatures of GB-α caused by the different nucleation mechanisms of α lamellae.
{"title":"Grain Boundary α-Phase Precipitation and Coarsening: Comparing Selective Laser Melted and Conventional Manufactured Ti6Al4V","authors":"Jianwen Liu, Kai Zhang, Yi Yang, Hao Wang, Yuman Zhu, A. Huang","doi":"10.2139/ssrn.3889408","DOIUrl":"https://doi.org/10.2139/ssrn.3889408","url":null,"abstract":"Investigation into the precipitation and coarsening behavior of grain boundary α-phase (GB-α) in Ti6Al4V (Ti-64) manufactured by selective laser melting (SLM) were carried out and compared with that in as-cast Ti64 in this study. It was found that in SLM Ti64, the GB-α tends to precipitate first at the triple junctions (TJs) of the β-phase grain boundaries during the further annealing heat treatments in the α+β phase regime. With 750 ℃ annealings, the coarsening process of GB-α was controlled by the bulk diffusion mechanism with a small coarsening coefficient, different from as-cast Ti64. The interface reaction which has a large coarsening coefficient was dominant for the GB-α coarsening at 850℃ and 950 ℃ annealings. Such a difference in coarsening behavior at different annealing temperatures in SLM Ti64 was found to be related to the different curvatures of GB-α caused by the different nucleation mechanisms of α lamellae.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":"130 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73303590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chuanbo Xu, Jiaming He, Junhao Wu, Shaoze Li, Xinying Li
In this study, an index namely Carbon-Neutral Readiness Index (CNRI) is designed to compare the carbon-neutral readiness among China’s 30 provinces. The CNRI is decomposed into a hierarchical structure that combines four dimensions and associated 19 quantitative indicators. Several indicators are newly proposed such as ‘per capita carbon trading volume’, ‘maturity degree of carbon capture and storage deployment’, and ‘percentage of ocean cover’. To determine the importance weight of indicators, an improved Criteria Importance Though Intercriteria Correlation (CRITIC) approach is developed by considering the correlation between indicators. Then, the weighted averaging operator is used to evaluate the CNRI of China’s provinces. Our results indicate that: 1) the correlation between most indicators is significant, of which 3.51% has an extremely strong relationship; 2) the indicator ‘per capita steel production’ owns the largest weight (0.113); 3) Beijing provinces ranks first, followed by Sichuan and Yunnan province; 4) the spatial differences of CNPI show a pattern of ‘strong in the central and south provinces, week in north provinces’; 5) the sensitive analysis reveals that the ranking results are relatively robust.
{"title":"Measuring Carbon-Neutral Readiness Index of China's Provinces","authors":"Chuanbo Xu, Jiaming He, Junhao Wu, Shaoze Li, Xinying Li","doi":"10.2139/ssrn.3898488","DOIUrl":"https://doi.org/10.2139/ssrn.3898488","url":null,"abstract":"In this study, an index namely Carbon-Neutral Readiness Index (CNRI) is designed to compare the carbon-neutral readiness among China’s 30 provinces. The CNRI is decomposed into a hierarchical structure that combines four dimensions and associated 19 quantitative indicators. Several indicators are newly proposed such as ‘per capita carbon trading volume’, ‘maturity degree of carbon capture and storage deployment’, and ‘percentage of ocean cover’. To determine the importance weight of indicators, an improved Criteria Importance Though Intercriteria Correlation (CRITIC) approach is developed by considering the correlation between indicators. Then, the weighted averaging operator is used to evaluate the CNRI of China’s provinces. Our results indicate that: 1) the correlation between most indicators is significant, of which 3.51% has an extremely strong relationship; 2) the indicator ‘per capita steel production’ owns the largest weight (0.113); 3) Beijing provinces ranks first, followed by Sichuan and Yunnan province; 4) the spatial differences of CNPI show a pattern of ‘strong in the central and south provinces, week in north provinces’; 5) the sensitive analysis reveals that the ranking results are relatively robust.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87216346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Sabino, Bruno Gabriel Batista Cordeiro, L. Silva, A. Pukasiewicz, Edgar Dutra Zanotto, F. Serbena
Barium disilicate (BaO.2SiO 2 = BS2) is one of the very few stoichiometric glasses that allows for accurate control of the desired microstructure via thermal treatment, making it a (scarcely studied) model system for microstructure-property studies. Here, we performed a systematic research work on the variation in hardness, elastic modulus, fracture strength, and toughness as a function of the crystalline volumetric fraction, crystal size, and residual stresses in BS2 glass-ceramics (GC). These microstructural features were independently modified; the average crystal diameter varied from 5 to 100 μm and the crystallized volumetric fraction from 0 to 68%. The internal residual stresses in the crystals, are tensile in this system . Samples with an average spherulite size above 30 µm showed spontaneously fractured crystals due to the residual stresses. The samples with 5 and 10 µm spherulites have not cracked because the spherulites have a high volume fraction of residual glass (74%) and moderate internal stresses (40-70 GPa). The fracture toughness, K IC , increased with the spherulite size and volume fraction. However, the residual glass inside the spherulites rendered crack bowing, bridging, and trapping ineffective. The variation of K IC with the crystallized volume fraction is similar for GCs with different crystal sizes. Also, a comparison with a lithium silicate glass-ceramic showing compressive residual stresses yielded similar results. These combined findings indicate that the crystallization of a tougher phase is the crucial parameter controlling fracture toughness in these materials. The results with this model material can be extended to design novel strong and tough glass-ceramics.
{"title":"Decoupling Microstructural and Residual Stress Effects on Glass-Ceramic Toughening","authors":"S. Sabino, Bruno Gabriel Batista Cordeiro, L. Silva, A. Pukasiewicz, Edgar Dutra Zanotto, F. Serbena","doi":"10.2139/ssrn.3897766","DOIUrl":"https://doi.org/10.2139/ssrn.3897766","url":null,"abstract":"Barium disilicate (BaO.2SiO 2 = BS2) is one of the very few stoichiometric glasses that allows for accurate control of the desired microstructure via thermal treatment, making it a (scarcely studied) model system for microstructure-property studies. Here, we performed a systematic research work on the variation in hardness, elastic modulus, fracture strength, and toughness as a function of the crystalline volumetric fraction, crystal size, and residual stresses in BS2 glass-ceramics (GC). These microstructural features were independently modified; the average crystal diameter varied from 5 to 100 μm and the crystallized volumetric fraction from 0 to 68%. The internal residual stresses in the crystals, are tensile in this system . Samples with an average spherulite size above 30 µm showed spontaneously fractured crystals due to the residual stresses. The samples with 5 and 10 µm spherulites have not cracked because the spherulites have a high volume fraction of residual glass (74%) and moderate internal stresses (40-70 GPa). The fracture toughness, K IC , increased with the spherulite size and volume fraction. However, the residual glass inside the spherulites rendered crack bowing, bridging, and trapping ineffective. The variation of K IC with the crystallized volume fraction is similar for GCs with different crystal sizes. Also, a comparison with a lithium silicate glass-ceramic showing compressive residual stresses yielded similar results. These combined findings indicate that the crystallization of a tougher phase is the crucial parameter controlling fracture toughness in these materials. The results with this model material can be extended to design novel strong and tough glass-ceramics.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77580701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Polyethylene glycol-6000 supported copper-molybdenum nanoparticles (CuO-MoO3@PEG) have been synthesized as a highly efficient, novel and recyclable heterogeneous catalyst by simple impregnation method. The catalyst was characterized well by FTIR, XRD, SEM, EDX, elemental mapping, TEM, TGA, EPR, ICP-AES and UV-visible DRS analyses. The catalyst was successfully applied for synthesizing new pyrimidine diones derivatives and β-enaminones which have important biological activity. The catalyst was found to be efficient up to five cycles with minor loss in catalytic activity. The recovered catalyst (5th run) retained its structure integrity was confirmed by FTIR, XRD, SEM, TEM, TGA, ICP-AES analyses. The products (pyrimidine diones derivatives) were obtained in excellent yield (92%) and shorter reaction time period (30-35 min).
{"title":"Peg Supported Cu-Mo Mixed Metal Oxide (CuO-MoO 3@PEG): A Highly Efficient Catalyst for the Synthesis of Pyrimidine Diones","authors":"A. Ali, Mohd Umar Khan, Zeba N. Siddiqui","doi":"10.2139/ssrn.3874478","DOIUrl":"https://doi.org/10.2139/ssrn.3874478","url":null,"abstract":"Polyethylene glycol-6000 supported copper-molybdenum nanoparticles (CuO-MoO<sub>3</sub>@PEG) have been synthesized as a highly efficient, novel and recyclable heterogeneous catalyst by simple impregnation method. The catalyst was characterized well by FTIR, XRD, SEM, EDX, elemental mapping, TEM, TGA, EPR, ICP-AES and UV-visible DRS analyses. The catalyst was successfully applied for synthesizing new pyrimidine diones derivatives and β-enaminones which have important biological activity. The catalyst was found to be efficient up to five cycles with minor loss in catalytic activity. The recovered catalyst (5th run) retained its structure integrity was confirmed by FTIR, XRD, SEM, TEM, TGA, ICP-AES analyses. The products (pyrimidine diones derivatives) were obtained in excellent yield (92%) and shorter reaction time period (30-35 min).","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":"76 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85564208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Gwalani, M. Song, J. Silverstein, J. Escobar, Tianhao Wang, M. Pole, Kyle W. Johnson, B. Jasthi, A. Devaraj, K. Ross
The microstructural evolution under the extreme environments imposed during cold spray deposition of cermet coatings and the microstructural recovery during post-processing annealing treatments is rather complex and not well understood. Here, Ni-Yttria cermet coatings on an SS304 substrate were produced using cold spray technique, resulting in a bimodal grain structure. The grain growth, phase stability, hardness, and wear properties are observed in as-deposited and annealed (at 400 ⁰C) Ni-Yttria and pure Ni coatings. A multimodal microstructural characterization using electron microscopy, and atom probe tomography shows the structural and compositional stability of yttria particles and Ni grains. A fragmentation of Y-rich particles and dispersion in Ni was observed, however, no forced mixing/dissolution of Y in Ni is detected. Nano-yttria dispersed within the Ni grains slowed the grain growth during annealing. After annealing, Yttria reinforced coating was 1.5 times harder and showed better thermal and mechanical stability compared to the Ni coating.
{"title":"Thermal Stability and Mechanical Properties of Cold-Sprayed Ni-Yttria Coating","authors":"B. Gwalani, M. Song, J. Silverstein, J. Escobar, Tianhao Wang, M. Pole, Kyle W. Johnson, B. Jasthi, A. Devaraj, K. Ross","doi":"10.2139/ssrn.3897768","DOIUrl":"https://doi.org/10.2139/ssrn.3897768","url":null,"abstract":"The microstructural evolution under the extreme environments imposed during cold spray deposition of cermet coatings and the microstructural recovery during post-processing annealing treatments is rather complex and not well understood. Here, Ni-Yttria cermet coatings on an SS304 substrate were produced using cold spray technique, resulting in a bimodal grain structure. The grain growth, phase stability, hardness, and wear properties are observed in as-deposited and annealed (at 400 ⁰C) Ni-Yttria and pure Ni coatings. A multimodal microstructural characterization using electron microscopy, and atom probe tomography shows the structural and compositional stability of yttria particles and Ni grains. A fragmentation of Y-rich particles and dispersion in Ni was observed, however, no forced mixing/dissolution of Y in Ni is detected. Nano-yttria dispersed within the Ni grains slowed the grain growth during annealing. After annealing, Yttria reinforced coating was 1.5 times harder and showed better thermal and mechanical stability compared to the Ni coating.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72731873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Oscar Oyola-Rivera, Jiayue He, G. Huber, J. Dumesic, Nelson Cardona-Martínez
The catalytic conversion of cellulose to levoglucosenone (LGO) was studied using dilute sulfuric acid and propylsulfonic acid functionalized SBA-15 (PS-SBA-15) in tetrahydrofuran (THF). We show that the addition of small amounts of a liquid acid catalyst such as sulfuric acid complements the use of a solid acid catalyst for the conversion of cellulose. Sulfuric acid promotes the depolymerization of cellulose into levoglucosan (LGA). The main role of the solid Brønsted acid catalyst is to dehydrate the LGA into LGO. The addition of low concentrations of H 2 SO 4 to PS-SBA-15 resulted in an increase in LGO yield of up to 37% (from 18 % obtained using an equivalent amount of H 2 SO 4 only). Our approach provides a novel alternative for a more environmentally friendly production of LGO.
{"title":"Catalytic Conversion of Cellulose to Levoglucosenone Using Propylsulfonic Acid Functionalized Sba-15 and H2so4 In Tetrahydrofuran","authors":"Oscar Oyola-Rivera, Jiayue He, G. Huber, J. Dumesic, Nelson Cardona-Martínez","doi":"10.2139/ssrn.3863037","DOIUrl":"https://doi.org/10.2139/ssrn.3863037","url":null,"abstract":"The catalytic conversion of cellulose to levoglucosenone (LGO) was studied using dilute sulfuric acid and propylsulfonic acid functionalized SBA-15 (PS-SBA-15) in tetrahydrofuran (THF). We show that the addition of small amounts of a liquid acid catalyst such as sulfuric acid complements the use of a solid acid catalyst for the conversion of cellulose. Sulfuric acid promotes the depolymerization of cellulose into levoglucosan (LGA). The main role of the solid Brønsted acid catalyst is to dehydrate the LGA into LGO. The addition of low concentrations of H 2 SO 4 to PS-SBA-15 resulted in an increase in LGO yield of up to 37% (from 18 % obtained using an equivalent amount of H 2 SO 4 only). Our approach provides a novel alternative for a more environmentally friendly production of LGO.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74919750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Ge, L. Straka, M. Vronka, A. Sozinov, O. Heczko
Using common and high resolution transmission electron microscopy, we study the evolution of crystal structure with increasing thickness in a thin Ni50Mn25Ga20Fe5 foil. Iron alloying enables to observe the complete spectrum of known martensitic phases and respective transitions simultaneously. Starting from cubic austenite at about 30 nm foil thickness, the structure evolves via interleaved stripes of austenite and five-layered modulated 10M martensite to pure 10M phase with low density of stacking faults. With increasing thickness the 10M phase transforms gradually to seven-layered modulated 14M by increasing density of stacking faults. Finally the non-modulated tetragonal NM phase appears within the 14M phase by detwinning of nanotwins. We found large local variation of lattice parameters, which is ascribed to elastically very soft austenite and 10M phase and faulty 14M lattice. Our experiments show clearly that nanotwinning and stacking faults are inherent structure features tightly connected with lattice modulation and intermartensite transformations. This is important finding in broader attempt to bridge the gap between the nanotwinning and modulation period development with temperature and composition. From the application point of view, the observed instability of modulation or of particular phases in thin films imposes certain limits on the use of material on microscale.
{"title":"Transitions Between Austenite and Martensite Structures in Ni 50Mn 25Ga 20Fe 5 Thin Foil","authors":"Y. Ge, L. Straka, M. Vronka, A. Sozinov, O. Heczko","doi":"10.2139/ssrn.3813433","DOIUrl":"https://doi.org/10.2139/ssrn.3813433","url":null,"abstract":"Using common and high resolution transmission electron microscopy, we study the evolution of crystal structure with increasing thickness in a thin Ni<sub>50</sub>Mn<sub>25</sub>Ga<sub>20</sub>Fe<sub>5</sub> foil. Iron alloying enables to observe the complete spectrum of known martensitic phases and respective transitions simultaneously. Starting from cubic austenite at about 30 nm foil thickness, the structure evolves via interleaved stripes of austenite and five-layered modulated 10M martensite to pure 10M phase with low density of stacking faults. With increasing thickness the 10M phase transforms gradually to seven-layered modulated 14M by increasing density of stacking faults. Finally the non-modulated tetragonal NM phase appears within the 14M phase by detwinning of nanotwins. We found large local variation of lattice parameters, which is ascribed to elastically very soft austenite and 10M phase and faulty 14M lattice. Our experiments show clearly that nanotwinning and stacking faults are inherent structure features tightly connected with lattice modulation and intermartensite transformations. This is important finding in broader attempt to bridge the gap between the nanotwinning and modulation period development with temperature and composition. From the application point of view, the observed instability of modulation or of particular phases in thin films imposes certain limits on the use of material on microscale.","PeriodicalId":9858,"journal":{"name":"Chemical Engineering (Engineering) eJournal","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88316912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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