Rare earth-transition metal alloy articles
AssigneeROLLS-ROYCE plc
InventorsNone recorded
Life of this patent
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Abstract
A phosphate bonded ceramic is used to provide a protective coating on a rare earth-transition metal (RE-TM) alloy substrate, conferring degradation resistance to the alloy by being oxidation resistant and acting as a diffusion barrier, thereby minimising/preventing oxygen diffusion and elemental depletion. The alloy substrate may, for example, be a permanent magnetic alloy component and may be used in aerospace applications.
Claims13
A rare earth-transition metal (RE-TM) alloy structure comprising a RE-TM alloy substrate and a diffusion barrier disposed thereon,
- wherein the diffusion barrier comprises a single layer coating comprising a phosphate bonded ceramic;
- the phosphate bonded ceramic is the reaction product of a ceramic forming metal oxide and a phosphate source;
- the rare earth is samarium;
- and
- the ceramic coating is in contact with the alloy substrate on one side of the ceramic coating, the opposite side of the ceramic coating being exposed to the exterior environment.
A method of forming a single layer diffusion barrier on a rare earth-transition metal (RE-TM) alloy substrate, the method comprising:
- applying to the alloy substrate a coating comprising a source of a ceramic-forming metal oxide and a source of a phosphate binder for the metal oxide;
- and
- causing the metal oxide and the phosphate to cure to form a diffusion barrier comprising a phosphate bonded ceramic on the alloy substrate;
- wherein the diffusion barrier is in contact with the alloy substrate on one side of the ceramic coating, the opposite side of the diffusion barrier being exposed to the exterior environment;
- and
- the rare earth transition metal is samarium.
A method of reducing rare earth metal depletion at the surface of a RE-TM permanent magnet, which method comprises:
- providing over the surface a single layer diffusion barrier composed of a phosphate bonded ceramic;
- wherein
- the phosphate bonded ceramic is the reaction product of a ceramic forming metal oxide and a phosphate source;
- the diffusion barrier is in contact with the surface on one side of the ceramic coating, the opposite side of the diffusion barrier being exposed to the exterior environment;
- and
- the rare earth transition metal is samarium.
Dependencies are inferred from the claim text.