Recall the blistering or ruptures that can be experienced when you braze non-OFE Copper in Hydrogen (see Blog Post October 7, 2009). As a follow-up post, we want to briefly discuss “stringers.” Stringers are actual holes or leaks paths in the material that follow grain directions and are intrinsic to many grades of materials that are used in vacuum applications. Read the rest of this entry »
June 1st, 2010
A Vision and a Street Name
Back in the early 90’s, our founders Greg Cody along with Co-Founders Robert Butwell and Mike Green, set out to fill a niche within the TWT industry and brazing community. At the time Greg was in between jobs and contract manufacturing was becoming mainstream in nearby Silicon Valley. This along with their professions and experiences led them to believe their collective resolve could undoubtedly fill this void. They firmly believed they could be successful and managed to convince some friends and family to invest in their start-up as well. Read the rest of this entry »
April 30th, 2010
CTE Sample Calculation
Our last blog entry discusses the importance of understanding the thermal expansion behavior of dissimilar materials when brazing. This post will illustrate a sample calculation used for determining the nominal dimensions when designing an appropriate braze gap.
CTE is used to calculate the dimensions needed at the time of fabrication, in order to achieve a desirable braze gap (.000” to .005”) at braze temperature, between two dissimilar materials. Read the rest of this entry »
April 22nd, 2010
Thermal Expansion and Brazing
Thermal expansion is the material property of a volume change in response to changes in temperature. The net volume growth over a given temperature is dependant on the initial volume of the component. So, for most common braze materials (copper, stainless steel, ceramics, etc), this expansion varies from four to twenty thousandths of an inch of growth per inch of material in a given direction. With this in mind, brazed assemblies with different materials must be designed and toleranced such that the joint has the proper clearance at braze temperature taking into account the thermal expansion of each individual material.
To accomplish this, braze joint fit-up at room temperature may need to be made with “excessive” clearance or even interference such that at braze temperature, proper joint clearance exists to allow capillary action to work. Read the rest of this entry »
April 9th, 2010
Amparo Celebrates 10 Years with Altair
Altair Technologies is pleased to announce another wonderful employee has been inducted into the prestigious “Decade Club”, as Assembly Technician Amparo Contreras is celebrating 10 years of continual service. A major contributor for the many production and engineering projects here at Altair, she has been an absolute delight to work with and we all look forward to the next decade together. Congratulations!!
L-R: Chris Wallace, Amparo Contreras, Jeff Piazza
April 7th, 2010
Reading Phase Diagrams
Back in September 2009 we published a Post titled, “Wetting, Braze Flow and Filler Spreading,” and for those of you who were left hanging, here is our new Post on using phase diagrams to understand Spreading.
Why do we experience excessive spreading with some filler (braze alloys)/substrate interactions and poor spreading in others? Let’s examine phase diagrams to explain the following observations:
• Cusil on Cu blushes (excessive flow)
• Cu/Au on Cu flows well
• Cu on Ni flows poorly
• Cu on Fe flows very well (blush potential)
It is widely known by many in the brazing industry, that “Cusil” an Ag/Cu eutectic, flows like crazy on copper. In this interaction, molten Cusil dissolves copper (Cu) thereby increasing the melt volume, but the solidus temp doesn’t rise at all! Read the rest of this entry »
February 12th, 2010
Adam & Agyei Hit 10 Years with Altair
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
- L-to-R: Agyei Sowande, Chris Wallace
January 7th, 2010
Upcoming AVS Show
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).
November 4th, 2009
Brazing Ceramic to Metal
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 »
October 15th, 2009
How to read a Phase Diagram and Why You Might Want to.
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 »