Patent ID: 6670025
Filing Date: 2003-12-30
Classification: C04B,C23C,C30B,Y10T

Abstract:
An article comprising a first plurality of layers containing pyrolytic boron nitride (PBN) and a second plurality of layers containing PBN and at least one elemental dopant selected from the group of elements in groups 1-6 of the periodic table of elements, alkali metal(s), alkaline earth metal(s), transition metal(s) and rare earth metal(s) or combinations thereof; said second plurality of layers separating some or all of the first plurality of layers with the dopant in the second plurality of layers being present in a sufficient concentration to induce peeling upon a build up of internal stress along a fracture plane in at least one of the second plurality of layers with said dopant being present on both sides of the fracture plane and with said dopant having a minimum concentration of 2 atomic weight % at a depth ranging from about 1000 to 2000 angstroms measured from the surface of the peeled layer and with each of the layers in the second plurality of layers being spaced apart from one another a distance of at least one tenth of one micron.