Shielding Walls from Radiation

Nuclear energy has been a very controversial subject for the past 30 years.  The sixties film with the genie coming out of the bottle granting the wish for unlimited nuclear energy has not been fulfilled in our time.  However, the genie is out of the bottle and nuclear power is being used in limited applications.

Solar’s vacuum heat treating processes are used by hundreds of industries.  One application was to help construct walls that would block radiation for testing purposes.

One of Solar’s customers was contracted to build walls of tungsten.  Tungsten alloys are powdered metals and are configured through pressure forming and then sintering the material.  The first construction step was to sinter bar lengths of tungsten alloy, approximately 4″ x 4″ x 3′ long.  Next, the bars would have to stacked and bonded to each other.  This would be achieved by Solar using the vacuum heat treating process known as diffusion bonding.  There were a total of 6 bars per wall and two sets would be bonded in a cycle.  Each wall was over 3,000 lbs.

The vacuum furnace environment enabled the diffusion bonding to achieve consistency because of the chamber’s uniform heat.  Control thermocouples were placed within a few inches of the tungsten assembly.  Solar Atmospheres’ diffusion bonding cycle used a slow temperature ramping up to 2750° F, followed by a slow cooling for a total furnace time of 20 hours.  The process was essentially an activated sinter bond.  Innovative hot zone and furnace hearth modifications were utilized for the most efficient furnace usage.  Work was done in a VFS HL-36.

Ultrasonic tests revealed a complete bonding of the tungsten alloy bars.  The pyramidal shape was essentially one piece of material.  Surface micrographs revealed that is very difficult to see variation in the structure of the bonding area.