Dr. Yakov Epshteyn, Climax Molybdenum, UNITED STATES

Mr. Lawrence Corte, Climax Molybdenum, UNITED STATES

Spherical Molybdenum Disulfide (SMD) in brake pads applications

Authors:

Dr. Yakov Epshteyn, Lawrence Corte

Climax Molybdenum, A Freeport-McMoRan Company

Abstract

Molybdenum disulfide (MoS2) is one of the best known solid lubricants and is commonly found in a variety of lubrication and friction applications. In automotive brake pads, MoS2 is commonly used as a friction modifier to adjust and stabilize the friction coefficient, to eliminate squeaking noise, and for better uniformity of the distribution of friction forces across the brake pad surface.

Climax Molybdenum has developed and patented a new form of MoS2 - Spherical Molybdenum Disulfide (SMD). SMD powder was produced by spray drying of the slurry of the four different ingredients including molybdenum disulfide, liquid, a binder and a dispersant. Formulation and granulating the SMD particles can be arranged to modify the particle size, hardness, etc. It was demonstrated that the effect of oxidation through the spray drying process was insignificant. The average SMD particle size measured by MicroTrac® was about 60 microns.

For this study, a powder matrix without solid lubricants was used to evaluate the influence of various solid lubricants. The solid lubricant powders were added in a tumble mixer and subsequently pressed into pad material. Brake pads testing was conducted using the brake pad tester.

This presentation reviews the lubrication properties of brake pads containing Spherical Molybdenum Disulfide (SMD). Based on the multiple test results, it was established that brake pads containing novel SMD materials significantly outperformed conventional Molybdenum Disulfide (Climax Technical Grade) by 33.6% with respect to wear performance and by 29.1% with respect to coefficient of friction performance.

Also, it was established that the SMD with half the amount of binder was outperformed by SMD with the full amount of binder, therefore we have reason to believe that increasing the binder content of the SMD could even further improve the performance.