1、Designation: G73 10Standard Test Method forLiquid Impingement Erosion Using Rotating Apparatus1This standard is issued under the fixed designation G73; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision.Anumb
2、er in parentheses indicates the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers tests in which solid specimensare eroded or otherwise damaged by repeated discrete impactsof liquid drops or jets. Am
3、ong the collateral forms of damageconsidered are degradation of optical properties of windowmaterials, and penetration, separation, or destruction of coat-ings. The objective of the tests may be to determine theresistance to erosion or other damage of the materials orcoatings under test, or to inves
4、tigate the damage mechanismsand the effect of test variables. Because of the specializednature of these tests and the desire in many cases to simulate tosome degree the expected service environment, the specifica-tion of a standard apparatus is not deemed practicable. This testmethod gives guidance
5、in setting up a test, and specifies testand analysis procedures and reporting requirements that can befollowed even with quite widely differing materials, testfacilities, and test conditions. It also provides a standardizedscale of erosion resistance numbers applicable to metals andother structural
6、materials. It serves, to some degree, as atutorial on liquid impingement erosion.1.2 The values stated in SI units are to be regarded asstandard. The inch-pound units in parentheses are provided forinformation.1.3 This standard does not purport to address all of thesafety concerns, if any, associate
7、d with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1003 Test Method for Haze and Luminous Transmittanceof Transp
8、arent PlasticsE92 Test Method for Vickers Hardness of Metallic Materi-alsE140 Hardness Conversion Tables for Metals RelationshipAmong Brinell Hardness, Vickers Hardness, RockwellHardness, Superficial Hardness, Knoop Hardness, andScleroscope HardnessE177 Practice for Use of the Terms Precision and Bi
9、as inASTM Test MethodsE179 Guide for Selection of Geometric Conditions forMeasurement of Reflection and Transmission Properties ofMaterialsG1 Practice for Preparing, Cleaning, and Evaluating Corro-sion Test SpecimensG32 Test Method for Cavitation Erosion Using VibratoryApparatusG40 Terminology Relat
10、ing to Wear and ErosionG134 Test Method for Erosion of Solid Materials by aCavitating Liquid Jet2.2 Military Standards:3MIL-C-83231 Coatings, Polyurethane, Rain Erosion Resis-tance for Exterior Aircraft and Missile Plastic PartsMIL-P-8184 Plastic Sheet, Acrylic, Modified3. Terminology3.1 See Termino
11、logy G40 for definitions of terms that arenot defined below in either 3.2 or 3.3. Definitions appear in 3.2that are taken from Terminology G40 for important termsrelated to the title, Scope, or Summary of this test method.Definitions of Terms Specific to this Test Method are given in3.3 that are not
12、 in Terminology G40.3.2 DefinitionsAll definitions listed below are quotedfrom Terminology G4005 (some modified).3.2.1 cumulative erosion-time curve, nin cavitation andimpingement erosion, a plot of cumulative erosion versuscumulative exposure duration, usually determined by periodic1This test metho
13、d is under the jurisdiction of ASTM Committee G02 on Wearand Erosion and is the direct responsibility of Subcommittee G02.10 on Erosion bySolids and Liquids.Current edition approved April 1, 2010. Published May 2010. Originallyapproved in 1982. Last previous edition approved in 2004 as G7304. DOI:10
14、.1520/G0073-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Standardization Documents Orde
15、r Desk, DODSSP, Bldg. 4,Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:/dodssp.daps.dla.mil.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.interruption of the test and weighing of the specimen. This isthe primary rec
16、ord of an erosion test. Most other characteris-tics, such as the incubation period, maximum erosion rate,terminal erosion rate, and erosion rate-time curve, are derivedfrom it.3.2.2 damage, nin cavitation or impingement, any effecton a solid body resulting from its exposure to these phenom-ena. This
17、 may include loss of material, surface deformation, orany other changes in microstructure, properties, or appearance.3.2.2.1 DiscussionThis term as here defined should nor-mally be used with the appropriate modifier, for example,“cavitation damage,” “liquid impingement damage,” “single-impact damage
18、,” and so forth.3.2.3 incubation period, nin cavitation and impingementerosion, the initial stage of the erosion rate-time pattern duringwhich the erosion rate is zero or negligible compared to laterstages.3.2.3.1 DiscussionThe incubation period is usuallythought to represent the accumulation of pla
19、stic deformationand internal stresses under the surface hat precedes significantmaterial loss. There is no exact measure of the duration of theincubation period. See related term, nominal incubation periodin 3.3.9.3.2.4 liquid impingement erosion, nprogressive loss oforiginal material from a solid s
20、urface due to continued expo-sure to impacts by liquid drops or jets.3.2.5 maximum erosion rate, nin cavitation and liquidimpingement, the maximum instantaneous erosion rate in a testthat exhibits such a maximum followed by decreasing erosionrates. (See also erosion ratetime pattern.)3.2.5.1 Discuss
21、ionOccurrence of such a maximum istypical of many cavitation and liquid impingement tests. Insome instances it occurs as an instantaneous maximum, inothers as a steady-state maximum which persists for sometime.3.2.6 normalized erosion resistance, Ne, na measure ofthe erosion resistance of a test mat
22、erial relative to that of aspecified reference material, calculated by dividing the volumeloss rate of the reference material by that of the test materialwhen both are similarly tested and simliarly analyzed. By“similarly analyzed” is meant that the two erosion rates mustbe determined for correspond
23、ing portions of the erosionrate-time pattern; for instance, the maximum erosion rate or theterminal erosion rate.3.2.6.1 DiscussionArecommended complete wording hasthe form, “The normalized erosion resistance of (test material)relative to (reference material) based on (criterion of dataanalysis) is
24、(numerical value).”3.2.7 normalized incubation resistance, N0, nin cavitationand liquid impingement erosion, the nominal incubation periodof a test material, divided by the nominal incubation period ofa specified reference material similarly tested and similarlyanalyzed. (See also normalized erosion
25、 resistance.)3.3 Definitions of Terms Specific to This Standard:3.3.1 apparatus severity factor, Fan empirical factor thataccounts for the systematic differences between rationalizederosion rates (or rationalized incubation periods) as determinedfor the same material and impact velocity in different
26、 facilities.It reflects variations in test conditions not accounted for by thedata reduction procedures of this test method.3.3.2 erosion resistance number, NERthe normalized ero-sion resistance of a test material relative to a standardizedscale, calculated from test results with one or more designa
27、tedreference materials as described in this test method. See alsoreference erosion resistance (3.3.12).3.3.3 exposed surface (or area)that surface (or area) onthe specimen nominally subjected to liquid impingement.(1) For “distributed impact tests,” it is generally to be takenas the projected area o
28、f the exposed surface of the specimen ona plane perpendicular to the direction of impingement. How-ever, if a plane specimen surface is deliberately oriented so asto obtain impingement at an oblique angle, then the actualplane area is used.(2) For “repetitive impact tests,” it is to be taken as thep
29、rojected area of the impinging liquid bodies on the specimen,the projection being taken in the direction of relative motion.3.3.3.1 DiscussionIn practice, it is usually found that thedamaged area in repetitive impact tests is greater than theexposed area as defined above, but the above definition is
30、adopted not only for simplicity but also for consistencybetween some of the other calculations for distributed andrepetitive tests.3.3.4 impingement rate, UiLT1the volume of liquidimpinging per unit time on a unit area of exposed surface; fora plane target surface it is given by c V cos u.3.3.5 incu
31、bation impingement, H0Lthe mean cumula-tive impingement corresponding to the nominal incubationperiod; hence, impingement rate times nominal incubationtime.3.3.6 incubation resistance number, NORthe normalizedincubation resistance of a test material relative to a standard-ized scale, calculated from
32、 test results with one or moredesignated reference materials as described in this test method.See also reference incubation resistance (3.3.13).3.3.7 incubation specific impacts, N0same as rationalizedincubation period.3.3.8 mean cumulative impingement, H Lthe cumulativevolume of liquid impinged per
33、 unit area of exposed surface;impingement rate times exposure time.3.3.9 nominal incubation period, t0the intercept on thetime or exposure axis of the straight-line extension of themaximum-slope portion of the cumulative erosion-time curve;while this is not a true measure of the incubation stage, it
34、serves to locate the maximum erosion rate line on the cumu-lative erosion versus exposure coordinates.3.3.10 rationalized erosion rate, Revolume of materiallost per unit volume of liquid impinged, both calculated for thesame area.3.3.11 rationalized incubation period, N0the duration ofthe nominal in
35、cubation period expressed in dimensionlessterms as the number of specific impacts; hence, the specificimpact frequency times incubation time. (Also referred to as“incubation specific impacts.”)3.3.12 reference erosion resistance, Sera normalized ero-sion resistance, based on interlaboratory test res
36、ults, assignedto a specified reference material in this test method so as toG73102constitute a benchmark in the “erosion resistance number”scale. The value of unity is assigned to 316 stainless steel ofhardness 155 to 170 HV.3.3.13 reference incubation resistance, Sora normalizedincubation resistanc
37、e, based on interlaboratory test results,assigned to a specific reference material in this test method soas to constitute a benchmark in the “incubation resistancenumber” scale. The value of unity is assigned to 316 stainlesssteel of hardness 155 to 170 HV.3.3.14 specific impacts, Nthe number of imp
38、act stresscycles of damaging magnitude experienced by a typical pointon the exposed surface, or an approximation thereof asestimated on the basis of simplified assumptions as describedin this test method. (This concept has sometimes been termed“impacts per site.”)3.3.15 specific impact frequency, fi
39、T1the number ofspecific impacts experienced per unit time, given by (a/b) Ui.3.3.16 volume concentration, cthe ratio of the volume ofliquid to the total volume in the path traversed or swept out bythe exposed area of the specimen.3.3.17 volume mean diameter Lin a population of dropsof different size
40、s, the diameter of a sphere whose volumeequals the total volume of all drops divided by the total numberof drops.3.4 Symbols:A = exposed area of specimen, m2,a = projected area of impinging drop or jet, m2,b = volume of impinging drop or jet, m3,d = diameter of impinging drop or jet, m,F0= apparatus
41、 severity factor for incubation,Fe= apparatus severity factor for erosion rate,fi= specific impact frequency, s1,H = mean cumulative impingement, m,H0= incubation impingement, m,N0= number of specific impacts for incubation, or “ra-tionalized incubation period,” dimensionless,NER = erosion resistanc
42、e number,NOR = incubation resistance number,n = number of jets or drops impacting on exposedsurface of specimen in one revolution,Qe= volumetric erosion rate, m3/s,Re= “rationalized erosion rate,” (dY/dH), dimensionless,Se= normalized erosion resistance (relative to a speci-fied reference material),
43、Ser= reference erosion resistance,S0= normalized incubation resistance (relative to aspecified reference material),Sor= reference incubation resistance,t = exposure time, s,t0= nominal incubation time, s,Ue= linear erosion rate (dY/dt), m/s = Qe/A,Ui= impingement rate (dH/dt), m/s,Ur= rainfall rate,
44、 m/s,Ut= terminal velocity of drops in falling rainfield, m/s,V = impact velocity of drop or jet relative to specimen,m/s,Vn= component of impact velocity normal to specimensurface, m/s,Y = mean depth of erosion, m,u = angle of incidencethe angle between the direc-tion of impacting drops and the nor
45、mal to the solidsurface at point of impact,c = volume concentration of liquid in rainfield or inspace swept through by specimen, andV = rotational speed of specimens, rev/s.3.5 Except in equations where different units are expresslyspecified, the use of SI units listed in 3.4, or any other coherents
46、ystem of units, will make equations correct without the needof additional numerical factors. When referring to quantities intext, tables, or figures, suitable multiples or submultiples ofthese units may, of course, be used.4. Summary of Test Method4.1 Liquid impingement tests are usually, but not al
47、ways,conducted by attaching specimens to a rotating disk or arm,such that in their circular path they repeatedly pass through andimpact against liquid sprays or jets (Sections 6 and 7). Standardreference materials (Section 8) should be used to calibrate theapparatus and included in all test programs
48、.4.2 Data analysis begins by establishing a cumulativeerosion-time curve from measurements of mass loss (or otherdamage manifestation) periodically during the tests (Section9). These curves are then characterized by specified attributessuch as the nominal incubation time and the maximum erosionrate
49、(Section 10).4.3 For comparative materials evaluations, the results arenormalized (Section 10) with respect to the standard referencematerials included in the test program. A standardized scale of“erosion resistance numbers” is provided for structural bulkmaterials and coatings (10.4.3). For more in-depth analysis ofthe results, the incubation times or erosion rates are expressedin dimensionless “rationalized” forms that are based on morephysically meaningful exposure duration variables than clocktime as such (Section 11).4.4 The informat
