The NGK in Mooresville makes catalytic converter substartes. They are highly porous ceramic pieces that are extruded, they then get coated with other ceramics and precious metals to finally end up in a catalytic converter. In NC they make only the ceramic filter portion.
From their website "NGK Ceramics USA, which makes ceramic filters for auto engines, announced Tuesday it will invest $93 million to expand its Mooresville plant..."
This is a substrate for automotive:
this is what is used in diesel trucks(they are larger and can be made of different materials and sometimes have to be made in smaller pieces and "glued" together):
It is a growing business they make great parts and have great quality. Their biggest competitor in the USA is Corning.
I had visited the plant years ago, in Mooresville. They are a well run company!!
Yes they make spark plugs but not here in NC. They make all sorts of ceramic engine components through NGK Japan.
It is great they are expanding!