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1)  Performance of Fluid and Solid Lubricants in Spacecraft Applications, P. D. Fleischauer, J. Synth. Lubrication, 12(1), 1 (1995)

2)  Space-Flight Experience and Life-Test Performance of a Synthetic Hydrocarbon Lubricant, B. Bialke, 6th European Space Mechanisms & Tribology Symposium, Zurich, October 4-6, 1995.

An alternative wet-lubricant known as Pennzane TM SHF X2000 is recommended for some space-flight bearing systems where synthetic fluorocarbons such as Bray 815Z (and Fomblin Z-25) have proven to be unsatisfactory due to the potential for polymerization. 

In this paper, a comparison of the performance characteristics between Pennzane SHF X2000 and Bray 815Z is presented, followed by a compilation of the accumulated ITHACO life test data of the Pennzane SHF X2000 in four different mechanisms. 

The life tests have demonstrated excellent performance with continuous operation approaching three years in conservative operating environments.  In addition, space-flight performance data is provided for several of the tested mechanisms which have been operating successfully on-orbit since February 1994.

3)  On the Rheological Behavior of Synthetic Fluids Thickened by Solid Additives, P. Vergne and P. Prat, J. Synth. Lubrication, 15(3), 163 (1998).

4)  Cycloaliphatics, E. W. Casserly and C. G. Venier, Chapter 15 in Synthetic Lubricants and High-Performance Functional Fluids, Rudnick, L. R. and Shubkin, R. L., editors, Marcel Dekker, New York, NY 1999.

5)  Performance Evaluation of some Pennzane®-Based Greases for Space Application, A. K. Rai, M. Massey, L. Gschwender, C Snyder, J. Zabinski, and S. Sharma, 33rd Aerospace Mechanisms Conference, May 20, 1999, Pasadena, CA.

6)  Thermal characteristics of multiply alkylated cyclopentane and perfluoropolyether, Chun, S. W.; Talke, F. E.; Kang, H. J.; Kim, W. K., Tribology Transactions (2003), 46(1), 70-75 CODEN: TRTRE4; ISSN: 1040-2004

The thermal stability and degrdn. mechanism of a multiply alkylated cyclopentane and perfluoropolyether is investigated as a function of aluminum oxide, exposure time and environmental conditions.  It is found that the multiply alkylated cyclopentane does not catalytically react with Al2O3 since fluorine atoms and acetal units leading to Lewis acid are absent in cyclopentane mols.  However, the multiply alkylated cyclopentane is affected by temperature leading to thermal oxidation.

The perfluoropolyether is strongly affected by the presence of Al2O3 leading to chain scission at both mid and end-chain.  This results in faster weight loss than for the multiply alkylated cyclopentane, i.e., the thermal stability of the multiply alkylated cyclopentane is superior to that of the perfluoropolyether.

7)  Relative lifetimes of MAPLUB(TM). Greases for space applications(c), Marchetti M.; Jones Jr. W.R.; Sicre J., Lubrication Engineering 59/6 11-15 (June 2003).  ISSN: 0024-7154.

A Spiral Orbit Tribometer (SOT) was used to evaluate the tribological behavior and relative lifetimes of several commercially available greases under ultrahigh vacuum.  The greases were either based on a multiply alkylated cyclopentanes oil, or a perfluoropolyalkylether oil, and a thickener made of polytetrafluoroethylene (PTFE) telomer. 

The MAPLUB(TM) greases based on MAC oil showed a much greater lifetime than perfluoropolyalkylether-based greases.  Their lifetimes were of the same order of magnitude as Rheolube(TM) 2000, also based on MAC oil.  The presence of MoS(sub)2 increased the lifetime of the MAC-grease, and the presence of PTFE compound within the grease caused a progressive increase in the friction coefficient of the lubricant tested with the SOT. 

The SOT clearly made a distinction between the capabilities of different fluid lubricants.  Table, diagram, spectra, 23 references

8)  Spiral Orbit Tribometry - Part II: Evaluation of Three Liquid Lubricants in Vacuum, Pepper S.V.; Kingsbury E.P., Tribology Transactions 46/1 65-69 (January 2003).  ISSN: 1040-2004.

The coefficients of friction and relative degradation rates of three lubricants run in the boundary regime in vacuum were studied using a Spiral Orbit Tribometer (SOT).  SOT is a new rolling contact tribometer which is basically a thrust bearing consisting of a ball and flat races, with the ball driven in a spiral orbit by a rotating plate.  This tribometer subjected the lubricants to rolling contact conditions similar to those found in angular contact ball bearings. 

A multiply alkylated cyclopentane hydrocarbon lubricant suffered degradation at a rate almost two orders of magnitude less than the degradation rate of two perfluoropolyalkylether lubricants.  2 diagrams, spectra, and table

9)  Comparative physical and tribological properties of three Pennzane fluids, SHF X-1000, SHF X-2000, and SHF X-3000, Venier, Clifford G.; Jones, William R., Jr.; Jansen, Mark J.; Marchetti, Mario, European Space Agency, [Special Publication] SP (2003), SP-524, 337-340 CODEN: ESPUD4; ISSN: 0379-6566

Pennzane SHF X-2000, by itself or contg. additives or formulated into a variety of greases, has become an often used lubricant for aerospace applications.  A recent bibliog. contains over 100 refs. to Pennzane SHF X-2000 in the literature.  This paper serves to announce that two new Pennzane Synthesized Hydrocarbon Fluids, X-1000 and X-3000, will be available. 

Pennzane SHF X1000 is about half as viscous at low temperature as Pennzane SHF X2000, with almost the same low outgassing.  Pennzane SHF X3000 is a thickened version of X2000 having a viscosity at 100°C of 200 cSt, compared to that of X2000 at 14.5 cSt.  This paper provides a listing of phys. and tribol. properties of all three Pennzane fluids, and will compare them to a linear perfluoropolyether (Brayco 815Z or Fomblin Z-25). 

Phys. properties include viscosities at high and low temps., vacuum outgassing weight loss and condensables, and thermal properties, among others.  Spiral Orbit Tribometry shows all three Pennzane fluids to have much longer useful lifetimes than PFPEs.  Pennzane SHF X1000 has significantly better low temperature bearing torque than X2000 and is comparable to Z-25 at -15°C.

10)  The Tribological Properties of Several Silahydrocarbons for Use in Space Mechanisms, Jones Jr. W.R.; Jansen M.J.; Gschwender L.J.; Snyder Jr. C.E.; Sharma S.K.; Predmore R.E.; Dube M.J., Journal of Synthetic Lubrication 20/4 389-301 (January 2004).  ISSN: 0265-6582.

Silahydrocarbons are members of a relatively new class of liquid lubricants with great potential for use in space mechanisms.  The tribological properties (viscosity-temperature, viscosity-pressure, vapor pressure, lubricant life, traction, and reciprocating and four-ball wear rates) of several members of silahydrocarbons (tri-, tetra-, and penta-compounds) were presented.  These properties were compared to those of existing state-of-the-art space lubricants.

Silahydrocarbons yielded pressure-viscosity coefficients substantially greater than Pennzane, which would result in thicker EHL films.  Silahydrocarbons provided lower traction coefficients compared to paraffinic mineral oils. 2 diagrams, 3 tables, 2 photographs, and 7 graphs

11)  Life of scanner bearings with four space liquid lubricants, Bazinet D.G.; Espinosa M.A.; Loewenthal S.H.; Gschwender L.; Jones Jr. W.R.; Predmore R.E., NASA/CP-2004-212073, 37th Aerospace Mechanisms Symposium, May 19-21, 2004

The results of a life test program to evaluate bearing life with different space lubricants and cleaning solvents is presented.  Thirty pairs of flight-like scanner bearings were tested over a period of seven years.  Lubricants included two well known perflorinated space oils (Brayco 815Z and Krytox 143AB), a more recent synthetic hydrocarbon oil (Pennzane 2001), and one yet to be in space service (silahydrocarbon oil). 

Bearings lubricated with Pennzane 2001 oil were found to have the longest lives.  Life improvements up to 18X relative to perflourinated oils and 3X relative to the silahydrocarbon oil were measured.  No statistically significant life improvement was found with TiC-coated balls relative to standard plain steel balls for Pennzane 2001 bearings. 

Bearing life was generally longer when the bearings were cleaned with ozone-safe aqueous or hydrocarbon (HFC) solvents as alternatives to the discontinued CFC-113.

12)  New types of liquid lubricants for aerospace, Feng D.; Wang H.; Liang Y.; Liu W., Fuels and Lubes International 11/1 24 (First Quarter 2005).  ISSN: 0117-9470.

Spacecraft contain various instruments and mechanisms that require lubrication.  For decades, many organic liquid lubricants, e.g., silicon oils, mineral oils, polyalphaolefins, perfluoropolyether, polyolesters, and multi-alkylated cyclopentanes, were used in space.

To obtain liquid lubricants with good performance for aerospace, efforts were made for chemical synthesis and tribological investigation for some new types of silicon oil, which contain chlorobenzene and trifluoropropyl.This is an abstract of a paper presented at the 11th Annual Fuels & Lubes Asia Conference (Beijing, China 3/15-18/2005).

13)  Deposition and measurement of nanoscale complex hydrocarbon films on magnetic hard disk surfaces, Gates R.S.; Hsu S.M.; Gunsel S., Proceedings of the World Tribology Congress III - WTC 2005 (ASME, Tribology Division 2005 World Tribology Congress III, Washington, D.C. 20050912-20050916) 2p (2005) Paper No. WTC2005-64308.

Measurement of complex hydrocarbon film thickness on engineering surfaces such as magnetic hard disks is difficult when the film thickness is below the peak to valley distance of the surface roughness.  A novel calibration technique that allows accurate measurement of such films within 5-10% accuracy was developed. The hydrocarbon lubricant used was a multiple alkylated cyclopentane synthetic compound. 

The ability to deposit known and controlled thicknesses of hydrocarbon films on magnetic hard disk surfaces had significant impact on the potential exploration of this branch of lubricant chemistry.  This is an abstract presented at the World Tribology Congress III (Washington, DC 9/12-16/2005).  Diagram, 3 graphs, and photograph

14)  The effect of 17-4 PH stainless steel on the lifetime of a Pennzane® lubricated microwave limb sounder antenna actuator assembly ball screw for the Aura spacecraft, Jones, W.R.;  Jansen, M.J.; Chen, G.-S.; Lam, J.; Balzer, M.; Lo, J.; Anderson, J.; Schepis, J.P., 11th European Space Mechanisms and Tribology Symposium (ESMATS 2005), 2005, p. 57-63 of vi+360 pp., 13 refs. Published by: ESTEC, Noordwijk, Netherlands Conference: 11th European Space Mechanisms and Tribology Symposium (ESMATS 2005), Lucerne, Switzerland, 21-23 Sept. 2005

During ground based life testing of a microwave limb sounder (MLS) antenna actuator assembly (AAA) ball-screw assembly, lubricant darkening and loss were noted when approximately 10% of required lifetime was completed. The MLS-AAA ball screw and nut are made from 17-4 PH steel, the nut has 440C stainless steel balls, and the assembly is lubricated with a Pennzane® formulation containing a three weight percent lead naphthenate additive. Life tests were done in dry nitrogen at 50°C.

To investigate the MLS-AAA life test anomaly, Spiral Orbit Tribometer (SOT) accelerated tests were performed. SOT results indicated greatly reduced relative lifetimes of Pennzane® formulations in contact with 17-4 PH steel compared to 440C stainless steel. Also, dry nitrogen tests yielded longer relative lifetimes than comparable ultrahigh vacuum tests. Generally, oxidized Pennzane® formulations yielded shorter lifetimes than non-oxidized lubricant.

This study emphasizes surface chemistry effects on the lubricated lifetime of moving mechanical assemblies

15)  Heat transfer across ball bearings in vacuum., Takeuchi, Yoshimi R. ; Demsky, Steven M.; Dickey, James T.; Eby, Matthew A., Proceedings of the ASME Summer Heat Transfer Conference v 1 2005.p 167-175, arn: HT2005-72410 Proceedings of the ASME Summer Heat Transfer Conference, HT 2005 ISBN: 0791847314

Accurate spacecraft bearing temperature predictions often require both system and bearing level heat source and thermal conductance information. Bearing thermal conductance data is usually the most significant unknown in the development of the thermal model and little has been published in open literature on the subject.Consequently experiments have been conducted at The Aerospace Corporation to address this topic, with special attention given to applications such as high-speed momentum and flywheels.

An experiment was designed to measure thermal conductance across a single bearing under both static and dynamic states. This paper will describe the test results for an angular-contact ball bearing under controlled inner race rotational speed, axial load, and thermal conditions. Tests were conducted on both dry and Nye Pennzane SHF2001 synthetic oil lubricated bearings.

Test data showed that thermal conductance is sensitive to a complex interdependent set of variables including maximum run-in speed, axial load and temperature. A basic physical understanding of the heat transfer mechanism across a bearing was developed based on experimental results. Copyright $CPY 2005 by ASME. 12 Refs.

16)  Award Winning PENNZANE(R) Lubricants Are Now Available in Customized Viscosities., , Business Wire, (9 Aug 2005).

FAIRHAVEN, Mass. -- PENNZANE(R) Synthesized Hydrocarbon Fluid, a low-vapor-pressure lubricant for vacuum and space based applications, is now available in two new grades, PENNZANE X1000 and PENNZANE X3000.

The introduction of higher and lower viscosity fluids opens the door to a wide range of PENNZANE fluid viscosities and expands the number of applications that can use this unique synthetic hydrocarbon lubricant. THIS IS THE FULL TEXT: COPYRIGHT 2005 Business Wire

17)  Presentations for 73rd annual meeting: Tribological Comparison of Pennzane-based grease to PFPE-based grease by ASTM D3704, Baker K.N., NLGI Spokesman 70/7 13 (October 2006).  ISSN: 0027-6782.

Alternative greases to PFPE chemistry were evaluated by block-on-ring oscillating wear tests (ASTM D3704) to support recent aerospace proposal work.  The application is to lubricate gear actuators for a commercial aircraft in conventional takeoff, suborbital flight, and return for conventional landing. 

Due to the range (temperature and pressure) involved, the application is deemed best suited to a new class of lubricants based upon multiple allcylated cyclopentane (MAC or trade-name Pennzane.trademark.). Such greases have been bench tested for space application with very promising results. MAC-based grease has the advantage in better wear resistance but the PFPE-based greases have the advantage of greater service temperature range and lower outgassing (lower vapor pressure).

18)  Life of scanner bearings with four space liquid lubricants, Bazinet D.G.; Espinosa M.A.; Loewenthal S.H.; Gschwender L.; Jones Jr. W.R.; Predmore R.E., Journal of Synthetic Lubrication 23/2 81-90 (April/June 2006).  ISSN: 0265-6582.

A life test program was used to evaluate bearing life with different space lubricants and cleaning solvents.  Lubricants included two well-known perfluorinated space oils (Brayco 815Z.trademark. and Krytox 143AB.trademark.), a more recent synthetic hydrocarbon oil (Pennzane 2001.trademark.), and one yet to be in space service (pentasilahydrocarbon oil). 

Bearings lubricated with Pennzane 2001 were found to have the longest lives.  Krytox 143 AB offered no life improvement relative to Brayco 815Z. The introduction of TiC-coated balls showed no statistical significant life improvement relative to the standard 440-C stainless steel balls for the Pennzane-lubricated bearings. Heptane was used to reclean the bearings prior to lubricating with the pentasilahydrocarbon lubricant. It also showed performance as good or better than Freon 113.

The pentasilahydrocarbon bearings enjoyed about a six times life advantage at 90% reliability.  Bearings lubricated with the four test oils exhibited similar failure distributions, i.e., Weibull slope.  Life differences between Krytox 143AB and Brayco 815Z lubricated bearings were not statistically significant.  2 tables, 2 graphs, spectra, 3 photomicrographs, and 2 diagrams

19)Precision Bearing Grease Selection Guide. Final rept., Rhee, I., 2006(24):00613   NTIS Order Number: ADA450746/XAB

The study was initiated to develop a precision bearing grease selection guide. As a pan of this study, forty lubricating greases used in precision bearings, including instrument bearings was evaluated in a comprehensive series of laboratory tests in order that their properties can be compared and to identify potential lubricating greases for the replacement of unavailable greases. The duration of this study was three years including laboratory testing and preparation times.

This study was accomplished in a joint effort between TARDEC and NRL and the ATM F-34 Tribology Subcommittee. TARDEC and NRL performed all routine tasks necessary to support the study with additional guidance and review was done by the ASTM F-34 Tribology Subcommittee.

20)  Tribological comparison of pennzane-based grease to PFPAE-based grease by ASTM D3704, Baker K.N., NLGI Spokesman 71/3 22-24 (June 2007).  ISSN: 0027-6782.

A comparison of wear resistance properties was conducted between a polyfluoropolyalkylether (PFPAE)-based grease and Pennzane (MAC)-based grease.  ASTM 3704 was used to measure tribology. The grease based on MAC gave the best wear resistance in ASTM D3704 protocol, which best simulates sliding of gear teeth. MAC-based grease could be substituted for the PFPAE-based grease in space systems with no loss in performance greater wear protection. Table and graph

21)  Lubricant for magnetic recording medium and use thereof, Gunsel S; Venier C; Chiu, IC, US Patent 7244522

A magnetic recording medium and method for forming the magnetic recording medium are described. The magnetic recording medium includes a magnetic layer formed on a non-magnetic support, and a lubricant layer over the magnetic layer.

The lubricant layer includes a compound selected from the group consisting of hydrocarbyl-substituted cyclopentanes, hydrocarbyl-substituted cyclopentenes, hydrocarbyl-substituted cyclopentadienes, and mixtures or derivatives thereof. The lubricant layer also may be used on a magnetic head for reading and writing information on a magnetic recording medium.

The magnetic recording medium and the magnetic head may be used to manufacture computer disk drives, compact disk drives, audio equipment, and video equipment.

22)  Effect of multiply-alkylated cyclopentane (MAC) on durability and load-carrying capacity of self-assembled monolayers on silicon wafer., Ma, Jianqi ; Liu, Jianxi; Mo, Yufei; Bai, Mingwu, Colloids and Surfaces A: Physicochemical and Engineering Aspects v 301 n 1-3 Jul 5 2007 2007.p 481-489 CODEN: CPEAEH    ISSN: 0927-7757

A novel hydrocarbon mobile lubricant, multiply-alkylated cyclopentane (MAC), was deposited on two kinds of self-assembled monolayers (SAMs), i.e.1H,1H,2H,2H-perfluorodecyltrichlorosilane self-assembled monolayer (FDTS-SAM) and decyltrichlorosilane self-assembled monolayer (DTS-SAM) to form two double-layer films by spinning coating method.

The double-layer films, which are called as MAC-FDTS and MAC-DTS, respectively, consist of a strongly bonded phase lubricant (self-assembled monolayer) and a non-bonded mobile lubricant (multiply-alkylated cyclopentane).

Friction behavior of FDTS-SAM, DTS-SAM, MAC-FDTS, MAC-DTS on silicon wafers was evaluated using a pin-on-plate test rig. Both FDTS-SAM and DTS-SAM markedly decreased the friction coefficient of Si substrate. However, they played the role of friction-reducing and anti-wear only at low loads of 50 and 100 mN, respectively.

In contrast, when MAC deposited on the two kinds of SAMs, it could markedly reduce the friction coefficient of DTS-SAM and significantly enhance their durability and carrying-load capacity from 50 and 100 mN to 150 and 200 mN, respectively. $CPY 2007 Elsevier B.V. All rights reserved. 31 Refs.

23)  Measuring the EHD Film Thickness in a Rotating Ball Bearing, Peter Ward, Alan Leveille and Peter Frantz, Proceedings of the 39th Aerospace Mechanisms Symposium, NASA Marshall Space Flight Center, May 7-9, 2008

'This paper presents two independent way to directly measure the change in axial deflection of a bearing that is proportional to the magnitude of the total elastohydrodynamic (EHD) film developed. The first uses multiple capacitance displacement gages as a direct measurement of the axial displacement and the second method uses the cahnge in operating preload force to calculate the axial change in the test fixture and bearing stack. 

Convergence of the results from two independent techniques adds confidence to the experimental process. Either method can provide accurate EHD film thickness over extended time for a complete bearing under varying load, speed, and lubrication conditions. Additionally, the methods are equally applicable to non-metallic materials, such as Si3N4 balls, which preclude the use of other techniques. 

The method has some advantages to the practicing engineer over the classical ball on a flat quartz plate because the full range of bearing design parameters and kinematic interactions are operating.

The EHD film thicknesses of two oils and one grease were measured in an operating 304 sized angular contact bearing for up to 600 hours of running time at 6000 rpm. EHD film thickness was determined by simultaneously measuring the resultant displacement and axial force change of the outer rings due to collapse of the EHD film when the bearing pair was brought from full speed to rest. Because each measurment of axial displacement was completed in 2 seconds, the results are not affected by a contribution due to thermal expansion. 

We compared a common synthetic hydrocarbon base oil (Pennzane) with a common mineral oil (Coray). We found the synthetic oil film thickness to be approximately one half that of the mineeral oil. We also compared film thickness with both large and small amounts of grease. 

We found that the large grease amount produced a prolonged run-in transient film that was thicker than the base oil steady state film. However, with a smaller amount of grease, the thickness fell to a value that was comparable to the base oil. 

Initial assessment indicates that the degree of lubricant starvation is greater than can be accounted for with conventional EHD theory.

24)  An Evaluation of Liquid, Solid, and Grease Lubricants for Space Mechanisms Using a Spiral Orbit Tribometer, Michael Buttery, Proceedings of the 40th Aerospace Mechanisms Symposium, NASA Kennedy Space Center, May 12-14, 2010

'We present the findings of the test program performed by The European Space Tribology Laboratory (ESTL) to evaluate the perfromance (friction and lifetime) of a number ofspace lubricants under vacuum using a Spiral Orbit Tribometer (SOT). 

Focus was given to a comparison of various popular space oils, a comparison study between the old and new MAPLAB grease formulations, and the performance of commonly used solid lubricants under various conditions.

Tests demonstrated that the lifetimes of hydrocarbon NYE oils 2001 & 2001A outperformed those of the perfluoropolyalkylether (PFPE) oils Fomblin Z25 & Z60, though these pairs displayed similar behavior. This relationship was also generally seen for greases;  with the lifetimes of the multiple alkylated cyclopentane (MAC)-based greases being extended in comparison to the PFPE-based greases. 

Testing on greases also demonstrated similar performance between the old (-a) and new (-b) formulations when considering PFPE-based MAPLUB greases, and indeed for all tested PFPE-based non-MAPLUB greases, but significantly shorter lietimes for the new formulations when considering MAC-based MAPLUB greases. MAPLUB MAC greases containing molybdenum disulphide (MoS2) thickener were also found to display reduced lifetimes.

For solid lubricants, lead displayed significantly extended lifetimes over MoS2, speculated to be casued by redistribution of lead from the ball onto contact surfaces during the test.  Friction coefficients were seen to be some 2.5x higher for lead than for MoS2 under similar conditions, a result that corresponds well with conventional bearing tests.

The work described was performed under contract for the European Space Agency as part of the Tribology Applications Program, with all funding for testing and apparatus provided by European Space Agency (ESA).