Steel Substrate Material Research Articles

Comparative analysis of microstructure and selected properties of WC-Co-Cr coatings sprayed by high-velocity oxy fuel on S235 and AZ31 substrates

Abstract The purpose of this work was to carry out comparative studies of WC-Co-Cr coatings deposited using the high velocity oxy fuel (HVOF) method onto two types of substrate material: structural steel S235 and magnesium alloy AZ31. The influence of the substrate material type on the microstructure, phase composition, crystallite size, porosity, Vickers microhardness, instrumental hardness (HIT), Young’s modulus (EIT), and fracture toughness was investigated. For both substrates, the deposited coatings deposited were characterized with fine-grained and compact microstructure. The X-ray diffraction (XRD) revealed presence of following phases: WC, W2C, Co0.9W0.1, and Co3W9C4. The WC phase was the most desirable and stable one with crystallites were below 100 nm. On the other hand, the size of the W2C crystallites was below 30 nm. The coatings obtained showed porosity values equal to 2.3 ± 0.4 vol% and 2.8 ± 0.7 vol% for AZ31 and S235, respectively. The average Vickers microhardness for both types of sample was appproximately 1200 HV0.3. The average HIT values for carbide particles and metallic matrix were around 29 GPa and 6.5 GPa, respectively. In the case of EIT, it was around 620 GPa and 190 GPa for WC and Co-Cr, respectively. The differences between coatings were negligible. The EIT value for both coatings was equal to 344 ± 11 GPa. The fracture toughness was around 4.5 MPa · m1/2 in both cases. The investigations revealed that it is possible to replace steel substrate material with a much lighter equivalent, in this case AZ31 alloy, without deterioration of the coating properties.

The Influence of the Hot Working Tool Steel Substrate Material on the Element Distribution, Microstructure and Hardness of Gas Metal Arc Welding Hardfaced Layers

The Influence of the Hot Working Tool Steel Substrate Material on the Element Distribution, Microstructure and Hardness of Gas Metal Arc Welding Hardfaced Layers

Amorphous plasma sprayed coating

The plasma spraying method has wide application in many industries, including the automotive industry, due to its diversity and efficiency. The interest in this technology is increasing as it is possible to replace expensive materials with iron-based alloys and use air instead of inert gas to activate plasma. There are a number of works that have emphasized the importance of properly selected spray parameters, but they used the plasma generation gas, which is an expensive inert gas such as argon, heli, or their gas mixture with a different ratio. The objective of this paper is to study the influence of the most specific parameters that affect the quality of the wear-resistant spray layer using Fe-based powder sprayed onto the steel substrate material. The experiment design with the ANOVA analysis helped to find out the nature of the elevation of the wear resistance under the influence of the particle velocity and the related technological parameters in the process. The research results provide an experimental formula that combines the main spray parameters with the evaluation of wear resistance in relation to the traditional material group.

Cold plasma studies on the influence of surface microstructured thickness in the secondary electron emission from tungsten coatings

The Secondary Electron Emission (SEE) from the Plasma Facing Components, (PFCs) affects the plasma sheath and edge structure of magnetically confined toroidal plasmas with effects on the Scrappe Off Layer (SOL), heat transport and incident plasma heat flux to the divertor targets. It is also behind the performance degradation in aerospace devices as Hall thrusters. In future reactor prototypes using tungsten (W) components, much more demanding and longer term conditions for the exposed PFCs are expected. These scenarios will exacerbate the material degradation of the exposed surfaces that will change its morphology, thus modifying its plasma material interaction behavior. In such scenario, specific studies on the influence of the microstructure in the tungsten SEE yields become necessary. In these laboratory experiments, the SEE emission of different microstructured tungsten coatings exposed to helium Glow Discharge (GD) plasmas has been analyzed by using a previously developed laboratory technique. It enables the characterization of the I-V characteristics of the biased sample and, at the same time, the acquisition of the electron incident flux by using a gridded probe adjacent to the exposed sample. Different microstructured W coated samples differing in coating thickness (2500 nm and 500 nm) and primal substrate surface finishing (translated in final differences within the W coating topologies) were analyzed, also including cold rolled tungsten and original stainless steel (SS) substrate (material in which the microstructured tungsten film was deposited) as benchmarks for comparison. The overall results have shown that the presence of a 2500 nm thick microstructured W coating decreases the SEE yield of tungsten (cold rolled) up to a factor 40% at electron mean energies of 100-175 eV. Conversely, 500 nm coatings did not reduce the SEE yield even showing an increase at 25-100 eV. The final increase/decrease in the obtained SEE yields seems to be more influenced by the microstructured coating thickness (where the role of intrinsic differences in oxygen content of the surfaces is discussed) rather than other questions possibly derived by the differences in surface topology (ordering, directionality and/or roughness of the microstructure features).

Features of the Macro-, Micro-, and Fine Structure of the Nickel Superalloy Product Material Formed by the Method of Electron Beam Additive Manufacturing.

In the present work, the products in the form of vertical walls were made of heat-resistant nickel-based superalloy ZhS32 via the method of electron beam additive technology. Unidirectional printing strategy was applied. The effect of heat input and 3D printing strategy on the macrostructure, dimensions, and morphology of microstructure elements was established. It was shown that the additive product material has a directed macrostructure. The only exclusion was the final layer with a thickness of no more than 3.5 mm. The directed macrostructure consisted of dendrites oriented predominantly along the crystallographic direction {001} of the primary dendrite arms. The misorientation of the dendrite axes did not exceed 9 degrees. The angle between the predominant dendrite growth direction and the normal to the substrate was 23 degrees. The average primary dendrite arms' spacing increased monotonically from 16 µm at 5 mm from the substrate to 23 µm in the final layers of the product material (the overall height was 41 mm). It was found that the average size of γ' (Ni3Al)-phase precipitations in the form of nanoscale and submicrocrystalline cuboids varied in the range of 76 to 163 nm depending on the distance from the substrate. The size of γ'-phase precipitations reached a maximum at about 30 mm from the substrate, while in the final layers of the product material, the average cuboid size did not exceed 135 nm. Extreme dependence of the size of γ'-phase precipitations on the height of the product followed from a combination of a given monotonic decrease in heat input and heat accumulation in the product material as it formed, as did additional heat removal by means of radiation during formation of the final layer of the product without re-melting. Chemical elements of the austenitic steel substrate material were not detected in the product material more than 8 mm from the substrate. There were no macrodefects, such as voids, in the entire volume of the product material.

Impact Abrasive Wear of Cr/W-DLC/DLC Multilayer Films at Various Temperatures

Diamond-like carbon (DLC) films are widely used in key parts of nuclear reactors as a protective coating. A study on the abrasive wear property of Cr/W-DLC/DLC multilayer films was performed at various temperatures. Results show that the mechanism of impact wear under no sand condition is mainly plastic deformation. The multilayer film still has excellent impact wear resistance and favorable adhesion with 308L stainless steel substrate at elevated temperatures under no sand conditions. Sand particles destroy the surface of the multilayer film due to the effect of cutting and ploughing, leading to a nine-fold increase in the wear area. The impact wear mechanism changes into abrasive wear with sand addition. Oxidation wear exists on 308L stainless steel substrate material due to the removal of the multilayer film at high temperatures. More energy is absorbed for plastic deformation and material removal under sand conditions, resulting in lower rebound velocity and peak contact force than under no sand conditions. The temperature leads to the softening of the substrate; thus, the specimens become more prone to plastic deformation and material removal.

Effect of duty cycle variation on Nickel electrodeposits at 10 Hz frequency

In this paper, nano nickel coating was made by pulsed electrodeposition technique to improve the surface properties of base metal. The developed nickel coating was characterized using SEM, Xrd, Vickers microhardness, Potentiodynamic polarization and ball on plate wear testing. X-ray diffraction studies shown that predominant (111) crystalline plane and finer grain size were obtained with lower duty cycle at 10 Hz frequency of pulse current. Pitting corrosion resistance of coated samples was evaluated at 3.5 wt. % of sodium chloride solution. An improvement of corrosion protection efficiency and good mechanical properties were achieved at lower duty cycle. As the duty cycle decreases, the corrosion current and wear rate decrease, and the micro hardness value increases. The average grin size was observed to be 75 nm and the newly developed nickel coated surface shown strong metallurgical bonding with the low carbon steel substrate material.

Performance Evaluation of Cyclic Stability and Capacitance of Manganese Oxide Modified Graphene Oxide Nanocomposite for Potential Supercapacitor Applications

Supercapacitors are a revolutionary type of energy storage device. They must be able to charge and discharge quickly while maintaining a high energy density. A storage material’s cyclic stability is a desirable feature. The type of electrode materials employed for the specific study design affects supercapacitor performance. Manganese dioxide has long been regarded as one of the best and most abundant materials in nature, having a potentially high specific capacitance. They also offer a wider potential range, more electroactivity, and are more environmentally friendly. However, because of its decreased volume expansion and low conductivity, it is difficult to use as a capacitor material. As a result, carbon-based porous films and supports can be employed to produce critical composites to overcome the current shortcoming. These nanoparticle-based materials will have improved electrical conductivity and a large surface area. Graphene oxide (GO) has a high surface area, thermal stability, and porosity. As an electrode material, many types of MnO2/carbon-based materials have been widely used in supercapacitors. Their overall performance is influenced by their construction processes, metal ratios, electrolyte medium, and voltage factors. Microwave technology was chosen as a cost-efficient and effective alternative to expensive and laborious techniques for fabricating MnO2/GO composites. The production procedure of a supercapacitor has been explored in this study using MnO2-GO composite materials. Using the electrochemical deposition process, the nanocomposite materials of MnO2-GO are significantly deposited on the stainless steel (SS) substrate material. Galvanostatic charge-discharge techniques and cyclic voltammetry (CV) analytical methods were used to investigate the storage and cycle ability of supercapacitors. The composite MnO2-GO supercapacitor has a higher electrochemical capacitance based on these findings.

Surface integrity study of TiO2 based Sol-gel spin coatings on SS316L

This work presents the surface integrity study of titanium dioxide (TiO2) thin film coatings on stainless steel (SS316L) substrate material. The effect of composition of sol–gel and heat treatment temperature on the surface morphology, roughness, wettability, and the friction characteristics is studied. Titanium (IV) butoxide used as TiO2 precursor for inducing a titania based layer on stainless steel substrate. Results indicate that the samples prepared using maximum pre-cursor content gave minimum roughness parameters (Ra = 0.078 μm; Rq = 0.093 μm; Rz = 0.591 μm), C.O.F. (0.233) and water contact angle (ϴs = 47.8°), thereby outperforming other samples and the substrate material. The work finds application in bio-medical implants.

Hot corrosion behaviour of HVOF sprayed Ni3Ti and Ni3Ti + (Cr3C2 + 20NiCr) coatings in presence of Na2SO4-40%V2O5 at 650 °C

Ni3Ti and Ni3Ti + (Cr3C2 + 20NiCr) coatings were deposited on gas turbine based ASTM B265 titanium (Ti-15) and AISI 420 stainless steel (MDN-420) substrate materials using HVOF technique. Thermocyclic hot corrosion tests were carried out at 650 °C in molten salt environment of Na2SO4 − 40%V2O5 for about 50 cycles. Thermogravimetric analysis was carried out to study the hot corrosion kinetics of uncoated and coated titanium and stainless steel substrates. The weight gain per unit area showed that the coated substrate materials displayed better resistance to hot corrosion when compared with that of uncoated substrate materials. The surface morphology of uncoated and coated substrate materials were analysed using scanning electron microscopy and elemental analysis. The formation of different types of oxides and compounds were analysed using x-ray diffraction. The uncoated substrates surface showed microspalling at several regions while coated substrates surface were composed of protective oxide layers. The presence of ternary NiCr2O4 protective oxides on the surface of Ni3Ti + (Cr3C2 + 20NiCr) coated substrates leads to reduction in the diffusion of corrosive species inside the coating.

Investigations on the Characteristics of Thermally Sprayed NiCrBSi Coatings Fused by Flame and Inductive Processing

Ni-based materials are some of the most used hardfacing alloys to improve wear and corrosion resistance for parts functioning under severe conditions. For the current study, a NiCrBSi self-fluxing alloy powder with particle size in range of 45-106 μm was employed as feedstock material and deposited onto a steel substrate material using the oxyacetylene thermal spraying process. The as-sprayed components have been subsequently subjected to thermal post-processing in order to increase the adhesion to the substrate and to reduce the inherent porosity of the coatings. Consequently, two types of heating sources were chosen. One of them was the neutral oxyacetylene flame and the second one was based on high frequency currents. The aim of this work was to study the influence of the heat source type of the post treatment on the final characteristics of the coatings. Evaluation of the morphology and microstructure of the developed coatings was performed after the remelting process by means of scanning electron microscopy. Hardness tests were carried out in cross-section complying with the ASTM E384 standard. In both cases, after fusing, the microstructure was refined, with a drastic decrease in porosity. Evaluation of the hardness distribution along the coating cross-section revealed similar values of microhardness.

Superhydrophobic and superhydrophilic functionalized surfaces by picosecond laser texturing

The study of laser textured surfaces has been carried out in the pursuit of superhydrophobic and superhydrophilic functional surfaces on stainless steel and silicon carbide substrate materials, respectively. The theoretical aspects of laser texturing a surface were investigated in order to understand how replication of micro- and nanoscale features could be achieved by high intensity picosecond pulsed laser systems. A series of laser parameters, pre-processing, and post-processing steps were developed to achieve contact angles of 152° as well as 0° on stainless steel and silicon carbide substrates, respectively. The substrates were used to demonstrate functional characteristics such as water repellency, self-cleaning, water adhesion, and dispersion of water using micro-capillary forces.

Development & characterization of alumina coating by atmospheric plasma spraying

Ceramic coatings are applied on metals to prevent them from oxidation and corrosion at room as well as elevated temperatures. The service environment, mechanisms of protection, chemical and mechanical compatibility, application method, control of coating quality and ability of the coating to be repaired are the factors that need to be considered while selecting the required coating. The coatings based on oxide materials provides high degree of thermal insulation and protection against oxidation at high temperatures for the underlying substrate materials. These coatings are usually applied by the flame or plasma spraying methods. The surface cleanliness needs to be ensured before spraying. Abrasive blasting can be used to provide the required surface roughness for good adhesion between the substrate and the coating. A pre bond coat like Nickel Chromium can be applied on to the substrate material before spraying the oxide coating to avoid chances of poor adhesion between the oxide coating and the metallic substrate. Plasma spraying produces oxide coatings of greater density, higher hardness, and smooth surface finish than that of the flame spraying process Inert gas is often used for generation of plasma gas so as to avoid the oxidation of the substrate material. The work focuses to develop, characterize and optimize the parameters used in Al2O3 coating on transition stainless steel substrate material for minimizing the wear rate and maximizing the leak tightness using plasma spray process. The experiment is designed using Taguchi’s L9 orthogonal array. The parameters that are to be optimized are plasma voltage, spraying distance and the cooling jet pressure. The characterization techniques includes micro-hardness and porosity tests followed by Grey relational analysis of the results.

Development & Characterization of Alumina Coating by Atmospheric Plasma Spraying

Ceramic coatings are applied on metals to prevent them from oxidation and corrosion at room as well as elevated temperatures. The service environment, mechanisms of protection, chemical and mechanical compatibility, application method, control of coating quality and ability of the coating to be repaired are the factors that need to be considered while selecting the required coating. The coatings based on oxide materials provides high degree of thermal insulation and protection against oxidation at high temperatures for the underlying substrate materials. These coatings are usually applied by the flame or plasma spraying methods. The surface cleanliness needs to be ensured before spraying. Abrasive blasting can be used to provide the required surface roughness for good adhesion between the substrate and the coating. A pre bond coat like Nickel Chromium can be applied on to the substrate material before spraying the oxide coating to avoid chances of poor adhesion between the oxide coating and the metallic substrate. Plasma spraying produces oxide coatings of greater density, higher hardness, and smooth surface finish than that of the flame spraying process Inert gas is often used for generation of plasma gas so as to avoid the oxidation of the substrate material. The work focuses to develop, characterize and optimize the parameters used in Al2O3 coating on transition stainless steel substrate material for minimizing the wear rate and maximizing the leak tightness using plasma spray process. The experiment is designed using Taguchi’s L9 orthogonal array. The parameters that are to be optimized are plasma voltage, spraying distance and the cooling jet pressure. The characterization techniques includes micro-hardness and porosity tests followed by Grey relational analysis of the results

Experimental and Numerical Study of the Influence of Substrate Surface Preparation on Adhesion Mechanisms of Aluminum Cold Spray Coatings on 300M Steel Substrates

The effect of substrate surface topography on the creation of metallurgical bonds and mechanical anchoring points has been studied for the cold spray deposition of pure aluminum on 300M steel substrate material. The coatings adhesion strength showed a significant decrease from 31.0 ± 5.7 MPa on polished substrates to 6.9 ± 2.0 MPa for substrates with roughness of 2.2 ± 0.5 μm. Strengths in the vicinity of 45 MPa were reached for coatings deposited onto forced pulsed waterjet treated surfaces with roughnesses larger than 33.8 μm. Finite element analysis has confirmed the sole presence of mechanical anchoring in coating adhesion strength for all surface treatment except polished surfaces. Grit embedment has been shown to be non-detrimental to coating adhesion for the current deposited material combination. The particle deformation process during impacts has been studied through finite element analysis using the Preston–Tonks–Wallace (PTW) constitutive model. The obtained equivalent plastic strain (PEEQ), temperature, contact pressure and velocity vector were correlated to the particle ability to form metallurgical bonds. Favorable conditions for metallurgical bonding were found to be highest for particles deposited on polished substrates, as confirmed by fracture surface analysis.

Study of Slurry Erosive Wear Behavior of Titania-30 Wt% Inconel-718 Plasma Sprayed Mild Steel Using Taguchi Technique

Surface coating is sharing the responsibility between coating and substrate, which enhances the surface properties such as strength, hot hardness and toughness, wear resistance, antifriction and chemical inertness. The present work is focused on wear behavior of Mild Steel substrate material deposited with Titanium dioxide-30 wt % of Inconel718 incorporating plasma spray process. These composite coatings were subjected to slurry erosion wear test by simulating the corrosive-erosive atmosphere by mixing of silica sand and 3.5 percent of NaCl in distilled water. Under identical conditions, coated mild steels gave better wear resistance compared to uncoated sample.

Surface modification of biomedical AISI 316L stainless steel with zirconium carbonitride coatings

In the paper, by using radio frequency (rf) magnetron sputtering method, a zirconium carbonitride coating was produced on AISI 316L austenitic stainless steel. The influence of substrate temperature (Ts) on microstructure, mechanical properties, corrosion resistance and hemocompatibility were then investigated. XRD and TEM results revealed that the zirconium carbonitride coatings were almost amorphous when Ts was below 400°C, while nanostructured Zr2CN was formed at Ts of 400°C. The nanocrystalline formation resulted in a significant increase in the nanohardness of zirconium carbonitride coatings from 17GPa to over 32GPa. Electrochemical testing showed that the stable zirconium carbonitride coating had improved the corrosion resistance of AISI 316L stainless steel substrate material. The characterization of platelet adhesion indicated that the zirconium carbonitride coatings presented better hemocompatibility when Ts varied from 25°C to more than 200°C, which may be due to the lower surface roughness, interfacial tension and the rate γsd/γsp, where γsd and γsp are the disperse component and polar component of the surface, respectively.

Research on Fracture Behavior of a Cr Coating/Original Steel Substrate Material under Thermal Fatigue Loading

The facture behavior of a chromium (Cr) coating/ original steel substrate material was investigated in this work. The results presented in this work show the crack density of the Cr coating on the substrate increases with the increase of the thermal fatigue times, and the failure process and modes of the Cr coating /original steel substrate system can be described as follows: Firstly, the micro-cracks of the coating grew and interconnected as the thermal fatigue time increased. Secondly, the pocket cracking at the coating and the substrate interface occurred, and the main cracks of the coating formed. Finally, the spallation or (and) collapse of the coating occurred.

Investigating the Wear Behaviour of FeCrC/B4C Powder Alloys Coating Produced by Plasma Transferred Arc Weld Surfacing Using the Taguchi Method

Abstract In this study, the optimization of the abrasive wear behaviour of a medium carbon steel surface with a FeCrC/B4C powder coating applied by using the plasma arc weld surfacing process is examined. Optimization of the process parameters represents the key step in the Taguchi method to achieve high quality without increasing cost. The Taguchi method uses orthogonal arrays to maximize the effect of controllable parameters and to minimize the effect of uncontrollable process para­meters. The abrasive wear behaviour of the surface of a medium carbon steel substrate material coated with FeCrC and with 15 % or 25 % B4C was tested at loads of 10 N, 20 N, and 30 N and at distances of 10 m, 20 m, and 30 m. The lowest wear loss, representing the most important criterion in determining the wear behaviour, was optimized with the so-called lowest-the best control characteristics of the Taguchi method and the results were analyzed by graphical methods.

Dissolution of synthetic uranium dibutyl phosphate deposits in oxidizing and reducing chemical formulations

Permanganate and nitrilotriacetic acid (NTA) based dilute chemical formulations were evaluated for the dissolution of uranium dibutyl phosphate (U-DBP), a compound that deposits over the surfaces of nuclear reprocessing plants and waste storage tanks. A combination of an acidic, oxidizing treatment (nitric acid with permanganate) followed by reducing treatment (NTA based formulation) efficiently dissolved the U-DBP deposits. The dissolution isotherm of U-DBP in its as precipitated form followed a logarithmic fit. The same chemical treatment was also effective in dissolving U-DBP coated on the surface of 304-stainless steel, while resulting in minimal corrosion of the stainless steel substrate material. Investigation of uranium recovery from the resulting decontamination solutions by ion exchange with a bed of mixed anion and cation resins showed quantitative removal of uranium.