scholarly journals Influence of the Treatment Temperature on the Microstructure and Hydration Behavior of Thermoactivated Recycled Cement

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3937
Author(s):  
Sofia Real ◽  
Ana Carriço ◽  
José Alexandre Bogas ◽  
Mafalda Guedes
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mechanical Strength ◽  
Water Demand ◽  
Isothermal Calorimetry ◽  
Setting Time ◽  
Treatment Temperature ◽  
Diffraction Field ◽  
Resonance Spectroscopy ◽  
Scanning Electron

This paper intends to contribute to a better knowledge of the production and rehydration of thermoactivated recycled cement and its incorporation in cement-based materials. To this end, the influence of the treatment temperature on the properties of recycled cements and recycled cement pastes was assessed by means of a wide array of tests. Anhydrous recycled cement as well as the resulting pastes were characterized through density and particle size, water demand and setting time, thermogravimetry, X-ray diffraction, field emission gun scanning electron microscopy, isothermal calorimetry, 29Si nuclear magnetic resonance spectroscopy, flowability, mechanical strength, mercury intrusion porosimetry and scanning electron microscopy. The treatment temperature had a significant influence on the dehydration and hydration of recycled cement, essentially resulting in the formation of C2S polymorphs of varying reactivity, which led to pastes of different fresh and hardened behaviors. The high water demand and the pre-hydration of recycled cement resulted in high setting times and low compressive strengths. The highest mechanical strength was obtained for a treatment temperature of 650 °C.

Influence of Sodium Hydroxide on the Properties of FGD Gypsum-Slag Composite Materials

2014 ◽  
Vol 675-677 ◽  
pp. 750-755
Author(s):  
Fang Huang ◽  
Bao Long Jiao ◽  
Dong Dong Wang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Composite Materials ◽  
Flexural Strength ◽  
Sodium Hydroxide ◽  
Setting Time ◽  
Maximal Strength ◽  
Action Mechanism ◽  
Fgd Gypsum ◽  
Scanning Electron

By examining the compressive and flexural strength of composite and using scanning electron microscopy (SEM), we analyzed the influence of sodium hydroxide on the properties of FGD gypsum and slag composite materials and discussed the influence of sodium hydroxide on the setting time and mechanical strength of the composite materials and presented the action mechanism of sodium hydroxide as a stimulator. The results show that when the content of sodium hydroxide was percent of 0.25, the maximal strength of FGD gypsum-slag composite materials was reached.

scholarly journals Mechanism of Nanostructured Fluorapatite Formation from CaO, CaF2 and P2O5 Precursors by Mechanochemical Synthesis

2018 ◽  
Vol 43 (3-4) ◽  
pp. 201-210
Author(s):  
Raheleh Nikonam Mofrad ◽  
Sayed Khatiboleslam Sadrnezhaad ◽  
Jalil Vahdati Khaki
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mechanochemical Synthesis ◽  
Diffraction Field ◽  
Ambient Atmosphere ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

We determined the mechanism of mechanochemical synthesis of fluorapatite from CaO, CaF2 and P2O5 by characterisation of the intermediate compounds. We used atomic absorption spectroscopy, X-ray diffraction, field emission scanning electron microscopy, FTIR spectroscopy and transmission electron microscopy to find the transitional compounds. Investigation of the binary and ternary powder mixtures revealed the appearance of H3PO4, Ca(OH)2, Ca2P2O7 and CaCO3 as the intermediate compounds. At early stages of the milling, conversions of P2O5 to H3PO4 and CaO to Ca(OH)2 occurred in the wet atmosphere. Later, a combination of Ca(OH)2 and H3PO4 formed C a2P2O7 while the unreacted CaO was converted to CaCO3 by CO2 of the ambient atmosphere. Spherical crystalline Ca10 (PO4)6F2 particles formed after 48 hours of milling due to the reaction between Ca2P2O7, CaCO3 and CaF2.

scholarly journals Sodium alginate/cellulose nanocrystal fibers with enhanced mechanical strength prepared by wet spinning

2019 ◽  
Vol 14 ◽  
pp. 155892501984755
Author(s):  
Jie Liu ◽  
Rui Zhang ◽  
Meiyu Ci ◽  
Shuying Sui ◽  
Ping Zhu
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mechanical Strength ◽  
Sodium Alginate ◽  
Cellulose Nanocrystals ◽  
Cellulose Nanocrystal ◽  
Wet Spinning ◽  
Transmission Electron ◽  
Alginate Fibers ◽  
Scanning Electron

Sodium alginate/cellulose nanocrystal fibers were prepared using a wet spinning method to enhance the mechanical strength of sodium alginate fibers. Cellulose nanocrystals were prepared by sulfuric acid hydrolysis method. The particle diameter size was measured, and the morphology of cellulose nanocrystals was characterized by transmission electron microscopy and scanning electron microscopy. The structure and mechanical properties of sodium alginate/cellulose nanocrystal fibers were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and mechanical strength testing. The incorporation of cellulose nanocrystals significantly improved the strength of alginate fibers because of the uniform distribution of cellulose nanocrystals in the alginate matrix. The tensile strength and elongation at break of the alginate fibers increased from 1.54 to 2.05 cN/dtex and from 8.29% to 15.05% with increasing cellulose nanocrystals content from 0 to 2 wt%, respectively.

Graphene as a stimulus for mechanical strength in glass-fiber reinforced polymers composite

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Vijay Kumar Dwivedi ◽  
Dipak Kumar
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mechanical Strength ◽  
Glass Fiber ◽  
Fiber Reinforced Polymers ◽  
Synthesis Process ◽  
Fiber Reinforced ◽  
Content Type ◽  
Glass Fiber Reinforced ◽  
Scanning Electron

Purpose The purpose of this paper is related with the comparative study between graphene-based glass fiber–reinforced polymer composites and without graphene composite on polymer matrix. The current study explains the result of amalgamation of 4 Wt.% graphene oxide (GO), in comparison to without graphene, on the mechanical strength of glass fiber/epoxy (GE). Design/methodology/approach A hand layup technique is used for the experimental study. For this, chemical synthesis process is approached based on Hummer’s theory. For mechanical testing of glass fiber–reinforced graphene composites and without graphene composites, American Society for Testing and Materials-3039 (ASTM3039) standards was adopted. Furthermore, comparatively, composites were characterized by field emission scanning electron microscopy. Findings Reinforcement of 4.0 Wt.% GO in epoxy matrix material showed 7.46% and 12.31% improvement in mechanical strength and elongation, respectively. Scanning electron microscopy results showed the influence of graphene cumulations in the failure of GO-reinforced GE (GO-GE) composites. Originality/value The inimitable things of graphene grounded nanofillers have encouraged in the world of material for their thinkable manipulation in glass fiber polymeric composites. In this work, for the first time, graphene is used as nanofiller in glass fiber epoxy coatings, and their fractography study is investigated.

Diethylenetriamine-Assisted Hydrothermal Route to Synthesize Cuboidal Structure of PbSe Crystal

2009 ◽  
Vol 79-82 ◽  
pp. 1495-1498
Author(s):  
Pei Pei Xiao ◽  
Fei Xue ◽  
Ting Ting Wang ◽  
Yi Tai Qian
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Field Emission ◽  
Hydrothermal Process ◽  
Synthesis Method ◽  
Dendritic Structure ◽  
Molar Ratio ◽  
Diffraction Field ◽  
Luminescence Spectroscopy ◽  
Scanning Electron

With the assistance of diethylenetriamine(DETA), well-crystalline PbSe cuboidal structures with different concave faces in each plane have been successfully prepared through a hydrothermal process using Na2SeO3 as selenium source at 180 °C for 48 h. The products have been characterized by means of X-ray diffraction, field-emission scanning electron microscopy and luminescence spectroscopy. The field emission scanning electron microscopy showed that the edge lengths of these cuboidal crystals ranged from 1.5 to 2.5 µm, and the edges of a cube crystal extend outwards from its core with a tiny cubic center leaving step-like faces. The shape evolution of PbSe crystal from eight-dendritic structure to cuboidal structure was observed and the possible growth mechanism was proposed. Results revealed that the temperature played a crucial role in the final morphology of PbSe microstructures, and other factors such as the solvent composition and the molar ratio of metal/chalcogen were also discussed. The photoluminescence (PL) spectrum of as-prepared PbSe crystals shows the photoluminescence emission spectrum consists of a main intense peak at 435 nm and a shoulder at 420 nm. This synthesis method could be extended to the morphogenesis of other inorganic crystals with complex forms.

Study of Ru barrier failure in the Cu/Ru/Si system

2007 ◽  
Vol 22 (9) ◽  
pp. 2505-2511 ◽  
Author(s):  
M. Damayanti ◽  
T. Sritharan ◽  
S.G. Mhaisalkar ◽  
E. Phoon ◽  
L. Chan
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Reaction Mechanisms ◽  
Diffraction Field ◽  
X Ray Diffraction ◽  
X Ray ◽  
Barrier Failure ◽  
Transmission Electron ◽  
Secondary Ion ◽  
Scanning Electron

The reaction mechanisms and related microstructures in the Cu/Si, Ru/Si, and Cu/Ru/Si metallization system were studied experimentally. With the help of sheet resistance measurements, x-ray diffraction, field-emission scanning electron microscopy, secondary ion mass spectroscopy, and transmission electron microscopy, the metallization structure with Ru barrier layer was observed to fail completely at temperatures around 700 °C, regardless of the Ru thickness because of the formation of polycrystalline Ru2Si3 followed by Cu3Si protrusions.

scholarly journals Mechanical strength of stainless steel and titanium alloy mini-implants with different diameters: an experimental laboratory study

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Sérgio Estelita Barros ◽  
Viviane Vanz ◽  
Kelly Chiqueto ◽  
Guilherme Janson ◽  
Eduardo Ferreira
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Stainless Steel ◽  
Titanium Alloy ◽  
Mechanical Strength ◽  
Null Hypothesis ◽  
Mini Implants ◽  
The Mean ◽  
Torsional Fracture ◽  
Scanning Electron

Abstract Background The mechanical strength of mini-implants is a critical factor due to their small diameters. Currently, it is not possible to state whether there is a relevant difference between the mechanical properties of stainless steel (SS-MIs) and titanium alloy mini-implants (TA-MIs). The objective of this study was to test the null hypothesis that there is no difference in the mechanical strength of SS-MIs and TA-MIs, and to analyze, by scanning electron microscopy (SEM), the SS-MI, and TA-MI threads resistance to morphological damage after insertion. Methods A standardized sample of 504 SS-MIs and TA-MIs with diameters ranging from 1.2 mm to 1.8 mm was used. Torsional fracture was performed in 154 MIs. Flexural strength of 280 MIs was evaluated at 1 mm and 2 mm-deflection. The threads of 70 MIs were morphologically analyzed by scanning electron microscopy (SEM), before and after their insertion in high-density artificial bone blocks. Comparisons between SS-MIs and TA-MIs were performed with t tests or Mann-Whitney U tests. A multiple linear regression analysis was used to evaluate the influence of variables on the ranging of MI mechanical strength. Results SS-MIs had higher fracture torque. The mean difference between the SS-MIs and TA-MIs fracture torque was of 4.09 Ncm. The MI diameter explained 90.3% of the total variation in fracture torque, while only 2.2% was explained by the metallic alloy. The SS-MI group presented a higher deformation force during the 1mm and 2mm-deflection. The mean difference between the flexural strength of SS and TA-MIs at 1 mm and 2 mm-deflection was of 18.21 N and 17.55 N, respectively. There was no noticeable morphological damage to the threads of SS-MIs and TA-MIs. Conclusions The null hypothesis was rejected. SS-MIs were 13.2% and 20.2% more resistant to torsional fracture and deflection, respectively. The threads of the SS-MIs and TA-MIs were not damaged during the insertion and removal process. Thus, the use of SS-MI can reduce the fracture risk without increasing the MI diameter.

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