Patrick Spriet

An Improved Long Life Duration CMC for Jet Aircraft Engine Applications

A new concept of Ceramic Matrix Composite (CMC), mainly based on the use of a self–sealing technology for matrix and the use of a multilayer woven reinforcement, has been developed by Snecma for achieving high performance levels targeted by future jet engines. The driving force for this development has been to increase both lifetime and temperature capability of previous C/SiC and SiC/SiC materials using a monolithic SiC Chemical Vapor Infiltration (CVI) matrix and finishing treatment against oxidation. The first material, which has been developed with this new approach, is CERASEP® A410, using Hi-Nicalon™ fibers from Nippon Carbon. It has been submitted to a comprehensive characterization in order to determine thermo-mechanical properties and to evaluate lifetime duration, using fatigue and creep testing. Further material development is investigating the use of carbon fiber for economical objectives. The combination of such fibers with the new self-sealing matrix is providing promising results for long duration application at high temperature. Such results are permitted by the very high potential of the new matrix.Copyright

Engine Test and Post Engine Test Characterization of Self-Sealing Ceramic Matrix Composites for Nozzle Applications in Gas Turbine Engines

The advancement of self-sealing ceramic matrix composites offers durability improvements in hot section components of gas turbine engines. These durability improvements come with no need for internal cooling and with reduced weight. Building on past material efforts, ceramic matrix composites based on either a carbon fiber or a SiC fiber with a sequenced self-sealing matrix have been developed for gas turbine applications. The specific application being pursued on this effort is an F100-PW-229 nozzle seal. Full design life ground engine testing has been accomplished with both material systems. The ground testing has demonstrated a significant durability improvement from the baseline metal design. Residual properties are being determined for both systems by extracting tensile and microstructural coupons from the ceramic matrix composite seal. Nondestructive interrogation showed no material degradation and was used as a guide in setting cutting diagrams. The results from this effort will be presented along with documentation from flight test efforts.Copyright

Characterization and Nozzle Test Experience of a Self Sealing Ceramic Matrix Composite for Gas Turbine Applications

Advanced materials have the potential to improve gas turbine engine durability. One general area of concern for durability is in the hot section components of the engine. Ceramic matrix composites offer improvements in durability at elevated temperatures with a corresponding reduction in weight for nozzles of gas turbine engines. Building on past material efforts, a next generation SiC/SiC composite with a self-sealing matrix has been developed for gas turbine applications. An extensive baseline test characterization has been done that shows the overall material suitability. Prior to ground engine testing, a reduced test matrix was undertaken to aggressively test the material in a long-term hold cycle at elevated temperatures and environments. This tensile low cycle fatigue testing was done in air and a 90% steam environment. While the steam environment aggressively attacked the material, no appreciable debit in material life was noted. Nondestructive testing and post test characterization of this testing were performed. After completion of the aggressive testing effort, two nozzle seals of constant thickness were fabricated and installed in an F100-PW-229 engine for accelerated mission testing. The self sealing CMC seals were tested for over 250 hours in accelerated conditions without damage. The results of the engine testing will be shown and overall conclusions drawn.Copyright

Engine Test Experience and Characterization of Self Sealing Ceramic Matrix Composites for Nozzle Applications in Gas Turbine Engines

Advanced materials are targeting durability improvement in gas turbine engines. One general area of concern for durability is in the hot section components of the engine. Ceramic matrix composites offer improvements in durability at elevated temperatures with a corresponding reduction in weight for nozzles of gas turbine engines. Building on past material efforts, ceramic matrix composites using a carbon and a SiC fiber with a self-sealing matrix have been developed for gas turbine applications. Prior to ground engine testing, a reduced test matrix was undertaken to aggressively test the material in a long-term hold cycle at elevated temperatures and environments. This tensile low cycle fatigue testing was done in air and a 90% steam environment. After completion of the aggressive testing effort, six nozzle seals were fabricated and installed in an F100-PW-229 engine for accelerated mission testing. The C fiber CMC and the SiC Fiber CMC were respectively tested to 600 and 1000 hours in accelerated conditions without damage. Engine testing is continuing to gain additional time and insight with the objective of pursuing the next phase of field service evaluation. Mechanical testing and post-test characterization results of this testing will be presented. The results of the engine testing will be shown and overall conclusions drawn.Copyright

Applications of Continuous Fiber Reinforced Ceramic Composites in Military Turbojet Engines

Over the last twenty years, significant performance improvements of turbojet engines have been achieved by optimizing engine thermodynamic cycle along with the introduction of new materials providing higher temperature capability and weight reduction.Metal Matrix Composites (MMC) and Ceramic Matrix Composites (CMC) are candidate material systems to meet the required thrust-to-weight ratio of 15 or higher.Continuous fiber reinforced ceramic composites, which have been developed by SEP for more than 15 years for thermostructural applications in oxidative environment, aim at increased operating temperature over superalloys and intermetallic alloys.This paper is a review of the main CMC component demonstrations performed by SEP over the last 10 years for turbojet engines along with an analysis of consequences on materials development and design methodology.The development status of a new thermostructural material specifically developed for turbojet environment with the prospect of higher design stress allowables and longer operating life at high temperature is presented.© 1996 ASME

Post Engine Test Characterization and Flight Test Experience of Self Sealing Ceramic Matrix Composites for Nozzle Seals in Gas Turbine Engines

The advancement of self-sealing ceramic matrix composites offers durability improvements in hot section components of gas turbine engines. These durability improvements come with no need for internal cooling and with reduced weight. Building on past material efforts, ceramic matrix composites based upon a silicon carbide or carbon fiber with a novel self-sealing matrix have been developed for gas turbine applications. The specific application being pursued on this effort is an F100-PW-229 nozzle seal. Ground engine testing has been completed that exceeds the full design life. The ground testing has demonstrated a significant durability improvement from the baseline metal design. Residual properties have been determined by extracting tensile and microstructural coupons from the ceramic matrix composite seal. This was done as a function of design life. Nondestructive interrogation was used as a guide in setting cutting diagrams. The results from this effort will be presented.© 2005 ASME

Ceramic Matrix Composites to make breakthroughs in aircraft engine performance.

Since the early eighties Snecma Propulsion Solide (SPS) pioneered development into the Ceramic Matrix Composites (CMC) to increase the durability of the Carbon-Carbon materials in oxidative environment. Because aircraft engine application are aimed, long life endurance of thousands hours in operation are needed. Moreover, CMC very high temperature resistance much more over current metallic alloys capacities, allows to increase performance and comply with new environmental constraints requested for future aircraft engines. SPS has now a palette of industrial CMC materials relevant for aircraft engine applications as for nozzle mixers, nozzle plugs, flaps, etc…

Evaluation Of Ceramic Matrix Composite Exhaust Nozzle Divergent Seals

During the last six years substantial research efforts have been devoted towards evaluating ceramic matrix composite (CMC) materials for aerospace gas turbine engines. A majority of these technical activities have been directed towards the insertion of CMCs into the exhaust nozzles of aerospace military turbine engines that utilize an afterburner. The effort discussed here is studying an advanced self-sealing ceramic matrix composite called SEPCARBINOX A500. Carbon fibers are utilized as the reinforcement. The matrix is applied by Chemical Vapor Infiltration (CVI), and consists of a novel technology that utilizes sequential layers of Silicon Carbide (SiC) and specific sequences of Si, C, and B. The specific application involves the F100 gas turbine engine exhaust nozzle divergent seals. This CMC has been subjected to extensive material evaluations, subelement testing in simulated exhaust nozzle environment conditions, and over two years of ground testing. The lack of any degradation in the ground tested hardware run to 1.5X the design life prompted the start of a feld service evaluation (FSE). Starting in July, 2005, a total of 8 CMC divergent seals began flying at an operation base on two F-16 aircraft. In February, 2006, 20 additional CMC divergent seals began flying on F-15 aircraft at a second operational base. Discussion will address the unique CMC material and how it is performing in flight. A CMC seal has been removed from the FSE program and evaluated for retained tensile strength and microstructural stability. The seal showed no evidence of wear, the micrographs of the microstructure showed no signs of degradation, and no decrease in strength was measured.