Patent ID: 6871998

Claim:
A method to provide a temperature calibration for a vacuum thermogravimetric analyzer (VTGA) comprising: selecting a plurality of ferromagnetic slugs wherein each slug includes an alloy including nickel and copper and wherein the amount of cooper is within the range of 15% to 28%; determining the Curie temperature of a each slug; placing each slug in a sample holder of a VTGA within a magnetic field; setting a temperature of the VTGA to a temperature corresponding to a first set-point temperature greater than the Curie temperature of each slug by an amount equal to a first offset value; holding the temperature of the VTGA at a temperature corresponding to a said first set-point temperature for a first time interval sufficient to allow the VTGA to thermally equilibrate; increasing the temperature of the VTGA to a second set-point temperature greater than an immediately preceding set-point by an amount equal to a second offset value; holding the temperature of the VTGA at a temperature corresponding to a said set-point temperature for a second time interval sufficient to allow the VTGA to thermally equilibrate; and, if each slug does not lose magnetization, then repeating the previous two operations, afterwards retuming to this test; but if not, then recording the set-point temperature at which each slug loses magnetization as the apparent Curie temperature of each slug.