Use of silver-copper-palladium brazing alloys

• US 6,352,196 B1
• Filed: 07/17/2000
• Issued: 03/05/2002
• Est. Priority Date: 07/18/1997
• Status: Expired due to Term

• Current Assignee: Endress+Hauser Flowtec AG (Endress+Hauser AG)
• Original Assignee: Endress+Hauser Flowtec AG (Endress+Hauser AG)
• Inventors: Lorenz, Rainer
• Primary Examiner(s): Dunn, Tom
• Assistant Examiner(s): EDMONDSON, LYNNE RENEE
• Application Number:
  US09/618,068
• Time in Patent Office: 596 Days
• Field of Search: 228/131, 228/126, 228/121, 736/44, 738/613.8, 738/613.57
• US Class Current: 228/131
• CPC Class Codes: B23K 1/0008 specially adapted for particular articles or work
• CPC Class Codes: B23K 1/19 taking account of the properties of the materials to be soldered
• CPC Class Codes: B23K 2103/24 Ferrous alloys and titanium or alloys thereof
• CPC Class Codes: B23K 35/3006 Ag as the principal constituent
• CPC Class Codes: G01F 1/8404 details of flowmeter manufacturing methods
• CPC Class Codes: G01F 1/8409 constructional details
• CPC Class Codes: G01F 1/8413 means for influencing the flowmeter's motional or vibrational behaviour, e.g., conduit support or fixing means, or conduit attachments
• CPC Class Codes: G01F 1/849 having straight measuring conduits
• CPC Class Codes: Y10T 428/12812 Diverse refractory group metal-base components: alternative to or next to each other
• CPC Class Codes: Y10T 428/12896 Ag-base component

Abstract

Surprisingly, silver-copper-palladium brazing alloys, which have hitherto been used only for the brazing of components of the same material, are also very well suited for brazing directly titanium to stainless steel if, the latter component clasps the titanium component tightly, so that the cold joint is under constant compressive stress. In a method for forming the titanium-steel compound the titanium component is provided with a cylindrical end which has a smaller outside diameter than an adjacent main portion whose external surface is a first surface to be brazed. The cylindrical steel component is a sleeve whose inside diameter is equal to the outside diameter of the main portion and whose internal surface is a second surface to be brazed. A silver-copper-palladium brazing alloy is placed around the end of the titanium component. The steel sleeve is slipped thereover. The whole is heated in a vacuum or an inert gas until the silver-copper-palladium brazing alloy melts and wets the surfaces to be brazed, and is then allowed to cool down.

Claims

1. A method of brazing a titanium surface directly to an unplated stainless steel surface, the method comprising the steps of:

forming a joint with the titanium surface and the unplated stainless steel surface;

applying a brazing alloy adjacent the joint;

heating the joint and brazing alloy so that the brazing alloy melts and penetrates into the joint between the surfaces to be brazed and wets the surfaces; and

cooling the joint and brazing alloy so that the unplated stainless steel surface exerts compressive stress on the titanium surface and is brazed directly to the unplated stainless steel surface.

2. The method of claim 1, wherein the joint is formed by inserting a titanium cylinder into a stainless steel cylinder, the stainless steel cylinder having an unplated interior surface to be brazed.

3. The method of claim 1, wherein the brazing alloy is a silver-copper-palladium brazing alloy.