ASTM D2715-92(2007)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D2715–92(Reapproved 2007)
Standard Test Method for
Volatilization Rates of Lubricants in Vacuum
This standard is issued under the fixed designation D2715; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 5. Apparatus
1.1 Thistestmethodcoversthedeterminationoftheratesof 5.1 Recording Vacuum Microbalance, with capacity of 1 g
volatilizationoflubricantsinathermal-vacuumenvironmentat or more, sensitivity of 0.01 mg or less, zero stability of 0.025
pressures and temperatures necessary to obtain a measurable mg or less for 8 h with ranges of weight change of 10 mg or
−5
rate of evaporation, or evidence of decomposition. more, and 0.1 mg or less, capable of being pumped to 10 Pa
−7
1.2 The values stated in SI units are to be regarded as the (10 torr) or less.
standard. 5.1.1 When Procedure B for the more volatile samples is
−2 −4
1.3 This standard does not purport to address all of the used, the vacuum requirement shall be 10 Pa (10 torr) or
safety concerns, if any, associated with its use. It is the less.
responsibility of the user of this standard to establish appro- 5.2 Vacuum System—A pumping system capable of main-
−6 −5 −8 −7
priate safety and health practices and determine the applica- tainingastartingpressureof10 to10 Pa(10 to10 torr)
bility of regulatory limitations prior to use. (5.1.1). An optically dense baffle system should be used to
ensure freedom from back-streaming. A conventional bell jar
2. Referenced Documents
system with an oil diffusion pump, a mechanical back-up
2.1 ASTM Standards:
pump,andanopticallydense,liquid,nitrogen-cooledbafflehas
E296 Practice for Ionization Gage Application to Space beenfoundsatisfactoryontheconfigurationasshowninFig.1.
Simulators
5.3 Furnace, with thermocouple indicator, capable of main-
E297 Methods for Calibrating Ionization Vacuum Gage taining a constant sample temperature 63°C. All parts of this
Tubes
furnace must be proved to be usable at the highest temperature
and vacuum contemplated.
3. Summary of Test Method
5.4 Recorder, capable of recording weight changes continu-
3.1 A known quantity of specimen is placed in a thermal
ously with the balance used, to the performance specified in
vacuum balance system and the evaporated material is con-
5.1.
densed on a cold plate. The weight of the specimen is
5.5 Specimen Container, made of 300 series stainless steel
continuallyrecordedasafunctionoftimefornominalconstant
in the form of a straight cylinder with an aspect ratio of height
surface area.
to diameter of approximately 1:14. Where chemical reactions
are experienced with the container, alternative materials may
4. Significance and Use
be used.
4.1 This test method provides data for comparison of the
5.6 Contacting Thermocouple, touching solid or immersed
evaporation rate of lubricants used in unshielded bearings in
in liquid specimens, with the leads brought out in such a way
the space environment.
as not to influence balance indication.
5.7 Cold Plate—A condensing shield cooled with liquid
nitrogen to immobilize molecules evaporated from the lubri-
This test method is under the jurisdiction of ASTM Committee D02 on
cant which subtends, at least, a 160° arc from the center of the
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
sample.
D02.L0.07 on Engineering Sciences of High Performance Fluids and Solids
(Formally D02.1100).
5.8 Nude Ionization Gage, installed as described in Practice
Current edition approved May 1, 2007. Published June 2007. Originally
E296 and calibrated as described in Methods E297.
approved in 1968. Last previous edition approved in 2002 as D2715–92 (2002).
5.9 Optional Supplemental Equipment:
DOI: 10.1520/D2715-92R07.
5.9.1 MassSpectrometer,toidentifydegassingproductsand
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
evaporating species.
Standards volume information, refer to the standard’s Document Summary page on
5.9.2 Infrared Optical Pyrometer System, for determining
the ASTM website.
3 the specimen temperature. This must be calibrated against the
Withdrawn. The last approved version of this historical standard is referenced
on www.astm.org. thermocouple for each material used, due to emissivity effects.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D2715–92 (2007)
FIG. 1 Apparatus for Measuring Evaporation Rates in Vacuum
5.9.3 Copper Tab, on a cold plate facing the specimen, for 6.3 Liquid Nitrogen, commercial grade.
X-ray analysis of the condensate.
6.4 Helium, ACS purified grade.
5.9.4 Noncontact Specimen Thermocouple, calibrated
against 5.5.
7. Specimen Preparation
5.9.5 Pressure Recording Pen, added to the recorder.
7.1 Remove dissolved gases from the bulk lot prior to test
5.9.6 Time Derivative Computer, to report the rate directly.
using a separate vacuum chamber. Break the vacuum in the
6. Reagents and Materials chamber with helium. A large enough sample of material
shouldbedegassedinthispretreatmentsothatitwillsufficefor
6.1 Antiwetting Agent—A low-surface tension material for
all anticipated test runs. A mass spectrometer can be used to
coating the specimen container and the thermocouple. Its
verify complete degassing.
volatilitymustbelowenoughtocontributelessthan5%tothe
evaporation rate of any sample to be tested.
7.2 If required as evidenced by creepage of lubricant in first
6.2 Calibration Material—Pure compound of suitable
run, coat the container and the thermocouple with the anti-
physical properties to simulate the lubricant under investiga-
wetting agent (6.1). Silicones are especially likely to require
tion. (N-heptadecane and bis m-(m-phenoxyphenoxy) phenyl
this precaution.
ether have been found satisfactory. Tin provides a low evapo-
7.3 Add to the container the required amount of sample, 75
ration rate material, the performance of which can be checked
6 5 mg/cm of area exposed for evaporation. Press solids and
by the Langmuir equation.)
semisolids into the container with sufficient pressure to assure
the apparent surface area approximates the real surface area. If
4 a coherent surface cannot be achieved, note this fact in the
Freundlich, M. M., “Microbalance for Measuring Evaporation Rates in
Vacuum,” Vacuum, Vol 14, 1963, pp. 293–297. report.
D2715–92 (2007)
NOTE 2—If the sample is known to be an essentially pure compound,
8. System Calibration
repetitive measurements are permissible. If such purity is merely sus-
8.1 Calibrate the system in the vacuum, using one of the
pected, judgment may be made on the basis that a sample is not to be
calibration materials, over the temperature range to be used,
reused after a determination in the course of which the rate has changed
following the procedure shown in 9.1-9.8.
morethan25%atasingletemperature.However,ifthesupplyislimited,
8.2 Theratesobtainedarecomparedwiththosepredictedby it is possible to obtain some meaningful data on a spot basis, as indicated
below.
the Langmuir equation:
9.10 After primary data have been obtained at increasing
G 57.77p=M/T (1)
temperaturelevelsonasamplewhichmeetstheabovecriterion
where:
oflessthan25%ch
...