Northern California Brazing
We are pleased to announce that our resident Engineer, Adam Mitchell, and QA Engineer, Agyei Sowande were both recently inducted into the “Decade Club”, having reached a pinnacle of 10 years continuous employment with Altair Technologies. It has been an absolute pleasure to work with and see Adam and Agyei grow and excel here at Altair. We all look forward to their next ten years of smiles and contributions.
L-to-R: Chris Ferrari, Adam Mitchell, Curtis Allen
Please come visit Altair Technologies, Inc. at the 31st NCCAVS Vacuum Equipment Exhibition (Booth #53) on Wednesday February 10, 2010 at the Wyndham Hotel @ 1350 North First Street in San Jose, California (California Ballroom – Second Floor).
Metallization vs. Active Alloy Brazing
Applications for brazing ceramic to metal are most commonly found in microwave tube, semiconductor feedthru and laser devices, where high vacuum integrity and dielectrical properties are required.
More recently, medical and military devices have brought forward new demands for ceramic to metal seals, which require biocompatibility and high joint strength.
The difficulty in brazing ceramics to metals is largely due to the inability of most braze alloys to “wet” directly to ceramic materials and the accumulation of residual stress once the materials have been successfully “wetted”. Read the rest of this entry »
Phase diagrams are a great tool for the Brazing Engineer. While its is certainly true that most brazing applications involve systems more complicated than a binary alloy represented by the common phase diagram, nevertheless, the binary phase diagram is an invaluable tool both for answering questions about why a particular braze alloy and substrate interact the way they do and it can also help to predict what to expect from a novel application. While they are extremely useful, like any power tool, they can be difficult to use and must be fully understood to be of most use.
So how do you read a phase diagram? Read the rest of this entry »
Hydrogen Brazing
Here at Altair Technologies most of our products are for high vacuum applications and we therefore do most of our brazing in Hydrogen Gas or in a high vacuum atmosphere. During the braze run, while assemblies are being heated up to braze temperature, the furnace “bell” sees a steady flow of Hydrogen gas. This process continues until parts are below a certain temperature at which time the bell is backfilled with Nitrogen gas. Products or assemblies that are commonly hydrogen brazed include X-Ray Tubes, Traveling Wave Tubes, Linear Accelerators for medical, research and security applications and similar ion or electron beam devices. For reasons to be explained below, Hydrogen brazing is arguably the best process for bonding metals and ceramics regardless of the application. Read the rest of this entry »
Braze alloy penetrates full thickness of cavity wall
When fabricating complex geometries, whether it’s by die casting, e-beam welding, or 5- axis machining, there can be distinct advantages when brazing is used as a means of creating the final assembly. Manufacturing of cavity structures utilizing standard brazing principles, for example, is becoming a current trend.
Structures with internal cavities are used in many applications including RF power, fuel cells, heat exchangers, cryogenic systems and chemical processing. These arrangements are fabricated from many types of materials including copper, stainless steel, niobium, Inconel, titanium and alumina.
Orbital EBW is often used to bond two hemispheres together in order to produce a cavity; however, due to the limits in the amount of penetration possible with EBW, there are limits on possible wall thicknesses of the cavity (typically 2” in soft vacuum machines and 6” in hard vacuum machines). With brazing, there is virtually no limit on wall thickness. Read the rest of this entry »
The term “wetting” is commonly used to describe the flow of braze alloy or braze filler across a surface. However, before we get more into wetting, let’s recap the brazing process: First, two components are placed very close to or in contact with each other and a braze filler metal is placed in contact with BOTH parts. The filler and components are heated to just past the melting temperature of the filler braze alloy. The filler alloy “wets” the parts and capillary forces draw the braze alloy between the mating components, making up what is called the braze joint. The assembly is then cooled, solidifying the braze joint.
Good wetting occurs when the surface is clean & metallic and is Read the rest of this entry »
Laser Beam Welding (LBW) is a high energy welding process that continues to expand into modern industries and new applications because of its many advantages. Some of the advantages of laser welding versus arc-welding are:
From a furnace brazing standpoint, laser welding is an important process used to reduce cost and increase productivity. Read the rest of this entry »
Most of the brazing we do at Altair Technologies occurs between 800° C – 1270° C. Finding a suitable braze-alloy or “filler” to melt in this temperature range is not difficult. However finding a braze alloy, or even base materials, that will withstand operation over 1000° C can be tricky. One of the first questions to ask is what is the operating atmosphere or environment (high vacuum, air or?) and what are the base materials? At those elevated temperatures, many unwanted phenomena can occur. Read the rest of this entry »
Here at Altair Technologies we don’t maintain in-house plating capability and in general we try to avoid the use of plating(s) due to its additional costs and lead-times as well as yield issues associated with poor process controls. However, the plating of base material can benefit the operational performance and reliability of certain applications, benefit the brazing process and even assembly. Read the rest of this entry »