| The Monthly Newsletter of VAC AERO International Inc. | If you are having trouble viewing this e-mail, click here. To log on to the VAC AERO web site, please click here. |
August 2010 |
905-827-4171 |
| Leak Rates, Leak Detection and Leak Repair | by Dan Herring | This is the 12th in a series of articles in our Vacuum Heat-Treatment Series. What follows is a discussion about acceptable leak rates, leak detection and leak repair methods used on most vacuum vessels. Controlling the leak rate is of major importance in producing sound metallurgical components.
|
 |
A common problem experienced by almost every vacuum user is that, over time, leaks develop that are both damaging to product quality and to furnace internal components. In extreme cases, the problem is obvious: the furnace will not pump down and/or the hot zone (or heating elements) shows obvious signs of oxidation. Small leaks, which are more common, often go undetected because the pumping system can overcome any air infiltration. However, even small leaks can cause continuous and sometimes catastrophic damage. Thus, routine leak checking should become a part of any good vacuum furnace maintenance program. Read more >> |
Next Time: Part 13 of this series discusses the importance of cleaning and discusses/compares solvent-based systems to aqueous solutions as well as talks about alternative cleaning methods that have been used over the years.
|
| Repair Brazing - Fixing faulty jobs and worn-out components - Part 2 | by Dan Kay | The second part of this article deals with cleaning and surface preparation.
|
 |
Good cleaning and surface preparation are extremely important. Cleaning may not be too difficult on the outside surfaces of a part but can be very difficult on the inside surfaces of a deep, thin surface crack. First, the oil, grease, and dirt must be removed with suitable water- or solvent-based degreasing techniques, and then the surface oxides can be dealt with. This sequence never should be reversed. Read more >> |
Next Month: In the next article we will be discussing that when a brazing filler metal (BFM) is melted during a brazing process, it is not uncommon for "liquation" to occur.
|
| Heat & Corrosion Resistant Materials/Composites: A Survey of High Temperature Alloy Selection in Heat Treating | ||
| by Dan Herring | ||
The subject of high-temperature alloys encompasses both cast and wrought products that are available from a number of qualified suppliers. The intent of this article is to provide a simplified overview of the basic requirements necessary for selection of alloy systems for use in thermal processing applications running from - 320F (-195C) to 2250F (1225C) and beyond.
|
||
 |
The information is presented for the purpose of aiding those in the selection process who have not had the opportunity to work with these alloys in great detail. More detail can be obtained from a number of sources and standards from organizations such as SAE International (www.sae.org), ASTM International (www.astm.org) and the Alloy Casting Institute to name a few. There are many other sources of technical and research information specific to a given application such as from the many suppliers of these materials. |
|
|
||
