scholarly journals Oxidation of Copper Nanoparticles Protected with Different Coatings and Stored under Ambient Conditions

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Noemi Jardón-Maximino ◽  
Marissa Pérez-Alvarez ◽  
Rubén Sierra-Ávila ◽  
Carlos Alberto Ávila-Orta ◽  
Enrique Jiménez-Regalado ◽  
...  

The synthesis of copper nanoparticles (Cu NPs) stable to chemical oxidation has attracted much attention due to their novel application possibilities. The physicochemical properties of Cu NPs define their utilization in diverse fields, including biological applications, solar cells, high conductivity inks for printed electronics, and other specific applications. In this study we present the synthesis of oxide-free Cu NPs by wet chemistry routes and their chemical oxidation during the storage exposed to ambient conditions. The Cu NPs synthesized in PAAm and AAm/glycerol presence exhibit no oxidation during synthesis and atmospheric conditions storage for 60 and 37 months, respectively. The obtained results compared with those coming from oxidation of partially passivated commercial Cu NPs at 99.8% purity, are presented. The role of the Cu NPs coating is critical to avoid oxidation, and it can be an important feature to achieve good dispersion in different polymers. The Cu NPs oxidation was studied by XRD, TGA, TEM, FTIR, and HR-TEM.

The authors' methodic for assessing the role of chemical and physic-chemical factors during the structure formation of gypsum stone is presented in the article. The methodic is also makes it possible to reveal the synergistic effect and to determine the ranges of variation of controls factors that ensure maximum values of such effect. The effect of a micro-sized modifier based on zinc hydro-silicates on the structure formation of building gypsum is analyzed and corresponding dependencies are found. It is shown that effects of influence of modifier on the properties of gypsum compositions are determined by chemical properties of modifier. Among the mentioned properties are sorption characteristics (which depend on the amount of silicic acid and its state) and physicochemical properties - the ability to act as a substrate during crystal formation. The proposed method can also be extended to other binding substances and materials. This article contributes to the understanding of the processes that occur during the structure formation of composites, which will make it possible to control the structure formation in the future, obtaining materials with a given set of properties.


2008 ◽  
Vol 19 (41) ◽  
pp. 415604 ◽  
Author(s):  
Youngil Lee ◽  
Jun-rak Choi ◽  
Kwi Jong Lee ◽  
Nathan E Stott ◽  
Donghoon Kim

Author(s):  
Do Phuc Quan ◽  
Bui Thi Phuong Thao ◽  
Nguyen Van Trang ◽  
Nguyen Le Huy ◽  
Nguyen Quoc Dung ◽  
...  

2020 ◽  
Vol 18 (1) ◽  
pp. 129-137
Author(s):  
Yayuk Astuti ◽  
Rizka Andianingrum ◽  
Abdul Haris ◽  
Adi Darmawan ◽  

AbstractSynthesis of bismuth oxide synthesis through the precipitation method using H2C2O4 and Na2CO3 precipitating agents, identification of physicochemical properties and its photocatalysis activity for methyl orange degradation were conducted. The bismuth oxide synthesis was undertaken by dissolving Bi(NO3)3.5H2O in HNO3, then added precipitating agents to form precipitate. The results showed that bismuth oxide produced by H2C2O4 precipitating agent was a yellow powder containing a mixture of α-Bi2O3 (monoclinic) and β-Bi2O3 (tetragonal), porous with size of 28-85 μm. Meanwhile, the use of Na2CO3 as precipitating agent resulted in bismuth oxide consisting of α-Bi2O3 and β-Bi2O3 and Bi2O4, irregular shape without pore being 40-115 μm in size. Bismuth oxide synthesized with H2C2O4 precipitating agent showed higher photocatalytic activity compared to bismuth oxide synthesized using Na2CO3 on degrading methyl orange dye with degradation rate constants of 2.35x10-5 s-1 for H2C2O4 and 1.81x10-5 s-1 for Na2CO3.


2021 ◽  
Vol 55 (4) ◽  
pp. 2628-2638
Author(s):  
Zhen Cao ◽  
Hao Li ◽  
Gregory V. Lowry ◽  
Xiaoyang Shi ◽  
Xiangcheng Pan ◽  
...  

2010 ◽  
Vol 107 (15) ◽  
pp. 6646-6651 ◽  
Author(s):  
A. Metzger ◽  
B. Verheggen ◽  
J. Dommen ◽  
J. Duplissy ◽  
A. S. H. Prevot ◽  
...  

2015 ◽  
Vol 126 ◽  
pp. 374-380 ◽  
Author(s):  
Azahara Rata-Aguilar ◽  
Nathaly Segovia-Ramos ◽  
Ana Belén Jódar-Reyes ◽  
Víctor Ramos-Pérez ◽  
Salvador Borrós ◽  
...  

2014 ◽  
Vol 24 (7) ◽  
pp. 727-753 ◽  
Author(s):  
Myoungsun Suh ◽  
Hyoungeun Moon ◽  
Heesup Han ◽  
Sunny Ham
Keyword(s):  

2015 ◽  
Vol 22 (03) ◽  
pp. 1550035 ◽  
Author(s):  
WEI-YUAN YU ◽  
SEN-HUI LIU ◽  
XIN-YA LIU ◽  
JIA-LIN SHAO ◽  
MIN-PEN LIU

In this study, Sn - Ag - Ti ternary alloy has been used as the active solder to braze pure aluminum and graphite in atmospheric conditions using ultrasonic vibration as an aid. The authors studied the formation, composition and decomposition temperature of the surface oxides of the active solder under atmospheric conditions. In addition, the wettability of Sn -5 Ag -8 Ti active solder on the surface of pure aluminum and graphite has also been studied. The results showed that the major components presented in the surface oxides formed on the Sn -5 Ag -8 Ti active solder under ambient conditions are TiO , TiO 2, Ti 2 O 3, Ti 3 O 5 and SnO 2. Apart from AgO and Ag 2 O 2, which can be decomposed at the brazing temperature (773 K), other oxides will not be decomposed. The oxide layer comprises composite oxides and it forms a compact layer with a certain thickness to enclose the melted solder, which will prevent the liquid solder from wetting the base metals at the brazing temperature. After ultrasonic vibration, the oxide layer was destroyed and the liquid solder was able to wet and spread out around the base materials. Furthermore, better wettability of the active solder was observed on the surface of graphite and pure aluminum at the brazing temperature of 773–823 K using ultrasonic waves. The ultrasonic wave acts as the dominant driving factor which promotes the wetting and spreading of the liquid solder on the surface of graphite and aluminum to achieve a stable and reliable brazed joint.


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