Furnace gradient

Archaeological Ceramic Study Possibilities with a Thermal Gradient Furnace... 

Recently it was possible to construct for archaeological studies a thermal gradient furnace similar to one used in the ceramic laboratories of the College of the Earth and Mineral Sciences of The Pennsylvania State University. Robert Frantz modified the design of the earlier furnace so that it would be suitable for testing archaeological clays and sherds that are available only in small quantities. 

Figure 2. Thermal gradient furnace with control panel...

Figure 3. Thermal gradient furnace showing thermocouple distribution...

Figure 5. A time-temperature firing schedule of the thermal gradient furnace at the 12 thermocouple points of measurement...

A small-scale, controlled atmosphere, gradient furnace is a valuable addition to the laboratory since it allows optimum sintering conditions to be quickly determined. 

To prepare the undoped crystals, pure 60 powder was first extracted ftom carbon soot via standard liquid chromatography with an alumina column. The powder was baked at 250°C under dynamic vacuum for 24 hours and then sealed in quartz tubes with a few hundred torr of argon gas. Sealed tubes were placed in a gradient furnace with the powder held at 650 C crystals formed in the tube at about 450 C. With this vapor... 

Simultaneous thermal exposure of a sample at various temperatures is provided by the so-called gradient furnace, i.e. a furnace with an approximately linear temperature distribution within the required range. A rod-shaped sample in a platinum boat, or glass fragments on a platinum bridge 10—15 cm in length are placed in the furnace. The method is less accurate but significantly more rapid. 

I) Zirconia specimen (2) zirconia tube electrodes (3) Pt,02 reference electrode (4) thermocouple (S) temperature gradient furnace (6) reference gases. 

Experimental arrangement for measuring thermoelectric emfs of glass-forming melts by means of zirconia microelectrodes. (1) Zirconia electrodes (2) melt (3) temperature gradient furnace (4) leads from PtiOj reference electrodes (5) leads from thermocouples (6) reference gas inlet (7) outlet. 

Schmid. F. and Viechnicki, D. (1970) Growth of sapphire disks from melt by a gradient furnace technique, J. Am. Ceram. Soc. S3, 528. 

ASTM-American Society for Testing and Materials, Standard Practices for Measurement of Liquidus Temperature of Glass by the Gradient Furnace Method, ASTM C 829-81 (Reapproved 2010), ASTM International, West Conshohocken, Pennsylvania. 

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