Paraffinic resins, in high temperature applications, improve strength of thin lubricant film in Hertzian contacts even though they do not increase bulk oil viscosity. Use of resin circumvents corrosivity and high volatility problems inherent with many chemical additives

Johnson, R. L.

Loomis, W. R.

English

NASA Technical Reports Server

October 1971
	
Brief 71-10394 
NASA TECH BRIEF 
Lewis Research Center 
-. 
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commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
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be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
J•iiiiii	 -.	 ---	 .- -	 -' 
Resin Additive Improves Performance of High-Temperature

Hydrocarbon Lubricants 
.
The lubricating performance of selected naph-
thenic and paraffinic hydrocarbon lubricants has been 
significantly improved by the use of a resin 
additive. Advanced aircraft engines and other highly 
developed machinery show a continuing trend toward 
operation at higher speeds and higher temperatures. 
Bearings and other mechanical components require 
improved lubricants for operation at these increas-
ingly severe conditions. The solid surfaces in such 
components must be separated by stable films at 
high shear rates and high tempera.ures without 
deterioration of either the lubricant or the surfaces. 
Several lubricants evaluated in a series of 
screening tests using 25-mm bore angular-contact 
ball bearings included: (I) synthetic-paraffinic 
hydrocarbon; (2) super-refined naphthenic mineral 
oil; (3) super-refined naphtheiiic mineral oil plus 
resin additive; and (4) synthetic-paraffinic hydrocarbon 
plus resin additive. 
In the high temperature application, the paraffinic 
resins, commercially developed as viscous, non-
volatile, stable lubricants for use as hydraulic 
fluids and low speed industrial gear lubricants, or 
for blending with such fluids and lubricants to 
improve viscosity, improve the strength of the thin 
lubricant film in the Hertzian contacts even though 
they do not increase the bulk oil viscosity. 
One-hundred-hour tests at 590 K and 44,000 rpm 
were conducted on 25-mm bore angular-contact 
(maximum Hertz stress 1,509 GN/m 2) ball bearings 
with each of the candidate lubricants. The best of a 
number of lubricants tested, with regard to film 
strength and ability to prevent lubrication distress, 
surface damage, and lubrication related failures 
of the bearings, proved to be the super-refined
naphthenic-mineral oil base blended with 10% by 
weight of high molecular weight heavy paraffinic 
resin. Other data suggest that as little as two percent 
can also be effective. 
Addition of the resin permitted the successful 
completion of 100-hour bearing tests with the for-
mulated lubricants. Without the resin addition to the 
fluids, the bearings failed considerably short of the 
100-hour period, generally at less than 50 hours. 
Bearing raceway distress such as surface glazing or 
spalling was reduced or eliminated by the resin 
addition. 
A substantial lubricant film is desirable for 
preventing metal-to-metal contact. However, where 
there are asperities, there is some contact, increas-
ing the importance of chemical and physical 
factors that inhibit welding and reduce friction. The 
prevention of surface-initiated spalling under 
glazing conditions and other forms of surface 
distress could preclude early bearing failure in the 
thin film region, both elastbhydrodynamic and bound-
ary. For example, the performance of the fully 
formulated naphthenic mineral oil without the resin 
additive was unsatisfactory under the marginal 
operating conditions. This deficiency was overcome by 
the addition of the heavy paraffinic resin. 
Conceptually, the resin, a complex long-chain 
high molecular weight hydrocarbon, preferentially 
absorbs on the critical lubricated surfaces. Thus, 
the lubricating properties of a fluid can be substanti-
ally improved without adversely affecting the bulk 
physical properties or reducing the thermal 
stability of the formulated lubricant. The use of the 
resin also circumvents the corrosivity and high 
volatility problems inherent with many chemical 
additives.	 rieai 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19710000392 2020-03-17T02:30:24+00:00Z
Notes: 
1. The following documentation may be obtained 
from: 
National Technical Information Service 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.95) 
Reference: 
NASA-CR-726 15 (N70-22075), High Tempera-
ture Lubricant Screening Tests
2. Technical questions may be directed to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B71-10394 
Patent status: 
No patent action is contemplated by NASA. 
Source: W. R. Loomis and R. L. Johnson 
Lewis Research Center 
(LEW-1 1364)
. 
Brief 71-10394	 Category 04


Resin additive improves performance of high-temperature hydrocarbon lubricants

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