Sridhar SeetharamanSridhar Seetharaman Carnegie Mellon UniversityCarnegie Mellon UniversityDepartment of Materials Science and EngineeringDepartment of Materials Science and EngineeringPittsburgh, PA 15213-3890Pittsburgh, PA 15213-3890

Development of a High Temperature Maximum Development of a High Temperature Maximum Bubble Pressure Apparatus For Measuring Surface Bubble Pressure Apparatus For Measuring Surface

Tension of Molten MetalsTension of Molten Metals

DMR-0112792DMR-0112792

Sridhar SeetharamanSridhar Seetharaman Carnegie Mellon UniversityCarnegie Mellon UniversityDepartment of Materials Science and EngineeringDepartment of Materials Science and EngineeringPittsburgh, PA 15213-3890Pittsburgh, PA 15213-3890

                  Intellectual Merits•The overall objective of this program is to develop an experimental methodology to measure surface tensions of liquid alloys under controlled oxygen contents in the gas.

•This will be used for characterizing surface tension of melts containing reactive elements such as Al, Cr and Ti. The effect of oxygen potential on the surface tension and surface phases will be elucidated and the results will be used to improve the understanding of surface physical chemistry of metallic melts and to address current industrial problems.

Sridhar SeetharamanSridhar Seetharaman Carnegie Mellon UniversityCarnegie Mellon UniversityDepartment of Materials Science and EngineeringDepartment of Materials Science and EngineeringPittsburgh, PA 15213-3890Pittsburgh, PA 15213-3890

Gas

2r

Melth

Principle behind MBP

2

6

1

3

21

2

P

gr

P

grrP

•The pressure needed to form a bubble at the tip of the tube is registered.

•The maximum bubble pressure (P) to form a bubble is related to the surface tension and to the pressure necessary to create a new surface (P ) through the equation:.

Sridhar SeetharamanSridhar Seetharaman Carnegie Mellon UniversityCarnegie Mellon UniversityDepartment of Materials Science and EngineeringDepartment of Materials Science and EngineeringPittsburgh, PA 15213-3890Pittsburgh, PA 15213-3890

Ar

5

Ar

3 9

2

4 1

6 7

8

MBP apparatus used for molten metals

(1)   Furnace (2) Zr-oxide capillaries for oxygen monitoring.(3)   Pt/Pt-Rh thermocouple (4)   Alumina crucible (5)   Ambient oxygen-gettered gas(6) Protective alumina tube (7)   Pressure transducer. (8)   With the help of a gas flow controller(9)   Capillary lifting device

Sridhar SeetharamanSridhar Seetharaman Carnegie Mellon UniversityCarnegie Mellon UniversityDepartment of Materials Science and EngineeringDepartment of Materials Science and EngineeringPittsburgh, PA 15213-3890Pittsburgh, PA 15213-3890

The MBP developed under this grant

High temperature furnace and controller

Computer control for gas flow rate, pressure monitoring and temperature control

Sridhar SeetharamanSridhar Seetharaman Carnegie Mellon UniversityCarnegie Mellon UniversityDepartment of Materials Science and EngineeringDepartment of Materials Science and EngineeringPittsburgh, PA 15213-3890Pittsburgh, PA 15213-3890

                  Broader Impacts•Two graduate students have been supported by this project and a laboratory is being designed for undergraduate students.•Collaboration is being established with industrial companies to use the equipment to determine properties that are key for manufacturing primary metals.

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

0.0035

0.004

0 0.2 0.4 0.6 0.8 1 1.2

Lance depth (cm)

Max

imu

m P

ress

ure

-Bas

e L

ine

Pre

ssu

re (

psi

)

Initial results for the maximum bubble pressure in molten copper are shown below: