Structural Material Trends in Future Power Plants

2000 ◽  
Vol 122 (3) ◽  
pp. 256-258 ◽  
Author(s):  
Horst Hack
Keyword(s):  
High Temperature ◽  
High Performance ◽  
Power Plants ◽  
Ceramic Matrix Composites ◽  
Ceramic Composites ◽  
Strength Properties ◽  
Combined Cycle ◽  
Maximum Efficiency ◽  
High Temperature Strength ◽  
Matrix Composites

Environmental and economic concerns necessitate advances in power generation technology. Future power plants will be more fuel efficient, environmentally benign, and economical than current power plants. A high performance power system (HIPPS), based on a coal-fired combined cycle, is currently being developed. The corrosion and temperature-strength properties of currently available metallic materials limit the maximum efficiency of this cycle. Recently, ceramic matrix composites have shown promise in overcoming the design limitations on future power plants. In particular, the high-temperature strength, and corrosion and erosion resistant properties of continuous fiber ceramic composites (CFCCs) will allow engineers to design high-temperature heat exchangers, cyclone vortex finder tubes, and other components. Research is being performed to evaluate candidate materials for use in future power plants. [S0094-4289(00)00203-6]

Properties of In Situ Reinforced Silicon Nitride Ceramics

1991 ◽  
Vol 251 ◽  
Author(s):  
C.-W. Li ◽  
J. Yamanis ◽  
P.J. Whalen ◽  
C.J. Gasdaska ◽  
C.P. Ballard
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Metastable Phase ◽  
Abrasive Particle ◽  
Ceramic Matrix Composites ◽  
Ceramic Composites ◽  
High Fracture Toughness ◽  
High Temperature Strength ◽  
Nitride Ceramics

ABSTRACTIn situ reinforced (ISR) silicon nitride ceramics have been developed to have microstructures that mimic the best whisker containing ceramic matrix composites. Large, interlocking needle-like grains of beta silicon nitride can be produced throughout these materials to create an isotropic, high-temperature ceramic with high fracture toughness (˜9 MPa√m), good high-temperature strength (4 Pt MOR = 750 MPa at 25°C and 500 MPa at 1375°C), high Weibull modulus (m >20), and low creep at high temperature. Since these materials do not rely on transforming metastable phase inclusions as a toughening mechanism, their fracture resistance is virtually insensitive to temperature. The high crack growth resistance of these ceramics also yields a material which is extremely defect tolerant. Residual MOR strengths of 300–400 MPa are typical after multiple 50-kg Vicker's indentations of the sample tensile surface. After abrasive particle impact, the biaxial strengths of the in situ reinforced ceramics are typically more than twice that of traditional, fine-grained silicon nitrides.Unlike ceramic composites toughened using whisker additives, the in situ reinforcement approach to silicon nitride development does not require the use of complicated whisker dispersion techniques for green processing, nor is shape-limiting hot pressing required for densification during sintering.

Ceramics and ceramic composites as high-temperature structural materials: challenges and opportunities

1995 ◽  
Vol 351 (1697) ◽  
pp. 511-527 ◽  
Keyword(s):  
High Temperature ◽  
Ceramic Matrix Composites ◽  
Inelastic Strain ◽  
Ceramic Composites ◽  
Constitutive Law ◽  
Matrix Composites ◽  
Degradation Mechanisms ◽  
Stress Concentrations ◽  
Challenges And Opportunities ◽  
Design Calculations

Perspectives are presented on the development of ceramics and ceramic matrix composites (CMCs) for high-temperature structural components. The emphasis is on design requirements and their role in directing research toward actual products. An important theme concerns the relative roles of fracture toughness and inelastic strain (ductility) in the application of materials in primary structures. Ceramics with high toughness have been developed, but macroscopic inelasticity has not been achieved. Robust design procedures have yet to be developed for such materials. This deficiency, as well as relatively high manufacturing and qualification costs, has retarded their commercial exploitation. Strategies for addressing this problem are considered. CMCs are more ‘design friendly’ because they exhibit appreciable inelastic strain, in shear and/ or in tension. Such strain capacity is an efficient means of redistributing stress and eliminating stress concentrations. The design process thus has commonality with that used for metallic components. Also, processing approaches that provide acceptable manufacturing costs have been devised. The sources of the inelastic strain are examined and models that lead to a constitutive law are described. Some examples are given of its FEM implementation for design calculations. A limitation on the extensive exploitation of CMCs in high temperature systems has been the existence of degradation mechanisms. These include a ‘pest’ phenomenon, manifest as oxidation embrittlement in non-oxide CMCs, as well as excessive creep in oxide-oxide CMCs. These degradation mechanisms are discussed, and pathways to affordable high-temperature CMCs are analysed.

scholarly journals Continuous Fiber Ceramic Matrix Composites for Gas Turbine Applications

1999 ◽  
Author(s):  
A. Szweda ◽  
T. E. Easler ◽  
D. R. Petrak ◽  
V. A. Black
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Gas Turbine ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Ceramic Composites ◽  
Matrix Composites ◽  
Continuous Fiber ◽  
Temperature Capability ◽  
Polymer Impregnation

Continuous fiber ceramic composites (CFCCs) are being considered as high temperature structural materials for gas turbine applications due to their high temperature capability, toughness, and durability. Polymer impregnation and pyrolysis (PIP) derived CFCCs are one class of these materials that can be fabricated using widely available polymer composite processing methods. This paper will discuss the general PIP fabrication process and thermo-mechanical properties of these materials, and show examples of complex prototype gas turbine components that have been fabricated and evaluated.

Microstructural characterization of plasma-processed Ti-Al metal matrix composites

1989 ◽  
Vol 47 ◽  
pp. 552-553
Author(s):  
M. G. Burke ◽  
M. N. Gungor ◽  
M. A. Burke
Keyword(s):  
High Temperature ◽  
Titanium Aluminide ◽  
Plasma Processing ◽  
Microstructural Characterization ◽  
High Temperature Strength ◽  
Matrix Composites ◽  
Intermetallic Matrix ◽  
Long Time ◽  
Strength And Stiffness ◽  
Intermetallic Matrix Composites

Intermetallic matrix composites are candidates for ultrahigh temperature service when light weight and high temperature strength and stiffness are required. Recent efforts to produce intermetallic matrix composites have focused on the titanium aluminide (TiAl) system with various ceramic reinforcements. In order to optimize the composition and processing of these composites it is necessary to evaluate the range of structures that can be produced in these materials and to identify the characteristics of the optimum structures. Normally, TiAl materials are difficult to process and, thus, examination of a suitable range of structures would not be feasible. However, plasma processing offers a novel method for producing composites from difficult to process component materials. By melting one or more of the component materials in a plasma and controlling deposition onto a cooled substrate, a range of structures can be produced and the method is highly suited to examining experimental composite systems. Moreover, because plasma processing involves rapid melting and very rapid cooling can be induced in the deposited composite, it is expected that processing method can avoid some of the problems, such as interfacial degradation, that are associated with the relatively long time, high temperature exposures that are induced by conventional processing methods.

PRESSURDIE-1

Alloy Digest ◽  
1967 ◽  
Vol 16 (4) ◽  
Keyword(s):  
High Temperature ◽  
Die Casting ◽  
Heat Treating ◽  
High Heat ◽  
Strength Properties ◽  
High Temperature Strength ◽  
High Heat Resistance ◽  
Die Steel ◽  
Temperature Performance ◽  
Steel Industries

Abstract PRESSURDIE-1 is an air-hardening hot work tool and die steel having high heat resistance and good high temperature strength properties. It is recommended for die casting dies, extrusion and forging dies. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: TS-191. Producer or source: Continental Copper & Steel Industries Inc..

Rewiew of Fracture and Fatigue in Ceramic Matrix Composites

2000 ◽  
Vol 53 (6) ◽  
pp. 147-174 ◽  
Author(s):  
Victor Birman ◽  
Larry W. Byrd
Keyword(s):  
High Temperature ◽  
State Of The Art ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Review Article ◽  
Successful Implementation ◽  
Matrix Composites ◽  
Recent Developments ◽  
Hostile Environments

A review of recent developments and state-of-the-art in research and understanding of damage and fatigue of ceramic matrix composites is presented. Both laminated as well as woven configurations are considered. The work on the effects of high temperature on fracture and fatigue of ceramic matrix composites is emphasized, because these materials are usually designed to operate in hostile environments. Based on a detailed discussion of the mechanisms of failure, the problems that have to be addressed for a successful implementation of ceramic matrix composites in design and practical operational structures are outlined. This review article includes 317 references.

Metal-Reinforced Ceramic Composites for Turbine Vanes

1972 ◽  
Author(s):  
S. A. Bortz
Keyword(s):  
Ceramic Matrix Composites ◽  
Ceramic Composites ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Metal Fiber ◽  
Turbine Engine ◽  
Turbine Vanes ◽  
The Matrix ◽  
The Relationship ◽  
Structural Matrix

Experiments have been performed which indicate the potential of metal-fiber reinforced-ceramic matrix composites for use as a high temperature structural matrix. The results of this work reveal that metal-fiber reinforced ceramics obey compostie theory, and that after cracks occur in the matrix, a pseudo-ductility can be introduced into the composite. This toughness can be predicted from equations of work required to pull the fibers through the matrix. The relationship between strength, toughness, and crack depths, are dependent on the inter-facial bond between the fibers and matrix as well as fiber diameter and length. Based on the results of these experiments, multicomponent materials with superior resistance to failure from oxidation, thermal shock, and high mechanical stresses in air above 2400 F can be postulated. These materials have potential for use as gas turbine engine vanes.

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