Title

Not All Alloys are Created Equal: Recovery Temperature Testing Apparatus (RTTA)

Format

SOECS Senior Project Demonstration

Abstract/Artist Statement

Nickel titanium or Nitinol is a shape memory alloy, which is a material that "remembers" its shape, and can be returned to that shape after being deformed. This shape memory property is a result of a reversible, solid phase martensitic transformation that occurs at a certain transformation temperature. When Nitinol is deformed, it will remain in that shape until heated above its transformation temperature, at which time it will return to its original shape. These properties make Nitinol uniquely suited for a variety of applications, from aerospace to medical devices. Nitinol is commonly used in dentistry, for orthodontic brackets and wires, and for endodontic files, used to clean and shape root canals. Nitinol is typically composed of approximately 50 to 55.6% nickel by weight. However, small changes in the composition can change the transition temperature of the alloy significantly. A team of University of the Pacific bioengineering seniors collaborated with the American Dental Association (ADA) to create a testing apparatus that could be used to determine Nitinol transformation temperature in compliance with ASTM F 2082 –– 06 ““Standard Test Method for Determination of Transformation Temperature of Nickel- Titanium Shape Memory Alloys by Bend and Free Recovery.”” The standard states that a straight sample must be deformed in a semi-circle and heated back into its original shape. The transformation temperature is determined by analyzing graphical data of temperature versus displacement of the sample. With the Recovery Temperature Testing Apparatus (RTTA), the transformation temperature of any Nitinol sample can be easily and accurately determined.

Location

School of Engineering & Computer Science

Start Date

2-5-2009 2:00 PM

End Date

2-5-2009 3:30 PM

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May 2nd, 2:00 PM May 2nd, 3:30 PM

Not All Alloys are Created Equal: Recovery Temperature Testing Apparatus (RTTA)

School of Engineering & Computer Science

Nickel titanium or Nitinol is a shape memory alloy, which is a material that "remembers" its shape, and can be returned to that shape after being deformed. This shape memory property is a result of a reversible, solid phase martensitic transformation that occurs at a certain transformation temperature. When Nitinol is deformed, it will remain in that shape until heated above its transformation temperature, at which time it will return to its original shape. These properties make Nitinol uniquely suited for a variety of applications, from aerospace to medical devices. Nitinol is commonly used in dentistry, for orthodontic brackets and wires, and for endodontic files, used to clean and shape root canals. Nitinol is typically composed of approximately 50 to 55.6% nickel by weight. However, small changes in the composition can change the transition temperature of the alloy significantly. A team of University of the Pacific bioengineering seniors collaborated with the American Dental Association (ADA) to create a testing apparatus that could be used to determine Nitinol transformation temperature in compliance with ASTM F 2082 –– 06 ““Standard Test Method for Determination of Transformation Temperature of Nickel- Titanium Shape Memory Alloys by Bend and Free Recovery.”” The standard states that a straight sample must be deformed in a semi-circle and heated back into its original shape. The transformation temperature is determined by analyzing graphical data of temperature versus displacement of the sample. With the Recovery Temperature Testing Apparatus (RTTA), the transformation temperature of any Nitinol sample can be easily and accurately determined.