WorldWide Drilling Resource

43 WorldWide Drilling Resource ® MAY 2013 New Alloy For Extreme Down Hole Conditions Adapted from Information by Sandia National Laboratories Geothermal and gas and oil wells have a great deal in common. Namely, the equipment used down hole must with- stand high temperatures and pressures, excessive vibrations, and other intense environments. Sandia National Laboratories has been working on an alloy which may im- prove high-temperature electronics for use in extreme down hole conditions. Sandia first investigated the gold-silver- germanium alloy about 15 years ago as a possible bonding material in a new neutron tube product. A design change caused Sandia to shelve the material, said Paul Vianco, who has worked in soldering and brazing technology at Sandia for 26 years. Then, a few years ago, researchers working on other projects with applica- tions inside a well asked Sandia’s geo- thermal group to develop electronics to monitor well conditions in field operations. They realized the gold-silver-germanium alloy would be suitable for those conditions. Vianco explained the alloy is tech- nically a solder, but it’s at the upper limits for what’s considered a solder - materials that melt at no higher temperature than 842ºF (450ºC). Additionally, the alloy is lead-free, making it environmentally friendly for the increasing number of locations moving away from materials containing lead. The alloy’s fundamental mechanical and pro- cessing properties also are nearly fully characterized. According to Vianco, this is important because it saves about two years of development required to estab- lish how well the alloy makes a reliable solder joint. “All that’s done,” he stated. “We have the preliminary work completed that allows us to consider this material for a range of applications, including down hole electronics.” He is now seeking funds to develop the material to a prototype stage for geo- thermal and oil and gas well tools. “We really think it is a material that’s suitable for these higher temperature applica- tions,” Vianco said. When interest in using the alloy for down hole applications came up, Vianco and his colleagues had to gather the alloy’s information from the mid-1990s. They had to reeval- uate the data and writeapaper assess- ing the alloy’s prop- erties. This was not an easy task. “Photographs were all on film; we had t o scan [the] pictures into an electronic format. Documen t s and p r e s e n t a t i o n s were in unusable formats or archived on software...no longer supported by t he l abs . So eve r y t h i ng was brought up to a level...compatible with current com- puter resources,” Vianco explained. He believes they may be able to use the gold-silver-ger- manium alloy as a joining material in h i g h - p r e c i s i o n components. T h e p a p e r , Ag-Au-Ge Alloys for High Temperature Geothermal and Oil Well Electronics Applications , was written to compile the data in case there is more interest within the geothermal and oil and gas industries for further development. The paper has raised awareness of the alloy and the growing need for high- temperature materials to support down hole electronics. # # " " $ $ $ ! $ ! # " Tom Crenshaw, a researcher for Sandia, sets up a specimen in a test frame which will pull the solder joint apart to determine its tensile strength. Photo by Norman Johnson.