Effects of Some Metal Additions on Properties of Molybdenum Disilicide Page: 4 of 24
This report is part of the collection entitled: National Advisory Committee for Aeronautics Collection and was provided to UNT Digital Library by the UNT Libraries Government Documents Department.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
NACA RM E54B15
Pieces 0.400 inch long were cut from one end of each bar for oxida-
tion and thermal shock evaluations. The long pieces were used for
density, resistivity, and modulus-of-rupture evaluations.
POWDER EVALUATION PROCEDURES
Density. - The true densities of the mixed powders were obtained by
the pycnometer method with freshly boiled distilled water.
Particle size. - Particle size analysis was conducted with a
photelameter as described in reference 3. Xylene was used as the dis-
persing medium in all analyses reported herein. This procedure was
checked by making a partial size analysis of a powder that had previously
been analyzed by both the photelameter and sub-sieve techniques.
SPECIMEN EVALUATION PROCEDURES
> Density. - The bars were carefully measured and weighed and the
density was calculated. Where specimens could not be measured accurately,
a thin coating of lacquer was applied and the density was calculated by
the water-immersion method.
Resistivity. - The potential drop across a known length was measured;
direct current was used. The current was held constant and at a low
enough value to avoid heating the piece being tested. A 12-volt storage
battery, combined in series with a 5-ohm rheostat, an ammeter (0.1 ampere-
divisions), and mercury contacts, was used to provide a constant current.
The resistivity was calculated from the measured current, potential drop,
and specimen dimensions.
Modulus of rupture. - The modulus-of-rupture evaluations were con-
ducted in a specially adapted Globar furnace as reported in reference 1.
The furnace is equipped with a lever-arm system for loading, and constant
loading rates are achieved by controlling water flow into a load container.
In all evaluations, a loading rate of 2000 pounds per square inch
per minute and a span of 2 inches were used. Each specimen 0.2 by 0.4
inch in cross section was soaked at temperature for 15 minutes prior to
loading.
Oxidation resistance. - The specimens approximately 0.400 by 0.400 by
0.200 inch were carefully measured and weighed. Evaluation of oxidation
resistance was conducted in a Globar furnace with alundum boats and in
still air. All spalled material was included in the weighing. Weight
changes per unit of area were recorded and compared.3
Upcoming Pages
Here’s what’s next.
Search Inside
This report can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Report.
DeVincentis, H. A. & Russell, W. E. Effects of Some Metal Additions on Properties of Molybdenum Disilicide, report, May 4, 1954; (https://digital.library.unt.edu/ark:/67531/metadc60122/m1/4/: accessed April 23, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.