Aircraft engine shroud

The thermal barriers have found applications as protective layers, for example steel surfaces of pistons and cylinders in Diesel engines and compressors housing parts of aircraft engines, made of titanium alloys, and working surfaces of exhaust nozzles, made of niobium alloys. Moreover, TBCs are widely used in gas turbine hot section components such as burners, transition ducts, shrouds, blades, and vanes [6]. 

For the past 15 years, research and development of CMCs has been sustained because of their potential for military and commercial applications. The applications of interest include (1) aircraft engine components, such as combustors, turbines, compressors and exhaust nozzles (2) ground-based and automotive gas turbine components, such as combustors, first and second stage turbine vanes and blades, and shrouds (3) aerospace engines for missiles and reusable space vehicles and (4) industrial applications, such as heat exchangers, hot gas filters, and radiant burners. 

Engine components. Parts fabricated from injection-molded fiber-reinforced polyamide-imides provide a lower-cost solution to previously machined metal pieces and maintain, due to low shrinkage, very tight tolerances which are required in these applications. Polyamide-imide compounds have replaced expensive titanium in air return grills for commercial aircraft engines (Fig. 12.13). The shroud on the interior of the aircraft engine, responsible for directing airflow, consists of an assembly of multiple polyamide-imide injection-molded pieces (Fig. 12.14). 

Thermally densified coatings (TDC). Generally used to protect shrouds. PVD and TDC are currently used mainly on aircraft engine components, although that will change as OEMs increase the market share of aeroderivatives in land-based use. 

Aircraft applications include exhaust-pipe shrouds, fireproof bulkheads, gas-turbine bypass ducts, hot-air ducts, engine cowlings, formed brackets and skins for hot areas. Other aircraft applications include galley equipment, chemical toilets and... 

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