APS brake discs are state-of-the-art CNC machined from a one-piece forging.
When the metal is forged it creates a directional grain flow that follows the contour of the disc. This allows for a much stronger disc that has a reduced risk of the cracking and catastrophic failures associated with the inferior welded design.
The APS "Black Steel" advantage is a proprietary heat treatment with a two-fold purpose. The heat treatment strengthens the steel by bonding the carbon, oxygen and nitrogen in the top layer of the metal. This is not a coating that can wear off. The steel itself is transformed. The heat treatment gives the steel its aesthetically pleasing black appearance and provides a surface with a high resistance to the corrosion and oxidation associated with the extreme thermal cycling experienced in aircraft braking systems. This makes it an excellent choice for agricultural aircraft that work in a harsh, chemical environment, as well as anyone who leaves their plane outside for most of its life.
Ive switched to these on my amphibious floats. I tend to leave the plane in the water for extended periods which is brutal on the brakes. Chrome discs corrode fairly quickly once the chrome wears off. So far, the black steel discs have lasted much longer than regular steel or chrome.