1、Designation: F 1864 05Standard Test Method forDust Erosion Resistance of Optical and Infrared TransparentMaterials and Coatings1This standard is issued under the fixed designation F 1864; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the resistance of transparentplastics and coatings used in aerospace windscr
3、eens, canopies,and viewports to surface erosion as a result of dust impinge-ment. This test method simulates flight through a definedparticle cloud environment by means of independent control ofparticle size, velocity, impact angle, mass loading, and testduration.1.2 This standard does not purport t
4、o address all of thesafety concerns, if any, associated 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:2D 618 Pr
5、actice for Conditioning Plastics for TestingD 1003 Test Method for Haze and Luminous Transmittanceof Transparent PlasticsD 1193 Specification for Reagent WaterE11 Specification for Wire Cloth and Sieves for TestingPurposesE 168 Practices for General Techniques of Infrared Quanti-tative Analysis3. Te
6、rminology3.1 Definitions of Terms Specific to This Standard:3.1.1 mass loading, nthe mass of dust per unit of totalexposed surface area (including the sample holder) that im-pinges on the specimens.3.1.2 mean IR transmission, nfor the purposes of thisstandard, the average percentage of light transmi
7、tted by amaterial in the 8- to 12-m bandwidth.3.1.3 sweep time, nthe time required for one translationpass.3.1.4 translation pass, nthe translation of the specimenplatform from the vertical or horizontal limit to the correspond-ing vertical or horizontal limit.3.1.5 translation cycle, nthe translati
8、on of the specimenplatform from the vertical or horizontal limit to the correspond-ing vertical or horizontal limit and back to the initial vertical orhorizontal limit. Two translation passes are equivalent to onetranslation cycle.3.2 Symbols:As= reference surface area of specimen platform (cm2),Cc=
9、 simulated cloud concentration (g/m3),ho= percent haze before exposure,he= percent haze after exposure,mp= rate of particle mass impacting the reference surfacearea (g/min),mi= incremental mass loading (g/cm2),mT= total mass loading (g/cm2),N = number of increments,Vp= particle impact velocity (m/s)
10、,ts= sweep time(s),Te= optical or mean infrared (IR) transmission afterexposure (%),To= optical or mean IR transmission before exposure (%),a = impact angle (normal incidence = 90),Dti= exposure time (min) for loading increment i,fi= incremental dust load (g/cm2) for loading incrementi,F = total dus
11、t load (g/cm2),Dh = change in percent haze, andDT = change in optical or IR transmission.4. Summary of Test Method4.1 This test method consists of: (1) measuring and record-ing the light transmission properties, at visual or infraredwavelengths, of test coupons; (2) mounting the coupons in atest fix
12、ture; (3) exposing the coupons to a dust particle stream;and (4) remeasuring the light transmission properties to deter-mine changes in these properties.1This test method is under the jurisdiction of ASTM Committee F07 onAerospace and Aircraft and is the direct responsibility of Subcommittee F07.08
13、onTransparent Enclosures and Materials.Current edition approved June 1, 2005. Published July 2005. Originally approvedin 1998. Last previous edition approved in 1998 as F 1864 98.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org.
14、 For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.2 The dust particle stream simulates flight at a specifiedvelocit
15、y through a dust cloud of specified density. Simulation isaccomplished through control of particle size distribution,mean particle velocity, particle mass flow rate, and angle ofimpact.4.3 The degree of abrasion is measured by the amount ofchange in haze and luminous transmittance for materialstrans
16、parent in the visual wavelengths and by the amount ofchange in IR spectral transmission for materials transparent inthe infrared wavelengths.5. Significance and Use5.1 All materials on exterior aircraft surfaces are subject toabrasion from airborne particles of various sizes and shapes.Transparent m
17、aterials are particularly vulnerable to abrasion,since their performance is based on their ability to transmitlight with a minimal amount of scatter. Scratches, pitting, andcoating removal and delamination as a result of abrasion mayincrease scatter, reduce transmission, and degrade the perfor-mance
18、 of transparent materials. Visually transparent materialsare required for pilot and air crew enclosures, such as canopies,windshields, and viewpoints. Materials transparent in the IRregion (8 to 12 m) are required for tracking, targeting, andnavigational instrumentation.5.2 This test method is inten
19、ded to provide a calibrated andrepeatable means of determining the relative abrasion resis-tance of materials and coatings for optical and IR transparentmaterials and coatings. The test parameters for this test methodcan be directly related to dust cloud densities and velocities towhich transparent
20、materials are exposed in the field.6. Apparatus6.1 Dust Erosion Abrader, as illustrated in Fig. 1. The testapparatus simulates flight through dust environments by blow-ing crushed silica particles, at a controlled mass flow rate andvelocity, onto samples that are stationary in the direction ofpartic
21、le flow. The dust erosion abrader consists of four distinctsubsystems: transport gas system, dust particle delivery sys-tem, dust velocity calibration system, and specimen platform.6.1.1 The transport gas system carries the dust particles atspecified velocity. The transport gas for the particles may
22、 bedry air or nitrogen. The transport gas shall be controlled by asystem of precision regulators and pressure transducers androuted through a nozzle which produces stable flow for theparticle sizes and velocities of interest. Dust particles areaccelerated to target velocities in a circular jet forme
23、d by theexpansion of compressed gas in the nozzle. The nozzlesconforming to Fig. 2 have been shown to produce stable flowfor inlet pressures in the range 5.50 to 620 kPa (0.800 to 90.0psi). The nozzle consists of converging-diverging sections,which accelerate the gas phase to supersonic speeds, and
24、aconstant diameter extension which provides sufficient residenttime for particle acceleration. Fig. 3 shows typical stablevelocities that can be achieved using the nozzle in Fig. 2. Thenozzle mount shall include adjustments for convenient accessto the specimen platform during mounting of the specime
25、nFIG. 1 Dust Erosion ChamberF1864052holder and for positioning the nozzle a distance of 25.4 mm(1.00 in.) from the specimen after mounting.6.1.2 The dust particle delivery system directs particles intothe transport gas stream. The delivery system shall deliveruniform and consistent mass flow over th
26、e range of 0.200 to10.0 g/min. The system consists of a pressurized holdingcontainer for the dust and a mechanism for directing the dustinto the transport gas stream. A screw feeder system housed ina pressurized plenum (Fig. 4) has been demonstrated to providethe required mass flow. The particle del
27、ivery system shallpossess control instrumentation separate from the transport gascontrol system so that mass flow rate of the dust can becontrolled independent of the transport gas velocity.6.1.3 The dust velocity calibration system shall consist of anoninvasive velocity measurement system (VMS) suc
28、h thatparticle velocity may be calibrated to transport gas pressureand dust mass flow rate. The laser doppler velocimeter (LDV)shown in Figs. 5 and 6 has been demonstrated to provide therequired velocity measurements. In-situ monitoring of velocityduring dust exposure is recommended. However, if the
29、 size orconfiguration of the noninvasive VMS prohibits in-situ moni-toring, pre- and post-exposure calibration shall be conducted toensure that the velocity/pressure calibration has remained validthrough the test.6.1.4 The specimen platform and test bed consists of stagesand fixtures onto which test
30、 specimens and the nozzle aremounted. The test bed shall include adjustments such that dustparticle incidence angles range from normal to 70 off-normal.Because the particle stream is substantially smaller than thespecimen holder, the specimen platform shall translate bothhorizontally and vertically
31、through the particle stream to ensureuniform coverage of all specimens. Screw-type mechanisms orFIG. 2 Recommended Nozzle ConfigurationF1864053stepper motors are recommended for platform translation.Translation rates shall be adjustable from 0 to 30 translationcycles per minute horizontally and 0 to
32、 4 translation cycles perminute vertically. The translation range shall be sufficient topermit the outermost specimens to translate completely past thedust jet in all directions. The specimen platform shall accom-modate a variety of test sample geometries. Samples ranging insize from 25.4 mm (1.00 i
33、n.) in diameter to 152 mm (6.00 in.)square have been exposed in the test bed shown in Fig. 7. Thespecimen platform shall include adjustment for convenientmounting of samples. Sample holders shall include a frontalmask to control the abraded area and prevent abrasion nearsample edges. The frontal mas
34、k shall include tapered edges(Fig. 8) to direct the dust flow onto the sample.6.2 A wire-cloth particle sieve shall be used to obtainspecific particle-size ranges. A continuous flow vibrating sieveFIG. 3 Typical Velocity/Pressure Profile for Fig. 2 NozzleFIG. 4 Screw Feeder and Pressurized PlenumFIG
35、. 5 Laser Doppler Velocimeter CalibrationF1864054system (Fig. 9) is recommended for optimum and efficientsieving of bulk sand. Sieve nominal dimensions and permis-sible variations shall comply with the U.S.A. Standard TestSieves Standard Series as detailed in Specification E11.6.3 Integrating Sphere
36、 Photoelectric Photometer,asde-scribed in Test Method D 1003, shall be used to measure thelight transmitted and scattered by the abraded surface ofoptically transparent materials and coatings.6.4 Fourier Transform Infrared (FTIR) Spectrometer shallbe used to measure the IR transmission properties of
37、 IRtransparent materials and coatings. The spectrometer shall becapable of measuring percent transmission in the 8- to 12-mbandwidth. A number of self-contained commercial FTIRsystems existing on the market have been demonstrated toprovide the required measurements. Spectrometers used in thistest me
38、thod shall comply with applicable sections of PracticesE 168.7. Materials and Reagents7.1 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Type II of Specification D 1193.FIG. 6 Laser Doppler Power Supply and InstrumentationFIG. 7 D
39、ust Erosion Test Bed with Programmable Stepper MotorsFIG. 8 Typical Frontal MaskFIG. 9 Continuous Flow Vibrating SieveF18640557.2 Crushed Silica SandThe dust particles shall consist ofcrushed silica sand. The sand shall be dry, nonclogging, andhave corners and edges that have not been rounded by oth
40、erthan the crushing process. Bulk dust particle sizes shall beuniformly distributed in the range 10 to 250 m.7.3 Compressed Air or NitrogenThe transport gas shall bedry and pressurized to a minimum of 827 kPa (120 psi) at thesource.7.4 Isopropyl Alcohol SolutionMix isopropyl alcohol(C3H7OH) with wat
41、er in a volumetric ratio of 1:1.8. Test Specimens8.1 Optically Transparent MaterialsTest specimens shallbe clean flat samples of the material or substrate/coatingsystem to be evaluated. Sample dimensions, including thick-ness, may be of any convenient dimension that can beaccommodated by the specime
42、n platform and test bed, with aminimum exposed surface area of 363 mm2(0.750 in.2).Samples ranging in size from 25.4 to 152 mm (1.00 to 6.00 in.)square have been found to accommodate most test require-ments. Sides of samples shall be substantially plane andparallel. Edge chipping and coating delamin
43、ation resultingfrom sample fabrication or preparation shall not extend into theunmasked portion of the sample.8.2 IR Transparent MaterialsTest specimens shall beclean flat samples of the material or substrate/coating system tobe evaluated. Sample dimensions, including thickness, may beof any conveni
44、ent dimension that can be accommodated by thespecimen platform and test bed, with a minimum exposedsurface area of 363 mm2(0.750 in.2). Samples 25.4 mm (1.00in.) in diameter have been found to be suitable for most testrequirements. Edge chipping and coating delamination result-ing from sample fabric
45、ation or preparation shall not extend intothe unmasked portion of the sample.8.3 Apply specimen ID numbers to the edges of specimensusing a permanent marker suitable for the material beingexposed.8.4 For each exposure condition, prepare and test a mini-mum of three samples.8.5 For storage purposes,
46、wrap samples in lint-free tissue orother suitable materials to prevent scratching or marring of thesurface.9. Preparation of Apparatus9.1 Identify the distribution of dust particles to be used inthe exposure and sieve the bulk sand to the desired distribution.Follow the operating directions of autom
47、ated sieving equip-ment if used. (WarningSieving of the bulk sand can createsmall airborne dust particles that can irritate the nose, throat,and lungs. Wear a breathing mask appropriate for the particlesize being sieved to minimize the hazard of inhaling airbornedust particles.)9.2 Fill the pressuri
48、zed holding chamber with the dustrequired for the exposure run.9.2.1 If the holding container requires simple replenishmentof dust, remove the chamber lid and add the required amountof dust. Check all pressure seals for damage, and replace ifdamaged or worn. Carefully replace the lid, ensuring thech
49、amber is adequately sealed.9.2.2 If the subsequent exposure run requires exchangingdust sizes, remove the chamber lid and remove the dust fromthe previous run. Thoroughly clean all chamber and deliverysystem components (disassemble if necessary) to remove alltraces of the previous dust. Wipe holding chamber surfaceswith a lint-free towel dampened with isopropyl alcohol solu-tion. Add the required amount of dust for the next exposurerun. Check all pressure seals for damage, and replace ifdamaged or worn. Carefully replace the lid, ensuring thechamber is adequatel
