Project Participants Sought:

Erosion Resistant Coatings for AGT1500 Gas Turbine Engine Compressor System Powering the Abrams M1A Tank Operating in Sand / Dust Environments

The US Army’s Abrams tank will continue to comprise a significant portion of the combat force for many more years. The Abrams’ AGT1500 gas turbine engine was designed in the 1960’s and has been operating in the field beyond its intended design life. The AGT1500’s reliability contributes approximately 60% of the Abrams tank repairable O&S costs.

Operation in severe sand / dust environments, such as in OIF, exacerbates the AGT1500’s reliability by eroding the compressor airfoils. The structural integrity of an engine’s compressor system is critical in maintaining overall engine performance. An eroded compressor results in decreased shaft horsepower (shp), increased fuel consumption, increased repair and overhaul costs, decreased readiness and increased logistical support.

As a reference, the T58 turbine engine is similar to the AGT1500 in configuration (10-stage vs. 9-stage compressor) and horsepower (1800 vs. 1500 shp). The T58 completed in July 2004 a comparison engine sand ingestion test of an uncoated compressor to an MDS-PRAD Technologies ER-7 coated compressor. The ER-7 coated engine demonstrated a minimum 2 X improvement in run time and horsepower retention over the uncoated engine. If similar improvements are demonstrated on a coated AGT1500 engine, significant O&S cost savings would be achieved.

Significant fuel savings would also be realized as the health of the compressor is maintained throughout the engines field operations. Maintaining the AGT1500 fuel efficiency during operations will drastically decrease the Abrams logistical O&S footprint and increase readiness.

The ER-7 erosion resistant coating for gas turbine engine compressor systems is currently in production on the GE T64 engine powering the CH-53 Super Stallion and the GE T58 engine powering the CH-46 Sea Knight. The coating is also in different phases of evaluation for the Rolls Royce GEM and Gnome engines powering the Lynx and Sea King helicopters respectively for the Royal British Air Force; the Rolls Royce AE1107 engine for the V-22 and the Honeywell T55 engine for the Chinook helicopter. OIF fleet data on coated T64 engines has demonstrated an average time-on-wing of approximately 800 hours for the initial 40 coated engines deployed versus uncoated T64 engines averaging approximately 100 hours. The high-time T64 engine is currently at 1168 hours and zero coated engines have been removed due to low power due to erosion as compared to over 50 uncoated engines removed for the same cause. The T58 coated engines have recently been deployed to support OIF and, as of yet, have not accumulated significant operational flight hours.

MDS-PRAD’s erosion resistant coating process can build on its extensive experience base of coating over 1 million airfoils, millions of flight hours in sand / dust environments and further enhance the coating for optimum application on the AGT1500 compressor system. Additionally, MDS-PRAD’s production facility located in Prince Edward Island, Canada has sufficient capacity today to coat at a rate of 100 plus AGT1500 compressor sets per month.

Two technology demonstration approaches are offered in evaluating MDS-PRAD’s erosion resistant coating for potential application on the AGT1500 engine:

1. a “rainbow” sand ingestion test consisting of MDS-PRAD coated airfoils, other vendor coatings and one uncoated airfoil per each of the nine (9) AGT1500 stages, or

2. a “rainbow” sand ingestion test followed by an uncoated engine sand ingestion.

The first approach would allow a direct comparison of the MDS-PRAD erosion resistant coating with other coatings and to uncoated compressor airfoils in each stage. The second approach will quantify the performance retention of a coated engine versus an uncoated engine. Determining how much longer it takes for a coated AGT1500 engine to reach 50% shp loss (the performance condition which an AGT1500 engine is removed from an Abrams tank) and the fuel consumption decrease of a coated versus uncoated AGT1500 engine, will quantify the return-on-investment in implementing the erosion resistant coating technology onto the AGT1500 fleet.

The NCMS contact is Debbie Lilu, debral@ncms.org, 734-995-7038.

Recently Completed Project:

Replacement for Hexavalent Chromium in Surface Finishing Processes

The purpose of this project was to optimize a new method for electroplating hard chromium coatings (using a pulse plating process) that is safer to work with than the traditional hexa­valent chromium process, while retaining the wear resistance characteristics of a hard chrome coating.

The project produced two particularly noteworthy results. One involves a novel variation on the pulse plating method that improves the integrity of the coating beyond what was possible to achieve at the start of the project. The other raises a fundamental question on how best to define and evaluate wear resistance, and opens the possibility that the coatings produced by the new method may even be superior, from a functional point of view, to traditional coatings.

These results have taken on particular significance in light of new Federal regulations that have reduced, by a factor of ten, the permissible hexavalent chromium exposure level in the workplace. Most hard chromium electroplating facilities in the U.S. will be required to make extensive equipment changes to comply with these requirements. Retrofitting existing tanks might require investments in the hundreds of thousands of dollars.

The Faraday trivalent process, as developed over the course of this project, appears to be a good candidate to become a safer, and possibly better, process for applying hard chromium coatings than the standard hexavalent process. The next logical step is to test the performance of the trivalent coating against that of the hexavalent coating for a wide range of functional requirements in specific applications. A follow-on project is being developed for consideration in the CTMA program.

Tightening workplace regulations and mounting liability concerns will make the hexavalent process increasingly costly and risky over the next few years. It seems only prudent to begin without delay to do the work necessary to fully qualify the trivalent process for commercial and military applications.

According to a recent estimate, compliance costs associated with the new federal worker exposure rule for hexavalent chromium for one DoD facility alone will exceed $14M over the next two years. Several other DoD facilities that also carry out extensive hexavalent chromium electroplating operations may face comparable costs. If the trivalent technology lives up to the promise indicated in this report, a substantial portion of that total may well turn out to have been spent needlessly. A small fraction of the projected total invested now to resolve the issue of how hard chromium will be plated in the future could save a substantial amount of money over the next few years.

The NCMS contact is Paul Chalmer, paulc@ncms.org, 734-995-4911.