×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Hygroscopic moly disulfide
2

Hygroscopic moly disulfide

Hygroscopic moly disulfide

(OP)
Has anyone any experience of molybdenum disulfide (MoS2) dry lube, in its baked (heat-polymerized) version, taking up humidity from humid atmospheres, thereby increasing its friction coefficient ? Increase in apparent friction factor during fastener torque/tension characterization tests has been experienced, although this may be due to film breakdown in humid conditions under the high point loads involved.

Yates

RE: Hygroscopic moly disulfide

2
Take a look at the NASA publications that Kenneth provides links to in thread 404-32366.  Very good discusion of wet atmosphere effects on MoS2.  Also, book by A.R. Lansdown, entitled "Molybdenum Disulphide Lubrication" (Elsevier Tribology Series, 35, 1999).

RE: Hygroscopic moly disulfide

(OP)
Thanks for the tip TEV

Kenneth, any chance of getting your NASA link in thread 404-32366, TEV mentioned this link, but I have no access to it as Keyword search is down.

RE: Hygroscopic moly disulfide

Yates - with my regards to Kenneth, I have copied his posting from thread 404-32366 and added a star to it for you:

From Kenneth:

NASA SPACE VEHICLE DESIGN CRITERIA LUBRICATION, FRICTION, AND WEAR
NASA SP-8063: http://mtrs.msfc.nasa.gov/mtrs/71/sp8063.pdf
(See Section 2.4.2.1 and Table VI)  Excerpt: "There are bonded solid lubricants ... which combine relatively small quantities of graphite with major portions of MoS2.  There behavior in vacuum is dominated by MoS2, and they perform satisfactorily with respect to friction."

NASA/TM-1999-107249, Chapter 7
Aerospace Mechanisms and Tribology Technology:
Case Studies: http://gltrs.grc.nasa.gov/reports/1999/TM-1999-107249-CH7.pdf
(See Sections 7.2.3.2 and 7.2.3.3)


NASA/TM-1999-209088/PART1
Friction and Wear Properties of Selected Solid Lubricating Films
Part 1: Bonded and Magnetron-Sputtered Molybdenum Disulfied and Ion-Plated Silver Films
http://gltrs.grc.nasa.gov/reports/1999/TM-1999-209088-PART1.pdf
(See Conclusions)


NASA/TM-2000-107249/Chapter 6
Solid Lubrication Fundamentals and Applications Friction and Wear Properties of Selected Solid
Lubricating Films: Case Studies: http://gltrs.grc.nasa.gov/reports/2000/TM-2000-107249-CH06.pdf
(See Table 6.2)


NASA/TM-2001-210360
Durability Evaluation of Selected Solid Lubricating Films
http://gltrs.grc.nasa.gov/reports/2001/TM-2001-210360.pdf
(See Experimental Results and Discussion)


Metals Handbook, Volume 18: Friction, Lubrication, and Wear Technology:

"In spite of its desirable crystal structure, graphite is not an intrinsic solid lubricant.  It lubricates in are but fails to lubricate at high temperatures or in vacuum.  Savage (Ref 21) reported convincing experimental evidence that graphite must absorb moisture or other condensable vapor such as hydrocarbons in order to be lubricative.  The model appeared to be substantiated by the observation that, even in the presence of condensable vapors, graphite failed to lubricate above the desorption temperature.

However, Peterson and Johnson (Ref 10) observed that graphite again becomes lubricative at high temperatures when the lubricated metal becomes visibly oxidized... The authors postulate that restoration of lubrication ... was due to interaction of graphite with oxides of the metal.  The surface oxides were thought to promote adhesion of the graphite to the lubricated surfaces.  The maximum temperature for lubrication with graphite films is limited by oxidation to about 550°C (1020°F)."

RE: Hygroscopic moly disulfide

Yates:  The original thread was by Boomerang, entitled "PTFE Graphite Molybdenum Disulphide".  It is about the 25th thread down in the Mechanical Engineering Other Topics forum.  It is quite lengthy.  Sorry I didn't include this in my original post.  I couldn't find it, but I have since learned how.  I am somewhat new to this site and an still learning my way around.

You chould also note that Kenneth states in a later post in the same thread that the first link is dead, and he gives another link to the same material.

RE: Hygroscopic moly disulfide

You can create links to other posts.  In this case:

Thread404-32366

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close