Engine manufacturer Pratt & Whitney, as part of the company’s “green engine” initiative, is testing an alternative coating for its high-pressure compressor disks, blades and spacers in legacy engines such as the JT8D. The company has proven in lab testing that a nickel-zinc coating is an acceptable replacement for its cadmium-based coatings. Cadmium is a probable carcinogen in humans. Testing of the nickel-zinc coating with an industrial turbine version of the JT8D is under way, and P&W expects to begin using the new coatings in legacy engines next year, assuming the company gets a thumbs-up from the U.S. FAA.
Using the nickel-zinc experience as a template for success, the company says it will eliminate other hazardous materials, including lead in lubricants and hexavalent chrome, a carcinogen the U.S. Occupational Safety and Health Administration will likely drastically limit with a new ruling. Equally durable compounds and substitute techniques the company is investigating for use in metal plating and anodizing include a non-carcinogenic trivalent chrome compound and sulfuric acid and boric/sulfuric acid anodizing. “Eliminating hexavalent chromium from our processes is absolutely necessary because both our OEM and service suppliers will see significant ramifications from the proposed OSHA requirements,” says Erin Yaeger, green materials program manager for Pratt & Whitney. -- John Croft
