From "Wear Debris Analysis"

An important tool used by analysts world-wide in determining material composition is spectrometric analysis. The spectrometric examination of particles usually requires much more expensive laboratory equipment. The glossary of terms describes a number of these analyzers, but generally what is achieved is a listing of the elements within the particle, or the compounds present. Where proportions are also determined, actual metal alloys can be identified, and hence the most likely origin of wear particles. Where compounds are suggested, then the presence of additives as well as debris may be decided. Those spectrometers which require the particle to be burnt will work only where the mass of the particle is sufficiently small. This means that the size limit associated with each spectrometer must be adhered to, otherwise totally misleading results will be achieved (8 microns or less may be the maximum particle size to be detected).

The basic idea of spectrometry is to cause the elements in a sample substance – in our case, the debris particle – to become excited and give away their presence! The excitation may arise from X-rays or high temperatures (up to 10,000 K), and the detection of the elemental wavelength could be by a photographic monochromator or ion detectors.

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QUESTION: What is the No. 1 contributor to abrasive wear?

Get the answer.

"Does molybdenum disulfide really bond with conveyor chain pins and links? When we take out a section of chain, inspection of wear on the pins and the links show only bright shiny metal with no darker buildup of moly. The only place that has any buildup is on the outside of the wear area, and this is a grease-type of a buildup. It seems to block the oil from getting down to the pins."

Yes, moly does bond with metallic surfaces. Moly most certainly helps minimize wear during periods of poor film thickness (which we call 'boundary' film condition. However, the bonding is not like Teflon bonding to a frying pan. The attraction that moly has for metallic surfaces allows the moly to adhere to the surfaces (from the "disulfide" component of the molecule), but as the surfaces rub, the adherent moly is wiped off and must be replenished.

Your pins should have a gray tint to them as a result of the moly coating the surfaces, but the moly is not going to grease a contiguous layer and complete obscure metallic surface area from view unless you are replenishing heavily enough that whenever the additive is taken off, it may be immediately replenished.

Mike Johnson, Noria Corporation

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