# US 8,784,575 B2 · Low pressure carbonitriding method and device

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

- Number: US 8,784,575 B2
- Document ID: US8784575B2
- Status: Granted
- Kind: B2
- Application number: 13/657,112
- Filed: 2012-10-22
- Published: 2013-02-21
- Granted: 2014-07-22
- Earliest claimed: 2005-04-19
- Assignees: ECM Technologies
- Applicants: ECM Technologies
- Inventors: Jean Berlier; Aymeric Goldsteinas; Xavier Doussot
- Web page: https://patentgrep.com/patent/US8784575B2

## CPC

- C23C 8/32: of ferrous surfaces
- C23C 8/34: more than one element being applied in more than one step
- 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 method for carbonitriding a steel part arranged in an enclosure maintained at a reduced internal pressure, the part being maintained at a temperature level, comprising an alternation of first and second steps, a carburizing gas being injected into the enclosure during the first steps only and a nitriding gas being injected into the enclosure only during at least part of at least two second steps.

## Claims

### Claim 1

A method for carbonitriding a steel part arranged in an enclosure maintained at a reduced internal pressure, the part being maintained at a temperature level, the method comprising: an alternation of first and second steps, in which each of the first steps is followed by one of the second steps, a carburizing gas being injected into the enclosure during the first steps only and a nitriding gas being injected into the enclosure only during at least part of at least two second steps, the nitriding gas being injected into the enclosure during at least a second step for a time shorter than the duration of said second step, the rest of the second step being carried out in the presence of a neutral gas.

### Claim 2 (depends on 1)

The method of claim 1, wherein the carburizing gas is propane or acetylene.

### Claim 3 (depends on 1)

The method of claim 1, wherein the nitriding gas is ammonia.

### Claim 4 (depends on 1)

The method of claim 1, wherein a neutral gas is injected into the enclosure simultaneously with the nitriding gas.

### Claim 5 (depends on 1)

The method of claim 1, wherein the first and second steps are performed at a constant pressure lower than 1,500 pascals.

### Claim 6 (depends on 1)

The method of claim 1, wherein the temperature level is in the range of 800° C. and 1050° C.

### Claim 7 (depends on 1)

The method of claim 1, wherein the temperature level is higher than 900° C.