Masters Theses
Abstract
"This thesis focuses on both the formation of defects in lost foam casting and the mechanisms by which these defects form. Paper 1 describes use of flange patterns in an attempt to determine the effect of foam density and foam type on the metal flow and formation of defects in the lost foam process. The experiment determined that the foam type had a significant effect on the metal front profile shape and the metal front profile related to the location of fold defects in some cases. The foam density did not have the expected effect on metal velocity for some patterns, possibly because of the abnormal metal front profiles in the tripolymer patterns or the possible discrepancy in pouring temperatures.
Paper 2 describes an attempt to classify defects in lost foam casting through the use of the flange pattern, several alloy types, and two different permeability coatings. Photomicrographs, SEM images, and AES results were used to examine the microstructure, surface topography, and composition of the folds, blisters, internal pores, and fracture surfaces present. The conclusion formulated in this work is that the composition of the defect surfaces relies heavily on the reactivity of elements present in the aluminum alloys with oxygen. Also, the microstructure surrounding these defects is related to the last constituent to form upon solidification. A theory on the mechanisms of formation for blister and fold defects is presented.
Paper 3 describes the design of a full factorial experiment with five variables to see their effect on the metal velocity and formation of defects in a thick-section t-shaped pattern. The variables used in this experiment were the foam density, the degree of fusion, the coating permeability, the pattern orientation, and the foam type. Through use of a statistical software package, the main effects influencing the metal velocity, and the severity of several casting defects were determined" Abstract p. iv
Advisor(s)
Askeland, Donald R.
Committee Member(s)
Ramsay, Christopher W.
Kluczny, Raymond Michael
Department(s)
Materials Science and Engineering
Degree Name
M.S. in Metallurgical Engineering
Publisher
University of Missouri--Rolla
Publication Date
Fall 1999
Pagination
xiii, 262 pages
Note about bibliography
Includes bibliographical references (pages 23, 90, and 189)
Rights
© 1999 Mark Allen Tschopp, All rights reserved.
Document Type
Thesis - Restricted Access
File Type
text
Language
English
Thesis Number
T 7699
Print OCLC #
43698633
Recommended Citation
Tschopp, Mark Allen, "Mechanisms of the formation of pyrolysis defects in aluminum lost foam castings" (1999). Masters Theses. 1893.
https://scholarsmine.mst.edu/masters_theses/1893
Share My Thesis If you are the author of this work and would like to grant permission to make it openly accessible to all, please click the button above.
