High-temperature oxidation and erosion of HVOF sprayed NiCrSiB/Al2O3 and NiCrSiB/WC Co coatings (original) (raw)
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Materials Research Express, 2019
Development of nanostructured high velocity oxy-fuel (HVOF) coatings with low porosity, high strength and increased wear resistance is still in its infancy. Combining nanoparticles with conventional microscale powders are increasingly being investigated to use with feedstock materials for thermal spray processes. Accordingly, this work investigates the addition of nano-Al 2 O 3 particles on the microstructure and erosion wear of NiCrSiB HVOF coating in a stainless steel (AISI 304) substrate. Particle analysis of the NiCrSiB feedstock was conducted and the maximum allowable addition of Al 2 O 3 nanoparticles have been identified using the 'mass mixture ratio' model considering both the particle size and density. Consequently, two cases are considered and their performance analysed: a maximum allowable case of 1.4 wt%, followed by a 0.17 wt% addition of nano-Al 2 O 3 with NiCrSiB. Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and x-ray Diffraction (XRD) analysis were employed to inform the microstructure, material composition and phase spectrum of the resulting coatings. Subsequently, the nanostructured coating was exposed to both a pull-off adhesion strength test and hot air jet (450°C) hard particle erosion to characterise its performance. It was found that the microhardness of the HVOF NiCrSiB coating improved from 576 HV 0.3 to 748 HV 0.3 with the addition of 1.4 wt% nano-Al 2 O 3. Furthermore, the nanostructured coating also exhibited high erosion resistance at a 90°erodent impact angle. The increase in erosion wear resistance was due to the increase in the hardness as a result of the nano-Al 2 O 3 addition.
Materials Research Express, 2019
Nickel (Ni) based alloy coatings are gaining momentum due to its superior mechanical properties contributed by the dispersion of hard carbides and borides, which is substantially influenced by the processing technique. Accordingly, this work investigates High-Velocity Oxy-Fuel (HVOF) thermal spraying of Nickel-Chromium-Silicon-Boron (NiCrSiB) and Aluminium Oxide (Al2O3) at a 60:40 (wt.%) ratio on AISI304 stainless steel substrate. The influence of HVOF spray parameters such as oxygen, fuel, and powder feed rate in addition to standoff distance on the erosion resistance was studied. The parametric model identified the rate of powder feed and standoff distance as the two most significant parameters affecting the erosion behaviour. The optimum parametric values for oxygen, fuel and powder feed rate was identified as 260 lpm, 65 lpm and 28 g/min respectively at a standoff distance of 250 mm for the highest wear resistance. The results of this study show that that NiCrSiB-Al2O3 HVOF coating features a ductile erosion behaviour and offers 1.6 times more wear resistance at a 90° impact angle in comparison to 30°.
Surface and Coatings Technology, 2006
The minimization of cost and the enhancement of reliability of rotating and stationary fluid machinery equipment that are subjected to highly erosive and corrosive environments is mandatory in the oil and gas production industries. This can be achieved by minimizing the material damage resulting from the combination of solid particle impingement and corrosion. The high velocity oxy-fuel (HVOF) process is one method of producing metallic coatings to protect metallic surfaces from high temperature, wear, and corrosive environments. Stainless steel components coated with Inconel-625 are very common in the oil/gas industry. In this study, the erosion-corrosion characteristics of HVOF thermally sprayed Inconel-625 powder coatings were evaluated when applied on three different metallic surfaces: (a) plain stainless steel (SS), (b) spot-welded stainless steel (SW-SS), and (c) a composite surface of stainless steel and carbon steel welded together (C-SS-CS). These coated surfaces were tested in a jet impingement rig under two fluid conditions: (i) free from added solids, (ii) containing 1% silica sand. Weight loss measurements were used to provide a measure of the amount of material loss that each coated surface experienced, and the influence of time during impingement testing was taken into consideration. The surface morphology and the elemental composition of the coating before and after the erosion-corrosion test were examined using the SEM and EDS techniques. The results indicated that the coating over both spot-welded and plain stainless steel surfaces exhibited a similar degree of weight loss. However, the coating on the composite surface experienced a greater degree of weight loss. Microscopic observations of the fracture surfaces showed that the metal removal of the tested surface was concentrated around the unmelted and the semi-melted particles of the deposit.
High velocity oxygen fuel coating for enhancing tribological behaviour of engineering metals
Proceeding of 2nd International Colloquium on Computational & Experimental Mechanics (ICCEM 2021)
High velocity oxy fuel (HVOF) is a thermal surface alteration method which improves or restores the surface morphology or dimensions of a component, therefore extending equipment life by considerably enhancing erosion and abrasion resistance, as well as corrosion control. Using a high-temperature, relatively high stream materials are sprayed onto the surface, resulting in a thick spray coating that may be ground to a very high surface polish. The HVOF coating process permits the application of various coating materials to generate a coating with extraordinary hardness, excellent adherence to the substrate, and significant abrasion resistance and cathodic protection. In this study, some of the recent researches carried out using HVOF techniques and the research finding are explored
Materials Science Forum, 2006
The erosion-oxidation (E-O) behavior of high velocity oxy fuel (HVOF) sprayed Ni20Cr alloy as well as WC and Cr 3 C 2 cermet coatings on a steel substrate were studied. The E-O tests were carried out in a rig with specimen assemblies that were rotated through a fluidized bed of erodent particles in the temperature range 500-850°C and with erodent impact velocities of 2.5-19.5 ms -1 . Alumina powder (~200µm) was used as the erodent. The E-O resistance of the coatings was determined as wastage, as a function of temperature. The three coatings did not exhibit any significant change in E-O at temperatures up to 500-600°C. At higher temperatures, wastage increased with temperature, reached a maximum at 700°C and then decreased with further increase in temperature. Different E-O regimes were identified.
Tribochemical behavior of alumina coatings deposited by high-velocity oxy fuel spraying
Ceramics International, 2015
Alumina is one of the most versatile coatings applied on tools whose working life is reduced due to high wear rate, high temperature, and highly corrosive environments. High-velocity oxy fuel (HVOF) methods are industrially used to deposit this type of coatings. In this study, the effect of the hydrochloric acid concentration on the wear behavior of an HVOF alumina coating was investigated through room-temperature and 60 1C pin-on-disk wear experiments. The results showed that the corrosive environments up to 5% acid did not meaningfully affect the wear damage rate, as compared to the dry condition, due to a contest between friction coefficient and corrosion damage. Nevertheless, the wear rate significantly increased at higher acid concentrations and higher temperatures, since the corrosion effect prevailed over the friction coefficient effect. Also, the predominant wear mechanism was recognized to be adhesive.
American Journal of Materials Science, 2018
In this study, coatings WC-10Co-4Cr and Cr3C2-25NiCr were deposited on the AISI H13 steel by oxy-fuel Thermal spraying (HVOF). This coating increases the wear resistance of surfaces subjected to severe conditions, such as: abrasive wear, thermal fatigue and plastic deformation. The coatings microstructure, hardness and wear resistance are investigated through friction and wear tests performed through a pin-on-disc type tribometer following the procedures defined in ASTM G99-04. It was verified that both materials used in the spraying have high resistance to wear, however, in the sample coated with Cr3C2-25NiCr there was a greater removal of material during the test.
Tribological Behaviour of Thermally Sprayed Coatings: A Review
SSRN Electronic Journal, 2018
Coatings are used for modifying the surface properties of critical components subjected to mechanisms such as corrosion, oxidation, wear, or under an excessive heat load failure. Selection of the coating material and method of depositions are very important for any application. Coatings are effectively and economically used to guard the substrate surface from wear also to reduce friction. The tribological response of a coating system depends on many factors like coating properties, counterpart, substrate, interface, and running conditions. Hence, selection of the appropriate coating for a given tribological application is difficult. Thermally sprayed WC and CrC based cermet coatings are extensively used in the hydro turbine for resistance to wear like abrasive, erosive and cavitation. The NiCrAlY coating showe d better resistance to high-temperature oxidation and corrosion due to the formation of protective oxides. At high temperature working environment and chemically aggressive condition NiCrSiBC alloy reveals a good balance between corrosion and wear resistance. The NiCrBSi coating showed a good surface finish as well as the bonding interface. This paper presented the review related to the selection of coating powder and process of protective wear resistance coating by thermal spray techniques. The effect of spraying techniques and spraying parameters on the performance of the coating is different for every coating. The wear types, powders, Plasma spray and HVOF spray methods are discussed to identify the coating for a specific application.
Coatings
This work analyzes the differences found in hard metal coatings produced by two high velocity thermal spray techniques, namely high velocity oxy-fuel (HVOF) and high velocity air-fuel (HVAF). Additionally, the effect of the metallic matrix and ceramic composition and the original carbide grain size on coating properties is compared to the most studied standard reference material sprayed by HVOF, WC-Co. For this evaluation, the physical properties of the coatings, including feedstock characteristics, porosity, thickness, roughness, hardness, and phase composition were investigated. Several characterization methods were used for this purpose: optical microscopy (OM), scanning electronic microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), and X-ray Diffraction (XRD), among others. The final performance (abrasive wear and corrosion resistance) shown by the coatings obtained by these two methodologies was also analyzed. Thus, the abrasive wear resistance was analyzed by the rub...