Solid particle erosion behaviour of metallic materials at room and elevated temperatures
TL;DR: In this article, the salient features characteristic of room temperature and elevated temperature erosion of metallic materials are described and a review of some of the recent results, which in their opinion, have enhanced our current understanding in the area of solid particle erosion of metal materials.
Abstract: The behaviour of metallic materials subjected to solid particle erosion has been studied extensively over the last few decades. It is not the purpose of this paper to provide a comprehensive review of the above body of work especially since many such reviews already exist. Rather, the aim of this paper is to describe briefly the salient features characteristic of room temperature and elevated temperature erosion of metallic materials and follow it up with a review of some of the recent results, which in our opinion, have enhanced our current understanding in the area of solid particle erosion of metallic materials. As a natural consequence, the paper concludes with a critical review of the areas which require further study.
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TL;DR: In this paper, the authors defined the process of removing coal ash from the heat transfer surfaces as a process of shedding, which can be then referred to as artificial shedding, where both mechanical and thermal shock devices for shedding can be implemented within into the boiler, and the mechanism that will dominate depends on the ash characteristics and the boiler operation.
Abstract: Ash deposits formed during fuel thermal conversion and located on furnace walls and on convective pass tubes, may seriously inhibit the transfer of heat to the working fluid and hence reduce the overall process efficiency. Combustion of biomass causes formation of large quantities of troublesome ash deposits which contain significant concentrations of alkali, and earth-alkali metals. The specific composition of biomass deposits give different characteristics as compared to coal ash deposits, i.e. different physical significance of the deposition mechanisms, lower melting temperatures, etc. Low melting temperatures make straw ashes especially troublesome, since their stickiness is higher at lower temperatures, compared to coal ashes. Increased stickiness will eventually lead to a higher collection efficiency of incoming ash particles, meaning that the deposit may grow even faster. Deposit shedding can be defined as the process of deposit removal from the heat transfer surfaces. Mechanical and thermal shock devices for deposit removal can be implemented within into the boiler, which can be then referred to as artificial shedding. Sootblowing is one such process, where a pressurized fluid is used to cause a mechanical and/or thermal shock that would cause a failure or fissure in the deposit. On the other hand, shedding can be caused without any operational or mechanical influence by erosion, gravity shedding, or simply by a thermal shock. The mechanism that will be dominant depends on the ash characteristics and the boiler operation. Different deposit characteristics will govern the ash deposit behaviour, and thus the mechanism of deposit shedding. The deposit strength will influence the erosion and gravity shedding mechanisms. The ash viscosity and the melting behaviour will govern the gravity shedding mechanism, while the thermal expansion coefficient will influence the thermal shock behaviour of the deposit.
174 citations
TL;DR: In this article, high-velocity oxy-fuel (HVOF) sprayed WC-Co/NiCrFeSiB coatings on GrA1 boiler tube steel exhibit composite ductile and brittle modes of erosion under angular silica sand erodent of size 125-180μm impacted at 40m/s.
Abstract: It is a well-known fact that materials that consist of both brittle and ductile constituents can show erosion behavior in either a ductile or a brittle manner. The high-velocity oxy-fuel (HVOF) sprayed WC-Co/NiCrFeSiB coatings on GrA1 boiler tube steel exhibit composite ductile and brittle modes of erosion under angular silica sand erodent of size 125–180 μm impacted at 40 m/s. The HVOF spraying leads to a high retention of WC in the coating matrix accompanied with lower porosity. The as-sprayed as well as eroded coatings have been characterized using scanning electron microscope and optical profilometer.
134 citations
TL;DR: In this article, a multi-phase hybrid composites consisting of polyester reinforced with E-glass fiber and ceramic particulates were used to construct a test rig for the measurement of the wear performance of glass polyester composites.
Abstract: This paper describes the development of multi-phase hybrid composites consisting of polyester reinforced with E-glass fiber and ceramic particulates. It further investigates the erosion wear response of these composites and presents a comparison on the influence of three different particulate fillers cement by-pass dust (CBPD), alumina (Al2O3) and silicon carbide (SiC) on the wear characteristics of glass–polyester composites. For this purpose, the erosion test schedule in an air jet type test rig is made following design of experiments approach using Taguchi’s orthogonal arrays. Taguchi approach enables to determine optimal parameter settings that lead to minimization of erosion rate. The results indicate that erodent size, filler content, impingement angle and impact velocity influence the wear rate significantly. The experimental results are in good agreement with the values from the theoretical model. An artificial neural network (ANN) approach is also applied to predict the wear rate of the composites and compared with the theoretical results. This study reveals that addition of hard particulate fillers like CBPD, Al2O3 and SiC improves the erosion resistance of glass–polyester composites significantly. An industrial waste like CBPD exhibits better filler characteristics compared to those of alumina and SiC. Finally, a popular evolutionary approach known as genetic algorithm (GA) is used to generalize the method of finding out optimal factor settings for minimum wear rate.
129 citations
TL;DR: In this paper, the effect of various operational and material parameters on erosive wear behavior of polyester composites in an interacting environment erosion tests are carried out, and an optimal parameter combination is determined, which leads to minimization of erosion rate.
Abstract: Polyester composites reinforced with three different weight fractions of woven E-glass fiber reinforcement are developed. To study the effect of various operational and material parameters on erosive wear behavior of these composites in an interacting environment erosion tests are carried out. For this purpose, air jet type erosion test rig and the design of experiments approach utilizing Taguchi's orthogonal arrays are used. The findings of the experiments indicate that the rate of erosion of composites by impact of solid erodent is greatly influenced by the control factors. An optimal parameter combination is determined, which leads to minimization of erosion rate. Analysis of variance (ANOVA) is performed on the measured data and S/N (signal to noise) ratios. A correlation derived from the results of Taguchi experimental design is proposed as a predictive equation for estimation of erosion wear rate of these composites. It is demonstrated that the predicted results obtained using this equation are consistent with experimental observations. Finally, optimal factor settings for minimum wear rate are determined using genetic algorithm.
102 citations
Cites background from "Solid particle erosion behaviour of..."
...Sundararajan and Roy [14] suggested that in addition to velocity, solid particle erosion is governed by the impact angle, particle size, particle shape and hardness....
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...Examples have been cited for transportation of airborne solids through pipes by Bitter [2], boiler tubes exposed to flyash by Raask [3] and gas turbine blades by Hibbert and Roy [4]....
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...Lindsley and Marder [13] found impact velocity (v) to be a critical test variable in erosion, and that it can easily over shadow changes in other variables, such as target material, impact angle etc. Sundararajan and Roy [14] suggested that in addition to velocity, solid particle erosion is governed by the impact angle, particle size, particle shape and hardness....
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TL;DR: In this paper, a comparative study was carried out of the behavior of plasma sprayed NiCrBSiFe and WC alloys subjected to conditions which simulate a post-combustion gas atmosphere from a coal-fired boiler combustor.
Abstract: A comparative study was carried out of the behaviour of plasma sprayed NiCrBSiFe and WC–NiCrBSiFe alloys subjected to conditions which simulate a post-combustion gas atmosphere from a coal-fired boiler combustor. The study first evaluates the effects of thermal exposure at high temperatures on the microstructure of the coatings and on the adherence between substrate (austenitic stainless steel) and coatings. The oxidation rates of these coatings in atmospheres with 3–3.5% of free oxygen at 773 and 1073 K were then evaluated. The effect of WC on the low-velocity corrosion–erosion behaviour produced by the impact of fly ashes in the gas stream at high temperatures (773 and 1073 K) was assessed under impact angles of 30° and 90°. Finally, the eroded surfaces were analysed using scanning electron microscopy in order to characterize the ash embedment phenomena and the operating erosive micromechanisms.
83 citations
References
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TL;DR: In this paper, the authors discussed some aspects of the fluid flow conditions which may lead to erosion and then analyzed the mechanism of material removal for ductile and brittle materials for both types of materials.
Abstract: The amount of surface material eroded by solid particles in a fluid stream depends on the conditions of fluid flow and on the mechanism of material removal. The paper first discusses some aspects of the fluid flow conditions which may lead to erosion and then analyses the mechanism of material removal for ductile and brittle materials. For ductile materials it is possible to predict the manner in which material removal varies with the direction and velocity of the eroding particles. The numerical magnitude of the erosion cannot be predicted with accuracy but does correlate with data from metal cutting tests. For brittle materials the conditions leading to initial cracking are deduced and ways of predicting the material removal are discussed. It was not found possible to develop an analysis as detailed as that for ductile materials. In addition, the influence of the properties of the abrasive particle on erosion is briefly considered.
1,398 citations
TL;DR: In this article, the authors derived an expression for the energy needed to remove a unit volume of material from the body surface and described the plastic-elastic behaviour of the substance.
Abstract: In fluid-bed systems, transport lines for solids, etc. heavy erosion may occur. This type of attack has been shown to comprise two types of wear, one caused by repeated deformation during collisions, eventually resulting in breaking loose of a piece of material, the other caused by the cutting action of the free-moving particles.
In practice these two types of wear occur simultaneously. Formulae could be derived expressing erosion as a function of mass and velocity of the impinging particles, impingement angle and mechanical and physical properties both of erosive particles and eroded body.
In this part of the publication only wear due to repeated deformation is considered; in a second part cutting wear and the combination of these two types will be described.
For deformation wear the following equation is found: WD = 12M(Vsinα − K)2e in which WD is erosion in units volume loss, M and V are respectively total mass and velocity of impinging particles, α is impact angle, K is a constant, which can be calculated from mechanical and physical properties and expresses the particle velocity at incipient erosion. e represents the energy needed to remove a unit volume of material from the body surface and describes the plastic-elastic behaviour of the substance. Test results confirm this equation.
1,075 citations
TL;DR: In this paper, the combination of the two types of wear is discussed and the equations are shown to agre% with the results of experiments on hard and brittle, and on soft and ductile mate&& Several erosion phenomena are explained by the furmuIae, and indications for preventing or reducing erosion in practice.
Abstract: In Part I of this work (Wear, 6 (1963) 5-2~) it was stated that erosion consists of twa types of wear: deformation and c&t@ w&r. For the former a fonnuta was derived containing two con&~&s expressing the influence of tht ~~~a~~~ properties of the eroded substance, In this part, equations are deduced for cutting wear, containing tvro new constants: C, whici represents the hardnem of the eroded substance, and p, which describes the plaatic_eIasti~ behaviour of the material. The combination of the two types of wear is discussed and the equations are shown to agre% with the results of experiments on hard and brittle, and on soft and ductile mate&& Several erosion phenomena are explained by the furmuIae, and indications are given for preventing or reducing erosion in practice.
815 citations
Book•
01 Dec 1976TL;DR: In this article, the impact response of engineering surfaces is considered and a zero-impact wear model is proposed to quantify the impact of impact on a given surface, based on elastic contact solutions.
Abstract: 1. Considerations of Friction and Wear. 2. Methods of Impact Stress Analysis. 3. Impact Response of Engineering Surfaces. 4. Erosion by Solid Particles: Ductile and Brittle Theories. 5. General Aspects of Solid Particle Erosion. 6. Experimental Background of Percussive Impact Wear. 7. The Zero Impact Wear Model. 8. Measurable Impact Wear Theory. 9. Impact Wear in the Plastic Stress Range. 10. Impact Wear Through Flexible Media. 11. Liquid Erosion. Appendices: 1. Computer Programs in APL Programming Language. 2. Elastic Contact Solutions. 3. Hardness Tests. 4. Surface Texture. Author Index. Subject Index.
200 citations