Electrical corrosion resistant mechanical seal

Patent metadata

Field	Value
Publication number	US-9695944-B2
Application number	US-201414560446-A
Country	US
Kind code	B2
Filing date	Dec 4, 2014
Priority date	Dec 23, 2013
Publication date	Jul 4, 2017
Grant date	Jul 4, 2017

Abstract

An improved mechanical face seal is provided which includes a pair of relatively rotatable seal rings having opposing seal faces. At least one of the seal faces and preferably the silicon carbide seal ring includes a tantalum coating over the seal face. The coating is formed such that the exposed seal face surface is formed of tantalum with a preferred thickness, and the substrate is the silicon carbide seal ring material. Between the silicon carbide substrate and exposed tantalum coating layer, an intermediate transformation layer of tantalum carbide is formed to enhance bonding of the substrate and coating layer. Preferably, the tantalum carbide layer is formed during the coating process wherein the tantalum is applied by chemical vapor deposition and the tantalum reacts with the silicon carbide to form the tantalum carbide at the interface between the tantalum coating layer and the seal ring substrate.

First claim

I claim:

1. A mechanical seal ring comprising:
a seal ring exposed to a process fluid, said seal ring having exposed ring surfaces which are defined on an exterior of said seal ring so as to be exposed to said process fluid and said exposed ring surfaces including a seal face;
said seal ring comprising a silicon carbide substrate and a coating layer applied to said substrate so as to define said exposed ring surfaces, said coating layer consisting essentially of tantalum and being electrical corrosion resistant, said seal ring including a transformation layer interfacing inwardly with said substrate and outwardly with said coating layer, said transformation layer consisting essentially of tantalum carbide; and
said seal ring formed by using chemical vapor deposition to apply said tantalum of said coating layer to said substrate of said seal ring to form said coating layer, and performing said chemical vapor deposition at an elevated temperature adequate to effect a reaction between said silicon carbide of said substrate and said tantalum being applied to form said tantalum carbide of said transformation layer.

2. The mechanical seal ring according to claim 1 , wherein an inner interface is defined between said transformation layer and said substrate on an inner side of said transformation layer and an outer interface is defined between said transformation layer and said coating on an outer side of said transformation layer wherein said inner interface transitions from said silicon carbide of said substrate to said tantalum carbide of said transformation layer and wherein said outer interface transitions from said tantalum carbide of said transformation layer to said tantalum of said coating layer.

3. The mechanical seal ring according to claim 1 , wherein said coating layer is bonded to said substrate by said intermediate transformation layer.

4. The mechanical seal ring according to claim 1 , wherein said coating layer includes a hydrodynamic face pattern formed by shallow grooves, said shallow grooves having a groove depth less than a thickness of said coating layer.

5. The mechanical seal ring according to claim 4 , wherein exposed surfaces of said shallow grooves are formed by said tantalum of said coating layer.

6. The mechanical seal ring according to claim 1 , wherein said exposed ring surfaces include a radial surface at a ring diameter of said seal ring.

7. The mechanical seal ring according to claim 1 , wherein said substrate defines unexposed ring surfaces in addition to said exposed ring surfaces.

8. A mechanical seal for sealing a process fluid against fluid leakage along a rotatable shaft comprising:
a housing defining a seal chamber for receiving the process fluid therein;
a seal ring located within said seal chamber, said seal ring having exposed ring surfaces which are disposed within said seal chamber for exposure to the process fluid wherein said exposed ring surfaces comprise a seal face;
said seal ring comprising a silicon carbide substrate and a coating layer applied to said substrate so as to define said exposed ring surfaces, said coating layer consisting essentially of tantalum and being electrical corrosion resistant, said seal ring including a transformation layer interfacing inwardly with said substrate and outwardly with said coating layer, said transformation layer consisting essentially of tantalum carbide; and
said seal ring formed by using chemical vapor deposition to apply said tantalum of said coating layer to said substrate of said seal ring to form said coating layer, and performing said chemical vapor deposition at an elevated temperature adequate to effect a reaction between said silicon carbide of said substrate and said tantalum being applied to form said tantalum carbide of said transformation layer.

9. The mechanical seal according to claim 8 , wherein an inner interface is defined between said transformation layer and said substrate on an inner side of said transformation layer and an outer interface is defined between said transformation layer and said coating on an outer side of said transformation layer wherein said inner interface transitions from said silicon carbide of said substrate to said tantalum carbide of said transformation layer and wherein said outer interface transitions from said tantalum carbide of said transformation layer to said tantalum of said coating layer.

10. The mechanical seal according to claim 8 , wherein said coating layer is bonded to said substrate by said intermediate transformation layer.

11. The mechanical seal according to claim 8 , wherein said coating layer includes a hydrodynamic face pattern formed by shallow grooves, said shallow grooves having a groove depth less than a thickness of said coating layer.

12. The mechanical seal according to claim 11 , wherein exposed surfaces of said shallow grooves are formed by said tantalum of said coating layer.

13. The mechanical seal according to claim 8 , wherein said exposed ring surfaces face axially relative to a shaft axis, and wherein said exposed ring surfaces include a radial surface at a ring diameter of the seal ring, and said radial surface faces radially.

14. The mechanical seal according to claim 13 , wherein said substrate defines unexposed ring surfaces in addition to said exposed ring surfaces, wherein said unexposed ring surfaces are sealed from said seal chamber and sealed from exposure to the process fluid.

Assignees

• Flowserve Man Co

Inventors

• Davis John

Classifications

• F16J15/3496 Primary

  use of special materials · CPC title

• C23C16/06

  characterised by the deposition of metallic material · CPC title

• F16J15/34

  with slip-ring pressed against a more or less radial face on one member · CPC title

• F16J15/3412

  with cavities (F16J15/3424 takes precedence) · CPC title

• F16J15/3424

  with microcavities · CPC title