# US 5,700,423 A · Hearth roll with superior endurance capacity

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 5,700,423 A
- Document ID: US5700423A
- Status: Granted
- Kind: A
- Application number: 08/518,350
- Filed: 1995-08-23
- Granted: 1997-12-23
- Earliest claimed: 1994-08-26
- Assignees: Praxair S.T. Technology, Inc.
- Inventors: Yang Gao
- Web page: https://patentgrep.com/patent/US5700423A

## CPC

- C23C 4/06: Metallic material
- F27D 3/026: {transport or conveyor rolls for furnaces; roller rails}
- B21B 27/00: Rolls, {roll alloys or roll fabrication}(shape of working surfaces required by special processes B21B1/00); Lubricating, cooling or heating rolls while in use
- B21B 39/008: {Rollers for roller conveyors (roller-ways in general B65G13/00, B21B39/00)}
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- F27D: DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- B21B: ROLLING OF METAL (auxiliary operations used in connection with metal-working operations covered in B21, see B21C; bending by rolling B21D; manufacture of particular objects, e.g. screws, wheels, rings, barrels, balls, by rolling B21H; pressure welding by means of a rolling mill B23K20/04)

## Abstract

A hearth roll with a cermet thermal spray coating on the roll surface which is composed of a heat resistant MCrA1Y (M: Fe, Ni, Co) alloy where the amount of A1 is below 10 at. % and the combined (Al+Cr) amount is between 13-31 at. % and at least one oxide ceramic from the group consisting of MgO, MgAl.sub.2 O.sub.4, and Y.sub.2 O.sub.3.

## Claims

### Claim 1

A continuous annealing furnace for annealing sheet strips which employs a hearth roll characterized by a cermet thermal spray layer on the surface of the roll body where the thermal spray layer is composed of (1) a heat resistant MCrAlY alloy where M is at least one metallic element from the group of Fe, Ni, and Co, with the amount of Al to be below 10 at. % and the combined amount of Al and Cr between 13 at. % and 31 at. % combined with (2) an oxide ceramic constituting between 5-90 wt. % of the thermal spray coating which has low reactivity with manganese oxide.

### Claim 2 (depends on 1)

The hearth roll described in claim 1 where the oxide ceramic having low reactivity with manganese oxide is magnesia spinel (MgAl.sub.2 O.sub.4).

### Claim 3 (depends on 1)

The hearth roll described in claim 1 where the oxide ceramic having low reactivity with manganese oxide is magnesia (MgO).

### Claim 4 (depends on 1)

The hearth roll described in claim 1 where the oxide ceramic having low reactivity with manganese oxide is yttria (Y.sub.2 O.sub.3).

### Claim 5 (depends on 1)

The hearth roll described in claim 1 where the oxide ceramic having low reactivity with manganese oxide is a material derived from a combination of at least two oxides chosen from the group of magnesia spinel (MgAl.sub.2 O.sub.4), magnesia (MgO), and yttria (Y.sub.2 O.sub.3).