scholarly journals Oxidation Behavior of Ceramics for Gas Turbines in Combustion Gas Flow at 1500°C

1997 ◽  
Author(s):  
Y. Etori ◽  
T. Hisamatsu ◽  
I. Yuri ◽  
Y. Yasutomi ◽  
T. Machida ◽  
...  
Keyword(s):  
Weight Loss ◽  
Oxide Layer ◽  
Gas Turbines ◽  
High Speed ◽  
Gas Flow ◽  
Oxidation Behavior ◽  
Loss Rate ◽  
Sintering Aids ◽  
Combustion Gas ◽  
Weight Losses

In order to evaluate the durability of silicon-carbides (SiC) and silicon-nitrides (Si3N4), we studied the oxidation behavior of SiC and Si3N4 in 1500°C combustion gas flow. We found that the exposure to the combustion gas flow resulted in the weight losses of those ceramics due to the partial disappearance of the oxidized surface layer. We investigated the effects of sintering aids and high speed gas flow as possible factors for the disappearance of the oxide layer. Two kinds of SiC, without sintering aids and sintered with B4C, were used as test specimens. After the exposure to combustion gas flow conditions of 1500°C, 150m/s, 0.18MPa, the weight loss rate and thickness of the oxide layer were quite the same for each specimen of SiC. The existence of sintering aids did not have any effect on the disappearance of the oxide layer. To investigate the effect of gas flow, we set each specimen in a tube made of SiC to protect it from the gas flow. The tube had two holes each acting both as inlet and exhaust vents. Consequently, the oxide layer formed thickly. But at the spots on the specimen facing the holes, the oxide layer was thin. Hollows occurred on the specimen of SiC at these spots. It seems that the existence of gas flow is a very important factor in the disappearance of the oxide layer. Alumina (Al2O3) and zirconia (ZrO2) as oxide ceramics were exposed to the combustion gas flow. The weight of these also decreased. There is a possibility that the weight loss of ceramics in combustion gas flow is caused by degradation of oxide layer on their surface from erosion and hot corrosion due to some oxide scales coming from the test equipment.

Exposure Test Results of Lu2Si2O7 in Combustion Gas Flow at High Temperature and High Speed

2004 ◽  
Author(s):  
Isao Yuri ◽  
Tohru Hisamatsu ◽  
Shunkichi Ueno ◽  
Tatsuki Ohji
Keyword(s):  
Weight Loss ◽  
Water Vapor ◽  
Partial Pressure ◽  
Gas Flow ◽  
Loss Rate ◽  
Gas Temperature ◽  
Weight Loss Rate ◽  
Combustion Gas ◽  
Vapor Partial Pressure ◽  
Water Vapor Partial Pressure

In order to understand recession behavior and the amount of recession of Lu2Si2O7 in the combustion gas flow, sintered Lu2Si2O7 specimens were manufactured by hot pressing and exposed under various combustion gas flow conditions (T = 1300–1500 °C, P = 0.3 MPa, V = 150 m/s, PH2O = 27–69 kPa, t = 10h). After the exposure tests, etch pits, which are assumed to form due to volatilization of SiO2 in the grain boundary phase, were observed at the surface of specimen. The amount of Lu2SiO5 phase at the surface of specimen increased with the increase of gas temperature or water vapor partial pressure. A corresponding decrease in the amount of Lu2Si2O7 phase was observed. Furthermore, by using the average weight loss rate for exposure times of ten hours, the influence of gas temperature and water vapor partial pressure on weight loss rate was examined, and the amount of recession under gas turbine conditions was calculated.

Model Combustor to Assess the Oxidation Behavior of Ceramic Materials Under Real Engine Conditions

1999 ◽  
Author(s):  
D. Filsinger ◽  
A. Schulz ◽  
S. Wittig ◽  
C. Taut ◽  
H. Klemm ◽  
...  
Keyword(s):  
High Temperature ◽  
International Development ◽  
Gas Turbines ◽  
Gas Flow ◽  
Oxidation Behavior ◽  
Elevated Temperatures ◽  
Ceramic Materials ◽  
Test Rig ◽  
Combustion Gas ◽  
Wide Range

A further increase of thermal efficiency and a reduction of the exhaust emissions of ground based gas turbines can be achieved by introducing new high temperature resistant materials. Therfore, ceramics are under international development. They offer excellent strengths at room and elevated temperatures. For gas turbine combustor applications, however, these materials have to maintain their advantageous properties under hostile environment. For the assessment and comparison of the oxidation behavior of different nonoxide ceramic materials a test rig was developed at the Institute for Thermal Turbomachinery (ITS), University of Karlsruhe, Germany. The test rig was integrated into the high temperature/ high pressure laboratory. A ceramic model combustion chamber was designed which allowed the exposure of standard four-point flexure specimens to the hot combustion gas flow. Gas temperatures and pressures could be varied in a wide range. Additionally, the partial steam pressure could be adjusted to real combustor conditions. The present paper gives a detailed description of the test rig and presents results of 100 hours endurance tests of ceramic materials at 1400°C. The initial strengths and the strengths after oxidation tests are compared. In addition to this, photographs illustrating the changes of the material’s microstructure are presented.

Development and Evaluation of Silicon Nitride Components for Ceramic Gas Turbine

1998 ◽  
Author(s):  
Yasushi Hara ◽  
Katsura Matsubara ◽  
Ken-ichi Mizuno ◽  
Toru Shimamori ◽  
Hiro Yoshida
Keyword(s):  
Silicon Nitride ◽  
Gas Turbines ◽  
High Speed ◽  
Gas Flow ◽  
Impact Damage ◽  
Turbine Blades ◽  
Impact Testing ◽  
Particle Impact ◽  
Inlet Temperature ◽  
Power Turbine

NGK Spark Plug Co., Ltd. has been developing various silicon nitride materials, and the technology for fabricating components for ceramic gas turbines (CGT) using theses materials. We are supplying silicon nitride material components for the project to develop 300 kW class CGT for co-generation in Japan. EC-152 was developed for components that require high strength at high temperature, such as turbine blades and turbine nozzles. In order to adapt the increasing of the turbine inlet temperature (TIT) up to 1350 °C in accordance with the project goals, we developed two silicon nitride materials with further improved properties: ST-1 and ST-2. ST-1 has a higher strength than EC-152 and is suitable for first stage turbine blades and power turbine blades. ST-2 has higher oxidation resistance than EC-152 and is suitable for power turbine nozzles. On applying these silicon nitride ceramics to CGT engine, we evaluated various properties of silicon nitride materials considering the environment in CGT engine. Particle impact testing is one of those evaluations. Materials used in CGT engine are exposed in high speed gas flow, and impact damage of these materials is considered to be a concern. We tested ST-1 in the particle impact test. In this test, we observed fracture modes, and estimated the critical impact velocity. This paper summarizes the development of silicon nitride components, and the result of evaluations of these silicon nitride materials.

scholarly journals Laser Cladding and Anti-Laser Ablative Behaviour of Si-SiC-MoSi2-ZrB2 Composite Coatings on Carbon Surface

2020 ◽  
Author(s):  
Qixuan Wang ◽  
Yi Zhuo ◽  
Wenhao Wang ◽  
Litong Guo ◽  
Xueyu Tao ◽  
...  
Keyword(s):  
Weight Loss ◽  
Laser Ablation ◽  
Oxide Layer ◽  
Laser Cladding ◽  
Bonding Strength ◽  
Loss Rate ◽  
Composite Coatings ◽  
Carbon Surface ◽  
Weight Loss Rate ◽  
Coating Surface

Abstract A Si-SiC-MoSi2-ZrB2 antioxidation composite coating was fabricated by laser cladding technology on the graphite matrix surface, and laser ablation was carried out on the coating surface to evaluate the anti-ablation capability of the coating surface. The phase transformation, microstructure reconstruction and the change of binding strength between the coating and the matrix during the laser cladding and ablation were investigated. The coating of Si-SiC-MoSi2 series modified by 40wt% ZrB2 had the lowest weight loss rate and the highest coating bonding strength. The oxide mostly existed in amorphous form after laser cladding, and the semi-melting particles in laser path lap zone on the coating surface disappeared. The oxide layer peeled off and Mo-Zr-Si-O composite glass phase was formed on the coating surface. The internal microstructure of the coating co-existed with non-oriented fine needle-like dendrites and irregular particles, which improved the coating strength. After laser ablation, the coating modified by 40wt% ZrB2 had lower weight loss rate and higher scratch bonding strength compared with the unmodified coating of Si-SiC-MoSi2 series, which indicated that the ablation resistance of the coating was improved by the formation of continuous oxide layer on the surface.

Oxidation Behavior of Alumina-Forming Austenitic Steels in Superheated Steam at 700 °C

2020 ◽  
Vol 6 (3) ◽  
Author(s):  
Bingjie Xiao ◽  
Nick Tepylo ◽  
Xiao Huang ◽  
Zhangjian Zhou ◽  
Sami Penttilä
Keyword(s):  
Weight Loss ◽  
Weight Gain ◽  
Oxide Layer ◽  
Internal Oxidation ◽  
Oxidation Behavior ◽  
Superheated Steam ◽  
External Surface ◽  
Austenitic Steels ◽  
Surface Oxide Layer ◽  
Oxide Spallation

Abstract In this study, three alumina-forming austenitic (AFA) steels (Fe-18Ni-12Cr-AlNbC, Fe-18Ni-12Cr-Al, and Fe-18Ni-16Cr-AlNbC) were exposed to superheated steam (SHS) at 700 °C for 1000 h to study their oxidation behavior. The Fe-18Ni-16Cr-AlNbC alloy showed the best performance as it had the least weight gain due to a denser surface oxide layer and the lack of internal oxidation. The Fe-18Ni-12Cr-AlNbC alloy suffered from internal oxidation and had a greater weight gain than Fe-18Ni-16Cr-AlNbC, while Fe-18Ni-12Cr-Al experienced weight loss due to perhaps external oxide spallation, leaving a less protective Fe-oxide on the external surface.

scholarly journals Corrosion Behavior of SMA490BW Steel and Welded Joints for High-Speed Trains in Atmospheric Environments

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3043 ◽  
Author(s):  
Xiangyang Wu ◽  
Zhiyi Zhang ◽  
Weichuang Qi ◽  
Renyong Tian ◽  
Shiming Huang ◽  
...  
Keyword(s):  
Weight Loss ◽  
Corrosion Behavior ◽  
Welded Joints ◽  
Corrosion Test ◽  
High Speed ◽  
Loss Rate ◽  
Corrosion Potential ◽  
Weight Loss Rate ◽  
Cyclic Corrosion ◽  
High Speed Trains

Currently, high-speed trains work under various atmospheric environments, and the bogie as a key component suffers serious corrosion. To investigate the corrosion behavior of bogies in industrial atmospheric environments, the periodic immersion wet/dry cyclic corrosion test for SMA490BW steel and automatic metal active gas (MAG) welded joints used for bogies was conducted in the present work. Corrosion weight loss rate, structure, and composition of rust layers as well as electrochemistry parameters were investigated. The results showed that the corrosion weight loss rate decreased with increasing corrosion time; furthermore, the corrosion weight loss rate of the welded joints was lower than that of SMA490BW steel. The XRD results showed that the rust layers formed on SMA490BW steel and its welded joints were mainly composed of α-FeOOH, γ-FeOOH, Fe2O3, and Fe3O4. The observation of surface morphology indicated that the rust layers of the welded joints were much denser and had a much finer microstructure compared with those of SMA490BW steel. After corrosion for 150 h, the corrosion potential of the welded joints with rust layers was higher than that of SMA490BW steel. In short, the welded joints exhibited better corrosion resistance than SMA490BW steel because of the higher content of alloy elements, as shown in this work.

scholarly journals Recession Characteristics of Lu2Si2O7 in Combustion Gas Flow at High Temperature and High Speed

2005 ◽  
Vol 54 (10) ◽  
pp. 1075-1079
Author(s):  
Isao YURI ◽  
Tohru HISAMATSU ◽  
Shunkichi UENO ◽  
Tatsuki OHJI
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Gas Flow ◽  
Combustion Gas

A Methodology and Case Study of Outboard Traverse Flame Detection on Aeroderivative Gas Turbines

2019 ◽  
Author(s):  
Jean-Roch Jacques ◽  
Noor Azman Mohamat Nor
Keyword(s):  
Gas Turbines ◽  
Life Cycle Cost ◽  
Gas Flow ◽  
Poor Quality ◽  
Outer Radius ◽  
Dual Immersion ◽  
Gas Temperature ◽  
Combustion Gas ◽  
Immersion Thermocouple ◽  
Flame Detection

Abstract Outboard-traverse flame migration in an annular profile, combustion gas pathway of a Siemens aero-derivative turbine engine can be detected with a dual immersion thermocouple. This solution is applicable for Oil & Gas operators using gas turbines fueled by natural gas. The typical flame profile within the annular combustion gas flow path is disturbed by introducing poor quality fuel into the engine. The skewed or outward bias flame profile in turn causes severe overheating of the hot section components around the outer radius of the annular combustor exit wall covering a number of hot section components. This ultimately causes accelerated components deterioration and failure to meet its target design life. Consequently, resulting in rejection of these components and increasing the life cycle cost of their asset operations. The introduction of the dual immersion thermocouple allow us to detect outward bias flame pattern using the exhaust gas temperature profile during operation and warn the operator of this condition via software alarm and trip provision. By implementing a means of detecting outward bias flame patterns, the operator will be made aware of this condition and can then take means to resolve this matter by first, allowing to optimize hot section components boundary limits and saving overhaul costs and second, avoid unplanned maintenance outages due to hot section premature failures.

Degradation of Silicon Carbide in Combustion Gas Flow at High Temperature and High Speed

2001 ◽  
Vol 44 (4) ◽  
pp. 520-527 ◽  
Author(s):  
Isao YURI ◽  
Tohru HISAMATSU ◽  
Yoshiyuki ETORI ◽  
Tohru YAMAMOTO
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
High Speed ◽  
Gas Flow ◽  
Combustion Gas
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