1、Designation: G 73 04Standard Practice forLiquid Impingement Erosion Testing1This standard is issued under the fixed designation G 73; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision.Anumber in parentheses
2、indicates the year of last reapproval.Asuperscriptepsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers tests in which solid specimens areeroded or otherwise damaged by repeated discrete impacts ofliquid drops or jets. Among the collateral f
3、orms 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 investigate the damage me
4、chanismsand 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 promulga-tion of a method is not deemed practicable. This practice givesguidance in setting up a test, and specifies
5、test and analysisprocedures and reporting requirements that can be followedeven with quite widely differing materials, test facilities, andtest conditions. It also provides a standardized scale of erosionresistance numbers applicable to metals and other structuralmaterials. It serves, to some degree
6、, as a tutorial on liquidimpingement 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, associated with its use. It is theresponsibil
7、ity 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:2D 1003 Test Method for Haze and Luminous Transmittanceof Transparent PlasticsE 92 Test Method for
8、Vickers Hardness of Metallic Mate-rialsE 140 Hardness Conversion Tables for Metals (RelationshipBetween Brinell Hardness, Vickers Hardness, RockwellHardness, Rockwell Superficial Hardness, Knoop Hard-ness, and Scleroscope Hardness)E 177 Practice for Use of the Terms Precision and Bias inASTM Test Me
9、thodsE 179 Guide for Selection of Geometric Conditions forMeasurement of Reflection and Transmission Properties ofMaterialsG 1 Practice for Preparing, Cleaning, and Evaluating Cor-rosion Test SpecimensG 32 Test Method for Cavitation Erosion Using VibratoryApparatusG 40 Terminology Relating to Wear a
10、nd ErosionG 134 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 Terminology G40for
11、definitions of terms that arenot defined below in either 3.2 or 3.3. 3.2 quotes definitions,taken from Terminology G40, for important terms related tothe title, Scope, or Summary of this practice. 3.3 givesdefinitions of terms specific to this practice that are not inTerminology G40.3.2 DefinitionsA
12、ll definitions listed below are quotedfrom Terminology G4002.3.2.1 cumulative erosion-time curve, nin cavitation andimpingement erosion, a plot of cumulative erosion versuscumulative exposure duration, usually determined by periodicinterruption of the test and weighing of the specimen. This is1This
13、practice is under the jurisdiction of ASTM Committee G02 on Wear andErosion and is the direct responsibility of Subcommittee G02.10 on Erosion bySolids and Liquids.Current edition approved Nov 1, 2004. Published November 2004. Originallyapproved in 1982. Last previous edition approved in 1998 as G 7
14、3 98.2For 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 Order Desk, Bl
15、dg. 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5098.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.the primary record of an erosion test. Most other characteris-tics, such as the incubation period, maximum erosion rate,ter
16、minal 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 may include loss of material, surface deformation, orany other changes in microstructure, properties, or ap
17、pearance.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,” and so forth.3.2.3 incubation period, n in cavitation and impingementerosion, the initial stage of the er
18、osion rate-time pattern duringwhich the erosion rate is zero or negligible compared to laterstages. Also, the exposure duration associated with this stage.(Quantitatively it is sometimes defined as the intercept on thetime or exposure axis, of a straight line extension of themaximum-slope portion of
19、 the cumulative erosion-time curve.)3.2.4 liquid impingement erosion, nprogressive loss oforiginal material from a solid surface due to continued expo-sure to impacts by liquid drops or jets.3.2.5 maximum erosion rate, n in cavitation and liquidimpingement, the maximum instantaneous erosion rate in
20、a testthat exhibits such a maximum followed by decreasing erosionrates. (See also erosion ratetime pattern.)3.2.5.1 DiscussionOccurrence 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 max
21、imum which persists for sometime.3.2.6 normalized erosion resistance, Ne, nthe volume lossrate of a test material, divided into the volume loss rate of aspecified reference material similarly tested and similarlyanalyzed. By “similarly analyzed” is meant that the twoerosion rates must be determined
22、for corresponding portions ofthe erosion rate-time pattern; for instance, the maximumerosion rate or the terminal 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 dat
23、aanalysis) is (numerical value).”3.2.7 normalized incubation resistance, N0, nin cavitationand liquid impingement erosion, the incubation period of a testmaterial, divided by the incubation period of a specifiedreference material similarly tested and similarly analyzed. (Seealso normalized erosion r
24、esistance.)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 f
25、acilities.It reflects variations in test conditions not accounted for by thedata reduction procedures of this practice.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 designatedre
26、ference materials as described in this practice. See alsoreference erosion resistance (3.3.11).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 of the ex
27、posed 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 theprojected
28、 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 isadopted
29、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 incubation i
30、mpingement, H0Lthe mean cumula-tive impingement corresponding to the incubation period;hence, impingement rate times incubation time.3.3.6 incubation resistance number, NORthe normalizedincubation resistance of a test material relative to a standard-ized scale, calculated from test results with one
31、or moredesignated reference materials as described in this practice. Seealso reference incubation resistance (3.3.12).3.3.7 incubation specific impacts, N0same as rationalizedincubation period.3.3.8 mean cumulative impingement, H Lthe cumulativevolume of liquid impinged per unit area of exposed surf
32、ace;impingement rate times exposure time.3.3.9 rationalized erosion rate, Revolume of material lostper unit volume of liquid impinged, both calculated for thesame area.3.3.10 rationalized incubation period, N0the duration ofthe incubation period expressed in dimensionless terms as thenumber of speci
33、fic impacts; hence, the specific impact fre-quency times incubation time. (Also referred to as “incubationspecific impacts.”)3.3.11 reference erosion resistance, Sera normalized ero-sion resistance, based on interlaboratory test results, assignedto a specified reference material in this practice so
34、as toconstitute a benchmark in the “erosion resistance number”scale. The value of unity is assigned to 316 stainless steel ofhardness 155 to 170 HV.3.3.12 reference incubation resistance, Sora normalizedincubation resistance, based on interlaboratory test results,assigned to a specific reference mat
35、erial in this practice so as toconstitute a benchmark in the “incubation resistance number”scale. The value of unity is assigned to 316 stainless steel ofhardness 155 to 170 HV.3.3.13 specific impacts, Nthe number of impact stresscycles of damaging magnitude experienced by a typical pointon the expo
36、sed surface, or an approximation thereof asG73042estimated on the basis of simplified assumptions as describedin this practice. (This concept has sometimes been termed“impacts per site.”)3.3.14 specific impact frequency, fiT1the number ofspecific impacts experienced per unit time, given by (a/b) Ui.
37、3.3.15 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.3.3.16 volume mean diameter Lin a population of dropsof different sizes, the diameter of a sphere whose volumeequals the total volume of all drops
38、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 severity factor for incubation,Fe= apparatus severity factor for erosion rat
39、e,fi= specific impact frequency, s1,H = mean cumulative impingement, m,H0= incubation impingement, m,N0= number of specific impacts for incubation, or “rationalized incubationperiod,” dimensionless,NER = erosion resistance number,NOR = incubation resistance number,n = number of jets or drops impacti
40、ng on exposed surface of specimenin one revolution,Qe= volumetric erosion rate, m3/s,Re= “rationalized erosion rate,” (dY/dH), dimensionless,Se= normalized erosion resistance (relative to a specified reference ma-terial),Ser= reference erosion resistance,S0= normalized incubation resistance (relativ
41、e to a specified referencematerial),Sor= reference incubation resistance,t = exposure time, s,t0= incubation time, s,Ue= linear erosion rate (dY/dt), m/s = Qe/A,Ui= impingement rate (dH/dt), m/s,Ur= rainfall rate, m/s,Ut= terminal velocity of drops in falling rainfield, m/s,V = impact velocity of dr
42、op or jet relative to specimen, m/s,Vn= component of impact velocity normal to specimen surface, m/s,Y = mean depth of erosion, m,u = angle of incidencethe angle between the direction of impactingdrops and the normal to the solid surface at point of impact,c = volume concentration of liquid in rainf
43、ield or in space swept throughby 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 coherentsystem of units, will make equations correct without the needof additional numerical fa
44、ctors. When referring to quantities intext, tables, or figures, suitable multiples or submultiples ofthese units may, of course, be used.4. Summary of Practice4.1 Liquid impingement tests are usually, but not always,conducted by attaching specimens to a rotating disk or arm,such that in their circul
45、ar 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.4.2 Data analysis begins by establishing a cumulativeerosion-time curve from measurement
46、s of mass loss (or otherdamage manifestation) periodically during the tests (Section9). These curves are then characterized by specified attributessuch as the incubation time and the maximum erosion rate(Section 10).4.3 For comparative materials evaluations, the results arenormalized (Section 10) wi
47、th 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 dimensionles
48、s “rationalized” forms that are based on morephysically meaningful exposure duration variables than clocktime as such (Section 11).4.4 The information to be given in the report depends on theobjectives of the test (Section 12).5. Significance and Use5.1 Erosion EnvironmentsThis practice may be used
49、forevaluating the erosion resistance of materials for serviceenvironments where solid surfaces are subjected to repeatedimpacts by liquid drops or jets. Occasionally, liquid impacttests have also been used to evaluate materials exposed to acavitating liquid environment. The practice is not intended norapplicable for evaluating or predicting the resistance of mate-rials against erosion due to solid particle impingement, due to“impingement corrosion” in bubbly flows, due to liquids orslurries “washing” over a surface, or due to continuoushigh
