# US 10,480,581 B2 · Electro-chemical hardening of bearing raceways

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- Number: US 10,480,581 B2
- Document ID: US10480581B2
- Status: Granted
- Kind: B2
- Application number: 15/953,025
- Filed: 2018-04-13
- Published: 2018-12-06
- Granted: 2019-11-19
- Earliest claimed: 2017-06-06
- Assignees: Sikorsky Aircraft Corporation
- Applicants: Sikorsky Aircraft Corporation
- Inventors: Bruce D. Hansen; William P. Fallon, Jr.
- Web page: https://patentgrep.com/patent/US10480581B2

## CPC

- F16C 33/62: Selection of substances
- C25D 11/024: {Anodisation under pulsed or modulated current or potential}
- C25D 11/026: {Anodisation with spark discharge}
- F16C 19/06: with a single row or balls
- F16C 19/16: with a single row of balls
- F16C 33/303: {of hybrid bearings, e.g. rolling bearings with steel races and ceramic rolling elements}
- F16C 33/64: Special methods of manufacture
- F16C 2202/04: Hardness
- F16C 2206/40: Ceramics, e.g. carbides, nitrides, oxides, borides of a metal
- F16C 2223/10: Hardening, e.g. carburizing, carbo-nitriding
- F16C 2240/60: Thickness, e.g. thickness of coatings
- F16C 2361/65: Gear shifting, change speed gear, gear box
- F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- C25D: PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR

## Abstract

A method of making bearings includes treating a metallic surface of a bearing raceway with a pulsed electrochemical processing nozzle to transform the amorphous oxide into a crystalline structure on the metallic surface electro-chemically and convert the metallic surface into a ceramic like hardness surface. Treating the metallic surface can include forming a gradient in material composition transitioning from a purely metallic material at a cross-sectional position within the bearing raceway to a purely crystalline structure material at the ceramic like hardness surface of the bearing raceway.

## Claims

### Claim 1

A method of making bearings comprising a bearing raceway rotatably housing a plurality of ceramic rolling elements, the method comprising:
treating a metallic surface of the bearing raceway with a pulsed electrochemical processing nozzle to transform amorphous oxide into a crystalline structure on the metallic surface electro-chemically and convert the metallic surface into a ceramic like hardness crystalline structure surface.

### Claim 2 (depends on 1)

The method as recited in claim 1, wherein treating the metallic surface includes forming a gradient in material composition transitioning from a purely metallic material at a cross-sectional position within the bearing raceway to a purely ceramic like hardness crystalline structure material at the surface of the bearing raceway.

### Claim 3 (depends on 2)

The method as recited in claim 2, wherein a gradient depth is defined from the cross-sectional position where the gradient in material composition is a purely metallic material, to the purely ceramic like hardness crystalline structure surface, wherein the gradient depth is within a range up to 300 microns.

### Claim 4 (depends on 1)

The method as recited in claim 1, wherein treating the metallic surface of the bearing raceway includes treating a radially outward facing metallic surface of an inner raceway, and leaving a radially inward facing metallic surface of the inner raceway metallic.

### Claim 5 (depends on 1)

The method as recited in claim 1, wherein treating the metallic surface of the bearing raceway includes treating a radially inward facing metallic surface of an outer raceway, and leaving a radially outward facing metallic surface of the inner raceway metallic.

### Claim 6 (depends on 1)

The method as recited in claim 1, wherein the bearing raceway is an inner bearing raceway, wherein treating the metallic surface of the bearing raceway includes treating a radially outward facing metallic surface of the inner raceway, and leaving a radially inward facing metallic surface of the inner raceway metallic, and further comprising:
treating a metallic surface of an outer bearing raceway with an electro-chemical processing nozzle to transform amorphous oxide into a crystalline structure on the metallic surface of the outer bearing raceway electro-chemically to convert the metallic surface into a ceramic like hardness crystalline structure surface, wherein treating the metallic surface of the outer bearing raceway includes treating a radially inward facing metallic surface of the outer raceway, and leaving a radially outward facing metallic surface of the inner raceway metallic; and
assembling the inner and outer bearing raceways together with a plurality of ceramic rolling elements therebetween.

### Claim 7 (depends on 1)

The method as recited in claim 1, wherein converting the metallic surface into a ceramic like hardness crystalline structure surface includes hardening the metallic surface into a ceramic like hardness crystalline structure surface with a hardness greater than or equal to a hardness of 80 on the Rockwell hardness scale.