Nano Surface Research Articles

Spongy nano surface architecture of chemically grown BiVO4: High-capacitance retentive electrochemical supercapacitor

Design of nanostructured surface architecture is currently playing a vital role to enhance the energy storage capability of electrode materials and opening up a new era for future technologies through electrochemical supercapacitors. Present effort portrays the growth of nanostructured bismuth vanadate (BiVO4) as an active electrode for supercapacitor application by using ease and industry scalable successive ionic layer adsorption and reaction (SILAR) method. Structural analysis reveals the development of orthorhombic structured BiVO4 with spongy nano-pebbles like surface architecture. Synthesized BiVO4 electrode yields remarkable capacitance of 707 F/g @3 mV/s scan rate. Faradaic and capacitive type contributions have been evaluated for in-depth understanding along with the estimation of electrochemical active surface area. Electrochemical impedance spectroscopy (EIS) analysis of BiVO4 electrode exhibits 5.723 and 0.89 Ω cm2 values of series and charge transfer resistances, respectively. Interestingly, BiVO4 electrode delivers outstanding capacitive retention of 102% even at 3500 cycles, indicating its potential candidature for the advancement in high capability supercapacitors with excellent stability for the future technologies.

Influence of optimization techniques and nano surface coating materials on microstructure of iron-nickel-chromium alloy using wire EDM process

Abstract This research proposes developing the new hybrid optimization techniques for getting optimized wire EDM machining parameters and analysing the performance and microstructure of hybrid treatment alloy 20 material (high-velocity oxygen fuel spraying and plasma nitriding on iron-nickel-chromium alloy) after machining in wire EDM. The devising optimization is carried out using back-propagation neural networks (BPNN) integrated with fuzzy logic techniques. Taguchi L27 method uses optimized parameters in 3 factors and 3 level methods to BPNN wire EDM processing parameters. Those processing parameter errors are controlled by applying fuzzy logic system in hybrid optimization techniques. The hybrid optimization provides best results (±5% error) while comparing other techniques. This proposal was started with research review of defined factors and BPNN parameters level for hidden layer number, learning algorithm, neurons numbers, and so on. The analysis of variance (ANOVA), analysis of means (ANOM) and signal to noise (S/N) ratio have been used to identify Taguchi results. The BPNN techniques have been employed significantly to tackle hidden layer's uncertain parameter structures. The fuzzy logic controllers in general have been designed engaging the relations between system performance and factor through error method calculation. The microstructure analysis showed that the no evidence was found of recast layer formation on hybrid treated material after machining in wire EDM due to compressive stress and compound layer on material surface.

Microscopic Characterization of Bioactivate Implant Surfaces: Increasing Wettability Using Salts and Dry Technology.

The surface topography of dental implants plays an important role in cell-surface interaction promoting cell adhesion, proliferation and differentiation influencing osseointegration. A hydrophilic implant leads to the absorption of water molecules and subsequently promotes the adhesion of cells to the implant binding protein. Dried salts on the implant surfaces allow one to store the implant surfaces in a dry environment while preserving their hydrophilic characteristics. This process has been identified as “dry technology”. The aim of the present study is to describe from a micrometric and nanometric point of view the characteristics of this new bioactivated surface obtained using salts dried on the surface. Topographic analysis, energy-dispersive X-ray spectroscopy, and contact angle characterization were performed on the samples of a sandblasted and dual acid-etched surface (ABT), a nanosurface (Nano) deriving from the former but with the adding of salts air dried and a nanosurface with salts dissolved with distilled water (Nano H2O). The analysis revealed promising results for nanostructured surfaces with increased wettability and a more articulated surface nanotopography than the traditional ABT surface. In conclusion, this study validates a new promising ultra-hydrophilic nano surface obtained by sandblasting, double acid etching and surface salt deposition using dry technology.

Nano surface modification of poly(ethylene terephthalate) fabrics for enhanced comfort properties for activewear

Moisture absorption and transport properties of fabrics determine the thermo-physiological comfort of the apparel. The study aims to investigate the application of hydrophilic metal oxide nanostructures on poly(ethylene terephthalate) (PET) fabrics and their influence on the comfort properties of PET. Both, the sol-gel synthesized nano sols and commercially available nanoparticles (NPs) of SiO2 and TiO2 with different concentrations were applied on PET fabric alone or in combination with a hydrophilic resin. The composite of nanoparticles and resin exhibited radical improvement in the moisture management behavior of PET substrate, which is crucial for its industrial viability for activewear. At add-on of < 2wt%, this nano-finishing agent led to remarkable enhancement in wettability, wickability, and evaporation of moisture. Based on the surface morphology and chemical characteristics of the treated fabrics, a mechanism has been proposed to explain the role of nanoparticles in the enhancement of moisture management properties. It has been shown that in the presence of resin, the nanoparticles form a durable network on the surface of PET fibers and play a synergistic role in moisture and heat management of the finished fabric. Infrared thermography has been used to demonstrate the potential of such combination to attain enhanced comfort properties.

Laser microplasma as a spot tool for glass processing: Focusing conditions

Indirect laser-based surface nano- and microprocessing of optical materials demonstrate promising applications in microoptics, microfluidics and electrofluidic. The methods principle is based on the conversion of laser energy to a plasma plume, which effectively and precisely etchуы the glass backside. However, there are a lot of variable occurs during fabrication, which we discuss in this research to improve the processing quality and maintain the repeatability of the LIMP method. Experimental methodologies supported with geometrical calculations of a plasma plume expansion and calculation of a laser beam distortion by the microlens formed on the glass backside are presented. The study contributes to understanding the importance of experimental conditions - an air gap and focus plane position. The results make LIMP method to be robust, low-cost, and easily implementable in the industry.

4-Iodophenylboronic Acid Stabilized Gold Cluster as a New Fluorescent Chemosensor for Saccharides Based on Excimer Emission Quenching.

4-iodophenylboronic acid (IPBA) ligated luminescent gold cluster was synthesized by mixing an aqueous solution of IBPA and polyvinylpyrrolidone stabilized gold cluster (Au:PVP) in water at room temperature through chemisorption of iodine on gold nano surface. Transmission Electron microscopy (TEM) and matrix assisted laser desorption ionization (MALDI) analysis revealed that the size of these Au-clusters (1.4±0.2nm) remain unchanged without any noticeable aggregation during synthesis. Owing to the formation of excimer between aryl moieties grafted over Au surface, the cluster exhibit strong emission peak at 335nm. This luminescent gold cluster is used for sensing different saccharides in water at physiological pH through quenching of excimer emission peak. This strong excimer emission is significantly quenched in presence of saccharides through interaction with boronic acid moieties. The selectivity for different saccharides follows the order: fructose > galactose > maltose > glucose ~ ribose > sorbitol with hight affinity for fructose (KSV = 1.54 × 104M-1) with Limit of Detection (LOD) of 100μM.

Progress in Raman Spectroscopy and Reduction of Carbon Dioxide

The metal catalyst has good electrical conductivity, is simple to prepare and easy to be applied in practice. It is currently the most in-depth researched catalyst for electrochemical reduction of carbon dioxide. In recent decades, metals such as copper, cobalt, tin, and gold have been used as electrode catalysts for reducing carbon dioxide. From the perspective of the reduction mechanism of carbon dioxide, it is generally believed that the formation of C intermediate is the rate-determining step of the entire reduction reaction. One of the main functions of metal catalysts is to enable the corresponding reaction intermediates to exist stably, thereby improving the energy efficiency of the reaction. According to the combination with different intermediates and the different products obtained, the metal electrode catalysts can be divided into three categories. In this paper, the current research status of electrocatalytic and photocatalytic reduction of carbon dioxide and carbon dioxide under Raman spectroscopy are introduced. Also elaborate, the Raman spectroscopic characterization of carbon dioxide has been introduced in this paper with emphasis on the changes of Fermi resonance peaks of CO₂ with temperature and pressure. The advantages and disadvantages of using metal and metal complexes, carbon materials, composite materials and MOF materials to reduce CO₂ are introduced. The method was improved, and finally focused on the core issues of improving reactivity and product selectivity, and analyzed the shortcomings of current electrocatalytic processes extended to large-scale production applications from surface engineering, chemical modification, nano or composite materials. There are other ways to improve the activity of the catalyst from these aspects, as well as the prospects for future research.

Surface Treatment of Cement based Composites: Nano Coating Technique

Geometry, size, and shape of the surface pores, as well as, capillarity, and exposure environment are directly influence strength and durability of cementitious composites. The current research aimed to improve the resistance to abrasion and decrease the surface porosity of cement-based composites by nano surface coating technique. All samples were coated with a mixture of methanol alcohol, ordinary Portland cement and nano powder of (TiO2, MgO, ZnO and ZrO2) separately in percentages of (1, 1.5, and 2 %) by weight of cement. The hardness, abrasion, water absorption, density, porosity, and microstructural analysis: Scanning Electron Microscopy and X-Ray Diffraction (SEM &amp; XRD) were studied for all coated and control specimens. Results showed an improvement in mechanical properties for all coated specimens as compared to control. The highest Vickers micro hardness value had reached 29%, while the largest value of abrasion resistance had increased by 39% for coated samples with 2% ZrO2. Also, the results showed a reduction in the porosity and water absorption of all coated samples, having highest scores obtained from the coated samples with 2% MgO. While the total water absorption rate decreased by 45% and the density had increased by 1% and the porosity had decreased by 46%. Additionally, the results of microstructural tests revealed pattern and images for each of SEM and XRD. Also, results indicated that the nano coating leads to significant consumption of Portlandite (CH) associated with production of a stable structure of CSH and reduction of voids, and this is evident from the enhancement in the physical properties.

Laser micro &amp; nano surface texturing for enhancing osseointegration and antimicrobial effect of biomaterials: A review

The worldwide significant rise of orthopedic and dental implant surgeries in the last decade is a matter of concern. The rate of subsequent failure of implants and revision surgeries are also considerable. Insufficient osseointegration and bacterial infections are the major causes of implant failure. The present methods of surface coatings and surface modifications are inadequate for long term stability. Over this scenario, laser surface texturing (LST) is the most promising method which has precise control over surface topography, morphology, wettability, and chemistry which makes this technique suitable for manufacturing biocompatible, antibacterial, and early bone healing surfaces. Researchers experimented with grooves, dimples, micro, and nano-texture patterns for optimizing cell adhesion and proliferation. Nanopillars, nano-ripples, spikes, LIPSS surface structures are used for examining antibacterial behaviour. Very few research papers discussed the combined approach for developing implant material having bio activeness and antibacterial behaviour. This paper explores the improvement of physical, biocompatible, antibacterial properties through LST. The introduction of challenges and future trends of the field will certainly help to investigate the new directions of biomaterial research.

Highly efficient and robust catalysts for the hydrogen evolution reaction by surface nano engineering of metallic glass

The synthesized hybrid electrocatalyst has excellent efficiency and stability for the HER.

Analysis of the Effects of ZrO2 Nanoparticles on the Penetration in GMAW Process

In this study, ZrO2 Nano-particles to improve the geometry and increased penetration welding has been used on the St37 sheet, in GMAW process. In the GMAW process of selecting appropriate values for the input parameters necessary in order to achieve weld is high with appropriate geometry and penetration. Since the stress-bearing capacity of the weld geometry, weld quality and also has an important role in determining the mechanical properties of the weld. In this study, the effects of voltage, wire feed speed, distance nozzle to the work piece, welding speed and coating thickness of ZrO2 Nano particles is intended as input parameters. The first, for coating Nano particles with specific dimensions on the surface of parts to be coated welding operation. After welding the weld penetration depth was evaluated. increasing the depth of penetration of the active coating on the surface (Nano zirconium oxide), which place the mechanisms leading to increased focus and arc current density at the top of the arc. Marangoni has also changed from negative to positive flow direction, the depth of penetration is increased. The results showed that fixed taking into account the input parameters and increase the coverage of ZrO2 Nano-particles on the surface to thickness 0.75 mm, weld penetration depth compared to non-Nano scale zirconium oxide coating has been increased. in addition to the effect of ZrO2 nanoparticles as a coating surface-active and increase the depth of penetration, such particles can cause tiny inclusions inside the structure weld, nucleation centers has been caused for the formation of acicular ferrite.

State of the art on atomistic modelling of laser polishing

Abstract The emergence of newer engineering materials led to the advent of the advanced manufacturing process (AMP). Laser polishing is one of AMP, specialized in creating ultra-fine surfaces on simple to complex features. Basically laser polishing is a combination of several overlapping thermophysical phenomena. But the most crucial shortcomings in laser polishing is difficulty in the proper selection of various input finishing parameters for best output responses such as nano surface roughness. This led to the need for modeling of the laser polishing mechanism, wherein by by giving various input parameters to predict output responses. In this paper, the literature behind three laser polishing models: theoretical model, statistical model and molecular dynamics simulation are discussed. These laser polishing models determine the relationship between various finishing parameter and final surface roughness.

Superior adsorption removal of dye and high catalytic activity for transesterification reaction displayed by crystalline CaO nanocubes extracted from mollusc shells

Nano structuring and surface functionalization of industrially important Calcium Oxide (CaO) material has broad spectrum applications in daily civic life. In this context, cubical shape CaO nanoparticles are extracted via an eco-friendly green approach from dead mollusc shells collected from sea beaches. The surface structural morphology of as-prepared catalyst is thoroughly characterized by XRD, DLS particle size, SEM, TEM-EDS, TGA, TPD, BET surface area (80 m2g−1) analysis, adsorption and electro-kinetic (zeta potential/point of zero charge) properties etc. measurement. Practical applications of this cubic nano crystal (lattice constant 12.51 Å and size 60–80 nm) for adsorption removal of toxic neutral red dye and catalytic activity for transesterification are systematically studied relative to commercial CaO particles under similar experimental conditions. Influential factors responsible for optimum dye adsorption isotherms, kinetics/thermodynamics of catalytic activity, stability and reusability/leaching are properly investigated in correlation with its observed crystal structural and physicochemical properties.

Histological and Nanomechanical Properties of a New Nanometric Hydroxiapatite Implant Surface. An In Vivo Study in Diabetic Rats.

Implant therapy is a predictable treatment to replace missing teeth. However, the osseointegration process may be negatively influenced by systemic conditions, such as diabetes mellitus (DM). Microtopography and implant surface developments are strategies associated to better bone repair. This study aimed to evaluate, in healthy and diabetic rats, histomorphometric (bone to implant contact = %BIC; and bone area fraction occupancy = %BAFO) and nanomechanical (elastic modulus = EM; and hardness = H) bone parameters, in response to a nanometric hydroxyapatite implant surface. Mini implants (machined = MAC; double acid etched = DAE, and with addition of nano-hydroxyapatite = NANO) were installed in tibias of healthy and diabetic rats. The animals were euthanized at 7 and 30 days. NANO surface presented higher %BIC and %BAFO when compared to MAC and DAE (data evaluated as a function of implant surface). NANO surface presented higher %BIC and %BAFO, with statistically significant differences (data as a function of time and implant surface). NANO surface depicted higher EM and H values, when compared to machined and DAE surfaces (data as a function of time and implant surface). Nano-hydroxyapatite coated implants presented promising biomechanical results and could be an important tool to compensate impaired bone healing reported in diabetics.

The Effect of Surface Nano and Microstructures on Hydrogen Gas Evolution Behavior on Ni Patterned Electrodes

Highly efficient water electrolysis process is one of the key technologies for hydrogen economy suppressing global warming. Now, alkaline water electrolysis (AWE) and Proton exchange membrane (PEM) electrolysis are regarded as the representative industrial process. The advanced electrode without precious metal or oxide catalysts for hydrogen evolution reaction (HER) in these processes plays an important role to design HER efficiently and economically. Tremendous efforts focusing to unique characteristic catalysts exploration have been engaged world-widely not only tediously and steadily but also with materials informatic-science utilization driven by AI technology. Roughly speaking based on electrochemical engineering aspects, the energy loss in water electrolysis is composed of electrode reaction kinetics governed by catalytic activity, concentration overpotential and ohmic drop in gas-liquid two phase dispersion layer. The concentration overpotential and ohmic resistance are sometimes result in significant energy loss in large scale industrial process. From the sustainable and economical views toward Hydrogen Economy Society, AWE with less precious catalysts is considered as hydrogen production candidate with cheaper cost and longer durability. Many papers on gas electrode behavior have focused on macroscopic observation, but more fundamental understanding on nucleation and growth behavior of gas bubbles is rather limited due to the experimental difficulties. It is believed that the electrode surface structure tailoring may also provide one of promising methods to improve the catalytic performance as well as advance catalytic HER activity. Especially, nano/micro-scale structures on the electrode surface are suggested to affect the catalyst performance by controlling the nucleation and growth behaviors of bubbles. However, the detailed mechanisms of the effect of surface nano/micro-scale structures on HER and bubble behaviors have not been elucidated. Therefore, to analyze the influence of microstructure and surface wettability of catalytic electrode on bubble behaviors and HER, this study focuses on bubble behaviors on the electrode surface using Ni micro-patterned electrode fabricated by electrodeposition and Pt single crystalline electrodes. Ni micro-patterned electrodes were electrodeposited in the electrolyte containing 0.05 mol dm-3 NiCl2∙6H2O (pH 2.5) on patterned Cu substrate. Pt and Ag/AgCl electrode were employed as CE and RE, respectively. Surface structures and wettability of prepared electrodes were evaluated by scanning electron microscopy (SEM) and contact angle measurement. Water electrolysis was performed in 1 M KOH and Pt mesh and Hg/HgO. The effect of surface roughness on bubble behaviors was additionally examined in 0.1 M H2SO4 with three electrode system; Pt single crystalline electrode prepared by the Clavier method as WE, carbon rod as CE, and reversible hydrogen electrode as RE, respectively. Microdot structures, cylinder-, semisphere- and square-like were prepared. Ni coverage ratio of Ni electrodeposited area to Cu substrate, was calculated to correlate surface wettability measured by sessile drop method and Ni microstructure. It was suggested that electrode surface wettability could be controllable by changing Ni coverage and each Ni microdot structure exhibited an apparent catalytic electrode by surface tailoring. The effect of microstructures and surface wettability on HER performance was then studied during galvanostatic electrolysis at -20 mA cm-2 for 30 min. Total overpotential measured from 200 s to 1800 s seemed to proceed water electrolysis stably. It increased with decreasing surface wettability. This may indicate lower surface wettability derived from Ni microarray structures increases overpotential by accumulating newly evolving H2 bubbles. To further analyze the phenomena, high-speed CCD camera cinematography was applied. The ratio of larger diameter bubble tended to increase with increasing the contact angle. It indicates lower surface wettability would enhance bubble growth behaviors on cathode surface. Moreover, larger diameter bubbles were generated on cylinder-like Ni microdots. These results suggest increasing contact area between bubbles and Ni micropatterned electrode would enhance bubble growth behaviors. The effect of Ni microdot height on bubble nucleation behaviors was also observed. It apparently demonstrated that taller Ni dot height rather increased the nucleation site of bubbles. In order to additionally investigate the effect of nano-scale roughness tailored by single crystalline growth technique on bubble behaviors, H2 bubble evolution behaviors on Pt single crystalline electrode were cinematographically recorded. No H2 bubbles were generated on smooth surface fabricated by Pt (111) microfacet, suggesting lower nano-scale surface roughness considerably suppressed bubble nucleation on Pt electrode surface. These results suggested micro and nano structures and surface wettability influenced on bubble nucleation and growth phenomena frequently encountered in industrial electrolysis. Further unknown room still remains to be challenged even in such a rather matured AWE. This work was partly carried out in Case Western Reserve University. Prof. Daniel Scherson’s supervisions are highly appreciated.

Energy deposition parameters revealed in the transition from 3D to 1D femtosecond laser ablation of fluorite at high-NA focusing

Ultrashort-pulse laser surface and bulk nano- and micromachining of dielectrics have multiple promising applications in micro-optics, microfluidics, and memory storage. The fundamental principles relate intrinsic inter-band multi-photon (MPA) and laser-induced intra-band free-carrier absorption (FCA) to particular ablation mechanisms and features. These principles are yet to be quantified into a complete set of basic experimental laser-matter interaction parameters, describing photoexcitation, relaxation, and final ablation. In this study, we considered the characteristic double-crater structure of single-shot ablation spots on dielectric surfaces and single-shot transmission spectra to extract crucial information about the underlying basic processes of ultrafast photoexcitation and laser energy deposition. Specifically, energy-dependent crater profiles and accompanying prompt self-phase modulation (SPM) spectral broadening were studied in single-shot surface ablation experiments on fluorite (CaF2) surface photo-excited by tightly focused 515- or 1030-nm, 300-fs laser pulses. Crater size dependence demonstrated two slopes, scaling proportionally to the squared focal 1/e-radius at higher energies (intensities) for larger ablated spots, and a much smaller squared 1/e-radius at lower energies (intensities) for (sub) micron-wide ablated spots, indicating a transition from 1D to 3D-ablation. As a result, these slopes were related to lower-intensity wavelength-dependent multi-photon inter-band transitions and wavelength-independent higher-intensity linear absorption in the emerging near-critical electron-hole plasma (EHP), respectively. Crater depth dependences on the local laser intensity fitted in the corresponding ranges by multi- and one-photon absorption provided the corresponding absorption coefficients. Spectral broadening measurements indicated even values for the red and blue shoulders of the laser pulse spectrum, representing the SPM effect in the weakly excited fluorite at the leading pulse front and providing the corresponding Kerr coefficient. In the second regime, the blue-shoulder broadening value saturated, indicating the appearance of near-critical plasma screening at the trailing pulse front, which is consistent with our calculations. These complementary experiments and related analysis provided an important set of key basic parameters, characterizing not only surface ablation, but also propagation of high-intensity ultrashort laser pulses in bulk fluorite, and enabling precise forecasting of optimal energy deposition for high-efficiency ultrashort-laser micro-structuring of this dielectric material.

Synthesis And Comparative Evaluation Of Traditional Herbomineral Nanoceuticals For Their Haemopoietic Activity

The traditional System of medicine comprises a wide variety of formulations for various ailments. It is essential to Standardize Ayurvedic drugs so that drugs having good quality can be used for better effect. Standardization is not only limited to the final preparation, but it also includes the materials used during the development and SOP adopted and the equipment used. The present study is an attempt to prepare anti anaemic herbomineral nanoceutical by two different processes, and to standardize and evaluate the haemopoietic effect of the prepared formulations and compare with a marketed formulation. Preparation was done based on Ayurveda Pharmacopoeia. Formulations were characterized by conventional methods and by AAS, XRD, EDAX, SEM, TGA, and IR. The toxicity and anti-anaemic effectiveness are evaluated by using albino Wister rats and histopathology and cytotoxicity studies. Products have a crystalline nature (XRD). TGA shows the decomposition temp of ferric oxide. SEM EDAX revealed surface smoothness and nano to the micro size of particles. AAS shows that the elements are within the prescribed limits. The in-process Standardization shows the effectiveness of adjuvants. There is an increase of haemoglobin and body weight on day 75 for first preparation than the Second and were comparable to that of standard. No toxicity in all rats and indicated no renal and gastrointestinal toxicity. The size, smoother surface, and the therapeutic effectiveness of the herbominerals prepared by the two methods can be attributed to the calcination steps and adjuvants. Thus, maybe dose reduction and rapid effect can be achieved.

Mechanical and wear behaviour of Friction stir processed surface composite through Self-Assembled Monolayer Technique

In the present research study, Friction stir processing (FSP) has been utilized to prepare nano surface composites, AA7075 based matrix was reinforced with B4C nanoparticles (size <30 nm). The aim of this study is to form a thin layer of B4C over the surface of AA7075 based matrix material through Self-Assembled Monolayer (SAM) technique followed by Friction stir processing. The major advantage of SAM is to minimize the quantity of B4C nanoparticles used in the preparation of nano surface composites. Additionally, this research also investigates the effect of tool rotation speed of Friction stir processing on mechanical and wear properties of processed nano surface composite. The results observed a uniform dispersion of nanoparticles in the processed nano surface composite and an improved value of microhardness with maximum value was found to be 185 Hv of the sample processed at 1200 rpm, compared to base metal. For the constant load, as FSP tool rotation speed increases, wear resistance increases from 1000 to 1200 rpm and decreases slightly for 1400 rpm. Scanning Electron Microscope (SEM) micrograph, tensile test and Field Emission Scanning-Electron Microscope (FESEM) fractography image used to study microstructure and the mechanical properties of processed nano surface composite. The x-ray Diffraction (XRD) showed the presence of B4C nanoparticles. Processed nano surface composites can be used for aircraft and automobile industry applications.

Wear Resistance of Nano Surface Modified Layer Based on Powder Metallurgy Parts in Stone Carving Design

Wear Resistance of Nano Surface Modified Layer Based on Powder Metallurgy Parts in Stone Carving Design

High temperature erosion behaviour of Type AISI 446 stainless steel under the combined effect of surface modification and pre hot-corrosion

In the present study, the effect of Surface nano crystallization (SNC), using Ultrasonic shot peening (USP), on pre-hot corrosion-erosion behaviour of Type AISI 446SS at elevated temperatures is studied. No phase change was revealed by X-ray diffraction (XRD), however, the microhardness is significantly increased in the shot peened region for USPed samples. The USPed samples were subjected to low-temperature hot corrosion (LTHC) tests under isothermal conditions for 20 h at 550, 650 and 750 ℃. The LTHC tests were carried out by spray deposition techniques using two salt mixture (Na2SO4/NaCl). Alumina (Al2O3) sand operated air-jet erosion tester was used to test the pre-hot corroded samples. The passive layer formed during LTHC suffered expulsion of metallic flakes and led to a significant change in erosion rate.