All experiments were conducted in an electrically-heated box furnace with a working volume of 360 mm by 360 mm by 360 mm and a maximum operating temperature of 1500 ºC. The bottom surface of the furnace is located on hydraulic elements and can be moved up and down for loading and unloading of specimens (Figure 3). A series of five Type N thermocouples, insulated for high temperature applications, were introduced into the furnace through an entry port in the top. The thermocouples were connected to a constant temperature zone box, where their differential voltages were monitored using a digital multimeter and digital voltmeter. The thermocouples were monitored periodically and recorded on a computer. Measurement in ice water yielded an average standard deviation of 0.05 ºC among the five thermocouples.