Controlled Atmospheres at High Temperature

Controlled Atmospheres at High Temperature for Neutron Scattering Experiments: 

Controlled Atmospheres at High Temperature for Neutron Scattering Experiments K. J. Volin and J. S. Fieramosca Intense Pulsed Neutron Source Division Workshop on Sample Environment at Neutron Scattering Facilities Abingdon, UK June 23-25, 2004

Science Drivers for Controlled Atmospheres: 

Science Drivers for Controlled Atmospheres Functional high strength materials at high temperatures Catalytic materials Ionic conductors High Tc superconductors

The Miller Furnace: 

The Miller Furnace RT to 1450°C(1723K) Atmospheres Oxidizing Reducing* Inert Vacuum Type S thermocouples furnace control sample temperature monitor Mass flow controllers adjustable concentration of several gas mixtures adjustable total flow rate Oxygen sensor % to ppm range BN collimation 90 Degrees

The Miller Furnace - Construction: 

The Miller Furnace - Construction Aluminum oxide sample space Aluminum oxide double threaded shell Incident and exit beam windows 90° scattered beam windows Tantalum ribbon windings Tantalum foil heat shields (2 ea) Dual type S thermocouples for furnace control (2 ea) Exposed furnace materials to atmosphere Aluminum oxide Platinum Stainless steel

The Miller Furnace – Sample Insert: 

The Miller Furnace – Sample Insert

The Miller Furnace: 

The Miller Furnace Structural Behaviors of Oxygen Permeable Ceramic Membranes

The Miller Furnace: 

The Miller Furnace Structural Behaviors of Oxygen Permeable Ceramic Membranes

The Miller Furnace: 

The Miller Furnace

The Miller Furnace – Atmosphere Control: 

The Miller Furnace – Atmosphere Control Brooks Instruments Model 5850 Mass Flow Controllers

The Miller Furnace – EPICS Interface: 

The Miller Furnace – EPICS Interface The Experimental Physics and Industrial Control System (EPICS) graphical user interface (GUI) for the Brooks Instruments mass flow controllers. This allows run file control of the concentration of individual gases and the total flow rate of the gaseous atmosphere.

The Miller Furnace – Data: 

The Miller Furnace – Data

The Howe Furnace: 

The Howe Furnace The Howe furnace, on semi-permanent loan from Leicester University, is a vanadium foil vacuum furnace capable of 1100°C. It has been modified with a vanadium sample well separating the sample and furnace vacuum spaces. Samples are typically held in an open vanadium can suspended on the end of a sheathed thermocouple. vanadium element vanadium heat shields vanadium sample well pedestal and thermocouple

The Howe Furnace – Modified for Atmospheres: 

The Howe Furnace – Modified for Atmospheres To accommodate a user requiring a flow of reactive gas through the sample, the Howe furnace was modified with a fused silica tube outfitted with a coarse quartz frit to hold the powder sample. The gas, along with sheathed thermometry, are attached to the fused silica tube with stainless Swagelok fittings. fused silica wool coarse quartz frit type K thermocouple type K thermocouple sample stainless steel Swagelok feedthroughs A professional scientific glassblower installed the quartz frit into the fused silica tubes while the rest of the modifications were done by IPNS staff.

Slide14: 

The Howe Furnace – Modified for Atmospheres

The Howe Furnace – Data: 

The Howe Furnace – Data

Convection Cryofurnace - Requirements: 

Convection Cryofurnace - Requirements Extended temperature range 10K < T < 800K Rapid temperature equilibrium order of minutes Measurement of gas temperature before and after sample Use of oxidizing, reducing, or reactive gases Simple changing of samples Capable of isolating samples during sample change Robust design – user friendly to even unfriendly users

Convection Cryofurnace: 

Convection Cryofurnace

Convection Cryofurnace : 

Convection Cryofurnace American Conference on Neutron Scattering College Park, MD, June 6-10, 2004 Breakout Session on Sample Environment for Neutron Scattering Experiments (Volin, Dender, Fieramosca, & Santodonato) Common interest in a flow through cryofurnace among facilities ANL/IPNS, NIST/NCNR, ORNL/SNS, and ORNL/HFIR Common interest among elastic and inelastic instruments Sharing of effort, expertise, and equipment among neutron facilities Common specifications as requirements Temperature range Performance specs Individual specifications as options Vacuum tails Sample mounting Open bid process through DOE and/or DOC

Summary: 

Summary Controlled atmospheres at high temperatures have afforded the neutron scatterer the opportunity to explore previously uncharted phase space, investigate engineering problems involving harsh environments, and follow chemical reactions in-situ. Neutron scattering facility users will not only continue make use of available controlled atmosphere sample environments but will continue to ask for more – higher temperatures, bigger (or smaller) sample sizes, more reactive atmospheres. It’s just a matter of money, manpower, and ingenuity.

Acknowledgements: 

Acknowledgements Many in the IPNS Division have contributed to the material presented but in particular the following have participated with the authors in the modifications of the furnaces Evan Maxey, Ashfia Hug, and Yaping Li General Purpose Powder Diffractometer (GPPD) Simine Short Special Environment Powder Diffractometer (SEPD) Rich Como Sample Environment and Ancillary Equipment Group John Hammonds and Rodney Porter Computer DAS Group Dave Leach Neutron Operations Group The work reported in this presentation is supported by the U.S. Department of Energy, BES Materials Sciences, under contract W-31-109-ENG-38