| Elevated-Temperature Behavior of High-Strength Silicon Carbide |
93 |
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| Authors:
David Woodilla; Michael Buonomo; Isa Bar-On; R. Nathan Katz; Thomas Whalen; WORCESTER POLYTECHNIC INST MA DEPT OF MECHANICAL ENGINEERING
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 | The room- and high-temperature mechanical properties of a high- strength, sintered silicon carbide were evaluated. Room-temperature strength was measured in four-point bending. The room-temperature fracture toughness was determined using a precracked single-edge-notched beam (SENB) bridge indentation technique. The high-temperature stress rupture (STSR) procedure. Both the room- and the high-temperature behavior are superior to those of previously tested commercial sintered alpha and beta silicon carbides. |
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| Applications of Silicon Nitride Based Ceramics in the U.S |
93 |
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| Authors:
R. Nathan Katz; ARMY LAB COMMAND WATERTOWN MA MATERIAL TECHNOLOGY LAB
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| Silicon nitride based ceramics have unique combinations of mechanical, thermal-physical and electrical properties. Additionally, silicon nitride based materials can be fabricated into near net shape components by several processing routes. This unique combination of properties and processing versatility have encouraged the use of silicon nitride based ceramics in a variety of demanding commercial applications over the past decade. In the U.S., these applications currently include cutting tools, bearings, and selected ... |
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| Structural Ceramics: Processing and Properties |
89 |
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| Authors:
G. L. Leatherman; R. Nathan Katz; WORCESTER POLYTECHNIC INST MA DEPT OF MECHANICAL ENGINEERING
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| RELIABILITY STRATEGIES FOR NOMINALLY BRITTLE MATERIALS |
OCT 80 |
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| Authors:
R. Nathan Katz; Edward M. Lenoe
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| the introduction of brittle materials as alternatives to traditional engineering materials offers many potential advantages. however, the unforgiving nature of such materials imposes the need for rigorously defined component reliability. yet, for such non-traditional materials; data, design experience or codes of practice are often limited or lacking. further, existent nde and fracture mechanics based life prediction formalisms may require modification to be appropriate. the authors present several case histories of ... |
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| Some Aspects of Materials and Structures Engineering with Ceramics for Engine Applications. |
JUL 1980 |
29 pages |
| Authors:
R. Nathan Katz; ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MA
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 | This paper identifies the benefits of the use of ceramics in heat engines, how one designs with brittle materials, and some key materials for heat engine application. Current engineering and materials problems in the use of ceramics for engine applications are summarized. Examples of how the materials science and engineering community is addressing two of these problems: time and environmental dependence of properties, and development of improved high temperature (ca ... |
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| Ceramics for Vehicular Engines: State-of-the-Art. |
JUN 1980 |
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| Authors:
R. Nathan Katz; ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MA
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| The use of silicon-based, high performance ceramics offers significant potential for energy conservation in heat engine technology. In particular, three families of silicon-based engineering ceramics, the alumino silicates, the silicon nitrides, and the silicon carbides, possess unique combinations of properties which make these materials very attractive candidates for components in gas turbine, diesel, and Stirling engines. After a brief discussion of the design process with brittle materials, this paper will ... |
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| Corrosion/Erosion Behavior of Silicon Nitride and Silicon Carbide Ceramics - Gas Turbine Experience. |
APR 1979 |
12 pages |
| Authors:
R. Nathan Katz; ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MA
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| Ceramic materials, silicon nitride and silicon carbide in particular, are under intensive engineering development for gas turbine applications. One of the factors which has encouraged this line of development is the excellent corrosion/erosion behavior of these ceramics. This paper will briefly review some of the fundamental mechanisms and critical materials properties thought to govern the corrosion/erosion behavior of ceramics and point out where these differ from those of metals. A ... |
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| Grain Boundary Engineering in Nonoxide Ceramics. |
SEP 1978 |
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| Authors:
R. Nathan Katz; George E. Gazza; ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MASS
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| The deliberate selection and control of composition, structure, and processes occurring in the grain boundary, both during and after fabrication, with the aim of specific property modification may properly be defined as grain boundary engineering. We will review various strategies for doing grain boundary engineering and give examples of the use of these strategies in the development of hot-pressed silicon nitride. Research needs for further development of grain boundary engineering ... |
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| Recent Developments in High Performance Ceramics. |
MAR 1977 |
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| Authors:
R. Nathan Katz; ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MASS
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| Newly developed ceramic materials, fabrication processes, and advances in brittle materials design capability are having a significant impact on our ability to utilize ceramics as substitute materials. This paper will briefly review ceramic materials and their methods of fabrication. We will then consider the use of silicon nitride and silicon carbide ceramics in hot flow path components of gas turbines. Emphasis will be on the advantages of ceramics of this ... |
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| A High-Temperature Engineering Ceramic (Si3N4) by Powder Metallurgical Methods. |
JUN 1972 |
10 pages |
| Authors:
Michael W. Lindley; R. Nathan Katz; ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MASS
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| Silicon nitride has become a major structural ceramic material in the past decade. One form of this material, referred to as reaction-bonded silicon nitride, is of particular interest because it permits the production of ceramic components requiring little or not machining. The review discusses the application of powder metallurgical techniques to the fabrication of reaction-bonded silicon nitride, the nitridation process, and resultant properties. (Author) |
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| Fractography of High Boron Ceramics Subjected to Ballistic Loading. |
JUL 1971 |
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| Authors:
R. Nathan Katz; William A. Brantley; ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MASS
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| Fractographic studies of B4C and AlB12 ceramics subjected to ballistic impact are presented. Results suggest that macroscopic texture of fracture-exposed surfaces is indicative of stress states occurring during the fracture event, whereas microscopic topography is strongly influenced as well by microstructural features. Variation observed as a function of distance from the impact axis allows some differentiation between the strain rate sensitivity of the fracture processes of the two materials. (Author) ... |
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| Transmission Microscopy of Ion-Bombardment Thinned Boron Carbide. |
NOV 1970 |
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| Authors:
R. Nathan Katz; Abram O. King; ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MASS
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| The use of the ion-bombardment etching technique to thin boron carbide ceramics for transmitted light optical and transmission electron microscopy is demonstnated. The results of the transmission electron microscopy provide the first direct evidence of the existence of dislocations in boron carbide. (Author) |
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| DISLOCATION BEHAVIOR IN ALKALINE EARTH FLUORIDES. |
NOV 1969 |
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| Authors:
R. Nathan Katz; ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MASS
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| A brief review of the basic approaches in the area of dislocation dynamics and a review of some of the past work in this field is presented. Studies of the mobilities of both edge and screw dislocations in CaF2 and BaF2 are discussed. It is shown that in pure CaF2 and BaF2 the mobility of screw dislocations apparently depends on the concentration of non-symmetrical impurities ie Nd(+3). The observed behavior ... |
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| RECENT DEVELOPMENTS IN PYROLYTIC GRAPHITE. |
FEB 1969 |
19 pages |
| Authors:
R. Nathan Katz; Charles P. Gazzara; ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MASS
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| A study of the fine microstructure of boronated pyrolytic graphite was made utilizing optical and electron microscopy and X-ray diffraction techniques. The influence of boron content on the laminar structure, the lattice parameter, the lattice strain, the particle size, and the flexural strength of pyrolytic graphite were studied. Significant changes in the behavior of all investigated parameters were observed in the 0.50 to 0.75 percent boron range. A mechanism relating ... |
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| IRREVERSIBLE DIMENSIONAL CHANGES AND THE INITIAL GRAPHITIZATION KINETICS IN ANNEALED PYROLYTIC GRAPHITE. |
JAN 1969 |
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| Authors:
R. Nathan Katz; Frederick P. Meyer; ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MASS
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| The irreversible dimensional changes in the 'a' and 'c' directions in pyrolytic graphite were studied as a function of time (up to 4 hours) and temperature (2500 to 2800 C). The change in the 'c' lattice parameter was also studied. Activation energies for the initial stages of dewrinkling and graphitization have been obtained. (Author) |
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| ROOM TEMPERATURE STRENGTH OF PYROLYTIC GRAPHITE AS AFFECTED BY MICROSTRUCTURE AND BORON CONTENT. |
FEB 1968 |
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| Authors:
Samuel J. Acquaviva; R. Nathan Katz; ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MASS
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| The strengths of pyrolytic graphites possessing four varieties of microstructure ranging from coarse-coned singularly nucleated to fine-coned continuously nucleated were examined. The fine-coned structure gave substantially higher strengths. Boron-doped pyrolytic graphite with percentages of boron varying from 0.25 to 3.3% were evaluated in terms of their modulus and flexural strength. The higher boron content material (1 to 3.3% B) achieved strengths as much as fifty percent greater than the undoped ... |
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| THE FINE MICROSTRUCTURE OF PYROLYTIC GRAPHITE AS INFLUENCED BY BORON. |
JAN 1968 |
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| Authors:
R. Nathan Katz; Charles P. Gazzara; ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MASS
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| A study of the fine microstructure of boronated pyrolytic graphite was made utilizing optical and X-ray diffraction techniques. The influence of boron content on the laminar structure, the lattice parameter, the lattice strain, the particle size, and the flexural strength of pyrolytic graphite were studied. Significant changes in the behavior of all investigated parameters were observed in the 0.50 to 0.75 percent boron range. A mechanism relating these changes to ... |
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Reports by Author
