Erosion Angle Research Articles

Study on Failure Behavior of Gas Well Tubing Under CO2 Corrosion After Erosion

The volcanic gas reservoir in Xushen gas field in the Northeast of China has the characteristic of low single-well production. Before gas wells are put into production, most of wells require fracturing transformation of the large sand amount and large displacement. Hence, an integrated fracturing and production string was developed. In the process of natural gas production, the integrated fracturing and production string is faced with the erosion caused by fracturing and CO2 corrosion. In order to ensure the safety of production, analysis and assessment of the dual effects of erosion and corrosion on the pipe string are required. The influence of the erosion angle, liquid velocity and sand ratio on the erosion rate of the integrated fracturing and production string was studied by using a self-made erosion experimental device and finally established the erosion rate prediction model; the samples of the tubing material after the erosion test were used in a high-temperature autoclave to carry out corrosion evaluation experiments to study the CO2 corrosion resistance of the tubing after erosion. The test results showed that severe corrosion occurred in the sample of P110 tubing after erosion, while slight corrosion occurred in the Super 13Cr tubing. On the basis of theoretical analysis results, the design and field construction of the integrated fracturing and production string are guided and ensured the safety of string in the whole life cycle.

Solid particle erosion resistance and electromagnetic shielding performance of carbon fiber reinforced polycarbonate composites

Thermoplastic polycarbonate (PC) has attracted tremendous attention due to its superior recyclability and environmental friendliness compared with thermosetting resins. In this work, thermoplastic polycarbonate was used as the matrix material and the solid particle erosion resistance of carbon fiber reinforced polycarbonate (CF/PC) composites, as well as the influence of solid particle erosion on the mechanical properties of composites were studied systematically. The results indicated that the maximum erosion angle for CF/PC is 30°, and samples are easier to be eroded when impacted in parallel direction to CF than the vertical. In addition, after 2 min solid particle erosion, the tensile strength and the maximum load decreased by 11.9% and 11.8% respectively, and flexural properties of all samples declined (flexural modulus by 49%, flexural strength and maximum load by 14.6%, flexural strain by 11.9%). Finally, an excellent EMI shielding effectiveness (SE) of around 40 dB over 12 GHz to 18 GHz was achieved for composites. Due to the destruction of CF/PC composite structure and the reduction of its thickness, its EMI shielding effectiveness was greatly decreased to 28 dB after sand erosion.

Study of Solid Particle Erosion Wear Resistance of WC–Co Cemented Carbide

In this paper, several major factors affecting the erosion wear of WC–Co cemented carbide were tested and analyzed by the cemented carbide solid particle erosion test. In addition to the erosion angle, the impact velocity, the hardness and dimensions of the abrasive and the degree of fracture of the abrasive after impacting the target material also have a significant effect on the erosion wear results. Abrasives with a high degree of fragmentation after erosion have lower erosion wear efficiency for cemented carbides. The increase in Co content and WC grain size will lead to the decline of erosion resistance of cemented carbide. After the energy spectrum analysis of the target material after erosion, it was found that Co particles were first detached during the erosion process. Later, due to the instability of the entire microstructure, a series of erosion wears was caused.

Performance and damage mechanism of TiN/ZrN nano-multilayer coatings based on different erosion angles

Nano-multilayer coating is an effective method for improving the sand erosion resistance of a material employed in any industrial field. However, very few studies have addressed this subject of research, especially in the aspects of the multi-angles erosion performance and the corresponding mechanism. In this study, a TiN/ZrN nano-multilayer coating was prepared on the Ti6Al4V substrate by employing physical vapor deposition; the nano-layer thickness of the alternating structure of this coating was less than 200 nm. The mechanical and erosion properties of TiN/ZrN were examined, accompanied by varying the erosion angles from 15° to 90°. The 3D surface topographies of the eroded surface were characterized by using a white-light interfering profilometer. The coating damage was examined by cross-sectioning the samples using the focused ion beam (FIB) method. The experiment shows that the maximum erosion rate occurs at 90°, which is approximately 3.1, 2.8 and 1.2 times larger than 15°, 45°, and 75° erosion angles, respectively. The diameter, depth and density of the erosion pit increases with a rise in the erosion angle. The erosion mechanism of the TiN/ZrN nano-multilayer coatings is governed by lateral cracks and the tensile stress of the coating itself at 15° and 45°; further, it is influenced by the longitudinal cracks at 75° and 90°. Lateral cracks in the erosion damage of coating are primarily Mode Ⅱ cracks. The average crack density in the effective FIB trenches reveals that the cracks are more probable to occur at high angles (75° and 90°); this further explains the results of a higher erosion rate at a high erosion angle.

Interdependence of slurry erosion wear performance and residual stress in WC-12wt%Co and WC-10wt%VC-12wt%Co HVOF coatings

High-velocity-oxygen-fuel deposited WC-12wt%Co and WC-10wt%VC-12wt%Co hardmetal coatings are well anchored to the mild steel substrates, giving good mechanical integrity, as well as low porosity. The mechanical integrity has been investigated in terms of erosion performance and its influence on the residual stress state in the eroded regions. Wear slurry erosion tests reveal similar rates of erosion for both systems, that becomes more severe as the impact angle increases due to higher direct impact deformation normal to the surface. The 10wt%VC-12wt%Co coating renders slightly better erosion performance throughout. Stress evaluations using X-ray and neutron diffraction reveal substantial compressive residual stresses in the WC-phases for both coating compositions in their as-coated conditions. Within their erosion scars, the stresses become more compressive with erosion angle due to the increased impact component normal to the surface. It is concluded that the better wear performance of the WC-10wt%VC-12wt%Co coatings with impact angle, correlates with larger induced in-plane compressive stresses in the WC phase.

Sand erosion resistance improvement and damage mechanism of TiAlN coating via the bias-graded voltage in FCVA deposition

Titanium aluminum nitride (TiAlN) coatings were deposited on Ti6Al4V alloy substrates using a filtered cathodic vacuum arc (FCVA) deposition method with bias-graded voltage ranging from -50 V to -200 V and constant bias voltage (-50 V, -125 V, and -200 V). The microstructure and mechanical properties of these coatings were investigated and compared. Sand erosion resistance at 30° and 90° was evaluated using sandblasting equipment. The coating deposited at a constant bias voltage of -200 V had the highest average hardness of 32.47 GPa. The bias-graded coating had a similar average hardness (32.08 GPa), but lower internal stress (-2.66 GPa) and considerably higher adhesion strength (44.03 N) than the constant-bias coatings. For both erosion angles (30° and 90°), the erosion rates of the constant-bias coatings increased with increasing bias voltage. In general, the erosion rates of the bias-graded coating (0.014 and 0.013 mg/g at erosion angles of 30° and 90°, respectively) were significantly lower than that of the constant-bias coatings. Bias-graded deposition is an effective method of improving the erosion resistance of coatings. The erosion mechanism of the coatings is coating chipping. The excellent erosion resistance of the bias-graded TiAlN coating is attributed to the high hardness and low internal stress of this coating.

Experimental study of subsurface erosion in granitic under the conditions of different soil column angles and flow discharges

Soil erosion leads to soil loss and affects the hydraulic and mechanical properties of soils, and as a result, the soil fertility, eco-environmental quality, and reliability of engineering facilities will decline. Thus, it is very significant to study the mechanisms of subsurface erosion of granitic under different natural environmental conditions. However, limited studies focus on the effects of combined erosion angles and flow discharges on the subsurface erosion amount. This study self-made a subsurface erosion simulator and designed a series of combinational conditions of different soil column angles (0°, 30°, 60°) and different flow discharges (25 l/h, 50 l/h, 100 l/h) to simulate the subsurface erosion phenomenon and processes of moisture migration within granitic collected from a collapsing erosion area in southern China. Results show that the subsurface erosion development in the soil column is a complex and progressive process with obvious preferential flow, which indicates the transportability of soil particles, and the processes of soil subsurface erosion change markedly along with the change of soil column angle and flow discharge. Moreover, the growth rates of wetting front and subsurface erosion amount will speed up along with the increase of soil column angle of flow discharge. The relations between the advance rate of wetting front and time since the beginning of the test demonstrate bilinear. The erosion amount has obvious fluctuation during the process of subsurface erosion in granitic due to fine particles erosion, reposition, pore clogging, and flushing.

Insulator ablation modes in different impact conditions of alumina droplets onto wall surfaces

Current understanding of insulator ablation modes under different alumina droplet impact conditions onto wall surfaces in solid rocket motors (SRM) is limited. This study uses theoretical analysis and numerical calculations to design a lab-scale experimental device and an ultra-high-temperature heat flow gauge. Alumina droplet/insulator wall surface impact characteristics such as erosion angle, speed, and droplets size distribution are discussed based on the resulting experimental data using the proposed design. Three ablation modes are established according to the droplet speed threshold: the weak erosion state, deposition state, and strong erosion state. On this basis, heat transfer characteristics are studied under the condition of high-density, two-phase flow and the general rules of the wall heat increment with droplet concentration, size, and velocity under different droplet/wall impact modes are obtained. Finally, discussing multi-factor variables, the coupling relationship among the thermal increment, thermal chemical ablation, and mechanical erosion under droplet/wall surface action is analysed, providing insights toward establishing an insulator ablation model.

Effect of erosion angle and Fe2B orientation on cavitation erosion and interfaces of Fe-B alloy in high-velocity flowing zinc

The effects of erosion angle and Fe2B orientation on cavitation erosion and interface structures of a directionally solidified (DS) Fe-B alloy in flowing liquid zinc were investigated to clarify erosion mechanism of liquid metal. The results indicate that the cavitation erosion rate of DS Fe-B alloy with Fe2B [001] orientation vertical to interface exhibits better erosion cavitation resistance. Erosion angle can strongly affect erosion performance that depends not only on interfacial orientation structure but also on local microturbulence. Erosion morphologies manifest that an obvious cavitation erosion occurs in strong flowing zinc disturbed and agitated zone, which results in severe cavitation pits and slip deformation of products, thus stimulating subsequent localized corrosion and pit-aggregation cracks. Cavitation erosion craters coupled with performance variations confirm that microturbulence-assisted fluid eddies and backflow are responsible for the cavitation pits. The combined effects of flow pattern and interface orientation significantly govern the epitaxial grown ζ removal/accumulation behaviors and multiphase pinning film adhesion. A model of hydraulic liquid-hammer action by cavitation-induced microjet and interface orientation interaction is proposed and discussed to account for cavitation pits and slip cracking, which reveals underlying erosion mechanism and material design of DS Fe-B alloy in flowing liquid zinc.

Study on Sand Erosion and Tribological Behavior of TiO₂ Films Prepared on a Glass Surface.

TiO2 films with one, three or five layers were prepared on a glass surface using the sol-gel method. The crystal structure, the surface morphology and the thickness of the films were characterized by X-ray diffraction, atomic force microscopy and ellipsometry. The tribological properties of the TiO2 films were investigated by a tribometer. TiO2 thin films were eroded by sand-air injection. The erosion behavior and mechanism of TiO2 thin films in a sandstorm were analyzed by scanning electron microscopy. The results showed that the films were highly abraded with increased erosion speed and dose of sand. With an increase in film layers, the erosion resistance and wear resistance of the TiO2 films increased gradually. The erosion mechanism consists of the film being damaged mainly from the cutting action of micro-scratches from low angle erosion. Alternatively, for high angle erosion, the material is damaged mainly by squeeze deformation by the action of erosion. Because of the high strength and toughness of the TiO2 thin films, the wear of its coating from high angle erosion is more severe than that from low erosion angle.

Multiphase interface structure induced erosion resistance of directional solidified Fe-B alloy in flow liquid zinc

The interfaces and erosion of oriented Fe-B alloy in flow zinc at various erosion angles were investigated. The results indicate that oriented Fe-B alloy exhibits better erosion resistance at 90° erosion. Erosion angle can strongly affect erosion resistance, which depends on not only the interfacial structure but also the epitaxial ζ accumulation. Meanwhile, cavitation erosion pits and interface spallation occur, which may be suppressed by ζ accumulation at 90° erosion, thus strengthening the adhesion of product films.

Transpiration cooling during ultra-high temperature erosion

In present study the static firing of the bi-propellant engine has been employed to investigate the transpiration cooling phenomenon of W-Cu materials during ultra-high erosion against liquid alumina droplets. For this purpose, two samples of W-10wt% Cu composite were prepared by sintering+infiltration method. The erosion test carried out at 3000°C for 40s at the alumina droplet speed of 1200ms−1. Two incident angle of 0° and 30° selected to study the effect of erosion angle on transpiration cooling. The microstructure evolutions were studied by SEM and EDS. The obtained results exhibited that erosion at 30° resulted in higher deposited alumina layer as well as lower erosion rate.

Modelling the particles impingement angle to produce maximum erosion

A semi-mechanistic, semi-empirical erosion model was developed and validated by experimental data. The novelty of the developed model is by accurately predicting the impingement angle that produce maximum erosion and relating it to measurable mechanical properties such as hardness and fracture toughness. The ratio of the target material fracture toughness (R) to its hardness (H) is the parameter which governs the erosion mechanism and consequently the angle for maximum erosion. It was noticed that for material with high R/H, i.e. ductile materials, the preferred mode is ploughing, a process analogous to rubbing in which the penetrating particle squeeze the target material out of the indentation to preform ridges, which are knocked off at subsequent impacts. The lower the ratio R/H is, a tendency to fracture mechanism occurs. The fracture mechanism is a process very similar to brittle chipping during metal cutting, where the applied force propagates cracks parallel to the surface. A simplified model, defining the horizontal force which is applied on the particle in its movement through the material, was introduced. This simplified model takes into account the relative effect of each of the ploughing and fracture mechanism on the total material removal. The material parameter which governs the relative effect of the mechanisms is R/H. Particle angularity also contributes to decreasing of the fracture mechanism, hence a governing non-dimensional number was received, R/H·deff, where deff is the effective diameter of the penetrating particle tip. Incorporating this parameter in the erosion model yielded good agreement with experimental data and was able to explain the phenomenon of different maximum erosion angle and velocity exponent for different target materials. The relation between the developed model empirical coefficients to target material mechanical properties was studied for eight different materials, ranging from soft metals to hardened stainless steel. Correlations between model coefficients to R/H were developed and exhibited good agreement with mechanistic analysis.

Erosion–corrosion interaction of Fe–B alloy in flowing zinc

The effect of erosion angle on the erosion–corrosion interaction of Fe–3.5 wt-%B alloy in flowing zinc was investigated. The total erosion–corrosion rate decreased linearly, whereas the pure erosion rate fluctuated slightly with increasing erosion angle, which was strongly dependent on the erosion–corrosion interaction. At an erosion angle of 0°, liquid zinc corrosion damaged the sample surface and facilitated erosion, which in turn increased corrosion via the removal of corrosion products. As the erosion angle increased, corrosion products accumulated and Fe2B flaked and cracked in front of the erosion interface, which resulted, in turn, in increased obstruction to the diffusion of liquid zinc. Accordingly, the erosion–corrosion interaction was reduced, thereby resulting in a low material loss at high erosion angles.

Surface erosion behavior of an intrusive probe in pipe flow

Unconsolidated sandstone reservoirs in northwestern China exhibit high sand production rates. This extreme working condition causes unusual erosion behaviors of ER (electrical resistance) probes. To describe the erosion behavior of an ER probe in this extreme condition, an intrusive probe is mounted in a pipeline in the same manner as an ER probe. The sand production rates are adjusted to simulate the working conditions of an unconsolidated sandstone gas field. Factors, including the evolution of the surface profile, unstable sand production rate and probe materials, are studied for erosion behaviors. The results show that the peak values of the sand production rate substantially affect the erosion progress. Different wear mechanisms were discovered for different materials. Under a 250-kg sand load, the most seriously eroded upstream surface was the top of the probe at the beginning of the erosion test, but the erosion surface shifted to the bottom of the probe by the end of the experiment. The erosion angle α of the upstream surface is decided by the upstream edge angle θ. A model, modified to account for the evolution of the surface profile, is suggested and validated using experimental data, and the model had an average relative deviation of 9.9% for a 330-kg erosion and 12.6% for a 480-kg erosion. The limitations and applicable range of the modified model are listed. This study offers a numerical model for the research and development of a strong, flexible ER probe to be used for higher sand production rates.

Erosive behaviors of SiC foam/epoxy co-continuous phase composites

SiC foam/epoxy co-continuous phase composites (SiCfoam/EPs) that were composed of the E-51 epoxy (EP) matrix and the SiC ceramic foam (SiCfoam) reinforcement were prepared as the erosion resistant materials. The erosive behaviors of SiCfoam/EPs were investigated by using a rotating disk rig. The effects of sand content (C), flow velocity (V), test duration and SiC volume fraction on the erosive behaviors of SiCfoam/EPs were studied through the mass loss test, SEM and CLSM (Confocal Laser Scanning Microscope) observations. Under different experimental conditions, the erosion rate (Er, defined as the ratio of erosion (Ec) and time) was relatively larger before the transition point, but Er clearly decreased after the transition point. Ec of SiCfoam/EPs increased with flow velocity (Ec∝V3) and sand content (Ec∝C). The erosion angle (α, the angle between the eroded and initial surfaces) of SiCfoam/EPs increased linearly with flow velocity and sand content. Under the test conditions, flow velocity was the dominant factor for the erosive behaviors of SiCfoam/EPs. Ec and α of SiCfoam/EPs both decreased with the increase of SiC volume fraction. The erosion of SiCfoam/EPs obeyed the linear rule of mixtures (LROM) averaging law since EP and SiCfoam were eroded by a parallel process.

Effects of Erosion Angle on Erosion Properties of Fe-B Alloy in Flowing Liquid Zinc

The effect of erosion angle on erosion behavior of the as-cast Fe-B alloy in flowing liquid zinc was investigated. The results show that the erosion rate of Fe-B alloy decreases linearly with increasing erosion angle. The erosion resistance of Fe-B alloy is better than that of 316L stainless steel, which is attributed to the favorable barrier effect of net-like Fe2B that resists erosion by flowing liquid zinc. Meanwhile, the ductile matrix can provide support in preventing borides from spalling and borides cause barrier effect on flowing liquid zinc during liquid zinc erosion, which shows a synergistic erosion-corrosion behavior between the matrix and borides. Moreover, an increase in erosion angle can cause a decrease in the removal effect of the flowing liquid zinc scouring component on the erosion compounds. Therefore, the quantity of erosion compounds increases at the erosion interface, weakening the mass transfer process and decreasing the erosion rate of the Fe-B alloy.

Erosion Effect of Rainfalls on Loess Plateau Soil and Its Experimental Researches

Based on the theoretical analysis on the rain erosion force index, this study researched the rainfall characteristics in Yangling loess area and its erosion on slope land. It chose the large runofi observation fleld in Yangling City which located in Shanxi Province in western Loess Plateau of China, as the experimental subject. Meanwhile, the fleld measurements from 2009 to 2013 were adopted as the experimental data. The results show that the magnitude and direction of the wind afiect the splash erosion angle between raindrop and ground during the rainfall in Loess Plateau region. That is, the values of cos(µ + ∞) greatly afiect the erosivity. In the Loess Plateau region, the rainfall intensity and raindrop kinetic energy have the most signiflcant impact on the splash erosion. The rainstorms usually have high energy. So the erosivity of Loess Plateau rainstorm on the soil is much higher than the ordinary rainfall. At the same time, the Loess Plateau region rainfalls have obvious monsoon rain characteristics, causing the concentrated time distribution of sloping fleld soil erosion. The rainfall in July and August is 52.7% of the rainfall during the total research time from May to September, and the erosive rainfall is 69.1% of it. The erosion amount in July and August is 77.4% of the annual erosion. The experiments show July and August are the critical period to control water and soil erosion.

Failure Mechanism of Ultra-High Pressure Fluid Control Products

The square elbows used in oil and gas fields were often failed because of serious erosion. Some of the products even burst. In this paper, the failure mechanism of square elbow was investigated by using electron microscopy (OM), electron microscopy (SEM) methods. The research results show that the elbow products failed due to its low impact toughness after carburizing and quenching. The erosion angle is nearly ninety-degree. By increasing the tempering temperature, reducing the surface hardness and improving toughness, the serious erosion phenomenon can be effectively avoided. There are two main reasons of the elbow products burst. One reason is the high inclusion content of the material. The other is the low impact toughness. Raising the quality specification of materials can appropriate increase the low impact toughness after heat treatment. It is pointed out that the product would be more safety by improve its impact toughness.

Research on Solid Particle Erosion Behaviors of TC4 Alloy at Different Erosion Angles

The solid particle erosion behaviors of TC4 Alloy were studied at different erosion angles. The results show that the erosion rate of TC4 alloy at impact angle 30o was higher than those at the impact angles of both 60o and 90o. At low impact angle, the erosion mechanism could be concluded as grinding erosion and furrow erosion. However, the erosion mechanism could be fatigue erosion at large impact angle.