Oxidation resistant coatings for molybdenum

Claim 2

As an article of manufacture, a molybdenum element comprising a molybdenum substrate in which said substrate has adherently bonded thereto a thermally self-healing plasma-sprayed coating consisting essentially of a composite of molybdenum and a refractory oxide material capable of reacting with molybdenum oxide under oxidizing conditions to form a substantially thermally stable refractory compound of molybdenum, said plasma-sprayed coating being formed of a plurality of interbonded plasma-sprayed layers of a composite of molybdenum/refractory oxide material produced from a particulate mixture thereof, said plurality of bonded layers ranging from a first layer adjacent to said substrate to an Nth or last layer which include: (a) a first layer of molybdenum plasma-sprayed bonded to the said molybdenum substrate of said molybdenum element, (b) a second layer of plasma-sprayed mixture of particulate molybdenum/refractory oxide consisting essentially of predominantly molydbenum bonded to said first layer, (c) with succeeding layers of said molybdenum/refractory oxide mixture providing from layer to layer a descending concentration gradient of molydbenum and a corresponding ascending concentration gradient of refractory oxide material, said concentration gradient continuing to an N-1 layer in which the refractory oxide concentration of the mixture predominates and terminates at the Nth layer, (d) said Nth layer consisting essentially of said refractory oxide material plasma-sprayed bonded to said N-1 layer.

Claim 3

The article of manufacture of claim 1, wherein said refractory oxide material is selected from the group consisting of zirconium oxide, hafnium oxide and aluminum oxide.

Claim 4

The article of manufacture of claim 2, wherein said refractory oxide is aluminum oxide.

Claim 5

As an article of manufacture, a molybdenum element comprising a molybdenum substrate in which said substrate has adherently bonded thereto a thermally self-healing plasma-sprayed coating consisting essentially of a composite of molybdenum and a refractory oxide material selected from the group consisting of zirconium oxide, hafnium and aluminum oxide, which refractory oxide material is capable reacting with molybdenum oxide under oxidizing conditions to form a substantially thermally stable refractory compound of molybdenum, said plasma-sprayed coating being formed of a plurality of interbonded plasma-sprayed layers of a composite of molybdenum/and said refractory oxide material produced from a particulate mixture thereof, said plurality of bonded layers ranging from a first layer adjacent to said substrate to an Nth of last layer which include: (a) a first layer of molybdenum plasma-sprayed bonded to the said molybdenum substrate of said molybdenum element, (b) a second layer of a plasma-sprayed mixture of said particulate molybdenum/refractory oxide consisting essentially of predominantly molybdenum bonded to said first layer, (c) with succeeding layers of said molybdenum/refractory oxide mixture providing from layer to layer a descending concentration gradient of molybdenum and a corresponding ascending concentration gradient of refractory oxide material, said concentration gradient continuing to an N-1 layer in which the refractory oxide concentration of the mixture predominates and terminates at the Nth layer, (d) said Nth layer consisting essentially of said refractory oxide material plasma-sprayed bonded to said N-1 layer.

Claim 6

As an article of manufacture, a molybdenum element comprising a molybdenum substrate in which said substrate has adherently bonded thereto a thermally self-healing plasma-sprayed coating consisting essentially of a composite of molybdenum and a refractory oxide material selected from the group consisting of zirconium oxide, hafnium and aluminum oxide, which refractory oxide material is capable reacting with molybdenum oxide under oxidizing conditions to form a substantially thermally stable refractory compound of molybdenum, said plasma-sprayed coating being formed of a plurality of interbonded plasma-sprayed layers of a composite of molybdenum/and said refractory oxide material produced from a particulate mixture thereof, said plurality of bonded layers ranging from a first layer adjacent to said substrate to an Nth of last layer which include: (a) a first layer of molybdenum plasma-sprayed bonded to the said molybdenum substrate of said molybdenum element, (b) a second layer of a plasma-sprayed mixture of said particulate molybdenum/refractory oxide consisting essentially of predominantly molybdenum bonded to said first layer, (c) with succeeding layers of said molybdenum/refractory oxide mixture providing from layer to layer a descending concentration gradient of molybdenum and a corresponding ascending concentration gradient of refractory oxide material, said concentration gradient continuing to an N-1 layer in which the refractory oxide concentration of the mixture predominates and terminates at the Nth layer, (d) said Nth layer consisting essentially of said refractory oxide material plasma-sprayed bonded to said N-1 layer.

Claim 7

The article of manufacture of claim 4, wherein said succeeding layers of said plasma-sprayed molybdenum/refractory oxide mixture starting from said first layer of plasma-sprayed molybdenum provides a layer to layer descending concentration gradient of molybdenum at increments of approximately 10% by weight and layer to layer ascending concentration gradient of the refractory oxide at increments approximately 10% by weight.

Claim 8

The article of manufacture of claim 5, wherein said refractory oxide is aluminum oxide.

Claim 9

As an article of manufacture, a molybdenum element comprising a molybdenum substrate in which said substrate thereof has adherently bonded thereto a thermally self-healing plasma-sprayed coating consisting essentially of a composite of molybdenum and aluminum oxide which reacts with molybdenum oxide under oxidizing conditions to form a substantially thermally stable refractory compound of molybdenum, said plasma-sprayed coating being formed of a plurality of interbonded plasma-sprayed layers of a composite of molybdenum/aluminum oxide material produced from a particulate mixture thereof, said plurality of bonded layers ranging from a first layer adjacent to said substrate to an Nth or last layer which include: (a) a first layer of molybdenum plasma-sprayed bonded to the said molybdenum substrate of said molybdenum element, (b) a second layer of plasma-sprayed mixture of particulate molybdenum/aluminum oxide consisting essentially of predominantly molybdenum bonded to said first layer, (c) with succeeding layers of said molybdenum/aluminum oxide mixture providing from layer to layer a descending concentration gradient of molybdenum at approximately 10% increments and a corresponding ascending concentration gradient of refractory oxide material at approximately 10% increments, said concentration gradient continuing to an N-1 layer in which the aluminum oxide concentration of the mixture is approximately 90% and terminates at the Nth layer, (d) said Nth layer containing approximately 100% of said aluminum oxide material plasma-sprayed bonded to said N-1 layer.

Claim 10

As an article of manufacture, a molybdenum element comprising a molybdenum substrate in which said substrate thereof has adherently bonded thereto a thermally self-healing plasma-sprayed coating consisting essentially of a composite of molybdenum and aluminum oxide which reacts with molybdenum oxide under oxidizing conditions to form a substantially thermally stable refractory compound of molybdenum, said plasma-sprayed coating being formed of a plurality of interbonded plasma-sprayed layers of a composite of molybdenum/aluminum oxide material produced from a particulate mixture thereof, said plurality of bonded layers ranging from a first layer adjacent to said substrate to an Nth or last layer which include: (a) a first layer of molybdenum plasma-sprayed bonded to the said molybdenum substrate of said molybdenum element, (b) a second layer of plasma-sprayed mixture of particulate molybdenum/aluminum oxide consisting essentially of predominantly molybdenum bonded to said first layer, (c) with succeeding layers of said molybdenum/aluminum oxide mixture providing from layer to layer a descending concentration gradient of molybdenum at approximately 10% increments and a corresponding ascending concentration gradient of refractory oxide material at approximately 10% increments, said concentration gradient continuing to an N-1 layer in which the aluminum oxide concentration of the mixture is approximately 90% and terminates at the Nth layer, (d) said Nth layer containing approximately 100% of said aluminum oxide material plasma-sprayed bonded to said N-1 layer.