Effect of Projectile Materials on Foreign Object Damage of a Gas-Turbine Grade Silicon Nitride

Choi, Sung R.; Rácz, Zsolt; Bhatt, Ramesh S.; Brewer, David N.; Gyekenyesi, John P.

doi:10.1115/gt2005-68866

Cited by 8 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The angle of the cone cracks was found to be around 120°. Generation of cone cracks by spherical projectiles (in either full or partial support) has been observed in monolithic silicon nitrides 5,6,11,17,19–21,25 and is typical to many brittle solids including glass dynamically 1,2,7 or statically 10 . Hence, regardless of the type of material, either composite or monolithic, a formation of cone cracks is one of the key damage evolutions in brittle materials.…”

Section: Resultsmentioning

confidence: 99%

“…Multiple crack systems were involved in impact event with increasing impact velocity. The FOD work was also extended to cover the effect of projectile materials on FOD in AS800 silicon nitride using hardened and annealed (350° and 700°C) steel, brass, and silicon nitride balls as impacting projectiles 21 . For a given impact condition and target material, the yield stress (or hardness) of projectiles was a key material parameter to affect most the impact damage of a target material.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Foreign Object Damage Phenomenon by Steel Ball Projectiles in a SiC/SiC Ceramic Matrix Composite at Ambient and Elevated Temperatures

Choi

2008

Journal of the American Ceramic Society

Self Cite

View full text Add to dashboard Cite

Foreign object damage (FOD) phenomenon of a gas‐turbine grade SiC/SiC ceramic matrix composite (CMC) was determined at 25° and 1316°C using impact velocities ranging from 115 to 440 m/s by 1.59‐mm diameter steel ball projectiles. Two types of target‐specimen support were employed at each temperature: fully supported and partially supported. For a given temperature, the degree of impact damage increased with increasing impact velocity, and was greater in partial support than in full support. The elevated‐temperature FOD resistance of the composite, particularly in partial support at higher impact velocities ≥350 m/s, was significantly less than the ambient‐temperature counterpart, attributed to a weakening effect of the composite. In full support, frontal contact stresses played a major role in generating composite damage; whereas, in partial support both frontal contact and backside tensile stresses were combined sources of damage generation. Formation of cone cracks initiating from impact site was also one of the key damage features. The SiC/SiC composite was able to survive higher energy impacts without complete structural failure, as compared with gas‐turbine grade AS800 and SN282 monolithic silicon nitrides.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Foreign Object Damage Phenomenon by Steel Ball Projectiles in a SiC/SiC Ceramic Matrix Composite at Ambient and Elevated Temperatures

Choi

2008

Journal of the American Ceramic Society

Self Cite

View full text Add to dashboard Cite

show abstract

“…The effects of FOD impact on ceramic turbine materials have been studied extensively [13][14][15][16]33]. Many studies have identified a "critical impact velocity," below which particles of a given mass that impact a substrate of specific dimensions may cause no damage at all.…”

Section: Foreign Object Damagementioning

confidence: 99%

“…Lower blade speeds also reduce the probability of foreign object damage (FOD), which can be a major problem at the high blade and gas speeds typical in gas turbine engines [13][14][15][16]. Since FOD particle kinetic energy (l/2mV^) controls the probability of impact damage, halving the blade speed should quadruple the limiting particle mass that an engine could ingest without damage.…”

mentioning

confidence: 99%

Engine Design Strategies to Maximize Ceramic Turbine Life and Reliability

Vick

Jadaan

Wereszczak

et al. 2012

Journal of Engineering for Gas Turbines and Power

Self Cite

View full text Add to dashboard Cite

Over a billion dollars have been spent on ceramic turbine research and development, but ceramic turbines "have not yet reached bill-of-materials status" [1]. Mature turbine-grade silicon nitrides (e.g., SN282^ AS800^ SN88^ NT154^) have excellent properties, but studies still cite life, reliability, and cost issues, often concluding that the materials themselves require further improvement. However, under less severe operating conditions, ceramics can excel in all these areas. In an ongoing long-term endurance test at NRL, a low cost porcelain vessel has been subjected to the thermal shock of hot coffee several times daily for ten years-over 5000 startup/shutdown cycles-with no perceptible degradation. Ceramic turbocharger rotors have been manufactured for the notoriously cost-sensitive automotive market at rates exceeding 10,000 per month, achieving good life and reliability in Japanese sports cars. These examples suggest that rather than just seeking higherperformance materials, it might also be fruitful to design gas turbines to create a more benign environment for existing ceramics.Foremost among stated concems is water vapor erosion [2-11], a process in which water in the combustion products reacts with silicon nitride at high temperatures, forming gases that get swept away by the freestream. This erodes the blade surfaces at a rate Engine Design Strategies to Maximize Ceramic Turbine Life and ReiiabilityCeramic turbines have long promised to enable higher fuel efficiencies by accommodating higher temperatures without cooling, yet no engines with ceramic rotors are in production today. Studies cite life, reliability, and cost obstacles, often concluding that further improvements in the materiais are required. In this paper, we assume instead that the problems could be circumvented by adjusting the engine design. Detailed analyses are conducted for two key life-iimiting processes, water vapor erosion and slow crack growth, seeking engine design strategies for mitigating their ejfects. We show that highly recuperated engines generate extremely low levels of water vapor erosion, enabling lives exceeding 10,000 hs, without environmental barrier coatings. Recuperated engines are highly efficient at low pressure ratios, making low blade speeds practical. Many ceramic demonstration engines have had design point mean blade speeds near 550 mis. A CARES/Life analysis of an example rotor designed for about half this value indicates vast improvements in slow crack growth-limited life and reliability. Halving the blade speed also reduces foreign object damage partide kinetic energy by a factor of four. In applications requiring very high fuei efficiency that can accept a recuperator, or in short-life simple cycle engines, ceramic turbines are ready for application today.

show abstract

Foreign Object Damage in Ceramic Matrix Composites and Monolithic Silicon Nitrides

Choi

2010

Ceramic Transactions Series

View full text Add to dashboard Cite

Effect of Projectile Materials on Foreign Object Damage of a Gas-Turbine Grade Silicon Nitride

Cited by 8 publications

References 0 publications

Foreign Object Damage Phenomenon by Steel Ball Projectiles in a SiC/SiC Ceramic Matrix Composite at Ambient and Elevated Temperatures

Foreign Object Damage Phenomenon by Steel Ball Projectiles in a SiC/SiC Ceramic Matrix Composite at Ambient and Elevated Temperatures

Engine Design Strategies to Maximize Ceramic Turbine Life and Reliability

Foreign Object Damage in Ceramic Matrix Composites and Monolithic Silicon Nitrides

Contact Info

Product

Resources

About