Nonintrusive ultrasonic sensor for monitoring and control of electroconsolidation{reg_sign} process. Page: 4 of 11
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NONINTRUSIVE ULTRASONIC SENSOR FOR MONITORING
AND CONTROL OF ELECTROCONSOLIDATION PROCESS
N. Gopalsami', H. T. Chien', and W. M. Goldberger2
Energy Technology Division, Argonne National Laboratory, Argonne, IL 60439
2Superior Graphite Co., Chicago, IL 60606
Abstract. Electroconsolidation is a proprietary process for rapid pressure-assisted
densification of complex-shaped parts made from powder preforms. The resistive
heating used in this method allows extremely high temperatures to be generated rapidly.
This paper describes an ultrasonic pitch-catch technique for nonintrusive measurement
of temperature within the die cell; this technique can be used for precise control of
densification and sintering of parts. Results of ultrasonic data for heating trials
conducted at up to 2000*C indicate that average axial temperature in the die can be
predicted within 3%.
INTRODUCTION
The Electroconsolidation (EC) process is a new proprietary method for rapid
pressure-assisted densification of preformed materials into complex-shaped parts by
simultaneous application of pressure and heat [1]. The key advantages of this method
compared to established methods such as hot isostatic pressing include (a) the ability
to densify complex-shaped parts to near net shape without the need to clad the part, (b)
capability to apply high temperatures up to 3000*C, (c) rapid cycle times, (d)
flexibility to introduce multiple parts, and (e) most important, low cost. It can be used
to manufacture parts from powders of many different materials, including metals,
ceramics, and polymeric composite materials.
Figure 1 is a schematic diagram of the basic apparatus used in the EC process.
The part to be densified is immersed within a bed of free-flowing, electrically
conducting granular medium within a cylindrical die chamber. Pressure is applied
uniaxially by double-acting hydraulic rams from the top and bottom of the die
chamber. Heat is generated resistively within the granular medium by passing
electrical current through it from a low-voltage, high-current DC power supply by a
water-cooled copper electrode on each of the two low-resistance rams. The ideal
pressure-transmitting medium should be free-flowing and electrically conducting, yet
more resistive than the rest of the circuit to act as resistive heat source; it should also
be chemically inert and stable at high temperature. Graphitic carbon powder (75- 500
sm) is one such material that closely meets these above requirements and is used as
the pressure-transmitting medium in our work.
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Gopalsami, N.; Chien, H. T. & Goldberger, W. M. Nonintrusive ultrasonic sensor for monitoring and control of electroconsolidation{reg_sign} process., article, September 25, 2000; Illinois. (https://digital.library.unt.edu/ark:/67531/metadc724638/m1/4/: accessed March 28, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.