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Mueller, J. I.

Publications and source records attributed to Mueller, J. I..

18 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Structural ceramics research

Ceramic research at the University of Washington, brittle materials design program, and NASA program research at the University of Washington are outlined.

Mueller, J. I.↗
NASA NTRS1980

Design with brittle materials - An interdisciplinary educational program

A series of interdisciplinary design courses being offered to senior and graduate engineering students at the University of Washington is described. Attention is given to the concepts and some of the details on group design projects that have been undertaken during the past two years. It is noted that ceramic materials normally demonstrate a large scatter in strength properties. As a consequence, when designing with these materials, the conventional 'mil standards' design stresses with acceptable margins of safety cannot by employed and the designer is forced to accept a probable number of failures in structures of a given brittle material. It is this prediction of the probability of failure for structures of given, well-characterized materials that forms the basis for this series of courses.

Mueller, J. I.↗
NASA NTRS1978

An educational program on structural design with brittle /ceramic/ materials

The organization of a proposed ceramic structural materials program is described, and a suggested course sequence for college-level and graduate-level courses is presented. The course work on ceramics and brittle fracture are intended to lead to a brittle material design project and a brittle material design problem. Criteria for the selection of appropriate projects/problems are considered.

Mueller, J. I.↗
NASA NTRS1975

Fundamental studies on the nature and properties of ceramic fiber insulation

Silica and mullite fibers used to fabricate reusable surface insulation (RSI) for the space shuttle orbiter may devitrify/recrystallize within the temperature range anticipated upon reentry. This is shown to be dependent upon impurity level, temperature, and time at temperature. It is determined that the effects of the material improvement and optimization program are positive. The degree of crystallinity is shown to have a predominant effect upon the strength of fabricated RSI tile, and limits are determined. Models are developed to predict tensile strengths and shrinkage rates of silica tile based upon readily measurable parameters. Thermal cycling which simulates reentry results in an increase in the crystallinity and in the porosity of tile coatings.

Mueller, J. I.↗
NASA NTRS1975

Formation mechanism of a silicon carbide coating for a reinforced carbon-carbon composite

Results are presented for a study to determine the mechanisms involved in a high-temperature pack cementation process which provides a silicon carbide coating on a carbon-carbon composite. The process and materials used are physically and chemically analyzed. Possible reactions are evaluated using the results of these analytical data. The coating is believed to develop in two stages. The first is a liquid controlled phase process in which silicon carbide is formed due to reactions between molten silicon metal and the carbon. The second stage is a vapor transport controlled reaction in which silicon vapors react with the carbon. There is very little volume change associated with the coating process. The original thickness changes by less than 0.7%. This indicates that the coating process is one of reactive penetration. The coating thickness can be increased or decreased by varying the furnace cycle process time and/or temperature to provide a wide range of coating thicknesses.

Rogers, D. C.↗
NASA NTRS1973

Characterization of RSI coating

X-ray diffraction analyses on mullite, silica, and ceramic mullite fiber coating materials to investigate the effects of thermal cycling, show that ceramic mullite fiber coating porosity is little affected by cycling to 1250 C and that material pores are mostly smaller than 15 nm. Some mullite coatings experience a slight increase in crystobalite with somewhat increased porosity. Silica coatings show a marked tendency to precipitate cristobalite with increased porosity and dimensional instability.

Miller, A. D.↗
NASA NTRS1973

Interdisciplinary research concerning the nature and properties of ceramic materials

Research projects involving the development of ceramic materials are discussed. The following areas of research are reported: (1) refractory structural ceramics, (2) solid electrolyte ceramics, and (3) ceramic processing. The laboratory equipment used and the procedures followed for various development and evaluation techniques are described.

Mueller, J. I.↗