Link to Standard Products Link to Custom Products Link to Case Studies Link to Ceramic and Glass Materials Link to Design Notes Link to Working Together Link to Accuratus Contact Form
link to Accuratus home page email link - voice: 908-213-7070 fax: 908-213-7069

Standard
Products

 

Accuflect®

MACOR®

> Fabrication
Machining
Cleaning
Bake Out
Annealing
Thick Film
Metallizing
Thin Film
Metallizing
Frit Sealing
Brazing
Adhesive Bonding

> Properties

> Available Sizes

Ceramic Rod & Tube

Aluminum Nitride Substrates

 

 

Brazing MACOR® Machinable Glass Ceramic

1. Brazing is accomplished using active alloy braze techniques. The active alloys generally contain titanium.
2. Brazing can be accomplished with titanium doped braze preforms available from Wesgo and Degussa. These are typical silver bearing braze alloys containing a few percent titanium. The other alternative is to paint the ceramic surface with an active metal hydride film followed by brazing using a standard commercially available braze alloy.
 

Surface Preparation

MACOR®
1. Grind surface to .8 micron (30 microinch) average roughness then lap to .1 micron (5 microinch) average roughness for best braze strength.
2. Degrease surface with organic degreasing agent. Isopropanol and acetone are acceptable.
3. Wash ultrasonically a minimum of 5 minutes in deionized water heated to at least 65° C (150° F)
4. Dry 2 hours at 100° C (212° F)
5. Handle with gloves to ensure cleanliness
6. Use as soon as possible to prevent contamination of cleaned surfaces.
Metal
1. Degrease using isopropanol and acetone.
2. Lightly etch the metal surface using standard etching solutions. The objective is to remove any contamination from the surface, lightly roughen the surface and provide a virgin metal surface for braze alloy flow.
3. Rinse in deionized water. (See MACOR® preparation above)
4. Dry at 100° C. (See MACOR® preparation above)
5. Handle with gloves.
6. Use as soon as possible.

Fixturing the MACOR® MGC to Metal Assembly

Active Alloy Preforms
1. Place a 14 to 75 micron (.001" to .003") thick preform on the area to be brazed.
2. Place the metal part over the preform.
3. Fixture to maintain alignment during firing.
4. Apply approximately 34 kPa (5psi) load on the assembly to facilitate braze alloy flow-out.
Hydride Process
1. Prepare a slurry of 2 cc ethylene glycol with 1 gram titanium hydride powder. Keep the mixture agitated.
2. Apply a thin layer of the slurry to the surface of the MACOR® to be brazed. The hydride must completely cover the area to be brazed. Thickness should be less than 15 microns (.0007").
3. Allow the hydride layer to air dry.
4. Place a 14 to 75 micron (.001" to .003") thick braze preform over the hydride layer.
5. Place the metal part over the preform.
6. Fixture to maintain alignment during firing.
7. Apply approximately 34 kPa (5psi) load on the assembly to facilitate braze alloy flow-out.

Firing the MACOR® MGC to Metal Assembly

1. Apply a minimum vacuum of 10–5 Torr or lower in the furnace and be sure to maintaim throughout the firing cycle. If using the hydride process, a pressure increase near 350° C (660° F) can be expected as the hydride decomposes. It is important to maintain the minimum vacuum level even during the pressure rise.
2. Heat at 50° to 200° C (90° to 360° F) per hour. Maintain equalized heating of both MACOR® and metal components.
3. Hold for 1 minute 20° to 30° C (65° to 85° F) over the braze alloy liquidus temperature.
4. Cool at a rate of 50° to 200° C (90° to 360° F) per hour. Maintain equalized temperatures on both the MACOR® and metal components.

Hints for MACOR® MGC to Metal Brazing

1. Maintain an oxygen free environment in the vicinity of the components being brazed. If necessary, titanium getters can be placed in close proximity to the braze joint.
2. Use a soft fixturing material such as boron nitride or graphite. It will help facilitate removal of the brazed assembly should the alloy flow onto the fixture supports. A brazing stop-off of liquid boron nitride can be applied to help keep braze alloy from flowing onto critical surfaces.
3. If using the hydride process, a fresh slurry should be prepared before each brazing operation due to the short shelf life of the hydride slurry.
4. Braze alloy preforms are recommended for consistent and uniform joint thicknesses.
 

See also: Materials > MACOR®

Standard Products | Custom Products and Services | Case Studies | Materials
Design Notes | Working Together | Vision | Contact Us | Site Map

1-908-213-7070

© 2013 Accuratus

Site Design M. Adams