Advances in Turbine-Engine Technology
Status report describes major advances in high-temperature materials, coatings, and turbine-blade coating technology for aircraft turbine engines, which are keys to achieving improved performance.
Freche, J. C.↗
Engineering topics
Freche, J. C.
Publications and source records attributed to Freche, J. C..
Composites for aeropropulsion
Report summarizes status of composite materials for aeropropulsion. It describes key advances made in past several years and lists 47 references published from 1971 to 1979.
Ault, G. M.↗
Strength enhancement of prealloyed powder superalloys
Strengthening and forming process for prealloyed powder superalloys greatly increases material strength in the 900-1,200F temperature range. Process which involves superplastically-deforming compacted powders at controlled rates and temperature is most effective on nickel-base alloys.
Freche, J. C.↗
Composites emerging for aeropropulsion applications
The paper deals with applying composites to the cold- and hot-section components of aircraft turbine engines and analyzing composite structures. The primary experience to date has been with graphite-epoxy materials. The emerging new composites based on fabricable polyimides will find application in components that can operate at temperatures higher than the 350 F allowed by the epoxies. Further major benefits would result if the fiber-reinforced polymer composites could be used for key rotating components, such as the fans of large high-bypass-ratio engines. For the very critical hot turbine components, fiber-reinforced superalloys for turbine blades are considered.
Ault, G. M.↗
Materials and structural aspects of advanced gas-turbine helicopter engines
Advances in materials, coatings, turbine cooling technology, structural and design concepts, and component-life prediction of helicopter gas-turbine-engine components are presented. Stationary parts including the inlet particle separator, the front frame, rotor tip seals, vanes and combustors and rotating components - compressor blades, disks, and turbine blades - are discussed. Advanced composite materials are considered for the front frame and compressor blades, prealloyed powder superalloys will increase strength and reduce costs of disks, the oxide dispersion strengthened alloys will have 100C higher use temperature in combustors and vanes than conventional superalloys, ceramics will provide the highest use temperature of 1400C for stator vanes and 1370C for turbine blades, and directionally solidified eutectics will afford up to 50C temperature advantage at turbine blade operating conditions. Coatings for surface protection at higher surface temperatures and design trends in turbine cooling technology are discussed. New analytical methods of life prediction such as strain gage partitioning for high temperature prediction, fatigue life, computerized prediction of oxidation resistance, and advanced techniques for estimating coating life are described.
Freche, J. C.↗
Materials and structural aspects of advanced gas-turbine helicopter engines
The key to improved helicopter gas turbine engine performance lies in the development of advanced materials and advanced structural and design concepts. The modification of the low temperature components of helicopter engines (such as the inlet particle separator), the introduction of composites for use in the engine front frame, the development of advanced materials with increased use-temperature capability for the engine hot section, can result in improved performance and/or decreased engine maintenance cost. A major emphasis in helicopter engine design is the ability to design to meet a required lifetime. This, in turn, requires that the interrelated aspects of higher operating temperatures and pressures, cooling concepts, and environmental protection schemes be integrated into component design. The major material advances, coatings, and design life-prediction techniques pertinent to helicopter engines are reviewed; the current state-of-the-art is identified; and when appropriate, progress, problems, and future directions are assessed.
Freche, J. C.↗
Progress in advanced high temperature turbine materials, coatings, and technology
Advanced materials, coatings, and cooling technology is assessed in terms of improved aircraft turbine engine performance. High cycle operating temperatures, lighter structural components, and adequate resistance to the various environmental factors associated with aircraft gas turbine engines are among the factors considered. Emphasis is placed on progress in development of high temperature materials for coating protection against oxidation, hot corrosion and erosion, and in turbine cooling technology. Specific topics discussed include metal matrix composites, superalloys, directionally solidified eutectics, and ceramics.
Freche, J. C.↗
Strength enhancement process for prealloyed powder superalloys
A technique involving superplastic processing and high-pressure autoclaving was applied to a nickel-base prealloyed powder alloy. Tensile strengths as high as 2865 MN/sq m (415 ksi) at 480 C (900 F) were obtained with as-superplastically deformed material. Appropriate treatments yielding materials with high-temperature tensile and stress-rupture strengths (980 C (1800 F)) were also devised.
Waters, W. J.↗
Progress in advanced high temperature turbine materials, coatings, and technology
Material categories as well as coatings and recent turbine cooling developments are reviewed. Current state of the art is identified, and as assessment, when appropriate, of progress, problems, and future directions is provided.
Freche, J. C.↗
Nickel base alloy
A nickel base superalloy for use at temperatures of 2000 F (1095 C) to 2200 F (1205 C) was developed for use as stator vane material in advanced gas turbine engines. The alloy has a nominal composition in weight percent of 16 tungsten, 7 aluminum, 1 molybdenum, 2 columbium, 0.3 zirconium, 0.2 carbon and the balance nickel.
Freche, J. C.↗
Progress in advanced high temperature turbine materials, coatings, and technology
Several NASA-sponsored benefit-cost studies have shown that very substantial benefits can be obtained by increasing material capability for aircraft gas turbines. Prealloyed powder processing holds promise for providing superalloys with increased strength for turbine disk applications. The developement of advanced powder metallurgy disk alloys must be based on a design of optimum processing and heat treating procedures. Materials considered for high temperature application include oxide dispersion strengthened (ODS) alloys, directionally solidified superalloys, ceramics, directionally solidified eutectics, materials combining the high strength of a gamma prime strengthened alloy with the elevated temperature strength of an ODS, and composites. Attention is also given to the use of high pressure turbine seals, approaches for promoting environmental protection, and turbine cooling technology.
Freche, J. C.↗
Strength enhancement process for prealloyed powder superalloys
A technique involving superplastic processing and high pressure autoclaving was applied to a nickel base prealloyed powder alloy. Tensile strengths as high as 2865 MN/sq m at 480 C were obtained with as-superplastically deformed material. Appropriate treatments yielding materials with high temperature tensile and stress rupture strengths were also devised.
Waters, W. J.↗
Progress in advanced high temperature materials technology
Significant progress has recently been made in many high temperature material categories pertinent to such applications by the industrial community. These include metal matrix composites, superalloys, directionally solidified eutectics, coatings, and ceramics. Each of these material categories is reviewed and the current state-of-the-art identified, including some assessment, when appropriate, of progress, problems, and future directions.
Freche, J. C.↗
Progress in advanced high temperature materials technology
Materials for intermediate temperature applications are considered, taking into account possibilities regarding the use of prealloyed powder processing to obtain superalloys with increased strength for turbine disk applications. Materials for high temperature application are also discussed. Attention is given to oxide dispersion strengthened alloys (ODS), ceramics, directionally solidified eutectics, ODS + gamma prime alloys, and composites. A description is presented of various approaches for providing environmental protection.
Freche, J. C.↗
Stress rupture resistance
Principles underlying the design of metallic systems for stress rupture resistance are outlined by considering the specific case studies of cobalt- and nickel-base superalloys. Ways in which superalloys can be designed for high stress rupture resistance are discussed. In describing the alloying procedures, the strengthening mechanisms involved and methods of avoiding phases detrimental to stress rupture resistance are identified. New processing techniques such as controlled solidification, prealloyed powder processing, and autoclave heat treatments are described as further means of achieving increased stress rupture resistance in superalloy and other systems.
Freche, J. C.↗
NASA vane alloy boasts high-temperature strength
The higher inlet-gas temperatures in new aircraft turbine engines make it necessary to use improved superalloys in engine design. Such superalloys are provided by WAZ alloys. NASA has explored the Ni-W-Al system in an attempt to find higher-strength nickel-based alloys for use as stator vane materials. Critical performance goals have been met with the new alloy WAZ-16. With suitable protective coatings, WAZ-16 appears to have considerable potential for high-temperature stator vane applications.
Waters, W. J.↗
Cobalt base superalloy has outstanding properties up to 1478 K (2200 F)
Alloy VM-103 is especially promising for use in applications requiring short time exposure to very high temperatures. Its properties over broad range of temperatures are superior to those of comparable commercial wrought cobalt-base superalloys, L-605 and HS-188.
Harlow, R. A.↗
High strength nickel base alloy, WAZ-16, for applications up to 2200 F
Alloy product is high strength, high temperature nickel base material with higher incipient melting temperature than all known nickel base alloys. It is microstructurally stable and has high impact resistance both before and after prolonged thermal exposure. It contains relatively few alloying constitutents and low content of expensive and rare metals.
Waters, W. J.↗