The gold standard for artificial joints can be improved by adding the actual gold to titanium, the study suggests -
Titanium is the leading material for the knee and hip replacement because it is strong, wear resistant and non-toxic, but an unexpected discovery by Rice University physicists demonstrates that the gold standard for artificial joints can be improved with the adding a bit of real gold.
"It is about 3-4 times harder than most steels," said Emilia Morosan, the lead researcher of a new study advances science that describes the properties a mixture of 3: 1 in titanium and gold with a specific atomic structure which imparts hardness. "It is four times harder than pure titanium, which is what is currently used in most dental implants and joints of substitution."
Morosan, a physicist who specializes in the design and synthesis of compounds with electronic and exotic magnetic properties, said the new study is
in fact, the atomic structure of matter " a first for me in a number of ways this compound is not hard to do, and this is not a new material .. "- its atoms are in a tight structure" cubic "lens that is often associated with the hardness - was previously known. It is not even clear that Morosan and former graduate student Eteri Svanidze, co-lead author of the study, were the first to make a pure sample of the ultra hard "beta" form of the compound. But because of a couple of lucky breaks, they and their co-authors are the first to document the remarkable properties of the material.
"It started with my basic research," said Morosan, professor of physics and astronomy, chemistry and materials science and nano-engineering at Rice. "We published a study there not long ago on the titanium-gold, a 1-to-1 ratio of compound which was a magnetic material made of non-magnetic elements. One of the things we do when we make a new compound is to try to grind to powder X-ray purposes. This identifies the composition, the purity, crystal structure and other structural properties.
"When we tried to grind the titanium-gold, we could not," she recalled. "I even bought a diamond (coated) mortar and pestle, and we could always not grind. "
Morosan Svanidze and decided to do follow-up testing to determine exactly how hard the compound was, and while they were at it, they also decided to measure the hardness of other compositions of titanium and gold that they used as comparisons in the original study.
one of the additional compounds is a mixture of three parts and a titanium piece of gold that was prepared at high temperature.
what the team did not know at the time was the fact that titanium-3-or relatively high temperature produces a nearly pure crystalline form of beta alloy - crystalline structure that is four times harder than titanium at lower temperatures, the atoms tend to arrange another cubic structure -. the alpha form of titanium-gold-3. The alpha structure is about as hard as regular titanium. It seems that laboratories have measured the 3-or titanium hardness were measured samples, which largely consisted of alpha arrangement of atoms.
The team measured the hardness of the beta crystal form together with colleagues Turbomachinery Laboratory of Texas A & M University and the National Laboratory of High Magnetic Fields Florida State University, and Morosan Svanidze also made of other comparisons with titanium. For medical implants, for example, two key measures are biocompatibility and resistance to wear. Because titanium and gold by themselves are the most biocompatible from metals and are often used in medical implants, the team believes titanium-3-or would be comparable. In fact, tests by colleagues from the University of Texas MD Anderson Cancer Center in Houston have determined that the new alloy was more biocompatible than pure titanium. History has proven the same wear resistance: Titanium-3-Gold also outperformed pure titanium
Morosan said she did not intend to become a materials scientist or change dramatically the orientation of his laboratory, but said his group. planning to conduct follow-up tests to further study the crystal structure of beta-3-or titanium and see if chemical dopants could improve its hardness further.
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