scholarly journals Study on Corrosion Mechanism of Different Concentrations of Na2SO4 Solution on Early-Age Cast-In-Situ Concrete

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2018
Author(s):  
Fei Zhang ◽  
Zhiping Hu ◽  
Li Dai ◽  
Xin Wen ◽  
Rui Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Of Hydration ◽  
Strength Development ◽  
Early Age ◽  
Corrosion Mechanism ◽  
Concrete Durability ◽  
Internal Corrosion ◽  
X Ray ◽  
Hydration Rate

The deterioration of early-age concrete performance caused by SO42− internal diffusion in concrete is a critical factor of concrete durability. In this study, the mechanical properties, heat of hydration, and pore structure of early-age cast-in-situ concrete with different sodium sulfate (Na2SO4) concentrations were studied. The mechanism of SO42− internal corrosion was evaluated by measuring the dynamic elastic modulus, compressive strength, and heat of hydration rate. Scanning electron microscopy, energy dispersive spectroscopy, X-ray computed tomography, X-ray diffraction, thermogravimetry-derivative thermogravimetry, and differential scanning calorimetry were applied to analyze microstructural variations and complex mineral assemblages of concrete samples. The results indicated that during the hardening process of cast-in-situ concrete, Na2SO4 first promoted and then hindered the hydration rate of cement, and also hindered the early strength development of the cement. As the concentration of Na2SO4 solution increases, the corrosion products of ettringite (AFt) and gypsum (Gyp) gradually increase, causing cross cracks in the concrete. The proportion of small and medium pores first increases and then decreases, and the large pores first decrease and then increase. The mechanical properties of concrete gradually decrease and diminish the mechanical properties of the concrete (thereby accelerating the damage to the concrete).

Corrosion behavior of in situ (TiC-TiB2)p/AZ91 magnesium matrix composites in Harrison solution

2014 ◽  
Vol 61 (5) ◽  
pp. 319-327 ◽  
Author(s):  
Mohamed Gobara ◽  
Mohamed Shamekh
Keyword(s):  
Mechanical Properties ◽  
Corrosion Behavior ◽  
Matrix Composite ◽  
Electrochemical Impedance ◽  
Magnesium Matrix Composite ◽  
Magnesium Matrix ◽  
Content Type ◽  
X Ray ◽  
Az91 Magnesium

Purpose – This paper aims to study both the mechanical properties and the corrosion behavior of the synthesized in situ (TiC-TiB2) particulates/AZ91 magnesium matrix composite and compare the results with that of the conventional AZ91D alloy. Design/methodology/approach – Scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) were used to study the surface morphology and crystalline structure. Mechanical compression tests were used to investigate the mechanical performance according to ASTM E9-89a. The corrosion behavior of the synthesized magnesium alloy was examined using both electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques in dilute Harrison solutions. Findings – The microstructure of the Mg composite showed a uniform distribution of reinforcing phases. Also, the reinforcing phases were formed without residual intermediate phases. The addition of titanium and boron carbides not only enhanced the mechanical properties of the matrix but also improve its corrosion behavior. Originality/value – This is the first time that magnesium matrix composite has been to synthesized with TiC and TiB2 particulates starting from starting from Ti and B carbides powder without adding aluminium using practical and low-cost technique (in situ reactive infiltration technique). This paper studies the corrosion behavior of synthesized Mg matrix in dilute Harrison solution and compares the results with that of conventional AZ91D.

Preparation of Hydrophobic CaCO3-Wood Composite In Situ

2010 ◽  
Vol 113-116 ◽  
pp. 1712-1715
Author(s):  
Cheng Yu Wang ◽  
Chang Yu Liu ◽  
Jian Li
Keyword(s):  
Mechanical Properties ◽  
Organic Substrate ◽  
Dodecanoic Acid ◽  
Wood Composite ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ft Ir ◽  
Contact Angle Analysis ◽  
Double Diffusive

The preparation of hydrophobic CaCO3-wood composite through a double-diffusive method using dodecanoic acid as organic substrate is demonstrated. The product was characterized by the contact angle analysis, X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). The mechanical properties of the product were measured. The results show that the synthesized CaCO3 fills in the wood cell and covers the surface of wood. The CaCO3-wood composite is hydrophobic. The mechanical properties of wood composite have significantly increased.

scholarly journals A comparison of mechanical properties and X-ray tomography analysis of different out-of-autoclave manufactured thermoplastic composites

2020 ◽  
Vol 39 (19-20) ◽  
pp. 703-720
Author(s):  
Diego Saenz-Castillo ◽  
María I Martín ◽  
Vanessa García-Martínez ◽  
Abhiram Ramesh ◽  
Mark Battley ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Raw Material ◽  
Thermoplastic Composites ◽  
Scanning Calorimetry ◽  
Consolidation Process ◽  
Plane Shear ◽  
X Ray ◽  
Void Distribution ◽  
Out Of Autoclave

Three different out-of-autoclave manufacturing processes of CF/poly-ether-ether-ketone thermoplastic composites were characterized, including innovative laser-assisted automated fibre placement with in situ consolidation. Characterization techniques included differential scanning calorimetry, ultrasonic non-destructive testing and matrix digestion, in addition to 3D X-ray microcomputed tomography to investigate the void distribution, size and shape. The results revealed that in situ consolidation process can lead to the accumulation of large voids between the upper layers. Interlaminar shear, in-plane shear, tensile and flexure testing were used for mechanical evaluation. A reduction in the mechanical properties was observed for in situ consolidation laminates when compared to the other out-of-autoclave methods. The drop in mechanical properties of in situ consolidation laminates was mainly attributed to the differences found in void distribution and size. Optimization of processing parameters along with higher quality prepreg raw material could be of assistance for the improvement of mechanical properties of in situ consolidation structures.

MECHANICAL PROPERTIES OF A POLYURETHANE/MONTMORILLONITE NANOCOMPOSITE FEATURING ORGANOMODIFICATION SYNTHESIZED VIA IN SITU POLYMERIZATION

2015 ◽  
Vol 88 (1) ◽  
pp. 138-146 ◽  
Author(s):  
Rouhollah Bagheri ◽  
Reza Darvishi
Keyword(s):  
Mechanical Properties ◽  
In Situ Polymerization ◽  
Xrd Analysis ◽  
Silicate Layer ◽  
X Ray Diffraction ◽  
X Ray ◽  
End Groups ◽  
Layer Sample ◽  
Silicate Layers

ABSTRACT In this study, polyurethane (PU)/organomodified montmorillonite (cloisite®30B) is synthesized via in situ polymerization by reaction of an ether-based prepolymer with the isocyanate end groups and adiamine chain extender (4, 4-methylene-bis(2-chloroaniline)) in the presence of different amounts of nanoparticles dispersed in the prepolymer matrix by an ultrasonic mixer for 1 h. The synthesized polymers are cast on a pretreated carbon steel sheet and cured at 120 °C in an oven. The PU and its composites have been characterized by using Fourier transform infrared spectroscopy, X-ray diffraction (XRD), and mechanical testing. The XRD analysis of the cured samples containing 1 to 3 wt% cloisite30B showed intercalation segments in the silicate layers and exfoliation for 0.5 wt% nanoparticles. The highest mechanical properties were obtained using the cured exfoliated silicate layer sample. A twofold increase in the ultimate tensile strength and a 2.3 times increase in the adhesion strength were found for 0.5 wt% organoclay/PU as compared with that of pure PU. In addition, the exfoliated structure sample exhibited a 16% reduction in abrasion compared with that of pure PU.

scholarly journals Effects of NiO content on the microstructure and mechanical properties of AgSnO2NiO composites

2019 ◽  
Vol 26 (1) ◽  
pp. 221-229 ◽  
Author(s):  
Xiaolong Zhou ◽  
Li Chen ◽  
Manmen Liu ◽  
Jie Yu ◽  
Damin Xiong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Internal Oxidation ◽  
Alloy Powder ◽  
X Ray Diffraction ◽  
Oxidation Method ◽  
X Ray ◽  
Microstructure And Mechanical Properties ◽  
Silver Matrix ◽  
Overall Performance

AbstractThe AgSnO2NiO composites were prepared by internal oxidation method. The effects of different NiO content on the microstructure and mechanical properties of AgSnO2NiO composites were studied. The phase structure and surface morphology of the prepared AgSnO2NiO materials were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Metallographic Microscopy (MM). The results showed that the AgSnO2NiO composites with different NiO content can be obtained by the process of preoxidation of AgSn alloy powder and internal oxidation of ingot containing Ni. The agglomeration phenomenon of Ni in the silver matrix was serious, which led to the agglomeration of in-situ generated NiO particles after internal oxidation. After the multi-pass drawing, the SnO2 particles dispersedly distributed in the AgSnO2NiO composites and the NiO particles gradually dispersed from the agglomerated state of the sintered ingot billet. The hardness of the prepared AgSnO2NiO composites increased slightly with the increase of NiO content. The mechanical properties test showed that the introduction of NiO particles significantly improved the tensile strength and elongation of AgSnO2 materials to a certain degree. Adding proper amount of NiO is beneficial to improve the overall performance of AgSnO2 materials.

scholarly journals Effects of Highly Crystalized Nano C-S-H Particles on Performances of Portland Cement Paste and Its Mechanism

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 816
Author(s):  
Yuli Wang ◽  
Huijuan Lu ◽  
Junjie Wang ◽  
Hang He
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Setting Time ◽  
Tricalcium Silicate ◽  
Strength Development ◽  
Early Age ◽  
Hydration Products ◽  
X Ray ◽  
Early Strength ◽  
Portland Cement Paste

In order to improve the early age strength of ordinary Portland cement-based materials, many early strength agents were applied in different conditions. Different from previous research, the nano calcium silicate hydrate (C-S-H) particles used in this study were synthesized through the chemical reaction of CaO, SiO2, and H2O under 120 °C using the hydrothermal method, and the prepared nano C-S-H particles were highly crystalized. The influences of different amounts of nano C-S-H particles (0%, 0.5%, 1%, 2% and 3% by weight of cement) on the setting time, compressive strength, and hydration heat of cement paste were studied. The hydration products and microstructure of the cement paste with different additions of nano C-S-H particles were investigated through thermogravimetry-differential thermal analysis (TG-DTA), X-ray powder diffraction (XRD), and scanning electron microscope (SEM) tests. The results show that the nano C-S-H particles could be used as an early strength agent, and the early strength of cement paste can be increased by up to 43% through accelerating the hydration of tricalcium silicate (C3S). However, the addition of more than 2% nano C-S-H particles was unfavorable to the later strength development due to more space being left during the initial accelerated hydration process. It is suggested that the suitable content of the nano C-S-H particles is 0.5%−1% by weight of cement.

Toughening of polybutene-1 with form I′ induced by rapid pressurization

CrystEngComm ◽  
2021 ◽  
Author(s):  
Yanping Liu ◽  
Yingchao Wang ◽  
Hongyu Zhang ◽  
Yuewen Wu ◽  
Shuo Zhao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
X Ray

Combined with in situ wide angle X-ray diffraction, the mechanical properties of polybutene-1 with rapid pressurization are investigated. The toughness of polybutene-1 can be improved significantly by forms I/I′ produced by rapid pressurization.

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