Erosion liquid impingement

Practice for measurement of corrosion potentials of aluminium alloys Practice for conducting and evaluating galvanic corrosion tests in electrolytes Practice for liquid impingement erosion testing... 

Impingement Attack localised corrosion resulting from the action of corrosion and/or erosion (separately or conjoint) when liquids impinge on a surface. 

ACCELERATION PERIOD - In cavitation and liquid impingement erosion, the stage following the incubation period, during which the erosion rate increases from near zero to a maximum value. 

EROSION, IMPINGEMENT - Loss of material from a solid surface due to liquid impingement. 

Current understanding of the erosion of polymer laminates has come chiefly from rain erosion studies of composite aircraft materials. Analogies have been drawn between cavitation and liquid impingement processes on metallic materials both involve extensive structural damage early in the incubation period as a result of short-term shock pulses. Furthermore, the deformed surfaces of materials which are subjected to both processes are very similar, and so are the methods used to improve their performance [99]. Attempts have been made to prioritize the factors affecting erosion of FRP by liquid impingement, with more or less predictable results [100] in respect of resin composition, fiber volume fraction and orientation, porosity and thermal conductivity. All these factors were found to affect performance. 

ASTM G 73, Practice for Liquid Impingement Erosion Testing—The behavior of solid specimens that are exposed to discrete impacts of liquid may be evaluated by conducting studies according to this standard. Specimens are subjected to hquid sprays or jets and the weight loss (or other metal loss data) is recorded with exposure time. This method presents test apparatus, test specimens, test procedures, and calculations and analysis of erosion resistance. 

Heymann, F. J., "Liquid Impingement Erosion, ASM Handbook, Vol. 18, Friction, Wear and Lubrication Technology, American Society of Metals, Materials Park, OH, 1992, pp. 222-232. 

ASTM G 73-98 Standard Practice for Liquid Impingement Erosion Testing, Annual Book of ASTM Standards, Vol 03.02, ASTM bitemational. West Conshohocken, PA. 

ASTM G73—Practice for Liquid Impingement Erosion Testing... 

ASTM G 40 ASTM G 73 Standard Terminology Relating to Wear and Erosion Standard Practice for Liquid Impingement Erosion Testing Definition of terms for erosion and wear. Resistance to erosion from impacts of liquid drops or jets. 

Plastics are frequently used for applications requiring erosion resistance, but there does not seem to be much activity or interest in the tribology community of the 1990s. However, there are a number of tests that are applied and have been used to rate erosion resistance of plastics. Erosion, by definition, is progressive loss of material fiom a solid surface due to mechanical interaction between that surfitce and a fluid, a multicomponent fluid, or impinging liquid or solid particles (3). The field of erosion is usually separated into a number of forms of erosion liquid erosion, either continuous stream or droplet, solid particle erosion, slurry erosion, and cavitation erosion. Each have separate laboratory tests. 

General Description. Erosion of a solid surface can take place in a liquid medium even without the presence of solid abrasive particles in that medium. Cavitation, one mechanism of liquid erosion, involves the formation and subsequent collapse of bubbles within the liquid. The process by which material is removed from a surface is called cavitation erosion, and the resulting damage is termed cavitation damage. The collision at high speed of liquid droplets with a solid surface results in a form of liquid erosion called liquid impingement erosion. 

Erosive wear, liquid droplets 0 73 Practice for Liquid Impingement Erosion Testing Mass loss... 

For optimum protection of pipe systems, a combination of resistant materials, low contents of corrosive gases in liquids, chemical tieatment for passivation of metal surfaces, low erosion and impingement geometries, suitable velocities, and cathodic protection may be required. 

Liquid impingement erosion has been defined as progressive loss of original material from a solid surface due to continued exposure to impacts by liquid drops w jets (Ref 8). The opoative words in this definition are inipacts by liquid drops or jets. Liquid impingement erosion connotes repeated impacts or collisions between the surface being eroded and small discrete liquid bodies. 

As noted earlier, cavitation erosion test methods such as the vibratory method (Rg. 6) have also been used to screen materials for service under liquid impingement conditions. 

E n g Classification of 22 alloys or alloy groups according lo their normalized erosion resistances relative to 18Cr- 8Ni austenitic stainless steal having a hardness of 170 HV. Data are applicable to both liquid impingement and cavitation erosion. Source Ref 26... 

Erosion. The abrasive is likely to be gas borne (as in catalytic cracking units), liquid borne (as in abrasive slurries), or gravity pulled (as in catalyst transfer lines). Because of the association of velocity and kinetic energy, the severity of erosion may increase as some power (usually up to the 3d) of the velocity. The angle of impingement also influences severity. At supersonic speeds, even water droplets can be seriously erosive. There is some evidence that the response of resisting metals is influenced by whether they are ductile or brittle. Probably most abrasion involved with hydrocarbon processing is of the erosive type. 

COMMENTS The Carnot vapor cycle as illustrated by Example 2.1 is not practical. Difficulties arise in the isentropic processes of the cycle. One difficulty is that the isentropic turbine will have to handle steam of low quality. The impingement of liquid droplets on the turbine blade causes erosion and wear. Another difficulty is the isentropic compression of a liquid-vapor mixture. The two-phase mixture of the steam causes serious cavitation problems during the compression process. Also, since the specific volume of the saturated mixture is high, the pump power required is also very high. Thus, the Carnot vapor cycle is not a realistic model for vapor power cycles. 

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