Test Adapter

Exploded view of pinori-disk arrangement as adapted for use on Falex Model No. 6 Multi-Specimen Test Machine.

test specimens will be based on the wear mechanism. Examination with a scanning electron microscope, optical microscope, and microprobe will be used to characterize wear and degradation.

Results from this initial wear and friction testing will be used to aid in selecting coating pairs for subsequent testing with the Hohman A-6 Double Rub Shoe test machine.

After initial screening with Pin-on-Disk testing, the wear and friction properties of the best combinations will be optimized. Variations in particulate size and composition, glass composition, and solid lubricants will be explored.

The selected coating pairs will be fully characterized for wear, friction, oxidation, thermal shock, adherence, uniformity, and for coating/substrate interactions. The following tasks will be accomplished:

* Coating surface finish and surface morphology will be examined and documented.

* The specimens will be tested for oxidation resistance in a nitrogen-oxygen atmosphere controlled furnace for 500 hours. The specimens will be examined for cracks and blisters.

* The wear and friction of the selected pairs will be measured with a double rub shoe machine. The friction will be measured at ambient temperature and 350C under both lubricated and unlubricated conditions. The wear will be measured at ambient temperature and 350C under lubricated conditions only. The wear process will be characterized.

* Thermal shock testing will consist of heating the specimens to 650C and quenching them into boiling water for 50 cycles. Specimens which survive the thermal cycling will be tested for wear using Pin-on-Disk measurements.

* Coating uniformity will be established.

* Coating adherence will be tested using a Revetest machine.

A selection process will be developed which will rank the performance results of the characterization. Similar ranking will be done for the manufacture and cost considerations of each coating. The variables which will be used in the ranking of the coatings are shown Table 8. Each variable will be weighted in accordance with its impact upon meeting the objectives of an adherent, wear resistant coating with long term reliability for use in low fuel consumption diesel engines.

Performance and manufacturablility/cost factors to be used to rank the coating systems and evaluate the cost/benefit relationship of each coating.

PERFORMANCE Wear

Adhesion

Friction Coeficient Thermal shock Resistance Thermal stability

MANUFACTURABILITY/COST

Ability to automate process Cleaning required Ease of coating application -number of steps -processing time -tolerance to variation Finishing requirements

-grinding/lapping vs. honing -diamond vs. alumina hones

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