Erosive Wear Study of HVOF Spray Cr3C2–NiCr Coated CA6NM Turbine Steel

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Deepak Kumar Goyal ◽  
Harpreet Singh ◽  
Harmesh Kumar ◽  
Varinder Sahni
Keyword(s):  
High Speed ◽  
Protective Coatings ◽  
Average Particle Size ◽  
Erosive Wear ◽  
Average Particle ◽  
Slurry Erosion ◽  
Spray Process ◽  
Hvof Spray ◽  
Turbine Steel ◽  
Ca6nm Steel

Degradation of surfaces of hydroturbine components caused by impact of abrasive particles carried by flowing water is a serious issue. To counteract the same, surface modification of turbine materials by the application of protective coatings is gaining popularity these days. In this work, Cr3C2–NiCr coating was deposited on CA6NM turbine steel by the HVOF spray process and studied with regard to its performance under different slurry erosion conditions. The effect of three parameters, namely average particle size of slurry particles, speed (rpm), and slurry concentration on slurry erosion of this coating material, was studied by using a high speed erosion test rig. The analysis of the surfaces of the samples before and after slurry erosion tests was done by using SEM. The HVOF sprayed Cr3C2–NiCr coating showed very good performance under slurry erosion in comparison with uncoated CA6NM steel.

Mechanical properties and erosive behaviour of 10TiO2-Cr2O3 coated CA6NM turbine steel under accelerated conditions

2019 ◽  
Vol 16 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Khushdeep Goyal
Keyword(s):  
Mechanical Properties ◽  
Mass Loss ◽  
Average Particle Size ◽  
Average Particle ◽  
Slurry Erosion ◽  
Experimental Conditions ◽  
Content Type ◽  
Uncoated Steel ◽  
Erosion Test ◽  
Turbine Steel

Purpose This paper aims to evaluate the mechanical properties and slurry erosion behaviour of 10TiO2-Cr2O3 coated turbine steel. Design/methodology/approach Slurry erosion experiments were performed on the coated turbine steel specimens using slurry erosion test rig under accelerated conditions such as rotational speed, average particle size and slurry concentration. Surface roughness tester, Vickers microhardness tester and scanning electron microscope were used to analyse erosion mechanism. Findings Under all experimental conditions, 10TiO2-Cr2O3 coated steel showed better slurry erosion resistance in comparison with Al2O3 coated and uncoated steel specimens. Each experimental condition indicated a significant effect on the erosion rate of both coatings and uncoated steel. The surface analysis of uncoated eroded specimen revealed that plastic deformation, ploughing and deep craters formation were the reasons for mass loss, whereas microchipping, ploughing and microcutting were the reasons for mass loss of coated specimens. Originality/value The present investigation provides novel insight into the comparative slurry erosion performance of high velocity oxy fuel deposited 10TiO2-Cr2O3 and Cr2O3 coatings under various environmental conditions. To form modified powder, 10 Wt.% TiO2 was added to 90 Wt.% Cr2O3.

Slurry erosion performance study of HVFS sprayed Ni-20Al2O3 and Ni-15Al2O3-5TiO2 coatings under hydro accelerated conditions

2018 ◽  
Vol 70 (4) ◽  
pp. 805-817 ◽  
Author(s):  
Rajeev Kumar ◽  
Sanjeev Bhandari ◽  
Atul Goyal ◽  
Yogesh Kumar Singla
Keyword(s):  
Particle Size ◽  
Rotational Speed ◽  
Average Particle Size ◽  
Synergetic Effect ◽  
Average Particle ◽  
Flame Spray ◽  
Slurry Erosion ◽  
Content Type ◽  
Slurry Concentration ◽  
Ca6nm Steel

Purpose This paper aims to cover all the aspects of development, investigation and analysis phases to evaluate the slurry erosion performance of test coatings. The powders having composition of Ni-20Al2O3 and Ni-15Al2O3-5TiO2 were deposited on CA6NM grade turbine steel by using high velocity flame spray (HVFS) technique. The characterization of the coatings was done with the help of SEM/EDS and XRD techniques. Various properties such as micro-hardness and bonding strength of the coatings were also evaluated. Thereafter, these coatings were subjected to an indigenously developed high speed slurry erosion tester at different levels of rotational speed, erodent particle size and slurry concentration. The effect of these parameters on the erosion behavior of coatings was also evaluated. The slurry erosion tests and SEM of the eroded surfaces revealed remarkable improvement in slurry erosion resistance of Ni-15Al2O3-5TiO2 coating in comparison with Ni-20Al2O3 coating. Design/methodology/approach Two different compositions of HVFS coating were developed onto CA6NM steel. Subsequently, these coatings were evaluated by means of mechanical and microstructural characterization. Further, slurry erosion testing was done to analyze the erosive wear behavior of developed coatings. Findings The coatings were successfully developed by HVFS process. Cross-sectional microscopic analysis of sprayed coatings revealed a continuous and defect-free contact between substrate and coating. Ni-15Al2O3-5TiO2 coating showed higher value of bond strength in comparison with Ni-20Al2O3 coating. Under all the testing conditions, Ni-15Al2O3-5TiO2 coatings showed higher resistance to slurry erosion in comparison with Ni-20Al2O3 coatings. Rotational speed, average particle size of erodent and slurry concentration were found to have proportional effect on specific mass loss of coatings. The mixed behavior (brittle as well as ductile) of the material removal mechanism was observed for the coatings. Originality/value From the literature review, it was found that researchers have documented the various studies on Ni-Al2O3, Ni-TiO2 and Al2O3-TiO2 coatings. No one has ascertained the synergetic effect of Alumina and Titania on the slurry erosion performance of Nickel-based coating. In view of this, the authors have developed Ni-Al2O3 and Ni-Al2O3-TiO2 coatings, and an attempt has been made to compare their mechanical, microstructural and slurry erosion characteristics.

Preparation and characterization of natural quercetin-based Mongolia Medicine SenDeng-4 nanoemulsion (N-QUE-NE) and its antibacterial activity..

2020 ◽  
Vol 18 ◽  
Author(s):  
Yanfang Zhang ◽  
Rina Du ◽  
Pengwei Zhao ◽  
Sha Lu ◽  
Rina Wu ◽  
...  
Keyword(s):  
Particle Size ◽  
Antibacterial Activity ◽  
Zeta Potential ◽  
High Speed ◽  
Antibacterial Effect ◽  
Average Particle Size ◽  
Antagonistic Effect ◽  
Dilution Method ◽  
Average Particle

Background: Quercetin is the main active ingredient of Xanthoceras sorbifolia Bunge. Traditional compatibility theory of traditional Chinese medicine has typically reported a synergistic interaction among multiple components, while the synergistic effects of nanoemulsion have not been fully clarified. Objective: To study preparation and characterization of quercetin-based Mongolia Medicine Sendeng-4 nanoemulsion (NQUE-NE) and its antibacterial activity and mechanisms. Methods: The morphology of the nanoemulsion was observed by transmission electron microscopy (TEM), and the zeta potential, polydispersity index (PDI), and particle size distribution were determined by the nanometer particle size analyze. The stability of nanoemulsion was investigated by light test, high speed centrifugal test and storage experiment at different temperature. The combined bacteriostatic effect of N-QUE-NE was studied in vitro by double-dilution method and checkerboard dilution method. Results: The appearance of N-QUE-NE was pale yellow, clear and transparent. The nanoemulsion particles were spherical and uniformly distributed under TEM. The PDI was 0.052, the average particle size was 19.6nm, and the Zeta potential was -0.2mV. When quercetin nanoemulsion (QUE-NE) was used in combination with tannin nanoemulsion (TAN-NE) and toosendanin nanoemulsion (TOO-NE), it exhibited a synergistic antibacterial effect. However, the combination of QUE-NE and geniposide nanoemulsion (GEN-NE) exhibited an antagonistic effect. It was revealed that the antibacterial effect was in order of quercetin-tannin-toosendanin nanoemulsion (QUE-TAN-TOO-NE) ＞ quercetin-tannin nanoemulsion (QUE-TANNE) ＞ QUE-NE ＞ quercetin-tannin-toosendanin-geniposide nanoemulsion (QUE-TAN-TOO-GEN-NE). Conclusion: This study explored the preparation and efficacy of N-QUE-NE, and the results showed that quercetin, tannin and toosendanin had satisfactory synergistic antibacterial effects. The antagonistic effect of quercetin and geniposide in nanoemulsion indicated that it is not beneficial to the antibacterial effect of Sendeng-4, and further research needs to be conducted to clarify its antibacterial effect.

scholarly journals Polydimethylsiloxane and Castor Oil Comodified Waterborne Polyurethane

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Xuan Ji ◽  
Yanming Zhou ◽  
Baoling Zhang ◽  
Caiying Hou ◽  
Guozhang Ma
Keyword(s):  
Thermal Stability ◽  
Castor Oil ◽  
Water Resistance ◽  
Fourier Transforms ◽  
Protective Coatings ◽  
Average Particle Size ◽  
Waterborne Polyurethane ◽  
Average Particle ◽  
Ft Ir ◽  
Fourier Transforms Infrared Spectroscopy

In view of both improving properties of waterborne polyurethane (WPU) and sufficient utilization of renewable resources, a series of polydimethylsiloxane (PDMS) and castor oil (C.O.) comodified anionic WPUs with internal cross-linking was prepared through a prepolymer mixing process. The chemical structure of synthesized polymers was characterized by Fourier transforms infrared spectroscopy (FT-IR). In comparison with traditional linear WPU synthesized from petroleum-based polyols, these novel WPU films exhibited superior properties in solvent and water resistance, thermal stability, and mechanical strength, which suggest promising applications of these new environmentally friendly materials, particularly in the area of decorative and protective coatings. In addition, the results showed that with the increase in PDMS content in these co-modified WPUs the average particle size, the water resistance, and the thermal stability increased accordingly while the solvent resistance and the mechanical properties decreased.

Influence of Micro-Milled Secondary Materials Used as Binders in Low Level Stabilized Cold Recycled Asphalt Mixtures

2017 ◽  
Vol 731 ◽  
pp. 29-36 ◽  
Author(s):  
Jan Suda ◽  
Jan Valentin
Keyword(s):  
High Speed ◽  
Economic Value ◽  
Average Particle Size ◽  
Environmental Benefits ◽  
Average Particle ◽  
Recycled Asphalt ◽  
Low Level ◽  
Foamed Bitumen ◽  
Materials Used ◽  
By Products

This paper presents an experimental verification of the alternative options for using by-products or mineral waste materials applied to cold recycled mixtures with low level of stabilisation intended for low-volume road structures. To achieve the necessary refinement and a certain level of reactivity potential, the by-products were activated mechanically, i.e. pulverized in a high-speed disintegrator with respect to the lowest possible energy demands of the process and to the level of wear-and-tear of the working components in the milling machine. Such refined material, with average particle size of 10-15 μm, is applies as an active filler component allowing to partly substitute hydraulic binder in cold recycled mixtures. The application of such materials in structural pavement layers should increase the environmental benefits and result in added economic value. The experimental measurements taken focused on cold recycled mixtures with low level of stabilisation, modified by a combination of binders, or namely cement, mechanically activated concrete from reclaimed concrete pavement slabs originating from the Czech backbone D1 highway modernisation, mechanical-chemically activated fluid ashes from the Pilsen heat plant and foamed bitumen. Both basic volumetric properties and strength and deformation parameters were set for the purposes of evaluation of the characteristic measured in the experimental mixes.

Formulation of Polymeric Nanoparticles of Lercanidipine by Two Bottom Down Techniques Optimized by Design of Experiment

2020 ◽  
Vol 57 (3) ◽  
pp. 1-18
Author(s):  
Alicia Menezes ◽  
Shanthi Lysetty ◽  
Anup Naha
Keyword(s):  
High Speed ◽  
Polymeric Nanoparticles ◽  
Average Particle Size ◽  
Tween 80 ◽  
Oral Route ◽  
Average Particle ◽  
Channel Blockers ◽  
Factorial Method ◽  
Major Disadvantage ◽  
Preformulation Studies

Lercanidipine has found to be effective in lowering blood pressure among the potent calcium channel blockers, through its action on L- type calcium channels. However, the major disadvantage associated with Lercanidipine is, it is a BCS class II drug having low solubility bioavailability is around 10% through oral route due of extensive first pass metabolism. The present study is aimed to prepare and evaluate polymeric nanoparticles of Lercanidipine using a combination of two bottom down techniques, High speed homogenizer and Probe sonication. Preformulation studies like, DSC, FTIR using surfactants such as Tween 80, Sodium Lauryl sulphate, Polyvinyl Alcohol, singely and in combination were used. A full factorial method was utilized to study the effect of various factors such as surfactant concentration, homogenization speed, sonication amplitude and sonication time on Lercanidipine nanoparticles in two levels. Optimized nanoparticles (with PVA as surfactant) showed an average particle size of 141 nm, PDI 0.248 and zeta potential +6.46. Formulation was further optimized using Design Expert 10 software. Optimized formulation was found to be stable during 3 months stability studies as per ICH guidelines.

The Effect of Annealing Heat Treatment on the Microstructure and Macroscopic Properties of Kinetic-Sprayed Ta Coating Layer

2014 ◽  
Vol 893 ◽  
pp. 64-68 ◽  
Author(s):  
Myeong Ju Lee ◽  
Jae Sung Oh ◽  
Hyung Jun Kim ◽  
Ik Hyun Oh ◽  
Kee Ahn Lee
Keyword(s):  
Heat Treatment ◽  
Coating Layer ◽  
Average Particle Size ◽  
Average Particle ◽  
Spray Process ◽  
Kinetic Spray ◽  
Annealing Heat Treatment ◽  
Coating Layers ◽  
Ar Gas ◽  
Annealing Heat

The effect of annealing heat treatment on the properties of high-density tantalum coating layer produced by the kinetic spray process was investigated. Pure Ta powder with an average particle size of 24.35μm and irregular shape was used to produce the coating layer through kinetic spray process. The annealing heat treatments of tantalum coating layers were applied for an hour in an Ar gas atmosphere under temperatures of 800°C, 900°C, 1000°C, and 1100°C. The manufactured coating layers have hardness and porosity of 270 Hv and 0.28%, respectively, showing even higher density levels than the kinetic-sprayed Ta coating layers reported to date. As the annealing temperature increased, the hardness value of the coating layer reduced from 270 Hv to 183 Hv and the porosity was verified to have decreased from 0.28% to 0.18%. The result of the additional XPS analysis confirmed that the phase generated between particle interfaces with heat treatment was Ta2O5 oxide. Based on these results, improving methods to dense the Tantalum coating layer with kinetic spray process was considered.

Nucleate Boiling Heat Transfer on Plain and Microporous Surfaces in Subcooled Water

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Seongchul Juna ◽  
Jinsub Kima ◽  
Hwan Yeol Kimb ◽  
Seung M. Youa
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Average Particle Size ◽  
Nucleate Boiling ◽  
Average Particle ◽  
Transfer Coefficients ◽  
Sem Image ◽  
Subcooled Water ◽  
Plain Surface ◽  
Bubble Sizes

The growth of hovering bubbles on Copper, High-Temperature Thermally-Conductive Microporous Coating (Cu-HTCMC) and plain surface were compared at 1,000 kW/m2 in nucleate boiling with different subcoolings. Images obtained by a high speed camera operating at 2,000 frames per second were used. The Cu-HTCMC was created by sintering copper powders with the average particle size of 67 μm and ∼300 μm thickness, which showed the optimized nucleate boiling and critical heat flux enhancement. The hovering bubble size became smaller as subcooling increased for both Cu-HTCMC and plain surface due to condensation by surrounding subcooled water. At 30 K subcooling, big hovering bubbles disappeared on both surfaces. Small bubbles were shown on plain surface and mists were shown on Cu-HTCMC surface. The hovering bubble sizes were close and the growth times were comparable for both surfaces in saturated and 10 K subcooling cases. However, the bubbles on Cu-HTCMC surface were smaller than those of plain surface at 20 K and 30 K subcoolings. This is believed to be due to the microporous structures shown in the SEM image (top left figure). The heat transfer coefficients of Cu-HTCMC were ∼300 kW/m2K for various subcoolings, about 6 times higher than those of plain surface (top right figure). The figure indicates slightly increasing trend of the heat transfer coefficient with subcooling. This is believed to be the result of the disappearance of relatively big size bubbles in Cu-HTCMC case.

Protective coatings of nanophase diamond deposited directly on stainless steel substrates

1996 ◽  
Vol 11 (8) ◽  
pp. 2042-2050 ◽  
Author(s):  
F. Davanloo ◽  
H. Park ◽  
C. B. Collins
Keyword(s):  
Stainless Steel ◽  
High Speed ◽  
Protective Coatings ◽  
Diamond Films ◽  
Erosive Wear ◽  
High Energy ◽  
Industrial Applications ◽  
Carbon Ions ◽  
Interfacial Layers ◽  
Steel Substrates

Composed of sp3 bonded nodules of carbon, nanophase diamond films are deposited in vacuum onto almost any substrate by condensing carbon ions carrying keV energies. These multiply charged ions are obtained from the laser ablation of graphite at intensities in excess of 1011 W cm−2. The high energy of condensation provides both the chemical bonding of such films to a wide variety of substrates and low values of residual compressive stress. Coatings of 2–5 μm thickness have extended lifetimes of materials such as Si, Ti, ZnS, ZnSe, and Ge against the erosive wear from high-speed particles by factors of tens to thousands. In this research emphasis has been placed on studies of the bonding and properties realized by the direct deposition of nanophase diamond films on stainless steel substrates. Examinations of interfacial layers showed deep penetrations of carbon atoms into steel substrates. Resistances to low and high impact wear estimated by a tumbler device and a modified sand blaster, respectively, and results indicated significant increases in the lifetime of stainless steel samples. The characterization studies in this work demonstrated nanophase diamond as an attractive material for use as a protective coating in current industrial applications.

Corrosion Properties of Magnetron Sputtered Al-Mg Alloy Coatings on High-Speed Electro-Galvanizing Steel

2009 ◽  
Vol 79-82 ◽  
pp. 1987-1990
Author(s):  
Xun Lei Gu ◽  
Yu Qiao Shan ◽  
Chang Sheng Liu
Keyword(s):  
Corrosion Resistance ◽  
Substrate Temperature ◽  
High Speed ◽  
Average Particle Size ◽  
Electrochemical Measurement ◽  
Corrosion Current ◽  
Average Particle ◽  
Corrosion Properties ◽  
Corrosion Resistance Property ◽  
Target Power

The Al-Mg coatings were deposited on high-speed electro-galvanizing steel by using double-target DC magnetron sputtering. Numerous Al-Mg coatings were prepared with a range of different Mg-target power at different substrate temperatures. The morphologies and compositions were analyzed by SEM, EDS and XRD, the corrosion-resistance properties with different sputtering parameters were discussed by electrochemical measurement. It was found that with the substrate temperature increasing, the porosity decreased, meanwhile, higher substrate temperature resulted in more granular particles and an increased average particle size, but that did not affect corrosion properties obviously. The corrosion-resistance properties were found to be significantly affected by the targets power. As the power of Al-target and Mg-target were 900W and 200W respectively, the film acted the best corrosion-resistance property. Corrosion current density was approximately 4μA/cm2, decreased significantly compared with galvanized sheet. After analysis, the coating was mainly composed of Al12Mg17 which afforded sacrificial anode protection. As the Mg-target power over high relative to Al-target, the coating was composed of Al12Mg17 and MgZn2, the latter can cause micro-galvanic acceleration of corrosion.

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