Archive for the ‘Metallurgy’ Category
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April 23rd, 2010
Gold is ‘supercool’
A great illustration of how important gold is to cutting edge research is the observation that most issues of the leading journal Nature appear to include new research on the metal; be it catalysis, nanotechnology, chemistry or materials science. The most recent issue is no exception, with a new paper – ‘Substrate -enhanced supercooling in AuSi eutectic droplets’ by researchers from the CNRS facility in Grenoble, France.
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March 24th, 2010
Seiko Instruments and gold-tin eutectic
Seiko Instruments has come up with a gold-tin eutectic bonding process that can take place at temperatures low enough to inhibit release of gases during bonding meaning that a higher level of vacuum sealing can be achieved. It is claimed that this method improves mechanical strength and also lowers fabrication costs for the intended application – a silicon based MEMS resonator.
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March 22nd, 2010
Best of the web
I couldn’t decide which story on the web was the mosty interesting this morning, so here they both are…..
Article on use of brazing alloys in aerospace (including gold alloys)
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January 4th, 2010
Materials science of wire bonding
Wire bonding remains the most important interconnection technology in semiconductor packaging. It also happens to be the single largest industrial use of gold. Whilst lots has been written about the wire bonding process itself, much less has been written about the materials science of the technology. This latest paper in Microelectronics Reliability by Chris Breach and Frank Wulff takes a look at this area, including how the reliability of the ball bonding process is affected by selection of gold or copper wire. -
December 21st, 2009
New Book – Gold Science and Applications
I’m excited to announce that a new book ‘Gold – Science and Applications’ has now been published.
There have been many excellent books written on certain aspects of the science and technology of gold, most notably the book of the Hanau gold conference, held in 1996 (“Gold. Progress in Chemistry, Biochemistry and Technology”, edited by Hubert Schmidbaur and published in 1999) and there are several new books covering specific sectors of gold science e.g. on catalysis, chemistry and nanotechnology (see here). However, for those seeking a broader reference source on gold and covering all technical sectors, the most appropriate book on gold, Gold Usage by Bill Rapson and Theo Groenewald, was published over 30 years ago in 1978. The world of gold has changed considerably since then. A few years ago Chris Corti and I believed it was time for an updated book that reflects the more recent developments.
With the co-operation of some of the leading experts in their field, we have attempted to produce a book that is a worthy successor to ‘Rapson’ and to provide an authoritive source of information. We have attempted to cover all the main scientific areas as well as the main areas of application. In some cases this has required some very detailed scientific chapters; other fields require less specific detail and have focused more on the practical application. In addition, to help readers place this science and technology in the context of a much wider gold market, a chapter on the supply, demand and pricing of gold is included. Taken together, our aim for the book is to appeal to both those working in academia and industry.
If you are interested, your can read more and purchase it here .
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October 14th, 2009
Powder Metallurgy & Gold
I’ve just received a complimentary e-version of the International Journal of Powder Metallurgy “Precious Metals” Focus Issue. This Journal is published 6 times a year, bringing the latest news in the powder metallurgy and particulate materials industries.In his editorial, Alan Lawley states:
Precious metal powders find wide commercial applications because of their unique characteristics and properties, including thermal/electrical conductivity, corrosion resistance, solderability, and stability at high temperatures, coupled with reliability. Applications include conductive adhesives, dental restorations, catalysts, and sensors to monitor temperature and corrosion, and to detect gases. In comparison with ferrous powder metallurgy (PM), particulate precious metal science and technology receives limited exposure and press in industry news coverage. This “Focus Issue,” coordinated by Pierre Taubenblat and Joe Strauss, traces the history of particulate precious metal technology and gives an overview of market dynamics and current and near-term industrial applications. Comprehensive reviews of precious metal powder production methods and the manufacture of dental restorations are also included.
With so much happening in the application of gold in nanotechnology, catalysis and chemistry, it is good to see the metallurgical applications of gold being highlighted….
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October 12th, 2009
Eureka!
This morning on the way to work I read an interesting letter in the London Times. I’m sure all of you will know the famous anecdote of the Greek philosopher and inventor Archimedes – legend has it on stepping into the bath he noticed the level of the water rise, which led to his sudden understanding that the volume of water displaced must be equal to the volume of the part of his body he had submerged. This meant that the volume of irregular objects could be calculated with precision, a task previously extremely difficult. On realisation of this fact, he is said to have leapt out of the bathtub, shouted ‘Eureka!’ (which translates from Ancient Greek to ‘I have found it’), and in his excitement taken to the streets of Syracuse completely naked.
What people are probably less familiar with is the real reason for his joy. Like any good scientist, Archimedes was excited by the potential applications of his Eureka moment. The King of Syracuse had recently set him a task – basically the King had commissioned a new crown be made for him from solid gold. However, when delivered King Hiero II was suspicious that the goldsmith in question had, in fact, not used pure gold but had instead alloyed the gold with silver, effectively making a ‘cheaper model’. Archimedes had realised that he may be able to tell whether the crown was pure gold or not by how much water it displaced.
Like any legend from millennia past, many people have questioned its authenticity. I like to think it’s true though…
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July 10th, 2009
Au-based die attach materials
The issues relating to the use of gold-based alloys as die attach materials in the electronic packaging industry is highlighted by Anwar Mohammed from Infineon Technologies in Solid State Technology. He writes:
“To keep up with demanding power requirements, some savvy companies rely on eutectic attach materials such as AuSn and AuSi for die attaching to obtain superior thermal performance. The die attach temperatures are much higher relatively: ~320°C for AuSn, and ~420°C for the AuSi; but the thermal conductivity is significantly better with AuSn performing at ~70W/mK and AuSi performing at >150W/mK. The disadvantage of this approach is that it is a very tricky and sensitive process with a narrow processing window that needs to be monitored carefully.”
The reason I found this interesting (other than because it explains why Au-based materials are useful in die attach applications) is that there are direct similarities with gold-based catalysts. Like the eutectics described above, these catalysts have significant performance benefits in many reactions (selectivity, activity), but applications have been limited due to processing concerns. The problems in ‘processing’ can be related to either making the catalysts or operating them under practical conditions, where the process window may be limited. Thankfully things are now progressing well. Gold catalysts can be successfully manufactured and purchased from the likes of 3M, Strem Chemicals, AuTEK and Nanostellar (automotive) and there are applications where they are able to operate under a suitable range of processing conditions.
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July 8th, 2009
Next issue of Gold Bulletin now available!!
Hi everyoneIt’s here at last, Issue 42(2) of Gold Bulletin.
We have an issue bursting with lots of gold news and science and a superb Guest Editorial from Prof James (Jim) Johnstone from Victoria University of Wellington New Zealand.
We have all the lastest information about Gold 2009 ; the Keynote presentations , the opening Plenary presentations and all the info on the main conference sessions
We have seven wonderful scientific papers from a range of disciplines including Metallurgy, Catalysis, Analytical and also Nanotechnolgy. Also a book review of Mark Grimwade’s Introduction to Precious Metals – Metallurgy for Jewellers and Silversmiths.
Also our regular features of Highlights from Recent Literature and a summary of Calendar Events comming up in the near future.
Hope you enjoy it. Let me know what you think. I always like to hear your views.
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May 8th, 2009
Hydrogen purification membranes
In the heart of the old gold mining region called Golden in Colorado, they are working on what could potentially be an important new industrial application for gold. …..Today I had a project review meeting at the Colorado School of Mines where a research group led by Prof Doug Way is further improving the alloys used in hydrogen purification using palladium membranes. This is an important technology for the emerging hydrogen economy and fuel cell power systems.
Doug Way’s team has demonstrated that the use of palladium-gold alloys in this application has clear advantages, especially with respect to reducing poisoning of the membrane with sulphur and carbon monoxide. He and his team have made great strides since his early findings and their latest results are summarised in a new publication ‘F. Roa, P.M. Thoen, S.K. Gade, J.D. Way, S. DeVoss, G.O. Alptekin, Palladium-copper and palladium-gold alloy composite membranes for hydrogen separations, in Inorganic membranes for energy and environmental applications, A.C. Bose, Editor. 2009, Springer: New York p. 221-239.’ See here.
The Wade research group will also be presenting their work on these membranes at GOLD 2009.
Richard Holliday
Trevor Keel
Tricia Harris
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