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Jonathan's Project Page - RISE summer 2005 |
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Intern: Jonathan Nguyen, Mechanical Engineering, California State University, Sacramento
Mentor: Noah Philips
Faculty Supervisor: Tony Evans
Department: Materials |
PARTICLE REARRANGEMENT DURING BRAZE INFILTRATION
Material advancements over the past 60 years have allowed U.S. Naval
ship hull designs to be thinned from six inches of solid steel to
about half an inch. Events such as the terrorist attack on USS Cole led
the Office of Naval Research to initiate a project that would investigate
sandwich structures with greater resistance to dynamic shock waves.
A sandwich structure is fabricated with a metal core joined to two outer
metal panels with a nickel alloy braze, however the braze creates undesirable
brittle phases in the joint. Effects of 303 Stainless Steel filler material
on the fracture toughness of a brazed joint were investigated. Varying particle
sizes along with powder packing strategies of the filler material in the joint
was explored to improve packing density. The ductility of the filler material
is expected to inhibit crack growth, thereby improving the overall integrity
of the joint. Voids in the joint were evaluated in order to minimize poor
joint characteristics. Joint fabrication techniques include pre-placed filler
material with braze outside and sintered filler material with braze outside.
It is anticipated that a binary particle distribution of the filler material
will yield the most promising microstructure.
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