# US 12,768,025 B2 · Gas wiping nozzle and methods for manufacturing hot-dip metal-coated steel strip and gas wiping nozzle

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- Number: US 12,768,025 B2
- Document ID: US12768025B2
- Status: Granted
- Kind: B2
- Application number: 18/716,260
- Filed: 2022-10-11
- Published: 2025-01-30
- Granted: 2026-10-20
- Earliest claimed: 2021-12-10
- Assignees: Jfe Steel Corporation
- Applicants: Jfe Steel Corporation
- Inventors: Yu Ito; Hideyuki Takahashi; Kenji Yamashiro; Takumi Koyama; Yoshihiko Kaku
- Web page: https://patentgrep.com/patent/US12768025B2

## CPC

- C23C 2/20: Strips; Plates
- C23C 2/06: Zinc or cadmium or alloys based thereon
- C23C 2/40: Plates; Strips
- 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)

## Abstract

A gas wiping nozzle and a method for manufacturing a hot-dip metal-coated steel strip using the gas wiping nozzle. The gas wiping nozzle adjusts the coating weight of a molten metal on the surface of a steel strip pulled up from a molten metal bath. At least the surface of the gas wiping nozzle is made of a ceramic, and the arithmetic mean roughness Ra and the peak count PPI of the gas wiping nozzle satisfy Formula (1): PPI > c ⁢ 1 × Ra + c ⁢ 2 ( 1 ) PPI: peak count (the number of peaks per inch) Ra: arithmetic mean roughness [μm] c1 and c2: determined constants for each ceramic used in the surface of the gas wiping nozzle.

## Claims

### Claim 1

A gas wiping nozzle that is configured to blow gas to a steel strip pulled up from a molten metal bath to adjust a coating weight of a molten metal on a surface of the steel strip, wherein:
at least a surface of the gas wiping nozzle is made of a ceramic, and an arithmetic mean roughness Ra and a peak count PPI, which are measures of surface roughness, of the gas wiping nozzle satisfy Formula (1)
PPI
>
c
⁢
1
×
Ra
+
c
⁢
2
(
1
)
PPI: peak count (number of peaks per inch)
Ra: arithmetic mean roughness [μm]
c1 and c2: determined constants for each ceramic used in a surface of the gas wiping nozzle, a surface roughness of the gas wiping nozzle satisfies Formula (2)
cos
⁢
θ
w
=
r
*
cos
⁢
θ
e
(
2
)
θw: apparent contact angle on a rough surface
θe: contact angle of a liquid droplet on a smooth surface
r: area ratio of the rough surface to the smooth surface (r≥1). the ceramic is SiAlON or alumina. when the ceramic is SiAlON, c1 is-35 and c2 is 100, and when the ceramic is alumina, c1 is-28 and c2 is 170.

### Claim 2 (depends on 1)

The gas wiping nozzle according to claim 1, wherein the entire gas wiping nozzle is made of a ceramic.

### Claim 3 (depends on 1)

A method for manufacturing a hot-dip metal-coated steel strip, the method comprising:
continuously dipping a steel strip in a bath of molten metal; and
adjusting a coating weight of the molten metal on both sides of the steel strip by blowing a gas to the steel strip from a plurality of the gas wiping nozzle according to claim 1 that are disposed to face each other with the steel strip, which is pulled up from the bath, therebetween to continuously manufacture the hot-dip metal-coated steel strip.

### Claim 4 (depends on 1)

A method for manufacturing the gas wiping nozzle according to claim 1, the method comprising:
selecting a material of the gas wiping nozzle or of a surface of the gas wiping nozzle; and
selecting a processing method and processing conditions for the surface of the gas wiping nozzle; and
manufacturing the gas wiping nozzle according to the selected processing method and processing conditions,
wherein the material and/or the processing method and the processing conditions are selected such that the arithmetic mean roughness Ra and the peak count PPI, which are measures of surface roughness, of the gas wiping nozzle satisfy Formula (1)
PPI
>
c
⁢
1
×
Ra
+
c
⁢
2
(
1
)
PPI: peak count (number of peaks per inch)
Ra: arithmetic mean roughness [μm]
c1 and c2: determined constants for each ceramic used in the surface of the gas wiping nozzle.

### Claim 5 (depends on 2)

A method for manufacturing a hot-dip metal-coated steel strip, the method comprising:
continuously dipping a steel strip in a bath of molten metal; and
adjusting a coating weight of the molten metal on both sides of the steel strip by blowing a gas to the steel strip from a plurality of the gas wiping nozzle according to claim 2 that are disposed to face each other with the steel strip, which is pulled up from the bath, therebetween to continuously manufacture the hot-dip metal-coated steel strip.

### Claim 6 (depends on 2)

A method for manufacturing the gas wiping nozzle according to claim 2, the method comprising:
selecting a material of the gas wiping nozzle or of a surface of the gas wiping nozzle;
selecting a processing method and processing conditions for the surface of the gas wiping nozzle; and
manufacturing the gas wiping nozzle according to the selected processing method and processing conditions,
wherein the material and/or the processing method and the processing conditions are selected such that the arithmetic mean roughness Ra and the peak count PPI, which are measures of surface roughness, of the gas wiping nozzle satisfy Formula (1)
PPI
>
c
⁢
1
×
Ra
+
c
⁢
2
(
1
)
PPI: peak count (number of peaks per inch)
Ra: arithmetic mean roughness [μm]
c1 and c2: determined constants for each ceramic used in the surface of the gas wiping nozzle.