Coated journals

Abstract

Molybdenum disulfide (MoS 2 ) is used as a journal coating for a gearing system. A particular application is the planetary gear system of a geared turbofan engine. Particularly advantageous coatings are deposited via physical vapor deposition (PVD) techniques.

1 . A journal having: 
 a metallic body portion having a generally cylindrical outer surface with at least one lubrication port; and    a coating comprising MoS 2  on said outer surface.    
   
   
       2 . The journal of  claim 1  further comprising: 
 a pair of shaft sections unitarily-formed with the body portion.    
   
   
       3 . The journal of  claim 1  wherein the coating comprises sputter or arc-deposited MoS 2 .  
   
   
       4 . The journal of  claim 1  wherein the coating comprises fullerene-like MoS 2 .  
   
   
       5 . The journal of  claim 1  wherein the coating consists essentially of fullerene-like MoS 2 .  
   
   
       6 . The journal of  claim 1  wherein the coating comprises sputter-deposited MoS 2 .  
   
   
       7 . The journal of  claim 1  wherein the coating consists essentially of sputter-deposited MoS 2 .  
   
   
       8 . The journal of  claim 1  wherein the coating comprises fullerene-like MoS 2 .  
   
   
       9 . The journal of  claim 1  wherein the coating has an XRD (0002) peak of about 8°.  
   
   
       10 . The journal of  claim 1  wherein the coating consists essentially of arc-deposited MoS 2 .  
   
   
       11 . The journal of  claim 1  wherein the coating has a thickness between 1.0 and 2.0 μm.  
   
   
       12 . The journal of  claim 1  wherein the coating has a thickness between 0.3 and 3.0 μm.  
   
   
       13 . The journal of  claim 1  wherein the metallic body portion is a steel element on which said coating is deposited.  
   
   
       14 . The journal of  claim 1  wherein: 
 the journal is further oil lubricated in addition to the coating.    
   
   
       15 . The journal of  claim 1  in combination with: 
 a gear carried by the journal; and    an oil is delivered through the lubrication port.    
   
   
       16 . A transmission comprising: 
 a sun gear;    a plurality of planetary gears meshed with the sun gear;    a ring gear surrounding and meshed with the planetary gears; and    a gear carrier carrying a plurality of journals, each journal carrying at least an associated one of the planetary gears and each journal having a MoS 2 -based coating.    
   
   
       17 . The transmission of  claim 16  wherein the coating is sputter-deposited.  
   
   
       18 . The transmission of  claim 16  wherein the coating comprises fullerene-like MoS 2 .