Papers by Keyword: Erosion-Corrosion

Abstract: Aluminium as matrix in particulars have been vastlys investigateds, this is becauses of the diverses applicationss of aluminium dues to its exceptional propertiess. Material scientistss alwayss face a challenges when it comess to the tribologicals and mechanicals propertiess of aluminium, as it exudess rather poors behaviours in these aspectss. Hences this works aims to improves the mechanicals and corrosives resistances of Aluminiums by reinforcings with aluminum oxides and Nickel throughs stir casting usings vortex techniques. Al-Ni-Al₂O₃ composites with percentages of Ni fixed at 20 % and Al₂O₃ differed through 4-8% in incrementss of 2 wt. % . Composites material was prepareds by stir castings using vortex techniques. The hardness value of the aluminiums matrix composites improved with increaseds percentages of Al₂O₃, maximums increase was obtaineds for 8% Al₂O₃ composite, viewing an increases of about 55%. A generals corrosions and erosion-corrosions for the Al-20%Ni bases alloys and the prepareds composites were carrieds out in 3.5wt% NaCl solutions as corrosives mediums for general corrosions while in erosion-corrosions with impacts angles 90° in slurry solutions ( 1wt%SiO₂ sand in 3.5wt% NaCl solution as the erodent). It was founds that the general corrosions rates for composite specimens is lower than thats of the bases alloy (Al-20%Ni). In case of erosion-corrosion resultss, it was founds that the erosion corrosions resistances property of the prepareds composites improveds significantlys with the increaseds percentages of Al₂O₃. There wass a noticeable improvements in the corrosion resistances of the aluminiums composites compareds to its purest forms, owing to the presences of nickel. Howevers, the increases in Al₂O₃ percentages decrease the corrosions rates. The extreme decreases was obtaineds for 8% Al₂O₃ composites, with a decreases of 26% corrosion rates in (mpy) unit for composites material is lowers than that of the bases alloys.

Abstract: The rotary experiment apparatus was built to study the erosion-corrosionresistance of carbon steel, 15CrMo steel, duplex stainless steel 2205, nickel based alloy 825 and stainless steel 316L which are commonly used in the sour water environment of refinery. Based on the electrochemical test, the carbon steel and alloys corrosion rates in different ammonium hydrosulfide concentration, fluid velocity and temperature were obtained. The corrosion products film morphology was analyzed by scanning electron microscope (SEM) to find the reasons for corrosion rates difference of carbon steel and alloys. The results showed that the corrosion rates of carbon steel and alloys were increasing with fluid velocity, ammonium hydrosulfide concentration and temperature increase, when the velocity exceeds 6 m/s the corrosion rates essentially unchanged. The maximum corrosion rate of carbon steel at 60 °C and 10 wt% ammonium hydrosulfide concentration was as high as 6.5 mm/year, while the nickel based alloys 825 and stainless steel 316L were less than 1.5 mm/year. The corrosion product films of carbon steel and 15CrMo steel was loose and cracking which can easy to fall off from the substrate when subjected to fluid impact and the corrosive media can easily penetrate into the bottom of corrosion product and continue to corrode substrate. However, the corrosion film of nickel based alloys 825 and stainless steel 316L was dense and tightly bonded to substrate making it has a good corrosion resistance.

Abstract: Erosion-corrosion behavior in downhole tubulars and oilfield ground gathering transferring system is interesting in optimum design. This work is addressed to investigate erosion-corrosion behavior of hydraulic perforating equipment during fracturing. The typical fracturing fluid of 0.2% hydroxypropyl guar gum solution mixed with quartz grain was selected. The relationship between erosion-corrosion rate and flow displacement, the effect of the flow impact angle on erosion-corrosion rate is performed on a jet impingement experimental apparatus. In the experiment situation, the erosion-corrosion rate reaches highest at the impact angle of 45°. The erosion-corrosion rate increased exponentially with the increase of flow displacement. The surface morphology of specimen suffer from erosion-corrosion is analyzed by scanning electron microscopy (SEM) to characterize the erosion-corrosion damage mechanisms.

Abstract: The work of this paper proposes a new technique for estimating and predicting erosion corrosion rate for laminar and turbulent flow in pipes. The technique depends on the neural networks Artificial Intelligent algorithms. Based on experimental results, which was applied to A 106 carbon-steel pipes, the networks are trained. Four velocities (Reynolds numbers) are used for laminar and four for turbulent regimes. The experiments also used seawater containment three different concentrations of sand. For each experiment the iron losses were measured six times in three hours’ time interval. The proposed estimating/predicting system managed to find values between the readings as well as predict the behavior of the erosion corrosion rate for extra three hours. The estimated/predicted results have been developed to find the transient zone between the Laminar and Turbulent flow regimes and investigating its effects on the erosion-corrosion behavior.

Abstract: The corrosion behaviour of Al (6061)-B4C-Graphite was investigated. The Aluminium Metal Matrix Composites (AMMC) was fabricated through two step stir casting method. The composites were fabricated with various volume percentages of Boron Carbide (5, 10 &15%) and Graphite (5, 10& 15%). Corrosion studies of AMMC was investigated with 4%, 8%, 12% wt. % NaCl solution at room temperature. Also erosion-corrosion test were performed on the specimens in the NaCl solution with silica sand. Erosion-corrosion tests indicated that the rate of material loss mechanism is mechanical abrasion with enhanced corrosion. The material loss mechanism was significantly higher in the case of erosion-corrosion tests.

Abstract: With the development of hydraulic fracturing technology, the failure of the equipments during production test and completion well becomes more and more severe due to the behaviors of erosion-corrosion. In this paper, the erosion-corrosion behaviors of N80, P110 and VM140 materials were investigated with the jet impingement experimental device. The corrosive rate of these materials by the weight loss method was carried out under different flow velocities and jet angles. It was observed that the weight loss of the three materials is increased by the rising of the impact velocity. The relation of erosion-corrosion weight loss to impact velocity is well described as the equation E=KVn (E is the speed, V is fluid velocity, k and n are the fitting parameters). As a results, the resistance ability for corrosion-erosion under experimental conditions is P110>N80>VM140.

Abstract: Due to high wear resistance and chemical stability at high temperature, cobalt base alloys have presently been used as materials for hardfacing in several applications, for example, coating a head of thermowell, a protecting part for thermocouple, in petrochemical production. One of various techniques used for hardfacing is often weld cladding by using a gas tungsten arc welding (GTAW) method. However, welding parameters should be exactly controlled in order to obtain desired materials due to their structure. The objective of this experiment is to study the influence of the GTAW parameters on the high-temperature erosion-corrosion resistance of Incoloy 800 thermowell cladded by the cobalt-base alloy filler, Stellite12 (Co-29.5Cr-8.5W-1.4C) at 900°C. The studied parameters were welding speed in the range of 0.1-0.9 mm s^-1, welding current in the range of 60-75 A, and flow rate of pure Ar used as shield gas in the range 3-20 liter min^-1. The results showed that when erosion rates had a tendency to increase with increasing current for all welding speed except 0.8 mm s-1. The erosion rate decreased with the increasing current for the welding speed of 0.8 mm s^-1. Using flow rate of 5 liter min^-1 induced the lowest erosion rate. The optimum GTAW parameters giving the lowest erosion rate were the welding current of 75 A, flow rate of 5 litter min^-1, and welding speed of 0.8 mm s^-1. However, it was found that hardness results did not correspond to the erosion rate. It was found that high hardness led to heavy mass loss due to the fracture on the surface. From metallographic observation, the oxidation could be observed on the sample surface before the erosion testing. However, the spallation of oxide scale might be involved due to the high erosion rate. It was also observed that the solid solution phases influenced more significantly on the erosion - corrosion resistance than the carbide did.

Abstract: The objective of this study is to improve the high-temperature erosion-corrosion resistance Incoloy 800 for the application used as thermowell at 900°C. In weld cladding procedure, silicon carbide (SiC) particles were pre-deposited on the Incoloy 800 substrate, followed by the cladding of Ni-base alloy filler (34Ni-25Cr-0.4C-Ti-W-Mo) by a gas tungsten arc welding. A theoretical amount of SiC particles mixed with filler was 2 - 30%wt. A particle size of SiC was in the range of 50-150 mm. The results showed that the addition of 15%wt SiC led to the maximum hardness of the cladding layer. Addition of particles more than 15wt% tended to provoke cracks in cladding layer. The larger particle size exhibited the higher hardness. An erosion rate of cladding surface was further tested by the perpendicular impingement of 1-mm SiC abrasion sands on the sample surface with air flow velocity of 220 m s^-1 at 900°C in air. For cladding layer with the same amount of SiC mixed, the one mixed with larger particle size exhibited the higher erosion-corrosion resistance. Likewise, for cladding layer mixed by the same size of SiC, the addition of particle with a smaller amount promoted the higher erosion-corrosion resistance. The addition of 2.6 wt% SiC particles with 150 mm size in cladding layer showed the surface with the best erosion-corrosion resistance in this study. No oxide scale was, however, observed on eroded surface due to the spallation by high impact erodent particles.

Abstract: Low carbon steel was coated by hot-dipping into a molten bath containing Al-2 wt.%Mn. The phase composition, morphology and the erosion-corrosion behavior of the aluminide layer were characterized by XRD, OM, SEM and erosion-corrosion tester, respectively. The results show that the coatings are mainly composed of Al, FeAl3, Fe2Al5 and MnAl6 phase. The coatings consist of two-layer structure, i.e., toplayer Al-Mn alloy layer and tongue-like intermetallic compound. The thickness of the coating layer is about 800 μm and all the coating layers show good adhesion to the steel substrate. Compared with the pure Al coatings, the Al-Mn alloy coatings exhibit lower wear rate irrespective of the rotation speed. The hot-dipped Al-Mn coatings possess considerable erosion-corrosion resistance.

Abstract: Al-2%Mn alloy matrix composites reinforced with Al2O3 particulates was fabricated by stirring cast, and the composites was characterized and analyzed by using a variety of analytical techniques, such as XRD, SEM, EDS, Brinell hardness tester, ring-on-block tribometer, and erosion-corrosion tester. The results show that the composites in as cast condition is mainly composed of Al,  -Al2O3, MnAl6 and Al11Mn4 phase, and the Al2O3 particles are dispersed uniformly in the Al matrix. Compared with the base aluminium and the Al-2%Mn alloy, the HB hardness of the composites is increased significantly, and the wear loss is far less under the SO4•Cl- Na•Ca• Mg corrosive alkalescent aqueous solution lubricated condition. The erosive-corrosive wear rates of the composites are lower than those of the Al-2%Mn alloy irrespective of the rotational speed or the size of grinding particles. The Al2O3 particulates reinforced Al-2%Mn alloy matrix composites possesses a good wear-resistance and erosion-corrosion resistance due to its higher hardness.