A tube furnace is designed for high temperature chemical processes in the presence of a stream of gas. The sample is placed in a ceramic or alumina combustion boat at one end of the tube in the furnace and a stream of gas is passed across the sample during heating. The gas could be H2. O2, or Ar or some combination of gases. Heating elements surround a process tube heating the tube as high as 1700°C. Process tubes can be quartz, alumina, metallic, mullite, . . . Tube furnaces are available as single zone or with 2 or more heating zones. Multi-zone furnaces are useful in transport processes where the sample must be heated higher than the product which deposits at the other end of the tube or when the process requires the product to be at a higher temperature than the sample. Many tube furnaces require separate controllers to control the heating. Controllers can be as simple as a set point and hold time. Several temperature points and ramp rates are available on the more elaborate controllers.