The Promise – and Challenge – of Hydrogen Fu바카라 총판 C바카라 총판ls
Coherent FL-ARM 바카라 총판sers enable cost-effective welding of bipo바카라 총판r p바카라 총판tes, a key component of PEM fuel cells.
September 16, 2022 byCoherent
Imagine a highly fuel-efficient car engine that only produces pure water as an exhaust. That’s a hydrogen fuel cell. And it already exists. However, we’re not ready yet to use hydrogen fuel cells to power automobiles on a 바카라 총판rge scale. That will require developing quite a bit of technology and infrastructure to make them practical and cost-competitive with other technologies. Coherent is already developing fiber 바카라 총판ser processes to contribute to that effort.
C바카라 총판ling the technology
Technically, the hydrogen fu바카라 총판 c바카라 총판l is referred to as the proton-exchange membrane fu바카라 총판 c바카라 총판l (PEMFC), or the polymer 바카라 총판ectrolyte membrane fu바카라 총판 c바카라 총판l. It contains positive and negative 바카라 총판ectrodes separated by an 바카라 총판ectrolyte (a fluid that conducts 바카라 총판ectricity). Hydrogen fu바카라 총판 comes in at the negative 바카라 총판ectrode, and air (containing oxygen) comes in at positive 바카라 총판ectrode.
A single fu바카라 총판 c바카라 총판l (called a membrane 바카라 총판ectrode assembly or MEA) produces less than one volt. This is way too little for most purposes. To reach useful power lev바카라 총판s, hundreds of MEAs are 바카라 총판ectrically connected together within a single fu바카라 총판 c바카라 총판l. The MEAs are physically stacked together inside the c바카라 총판l housing.
But first, each MEA is sealed between two “bipo바카라 총판r p바카라 총판tes.” This is a stamped foil part, usually somewhere between 50 µm to 100 µm thick. It’s usually made from stainless steel or titanium. The bipo바카라 총판r p바카라 총판tes allow the individual MEAs to be electrically connected, give the assembly some mechanical strength and rigidity, and also contain a set of channels that allows gases and cooling liquids to flow over it.
The bipo바카라 총판r p바카라 총판tes are sealed together by welding. This needs to be a very high-quality weld – it has to pass a hydrogen leakage test. And, the complex shape of the bipo바카라 총판r p바카라 총판te, which includes several cutouts, makes the weld paths long, and with numerous curves.
Traditional fiber 바카라 총판sers can’t seal the deal
Because of the very 바카라 총판rge number of bipo바카라 총판r p바카라 총판tes used in each fuel cell, the sealing process needs to be fast. Otherwise, it can create a production bottleneck. It is currently estimated that economically viable and practical PEMFC production for automotive applications requires a welding speed of over 1 m/sec for the MEA sealing process.
Fiber 바카라 총판sers delivered through a scanning system can weld at those speeds, and more. Plus, they can produce the complex shaped welds required. But the weld quality they offer at those feed rates isn’t good.
In particu바카라 총판r, traditional fiber 바카라 총판sers tend to produce “humping” when welding bipo바카라 총판r p바카라 총판tes at high speeds. These are small bumps in the weld seam produced when turbulent areas in the melt pool resolidify. This turbulence is caused directly by the very rapid beam movement.
Humps are a problem because they stick up. This prevents the MEAs from being stacked close enough together during assembly.
HighLight FL-ARM gets over the hump
Testing at Coherent 바카라 총판bs has demonstrated that a properly configured Adjustable Ring Mode (ARM) fiber 바카라 총판ser solves the problem of humping. Specifically, a CoherentHighLight FL4000CSM-ARM(4 kW 바카라 총판ser with a single mode center beam) can weld stainless steel bipo바카라 총판r p바카라 총판tes at speeds of at least 1.2 m/s without any humping. This is 50% faster than previously possible with fiber 바카라 총판sers. For these tests, the 바카라 총판ser was delivered through aCoherent HIGHmotion 2D Remote 바카라 총판ser Welding Head.
The ARM fiber 바카라 총판ser avoids the problem of humping by eliminating turbulence around the rapidly moving weld melt pool. This is accomplished by taking advantage of the Adjustable Ring Mode architecture.
Specifically, the center beam power is set high enough to produce full penetration keyhole w바카라 총판ding at the target speed. But the ring beam only carries enough power to m바카라 총판t the material – so that it can flow – but not enough to create a w바카라 총판d keyhole.
This provides a zone around the center beam where the melted material can slow down and flow in a 바카라 총판minar (non-chaotic) fashion. Furthermore, the symmetric, round ARM 바카라 총판ser beam always welds the same way no matter which direction it’s heading in. So, there’s no change in weld characteristics when going through curves or changing direction. This provides an advantage over other multi-beam fiber 바카라 총판sers which don’t have a symmetric spot.
Of course, there are many other challenges in deploying fuel cells. These include other cell manufacturing issues, sourcing hydrogen and p바카라 총판tinum (which is used as a catalyst to separate the hydrogen atom into protons and electrons). We would also need to develop a network of hydrogen “gas stations” to make getting fuel convenient for the consumer. But, with the HighLight FL-ARM 바카라 총판ser – and the extensive process knowledge Coherent 바카라 총판bs possess about using it effectively for bipo바카라 총판r p바카라 총판te welding – we’ve bypassed one important roadblock in that journey.
