Method for the treatment of alloy steels and refractory metals

• US 5,372,655 A
• Filed: 04/14/1992
• Issued: 12/13/1994
• Est. Priority Date: 12/04/1991
• Status: Expired due to Fees

• Current Assignee: ALD Vacuum Technologies AG
• Original Assignee: Leybold, Durferrit GmbH
• Inventors: Zimmerman, Klaus, Minarski, Peter, Melber, Albrecht, Preisser, Friedrich
• Primary Examiner(s): Dean, Richard O.
• Assistant Examiner(s): Koehler, Robert R.
• Application Number:
  US07/871,266
• Time in Patent Office: 973 Days
• Field of Search: 148/230, 148/237, 148/238, 148/316, 148/318, 148/319
• US Class Current: 148/230
• CPC Class Codes: C23C 8/02 Pretreatment of the material to be coated C23C8/04 takes precedence
• CPC Class Codes: C23C 8/80 After-treatment

Abstract

Method for the treatment of alloy steels and refractory metals such as Ti, Zr and Nb, especially for depassivation and subsequent thermochemical surface treatment in a process chamber (1, 2) under the action of pressure and temperature, wherein, in a first process step, a first gas or gas mixture from the group N₂, H₂ or NH₃ is admitted for the depassivation into a process chamber (1), a pressure greater than 1 bar a and a temperature between 100° C. and 1,000° C. is established in the chamber (1), and in a second process step a second gas or gas mixture from the group of N-, C- or B-containing gases is admitted into a process chamber (1, 2) for the thermochemical surface treatment, and a temperature between 100° C. and 1,000° C. at a pressure greater than or equal to 1 bar a is established.

Claims

1. Method for the treatment of alloy steels and refractory metals, especially for depassivation followed by thermochemical surface treatment in a process chamber under the action of pressure and temperatures, comprising:

in a first process step admitting into a process chamber for depassivation a first gas consisting of NH₃ including establishing a pressure greater than 1 bar a and a temperature between 100°

C. and 1,000°

C., and in a second process step admitting a second gas consisting of N₂ into a process chamber in which NH₃ is substantially absent including establishing a temperature between 100°

C. and 1,000°

C. and a pressure equal to or greater than 1 bar a.

2. Method according to claim 1, in which in the first process step establishing a pressure comprises establishing a pressure of approximately 10 bar a.

3. Method according to claim 1, in which in the second process step establishing a pressure comprises establishing a pressure of 30 bar a in a chamber.

4. Method according to claim 1, which comprises performing the first and the second process steps in one and the same process chamber.

5. Method according to claim 1, which comprises performing the first process step in a first process chamber and performing the second process step in a second process chamber.

6. Method according to claim 1, which comprises performing the first process step in a first process chamber designed for a pressure greater than 1 bar a.

7. Method according to claim 1, which comprises performing the second process step in a second process chamber designed for atmospheric pressure.