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February 2008 |
905-827-4171 |
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Abradable Coatings for Gas Path Seals in Turbine Engines
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For maximum fuel efficiency, many gas turbine engine designs depend on sacrificial coatings to tighten internal clearances between moving parts. An extra gap of .005" between the rotating blades and the engine casing can increase fuel consumption by as much as 0.5%. As fuel comprises more than half of direct operating costs, this waste can be significant. Engine efficiency largely depends on close clearance between blades and casing. Clearance can be affected by a number of engine operating variables, including casing expansion and contraction, loading due to maneuvering, thrust, gust, stall, vibration and manufacturing tolerances. An industrial turbine engine manufacturer was experiencing unsatisfactory results with the ring segment coatings used to maintain rotor-shroud clearance. Because of poor abradability, the coatings caused excessive wear on the tips of the turbine blades. The engine manufacturer and VAC AERO agreed to work cooperatively to develop an improved abradable coating for these applications. |
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Buying a Vacuum Furnace: New versus Used
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The purchase of a vacuum furnace involves a considerable capital investment. As a result, the question of buying a used furnace at a lower cost than a new furnace is a fairly common one. However, there are a number of potential issues with used equipment that should underscore the warning “buyer beware”. To begin with, good used vacuum furnaces are a rare commodity. When they do appear on the market, they don’t last long. Many of the best are purchased through industry networking and never reach the general market. Still, there are numerous dealers of used furnace equipment with inventories posted on their websites.
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