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Research was conducted to develop a criterion for selecting weld overlay coatings for erosion mitigation in circulated fluidized beds (CFBs). Initially, 11 weld overlay alloys were deposited on 1018 steel substrates using the plasma arc welding process and erosion tested at 400 o C. Erosion resistance was evaluated by determining the steady state erosion rate, and the microstructure of each...
The erosion of glass as a function of the velocity of alumina particles of 30 μm average size was studied. It was found that the use of the rotating double-disk method to determine particle velocity can lead to systematic deviations. Correcting for this effect, the results indicate that the erosion can be well described using indentation fracture mechanics. The exponent of the velocity-dependence...
The formation of ripples on the surface of pure aluminum during solid particle erosion was studied using sharp alumina and spherical glass beads as erodent particles in an air-blast type system. A new laboratory technique controlled the tangential velocity of the erodent particles relative to the samples with their placement on a velocity controlled rotating disk. With this technique, it was possible...
Experiments were performed to study the effect of erodent particle velocity, size and shape on the erosion rate os S-glass, and to investigate the erosion mechanisms associated with these variables. The S-glass specimens were subject to eroding particles of alundum and spherical glass beads. Particle sizes ranged from 60 to 400 μm; particle velocities varied from approximately 60 to 90 m s - ...
A unidirectional silicon carbide continuous fibre reinforced calcium aluminosilicate (CAS/SiC) glass-ceramic matrix composite has been subjected to silica sand solid particle erosion over the temperature range 20 to 726°C. At room temperature, tests were conducted at two velocities. The lower (7 m s -1 ) did not generate lateral cracks and a wear rate of 0.004 mg g -1 was...
Two novel methods have been used to assess the wear resistance of six different 20-70 μm thick polymer coatings on both galvanized steel and polymeric substrates. The coatings were commercially available 'clear-coats' which are used as the uppermost layer in automobile paint systems and are intended to provide resistance to both mechanical and corrosive damage. The first wear test involves solid particle...
The object of this study was to generate erosion maps for various particulate reinforced Ni-Cr/WC metal matrix composites by investigating the effect of erodent velocity with low velocity conditions, at elevated temperatures. The erodent used was alumina and the environment was oxidizing. The results showed that the ranking order of erosion resistance, as a function of volume fraction, reversed as...
A multilayer paint erosion indication technique to produce a highly visual and accelerated map of erosion damage occurring in a three-dimensional component model has been developed. An investigation to obtain an understanding of how the paint layers eroded as a function of a number of erosion variables was performed. It was observed that the erosion rate behaviour of paint layers as a function of...
Sand particles, produced in addition to petroleum fluid, present a major erosional hazard to transport and process control equipment within the petroleum industry. Control valves are most susceptible to erosion due to their fundamental action, experiencing failure through loss of control in a matter of days in extreme cases. This paper presents a computational fluid dynamics erosion model which allows...
Solid particle erosion of infrared transmitting materials is a particular problem to the aerospace industry, where such materials are frequently used as ‘windows’ over guidance systems. They are typically weak and brittle and may suffer severe optical degradation as a result of impacts. Added durability may be provided by the deposition of a coating. An optimum coating thickness has been found, both...
A study is made of the solid particle erosion behaviour of a set of thermal sprayed ceramic, metallic and polymer coatings as well as bulk alumina and stainless steel. The role of particle properties such as hardness and shape in slurry and airborne erosion is examined. The effect of varying the impingement angle of the airborne erodent stream on the erosion loss and rate of each coating is determined...
The solid particle erosion of the hot-pressed monolithic SiC and SiC-TiB 2 particulate composite by angular SiC particles was investigated at room temperature over a range of particle sizes (50-150 μm), velocities (40-100 m/s) and impact angles (30-90 o ) by weight loss measurements. The erosion of both materials exhibits an anomalous particle size dependence and evidences of plastic...
Deformation characteristics of a ductile material surface, impacted by erosive particles, was investigated at single impact sites. Surface of Cu-30% Zn (α-brass) was impacted by angular SiO 2 particles having an average size 5 and 25 μm in an evacuated experimental set-up. SEM and AFM studies were conducted to qualitatively and quantitatively characterize individual impact sites. Indent sizes...
The erosive wear of fibrous aluminosilicate insulating materials has been studied to establish the mechanisms of damage and to obtain quantitative measurements of erosion rate for use in plant design. The effects of erosive particle size, particle velocity and impact angle on wear rate have been examined in experiments with a gas-blast erosion rig and silica sand particles. For these extremely weak...
Velocity is a critical test variable in erosion, and can easily overshadow changes in other variables, such as target material, impact angle, etc. The effect of velocity on erosion rate was studied in 70-30 brass (cold worked and annealed) and Fe-C martensite (as-quenched and tempered) and it was found, as previously shown, that erosion rate is dependent on velocity by a power law, given by ER=kV...
Low-density fibrous ceramic components (e.g., aluminosilicates) are widely used as insulating materials in boilers and furnaces. In practical applications the impact of hard particles such as ash or clinker may result in serious damage. The high temperature erosive wear of fibrous aluminosilicate ceramics has been studied to verify whether the mechanisms of damage change with temperature. The effects...
The erosive and hydroabrasive wear are very intensive degradation processes of the surface layers of the metallic materials. The wear resistance is influenced by the working conditions and the material parameters like hardness and microstructure. These parameters of the hardfacings are determined by the technology of building-up and the chemical composition of the overlay. The present knowledge of...
Erosion of boiler tubes causes serious problems in many pulverized coal-fired utility boilers. The Eulerian approach was employed to predict the behaviour of the particulate phase. Traditionally, the Eulerian approach shows deficiencies when used in the numerical prediction of erosion, because of a lack of an appropriate wall boundary condition for the particulate phase. Comparison of the numerical...
Solid particle erosion of epoxy resin (EP) modified by various amounts of hygrothermally decomposed polyester-urethane (HD-PUR) was studied at oblique (30, 45, and 60 o ) and normal impact (90 o ). The cross-linked structure of the modified EP was characterised by the mean molecular weight between cross-links (M c ). It was established that the initial brittle erosion of the...
The erosive wear resistance of cermets with different composition, structure and properties has been investigated. It has been shown that cermets erosive wear resistance cannot be estimated only by hardness, characterised by resistance to penetration. The differences in wear resistance between cermet materials with equal hardness level can be attributed to differences in their resistance to fracture...
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