Scanning Electron Microscopic Studies of Microwave Sintered Al-SiC Nanocomposites and Their Properties

Al-metal matrix composites (AMMCs) reinforced with diverse volume fraction of SiC nanoparticles were synthesized using microwave sintering process. The effects of the reinforcing SiC particles on physical, microstructure, mechanical, and electrical properties were studied. The phase, microstructural, and surface analyses of the composites were systematically conducted using X-ray diffraction (XRD), scanning electron microscope (SEM), and surface profilometer techniques, respectively. The microstructural examination revealed the homogeneous distribution of SiC particles in the Al matrix. Microhardness and compressive strength of nanocomposites were found to be increasing with the increasing volume fraction of SiC particles. Electrical conductivity of the nanocomposites decreases with increasing the SiC content. ? 2018 M. A. Himyan et al.This publication was made possible by NPRP Grant 7159-2-076 from Qatar National Research Fund (a member of the Qatar Foundation).Scopu

Thermal insitu analyses of multicomponent pyrophosphate cathodes materials

Development of secondary batteries based on abundant and inexpensive elements are vital. Amongvarious alternative choices, sodium-ion batteries (NIBs) are promising because of plentiful resourcesand low costs of sodium metal. Different types of cathode materials for NIBs have been designed andstudied to meet the challenging requirements. Among them pyrophosphate cathodes have shownpromising electrochemical performance and thermal stability in sodium ion batteries (SIBs). In thepresent study, we report synthesis and thermal behavior of a novel Na2Fe0.33Mn0.33Co0.33P2O7 cathodematerial developed for sodium rechargeable batteries. The material was developed through solid stateprocess. The structural analysis of Na2Fe0.33Mn0.33Co0.33P2O7 revealed that the substitution ofmulticomponent transition metals have achieved triclinic crystal structure (P1 space group). TGA/DTAand thermal in-situ XRD analyses (25~550oC) confirm decent thermal stability of this material up to550oC even in the desodiated state with negligible weight loss (5%). Owing to its promising thermalstability, Na2Fe0.33Mn0.33Co0.33P2O7, would be an attractive cathode for sodium ion batteries.Scopu

Improvement in properties of Ni-B coatings by the addition of mixed oxide nanoparticles

A comparison of properties of electrodeposited Ni-B and Ni-B-ZrO2-Al2O3 nanocomposite coatings is presented to explain the benefits of addition of mixed nanoparticles of ZrO2 and Al2O3 into Ni-B matrix. A comparative study of the properties of Ni-B and Ni-B-ZrO2-Al2O3 nanocomposite coatings in their as deposited condition indicates that the addition of mixed nanoparticles into Ni-B matrix has significant influence on its structural, surface, mechanical and electrochemical properties. Incorporation of mixed nanoparticles into Ni-B matrix shows significant grain refinement, substantial enhancement in mechanical properties and decent improvement in corrosion resistance. The improvement in mechanical properties can be attributed to grain refinement of Ni-B matrix and dispersion hardening effect of insoluble hard ceramic nanoparticles. Similarly, corrosion inhibition efficiency of binary Ni-B coatings is considerably improved which can be presumably regarded as the effect of formation of dense structure and decrease in active area of Ni-B matrix due to incorporation of mixed inactive nanoparticles. There is simultaneous improvement in mechanical and anti-corrosion properties of Ni-B coatings by the incorporation of mixed nanoparticles demonstrating usefulness of Ni-B-ZrO2-Al2O3 nanocomposite coatings for many applications.Scopu

Structural and electrochemical properties of electrodeposited Ni-P nanocomposite coatings containing mixed ceramic oxide particles

Mixed oxide ceramic particles were incorporated into Ni-P matrix to synthesize Ni-P-TiO2-CeO2 nanocomposite coatings. In the present study, the effect of concentration of mixed oxide ceramic particles (TiO2 and CeO2) on structural, surface and electrochemical properties of Ni-P coating is investigated. The coatings were electrodeposited on mild steel substrate and were then characterized using various techniques. The compositional (EDAX) confirms the co-deposition of TiO2 and CeO2ceramic particles into Ni-P matrix. The structural analysis (XRD) indicates that addition of mixed oxide ceramic particles do not have any prominent influence on the structure of Ni-P coatings as parent amorphous structure is preserved even at high concentration of mixed ceramic particles (7.5 g/l). The SEM and AFM analyses indicate that the synthesized coatings are of fine nodular morphology containing uniformly distributed ceramic particles. However, their excessive amount may lead to agglomeration and surface defects. The surface analysis (AFM) also indicates that the surface roughness increases with the increase in amount of TiO2 and CeO2 particles. The enhancement in roughness of coatings can be ascribed to the fact the added ceramic particles are hard and remain insoluble in the Ni-P matrix. The potentiodynamic polarization analysis confirms that incorporation of mixed oxide ceramic particles into Ni-P matrix improves its anticorrosion properties. However, their excessive amount may cause decrease in corrosion resistance due to formation of galvanic cells at the defective metal/coating interface.Scopu

Cerium oxide loaded with Gum Arabic as environmentally friendly anti-corrosion additive for protection of coated steel

The depreciation of assets and safety threats because of corrosion has forced to develop eco-friendly and smarter corrosion protection strategies. In this study, natural Gum Arabic (GA) was used as a corrosion inhibitor and loaded into cerium oxide nanoparticles (CONPs) to develop an environment-friendly additive for corrosion protection of coated steel in the marine environment. This additive was uniformly dispersed into an epoxy formulation that was used to protect steel plates. Epoxy coatings containing CONPs, without GA, were also prepared as reference. High-Resolution Transmission Electron Microscopy (HR-TEM) and Fourier Transform infrared spectroscopy (FTIR) revealed the successful loading of GA into the CONPs. Thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET) techniques confirmed approximately ⁓30.0 wt% loading of GA into the CONPs. Electrochemical impedance spectroscopy (EIS) demonstrated the anticorrosion properties of the epoxy coatings modified with the GA loaded CONPs when compared to reference coatings. The corrosion protection mechanism postulates that GA loaded CONPs act as a filler material for epoxy coating and it can also aid the recovery of the protective properties of the epoxy coating leading to the formation of a stable protective layer.This publication was made possible by NPRP11S-1226-170132 from Qatar National Research Fund (a member of the Qatar Foundation). Statements made herein are solely the responsibility of the authors. The authors would like to thanks to the Central Laboratories Unit (CLU), Qatar University, 2713, Doha, Qatar for FE-SEM, and HR-TEM analyses. Authors from Portugal acknowledge FCT for the additional funding under the project UIDB/00100/2020 and UIDP/00100/2020. Open Access funding provided by the Qatar National Library. The raw data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.Scopu

Self-healing performance of multifunctional polymeric smart coatings

Multifunctional nanocomposite coatings were synthesized by reinforcing a polymeric matrix with halloysite nanotubes (HNTs) loaded with corrosion inhibitor (NaNO3) and urea formaldehyde microcapsules (UFMCs) encapsulated with a self-healing agent (linseed oil (LO)). The developed polymeric nanocomposite coatings were applied on the polished mild steel substrate using the doctor's blade technique. The structural (FTIR, XPS) and thermogravimetric (TGA) analyses reveal the loading of HNTs with NaNO3and encapsulation of UFMCs with linseed oil. It was observed that self-release of the inhibitor from HNTs in response to pH change was a time dependent process. Nanocomposite coatings demonstrate decent self-healing effects in response to the external controlled mechanical damage. Electrochemical impedance spectroscopic analysis (EIS) indicates promising anticorrosive performance of novel nanocomposite coatings. Observed corrosion resistance of the developed smart coatings may be attributed to the efficient release of inhibitor and self-healing agent in response to the external stimuli. Polymeric nanocomposite coatings modified with multifunctional species may offer suitable corrosion protection of steel in the oil and gas industry. - 2019 by the authors.Acknowledgments: This publication was made possible by NPRP Grant 9-080-2-039 from the Qatar National Research Fund (a member of the Qatar Foundation). Statements made herein are solely the responsibility of the authors. This research work was also partially supported by QU internal grant-QUCG-CAM-2018/2019-3

Study on the corrosion behavior of polymeric nanocomposite coatings containing halloysite nanotubes loaded with multicomponent inhibitor

In the present study, the halloysite nanotubes (HNTs) were loaded with a multicomponent inhibitor (LHNT) comprising mainly benzotriazole (BTA), sodium benzoate (SB), and lauric acid (LA) via the vacuum cycling method. The successful loading of the BTA + LA + SB inhibitor has been confirmed by the TGA, FTIR, and BET analyses. The TGA analysis has determined ? 14% loading of the BTA + LA + SB into the HNTs. Moreover, UV-vis analysis shows that the time and pH-dependent have incremental release of the multicomponent inhibitor in various studied media. The composite coatings (LHNT COAT) were developed by reinforcing the 3 wt% of LHNTs into the epoxy matrix. The corrosion protection of the developed LHNT COAT was enhanced by 99.6% and 98.88% compared to the blank epoxy and unloaded HNT coatings, respectively. This improvement in the corrosion behavior can be attributed to the active release of the multicomponent inhibitor, as was also demonstrated by the electrochemical impedance spectroscopic (EIS) test. It is further predicted that the improved corrosion inhibition efficiency of LHNT COAT may be due to the formation of some components produced from the reaction of the inhibitor components or from the inhibitor reaction with the corrosive medium. The high corrosion resistance of LHNT COAT makes it attuned to several industrial applications.This publication was made possible by NPRP Grant 11S-1226-170132 and NPRP 13S-0120-200116 from the Qatar National Research Fund (a member of the Qatar Foundation). Statements made herein are solely the responsibility of the authors. The authors would like to thank the Central laboratory Unit (CLU), Qatar University, for SEM and TEM analyses.Scopu

Development and properties of polymeric nanocomposite coatings

Polymeric-based nanocomposite coatings were synthesized by reinforcing epoxy matrix with titanium nanotubes (TNTs) loaded with dodecylamine (DOC). The performance of the developed nanocomposite coatings was investigated in corrosive environments to evaluate their anti-corrosion properties. The SEM/TEM, TGA, and FTIR analysis confirm the loading of the DOC into the TNTs. The UV-Vis spectroscopic analysis confirms the self-release of the inhibitor (DOC) in response to the pH change. The electrochemical impedance spectroscopic (EIS) analysis indicates that the synthesized nanocomposite coatings demonstrate superior anticorrosion properties at pH 2 as compared to pH 5. The improved anticorrosion properties of nanocomposite coatings at pH 2 can be attributed to the more effective release of the DOC from the nanocontainers. The superior performance makes polymeric nanocomposite coatings suitable for many industrial applications.Qatar University, University of Auckland, Qatar FoundationScopu

Properties of electrodeposited Ni-B-ZrO2 composite coatings

Ni-B coatings have high hardness and high wear resistance which make them suitable for automotive, aerospace, petrochemical, textile and electronics industries. Further improvement in properties (especially the corrosion behavior) will extend their range of applications and thus make them suitable to high wear and severe corrosion applications of oil and gas industries. Taking a note of above consideration, novel Ni-B-ZrO2 coatings were synthesized. In the present study, a comparison of properties of Ni-B and Ni-B-ZrO2 coatings in their as deposited state is presented to elucidate the effect of ZrO2 addition on structural, surface, thermal and electrochemical properties of binary Ni-B coatings. Mild steel samples were used as substrate material and the coatings were deposited through conventional electrodeposition process using dimethylamine borane (DMAB) as reducing agent. It is noticed that the addition of ZrO2 has a significant influence on crystal structure, surface roughness, thermal properties and corrosion behavior Ni-B coatings. It is noticed that Ni-B coatings are amorphous in their as deposited state while addition of ZrO2 significantly improves the crystallinity. Surface analyses confirm the formation of fine and dense structures in both Ni-B and Ni-B-ZrO2 coatings. However ZrO2 addition increases the surface roughness. The electrochemical polarization tests confirm that incorporation of ZrO2 into Ni-B matrix considerably improves the corrosion resistance due to reduction in active area of Ni-B matrix.This paper was made possible by NPRP grant # NPRP-4-662-2-249 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. The authors also greatly acknowledge the Center for Advanced Materials (CAM), Qatar University, 2713, Doha, Qatar for permitting them to use AFM facilities.Scopu