1、Designation: G77 05 (Reapproved 2010)G77 17Standard Test Method forRanking Resistance of Materials to Sliding Wear UsingBlock-on-Ring Wear Test1This standard is issued under the fixed designation G77; the number immediately following the designation indicates the year of originaladoption or, in the
2、case of revision, the year of last revision.Anumber 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 laboratory procedures for determining the resistance of materials to
3、 sliding wear. The test utilizesa block-on-ring friction and wear testing machine to rank pairs of materials according to their sliding wear characteristics undervarious conditions.1.2 An important attribute of this test is that it is very flexible. Any material that can be fabricated into, or appli
4、ed to, blocksand rings can be tested. Thus, the potential materials combinations are endless. However, the interlaboratory testing has beenlimited to metals. In addition, the test can be run with various lubricants, liquids, or gaseous atmospheres, as desired, to simulateservice conditions. Rotation
5、al speed and load can also be varied to better correspond to service requirements.1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.Wear test results are reported as the volume loss in cubic millimetres for both the block a
6、nd ring. Materials of higher wearresistance will have lower volume loss.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine t
7、he applicability of regulatorylimitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedb
8、y the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D2714 Test Method for Calibration and Operation of the Falex Block-on-Ring Friction and Wear Testing MachineE122 Practice for Calculating Sample Size to Estimate, With Specified Prec
9、ision, the Average for a Characteristic of a Lot orProcessE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodG40 Terminology Relating to Wear and Erosion3. Terminology3.1 Definitio
10、ns:3.1.1 sliding wear, nwear due to the relative motion in the tangential plane of contact between two solid bodies.3.1.2 weardamage to a solid surface, generally involving progressive loss of material, due to relative motion between thatsurface and a contacting substance or substances.3.1.3 For add
11、itional definitions pertinent to this test method, see Terminology G40.4. Summary of Test Method4.1 A test block is loaded against a test ring that rotates at a given speed for a given number of revolutions. Block scar volumeis calculated from the block scar width, and ring scar volume is calculated
12、 from ring weight loss. The friction force required to1 This test method is under the jurisdiction of ASTM Committee G02 on Wear and Erosion and is the direct responsibility of G02.40 on Non-Abrasive Wear.Current edition approved April 1, 2010June 1, 2017. Published May 2010June 2017. Originally app
13、roved in 1983. Last previous edition approved in 20052010 asG77G77 05 (2010).051. DOI: 10.1520/G0077-05R10.10.1520/G0077-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, re
14、fer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all c
15、hanges accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.
16、 United States1keep the block in place is continuously measured during the test with a load cell. These data, combined with normal force data,are converted to coefficient of friction values and reported.5. Significance and Use5.1 The significance of this test method in any overall measurement progra
17、m directed toward a service application will dependon the relative match of test conditions to the conditions of the service application.5.2 This test method seeks only to prescribe the general test procedure and method of calculating and reporting data. The choiceof test operating parameters is lef
18、t to the user. A fixed amount of sliding distance must be used because wear is usually non-linearwith distance in this test.6. Apparatus and Materials6.1 Test SchematicA schematic of one possible block-on-ring wear test geometry is shown in Fig. 1.36.2 Test RingA typical test ring is shown in Fig. 2
19、. The test ring must have an outer diameter of 34.99 6 0.025 mm (1.3776 0.001 in.) with an eccentricity between the inner and outer surface of no greater than 0.00125 mm (0.0005 in.). For coupleswhere surface condition is not under study, it is recommended that the outer diameter be a ground surface
20、 with a roughness of 0.152to 0.305 m (6 to 12 in.) rms or center line average (CLA), in the direction of motion. However, alternate surface conditions maybe evaluated in the test, as desired. It should be kept in mind that surface condition can have an effect on sliding wear results.6.3 Test BlockA
21、test block is shown in Fig. 3. Block width is 6.35 + 0.000, 0.025 mm (0.250 + 0.000, 0.001 in.). Forcouples where surface condition is not a parameter under study, a ground surface with the grinding marks running parallel to thelong axis of the block and a roughness of 0.102 to 0.203 m (4 to 8 in.)
22、CLAin the direction of motion is recommended. However,other surface conditions may be evaluated as desired.6.4 Analytical Balance, capable of measuring to the nearest 0.1 mg.6.5 Optical Device (or equivalent), with metric or inch-pound unit calibration, is also necessary so that scar width can bemea
23、sured with a precision of 0.005 mm (0.0002 in.) or equivalent.7. Reagents7.1 Methanol.3 Several machines have been found satisfactory for the purposes of this test. These models may differ in lever arm ratio, load range, speed control (variable or fixed),speed range, and type of friction measuring d
24、evice.FIG. 1 Test SchematicG77 1728. Preparation and Calibration of Apparatus8.1 Run the calibration procedure that is in Test Method D2714 to ensure good mechanical operation of the test equipment.9. Procedure9.1 Clean the block and ring using a procedure that will remove any scale, oil film, or re
25、sidue without damaging the surface.9.1.1 For metals, the following procedure is recommended: clean the block and ring in a non-chlorine containing solvent,ultrasonically, if possible; a methanol rinse may be used to remove any traces of solvent residue. Allow the blocks and rings todry completely. H
26、andle the block and ring with clean, lint-free cotton gloves from this point on.9.2 Make surface texture and surface roughness measurements across the width of the block and the ring, as necessary. Notethat a surface profile does not completely describe a surface topology. Scanning electron microgra
27、phs may be used, as desired, toaugment the description of the wear surfaces. Clean the block and the ring if necessary as in 9.1.9.3 Demagnetize the metal specimens and ferrous assembly. Weigh the block and ring to the nearest 0.1 mg.9.4 Measure the block width and ring diameter to the nearest 0.025
28、 mm (0.001 in.).9.5 Clean the self-aligning block holder, ring shaft, and lubricant reservoir with solvent.9.6 Put the self-aligning block holder on the block.NOTE 1The outer diameter and concentricity with the inner diameter are the only critical parameters. The inner diameter is optional depending
29、 onmachine design. The inside diameter taper shown fits a number of standard machines.FIG. 2 Test RingFIG. 3 Test BlockG77 1739.7 Place the block in position on the machine and, while holding the block in position, place the ring on the shaft and lock thering in place, using a test method in accorda
30、nce with the requirements of the specific machine design.9.8 Center the block on the ring while placing a light manual pressure on the lever arm to bring the block and ring into contact.Be sure the edge of the block is parallel to the edge of the ring and that the mating surfaces are perfectly align
31、ed. This isaccomplished by making sure the specimen holder is free during mounting so that the self-aligning block holder can properly seatitself. Release the pressure on the lever arm.9.9 One may choose either a preloading or a step-loading procedure. Generally, preloading is chosen for variable sp
32、eedmachines, while step-loading is chosen for fixed speed machines in order to avoid an initial high wear transient. The differencesin the two procedures are indicated in 9.10 9.22.9.10 Place the required weights on the load bale and adjust the lever arm in accordance with the requirements of the sp
33、ecificmachine design. Then remove the load by raising the weights, if using the preloading procedure, or by removing the weights ifusing the step-loading procedure.9.11 If running a lubricated test, clean all components that will come in contact with lubricant; fill the lubricant reservoir withlubri
34、cant to 6.4 mm (0.25 in.) above the lower surface of the ring; rotate the ring several times.9.12 Set the revolution counter to zero.9.13 Gently lower the weights, applying the required load, if using the preloading procedure.9.14 If using a variable speed machine, turn on the machine and slowly inc
35、rease the power to the drive motor until the ring startsto rotate, recording the “static” friction force. Continue to increase the rate of rotation to the desired rate. If using a fixed speedmachine, simply turn on the machine.9.15 If using step-loading, start the machine with no weights, then gentl
36、y add a 133-N (30-lbf) load every 200 rev until therequired test load is reached. Adjust the rate of rotation as needed. If the required load is less than 133 N, apply the load in onestep.9.16 During the test, record the friction force, lubricant or block temperature, as required, and, if desired, t
37、he verticaldisplacement of the block.9.17 Stop the test manually or automatically after the desired number of revolutions.49.18 A final “static” friction force may be measured with a variable speed machine. Leaving on the full load, wait 3 min 6 10s, then turn on the machine and slowly increase the
38、power to the drive motor until the ring starts to rotate, recording the “static”final friction force. Then turn off the motor.9.19 Remove the block and ring, clean, and reweigh to the nearest 0.1 mg.9.20 Make surface roughness measurements and profilometer traces across the width of the block and th
39、e ring as desired.Atracealong the long axis of the block, through the wear scar, is also useful to verify the scar depth and shape.59.21 Measure the scar width on the test block in the center and ;1 mm (0.04 in.) away from each edge. These measurementsshall be to the nearest 0.025 mm (0.001 in.). Re
40、cord the average of the three readings. Sometimes oxidation debris or a lip ofplastically deformed material will extend over the edge of the wear scar (Fig. 4). When measuring scar width, try to visually ignorethis material or measure the scar width in an area where this is not a problem.9.22 Tapere
41、d scars indicate improper block alignment during testing. If the three width measurements on a given scar have acoefficient of variation of greater than 10 %, the test shall be declared invalid.10. Calculation10.1 Calculation of Block Scar Volume:10.1.1 Block scar volume may be derived from block sc
42、ar width by using Table 1 (applicable only when ring diameter is 34.996 0.025 mm (1.377 6 0.001 in.) and scar length (block width) is 6.35 + 0.000, 0.025 mm (0.250 + 0.000, 0.001 in.).10.1.2 The preferred method of calculating block scar volume is by using the formula shown in Fig. 5. This formula m
43、ay beprogrammed on a calculator or computer.10.1.3 Block scar volume is not calculated generally from block mass loss because block mass is subject to effects of materialstransfer, generation of oxide films, or penetration of the material by the lubricant. Keeping in mind the above factors, block ma
44、ssloss may be interpreted semiquantitatively in a comparative evaluation of various material couples. If the block scar cannot beaccurately measured following 9.21 and the guidance in Fig. 4, a scar volume should not be calculated, but a notation made ofthe problem; for example, material transfer, p
45、lastic deformation, and so forth.4 5400 and 10 800 revolutions have been used for metals in interlaboratory test programs.5 On some of the old test machines, it is possible for the block to move back and forth slightly, increasing the apparent size of the wear scar. If this problem is suspected,a pr
46、ofilometer trace through the wear scar will verify whether or not the scar shape corresponds to the curvature of the ring.G77 17410.2 Calculate coefficient of friction values from friction force values as follows:f 5F/W (1)where:f = coefficient of frictionF = measured friction force, N (lbf), andW =
47、 normal force, N (lbf).10.3 Calculate ring volume loss as follows:volume loss5ring mass lossring density (2)NOTE 1If the ring gains mass during the test, the volume loss is reported as zero with a notation that weight gain occurred. Mass loss is effected bymaterial transfer from one component to ano
48、ther, by generation of oxide films, or by infiltration into porous material by the lubricant, or combinationsthereof. If material transfer to the ring is obvious, then a ring scar volume should not be calculated from the weight loss measurement, but a notationshould be made that material transfer oc
49、curred.11. Report11.1 Report any unusual event or an overload shutoff of the machine (on some machines it is possible to have an automaticshutoff at a preset frictional load). If the machine malfunctions or a test block has a tapered scar, the data shall not be used, andthe test shall be rerun.A. A good rectangular scar with straight edges.B. The center of the scar is curved because the block was crowned. Also, debris covers the center left edge of the scar. Ordinarily, the debris should be visuallyignored, but in this case scar curvature makes this too dif
