los alamos national laboratory and y_-twelve have created a process to
investigate the contents of high-value hermetically sealed containers
without destroying them or compromising their integrity.
We've designed and developed and fielded
... very complex systems that that involve sealed systems that have to last
a very long time. As part of this surveillance or maintenance activity we need to
take samples of what's inside of those devices uh... to ensure things like corrosion
aren't taking place. This was seen as a need to be able to go in and remotely
sample those systems without actually having to tear down and destroy it.
The systems are very expensive,
this is viewed as a way to obtain that data to understand the life and
any chemistry it might be going on inside of that system
it is projected that this non-destructive interrogation process
could save the national nuclear security administration
more than ten million dollars annually and that this technology could produce
substantial cost savings
in a number of industries that use and rely on hermetically sealed devices
This gives engineers
and designers in the future
the capability to use another process, it's something else on the tool belt
that they can implement
and um... and be able to use to
reduce the weight of systems, reduce the cost of production
and increase the life of systems
and also on in the long run
uh... reduce the need for valves. Hermetically sealed devices are used
extensively worldwide
These sealed environment protect against the invasion of oxygen, moisture,
humidity and other contaminants that can corrode electronics
degrade quality and lessen the lifetime of the system being protected.
To ensure reliable performance
sealed enclosures require initial and periodic interrogation of interior
conditions.
Attached hermetic valves are commonly used for this process.
They're complex, with moving parts. They create volume and weight, and they can be
costly.
Valveless laser processing uses a single laser to access, sample and reseal
hermetically sealed containers. The materials that we select at the time
that we made the vessels
had nothing to do with laser welding and in fact laser welding i don't
believe was even conceptualized at the time. "Back then they used a small tube
to insert a tracer gas and the back fill gas into the containers themselves
into the systems themselves.
the tubes were cramped sealed and so we were able to successfully drill through
the tubes but um... when when welded, ah, we we saw cracks in the welds.
We had a material scientist take a look at it.
And the process we developed was a system using an alloying technique
using a laser,
and by doing so we're changing
the structure
uh... the inherent material, the substrate material
from an austinite to a ferrite phase
during the resolidification of the laser weld.
And we're able to do that by
uh... alloying with um... a material with a higher chromium content that can later
be laser welded
crack free
the insertion tube for the container is made of 304-L stainless steel
and an ESD electro spark deposition technique is used to increase the
chromium content of the three oh four l stainless material by alloying a higher
chromium three twelve stainless steel filler metal to the surface of the
container.
this technique changes the crystal structure in a region of the material
so that no solidification cracking occurs when a seal weld is created
A manifold is installed and a protective shielding gas is introduced
for the mix welding.
The manifold has a window that is transparent to the laser wavelength and
allows for a hermetically sealed, contamination-free environment
The laser is defocused for mixing the alloy material on the container.
This prepares the laser alloy substrate for reseal welding later in the process.
The laser pulses throughout the mixing and moves the outgoing material down the
length of the crimp face
The shielding gas is then removed and the manifold is evacuated to a high
vacuum.
The laser is focused for drilling and a hole was drilled into the container
through the alloy material.
With the enclosure accessed the contents can be safely removed analyzed and
replaced if necessary.
To seal the hole, the laser settings are optimized for welding, the laser de-
focused
as the weld created by pulsing the laser in the alloyed material.
"We see this as an opportunity increase
the reliability of systems,
to reduce the cost of systems, and producing those systems.
And also a way to safely and remotely
interrogate
traditionally harmful or lethal contents
VLP works in a variety of materials of varying thicknesses
x and can be applied to containers that were not originally designed for ease of
interrogation. In environmental remediation
the VLP process provides the ability to penetrate a vessel without applying
drilling or clamping forces, remotely sampling the contents making it safer
for HazMat personnel to interrogate hazardous containers.
"The amount of
certification and rigor required to implement this
throughout the NNSA
uh... makes us believe this can be used in industry
and be used in other devices such as
implantable medical devices such as pacemakers."
the VLP detection process identifies tracer gasses
such as helium inserted into pacemakers and other implantable medical devices to
identify minute and often undetectable gross leaks,
certifying the seal integrity to the highest standards.
Valveless Laser Processing:
Safe, remote, contamination-free nondestructive sampling of hermetically sealed devices
producing more reliable and safer products. "It's been remarkable. This was
a
it was a cross-site, cross-functional, cross-disciplinary team can was uh... an
outstanding demonstration of how when we put our mind to things, we can accomplish
tremendous tasks."