The black smoke you see coming from the exhaust of jet engines in carbon. One of the effects of these carbon particles was erosion of the turbine blades. The jet engine manufacturers redesigned the combustion chambers to burn up the carbon internally instead of it coming out of the exhaust and this basically eliminated exhaust blade erosion.
Many years ago when I was working on the turboprop Grumman Gulfstream 1, the RR
Dart engines would build up a clump of carbon within the combustion chamber and when it grew large enough, it would let go and come out the exhaust pipe, you would see these on takeoff as a puff of black smoke. I believe the term RR
used was clingers and it was causing erosion problems on the turbine blades, RR
redesigned the combustion chamber and it solved the problem.
When I was flying the JetStar and ATC called out traffic and if the visibility was clear enough you could spot the airplane by the black smoke, especially if they were climbing out on takeoff.
It was in the late 1970’s or so when due to FAA, I believe under pressure from the EPA the engine manufacturers redesigned the combustion chambers and they had to be installed whenever the engine was overhauled.