ABSTRACT The manufacturing of a HVOF-sprayed functionally graded coating (FGC), consisting of two... more ABSTRACT The manufacturing of a HVOF-sprayed functionally graded coating (FGC), consisting of two NiAl/WC–Co composite layers with increasing cermet content and a pure WC–Co topmost layer, is discussed in this paper. As the stress build-up during spraying, measured via curvature method, is reduced in the NiAl-rich layers, thick coatings can be deposited with lower risk of delamination, in comparison to a pure WC–Co thick layer. Thermal stresses within the layers and the stainless steel substrate, measured from low temperature thermal cycling tests, are also reduced. The mechanical behaviour of the top layer in the graded structure at relatively low loads (i.e. pin-on-disk) is equivalent to the same layer without gradation, whereas at high loads (i.e. ball-drop impact test) the enhanced compliance with depth increases the load bearing capability of the graded structure. Electrochemical corrosion tests demonstrate no significant interconnected porosity and therefore, no interaction of the graded layers with the topmost WC–Co layer. The deterioration of the deeper layers under wear and corrosive conditions are also tested to investigate their performance in the scenario that the top layer coating wears out exposing the deeper layers to the surface.
The Journal of Thermal Spray Technology could not exist without the ongoing contributions of gues... more The Journal of Thermal Spray Technology could not exist without the ongoing contributions of guest editors and reviewers, which ensure the highest quality of our journal. Manuscripts are reviewed for technical excellence, quality, and relevance by competent reviewers. The editors identify and select reviewers based on their demonstrable and recognized research expertise, professional experience, critical judgment and foresight, and forward thinking in their field of expertise. We express our deepest appreciation to these guest editors who have created special topical issues of JTST published in 2012, and to these reviewers, all of whom have completed manuscript reviews during 2012. Thank you all for giving generously of your valuable time and expertise.
DLC are being used extensively for the protection and life extension of engineering components ex... more DLC are being used extensively for the protection and life extension of engineering components exposed to adverse environmental conditions of wear and/or corrosion during service in automobile engine, magnetic storage, IR optic devices. In many instances in industrial applications like automotive engine, magnetic storage DLC coating is considered as a part of the structure and is deposited on the components in batch process. In the industrial framework a much lean methodology for process and quality control is adopted. Integrated characterization study was carried on DLC deposited by electron cyclotron resonance (ECR) plasma on p-type Si (111) substrate using methane as precursor and argon as carrier gas to understand suitability of each technique in providing information about quality of DLC. The deposition bias voltage was varied from-60 V to-150 V using 13.56 MHz RF power applied to the substrate. The results obtained from Raman Spectroscopy, X-ray photoelectron spectroscopy (XPS), Spectroscopic Ellipsometry, Contact and X-ray reflectivity (XRR) are correlated. The results have been attempted to explain by newer advancement in the theory like quantum electronic activation of some sp 3 atomic rearrangement, subplantation and knock-on penetration mechanism of atomistic growth mechanism.
In the present work, magnetite (Fe 3 O 4 , avg. ~ 70 nm) synthesis employing Azadirachta indica (... more In the present work, magnetite (Fe 3 O 4 , avg. ~ 70 nm) synthesis employing Azadirachta indica (neem) leaf extract is reported originally using hydrothermal conditions and the results obtained were compared with that of D-glucose. Fourier transform infrared spectroscopy confirms the presence of polysaccharides and proteins in the extract which act as both surfactants and reducing agents, aided the formation of magnetite nanostructures. Authors also reported the selective doping of Zn, Cu and Co on nickel ferrite for the enhancement of adsorptive dye removal property, adopting and investigating the use of eloquent one-step green hydrothermal approach (T=180⁰C, t=4 hr, pH=12) with sodium dodecyl sulphate as surfactant. Xray diffraction studies reveal that all the materials synthesized are isometric spinel structures and furthermore, morphological evidences using scanning electron microscopy are accounted. Adsorptive dye removal ability of synthesized materials was investigated using trypan blue as a probe. It was evident from the results that magnetite using neem extract showed enhanced adsorption ability (75%) than that of D-glucose (62%). Also, exponential increase in dye removal efficiency from 55% to 81% due to the presence of copper in nickel ferrite was duly noted.
SiO2–TiO2 nanocomposite has been produced by a combination of sol–gel and mechanochemical process... more SiO2–TiO2 nanocomposite has been produced by a combination of sol–gel and mechanochemical process. The structural and chemical properties of the nanocomposite, produced by different milling time (1, 3, 10, and 20h at a constant speed of 200 or 350rpm), have been investigated and compared with its calcined counterpart (950°C for 2h). Variable pressure field-emission scanning electron microscope and transmission electron microscope were used to investigate surface morphology of the samples. The phases and chemical bonding of samples were, respectively, characterized by X-ray diffraction and Fourier transform infrared spectroscope. Brunauer–Emmett–Teller analysis was employed to estimate the particle size of the samples. Sample prepared by the longest milling time has shown the smallest particle size (∼40nm) with SiO2 amorphous structure mixed with crystalline anatase structure. Additional Si–O–Ti bond has been detected in the sample and the observation has been explained.
ABSTRACT The manufacturing of a HVOF-sprayed functionally graded coating (FGC), consisting of two... more ABSTRACT The manufacturing of a HVOF-sprayed functionally graded coating (FGC), consisting of two NiAl/WC–Co composite layers with increasing cermet content and a pure WC–Co topmost layer, is discussed in this paper. As the stress build-up during spraying, measured via curvature method, is reduced in the NiAl-rich layers, thick coatings can be deposited with lower risk of delamination, in comparison to a pure WC–Co thick layer. Thermal stresses within the layers and the stainless steel substrate, measured from low temperature thermal cycling tests, are also reduced. The mechanical behaviour of the top layer in the graded structure at relatively low loads (i.e. pin-on-disk) is equivalent to the same layer without gradation, whereas at high loads (i.e. ball-drop impact test) the enhanced compliance with depth increases the load bearing capability of the graded structure. Electrochemical corrosion tests demonstrate no significant interconnected porosity and therefore, no interaction of the graded layers with the topmost WC–Co layer. The deterioration of the deeper layers under wear and corrosive conditions are also tested to investigate their performance in the scenario that the top layer coating wears out exposing the deeper layers to the surface.
The Journal of Thermal Spray Technology could not exist without the ongoing contributions of gues... more The Journal of Thermal Spray Technology could not exist without the ongoing contributions of guest editors and reviewers, which ensure the highest quality of our journal. Manuscripts are reviewed for technical excellence, quality, and relevance by competent reviewers. The editors identify and select reviewers based on their demonstrable and recognized research expertise, professional experience, critical judgment and foresight, and forward thinking in their field of expertise. We express our deepest appreciation to these guest editors who have created special topical issues of JTST published in 2012, and to these reviewers, all of whom have completed manuscript reviews during 2012. Thank you all for giving generously of your valuable time and expertise.
DLC are being used extensively for the protection and life extension of engineering components ex... more DLC are being used extensively for the protection and life extension of engineering components exposed to adverse environmental conditions of wear and/or corrosion during service in automobile engine, magnetic storage, IR optic devices. In many instances in industrial applications like automotive engine, magnetic storage DLC coating is considered as a part of the structure and is deposited on the components in batch process. In the industrial framework a much lean methodology for process and quality control is adopted. Integrated characterization study was carried on DLC deposited by electron cyclotron resonance (ECR) plasma on p-type Si (111) substrate using methane as precursor and argon as carrier gas to understand suitability of each technique in providing information about quality of DLC. The deposition bias voltage was varied from-60 V to-150 V using 13.56 MHz RF power applied to the substrate. The results obtained from Raman Spectroscopy, X-ray photoelectron spectroscopy (XPS), Spectroscopic Ellipsometry, Contact and X-ray reflectivity (XRR) are correlated. The results have been attempted to explain by newer advancement in the theory like quantum electronic activation of some sp 3 atomic rearrangement, subplantation and knock-on penetration mechanism of atomistic growth mechanism.
In the present work, magnetite (Fe 3 O 4 , avg. ~ 70 nm) synthesis employing Azadirachta indica (... more In the present work, magnetite (Fe 3 O 4 , avg. ~ 70 nm) synthesis employing Azadirachta indica (neem) leaf extract is reported originally using hydrothermal conditions and the results obtained were compared with that of D-glucose. Fourier transform infrared spectroscopy confirms the presence of polysaccharides and proteins in the extract which act as both surfactants and reducing agents, aided the formation of magnetite nanostructures. Authors also reported the selective doping of Zn, Cu and Co on nickel ferrite for the enhancement of adsorptive dye removal property, adopting and investigating the use of eloquent one-step green hydrothermal approach (T=180⁰C, t=4 hr, pH=12) with sodium dodecyl sulphate as surfactant. Xray diffraction studies reveal that all the materials synthesized are isometric spinel structures and furthermore, morphological evidences using scanning electron microscopy are accounted. Adsorptive dye removal ability of synthesized materials was investigated using trypan blue as a probe. It was evident from the results that magnetite using neem extract showed enhanced adsorption ability (75%) than that of D-glucose (62%). Also, exponential increase in dye removal efficiency from 55% to 81% due to the presence of copper in nickel ferrite was duly noted.
SiO2–TiO2 nanocomposite has been produced by a combination of sol–gel and mechanochemical process... more SiO2–TiO2 nanocomposite has been produced by a combination of sol–gel and mechanochemical process. The structural and chemical properties of the nanocomposite, produced by different milling time (1, 3, 10, and 20h at a constant speed of 200 or 350rpm), have been investigated and compared with its calcined counterpart (950°C for 2h). Variable pressure field-emission scanning electron microscope and transmission electron microscope were used to investigate surface morphology of the samples. The phases and chemical bonding of samples were, respectively, characterized by X-ray diffraction and Fourier transform infrared spectroscope. Brunauer–Emmett–Teller analysis was employed to estimate the particle size of the samples. Sample prepared by the longest milling time has shown the smallest particle size (∼40nm) with SiO2 amorphous structure mixed with crystalline anatase structure. Additional Si–O–Ti bond has been detected in the sample and the observation has been explained.
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