AMMTIAC Quarterly, Vol. 2, No. 1 - Advanced Materials ...

A DVANCED M ATERIALS, MANUFACTURING AND T ESTINGAMMTIACindustry for many years. The addition of zirconium and itssubsequent oxidation during metal spraying create a grainstructure that limits grain growth and increases the hightemperature creep strength.Thermocouple DevicesPlatinum and platinum-rhodium wire pairs for thermocouplesare the most effective at measuring temperature.Platinum thermocouples exhibit the widest range oftemperature measurement, accuracy and linearity, whichis required for critical applications. Currently, the producersof wire are able to make wire diameters small enough thatthe cost of PM material is kept to a minimum.High Temperature Heating CoilsA heating coil can obviously only go as high as the meltingpoint of the material used to construct the device. Additionally,in many operations repeated oxidation cycles can reducethe life of the heating coil. The use of PGM alloys satisfiesboth the issue of high service temperature and the problemof long-term oxidation attack.Spark Erosion Resistance ApplicationsIn the new generation of cars and trucks, replacing sparkplugs could be a thing of the past. The developmentand application of Pt alloys, Ir alloys, and pure Ir (somecombinations of PMs are patented) make plugs thatlast for more than 100,000 miles. To accomplish this, somemanufacturers use ball bearing fabrication equipment tomake small Pt alloy spheres that are then resistance weldedonto the plug to form the electrode pair. For the morecritical applications on aircraft, short pieces of Ir rod stockmaterial are centerlessly ground § to an exacting size andform and then installed in the spark plug. Additionally,electrical contacts with an extended operational lifecapability have been made from Pt and Pd strip stockfor various devices by high speed stamping of smallcrowned circular blanks.Fuel Cell ApplicationsFuel cells are similar to conventional batteries in that theyare silent with no moving parts and generate electricalpower by an electrochemical reaction within the cell. Thebest part about a fuel cell, unlike a battery, is that itrequires no recharging and it will run continuously as longas the fuel supply lasts. The electrical output from thefuel cell is made by combining hydrogen (the fuel) andoxygen (from air) over a catalyst such as platinum.BiocompatibilityNot all materials have the ability to be implanted within orused in contact with the human body without causing anadverse reaction or poisoning. Those that can be are termedbiocompatible. The medical devices produced from PMsinclude: stents, marker bands for angioplasty devices,pacemaker wire, heart muscle screw fixations, endoscopytips and special surgical tools. The material used for suchapplications is mainly Pt (or alloys of Pt), and in dentalapplications the use of Au and Pd is common.Radio-opacityX-rays do not easily pass through Pt, Au and Ir becauseof their atomic absorption coefficients, as well as their highdensities, and thus these materials typically show up as awhite area on film or scanning device. This property,referred to as radio-opacity, coupled with their biocompatibilitycharacteristics allows for the location of thesematerials to be determined when used within the humanbody. The identified location of these materials is called the“marker band” because it marks the location to allow thesurgeon to correctly position the angioplasty device withinthe body during surgical procedures.Pharmaceutical UsePlatinum-based drugs, such as cisplatin, have been in usefor 30 years to treat cancer. The treatment of testicularcancer with cisplatin has been widely accepted as a standardcourse of treatment. A new drug, stataplatin, is under thelast stages of FDA approval for treatment of a form ofprostate cancer. This new drug will offer an alternative tothose patients that did not respond well to chemotherapy.Gold has also been used for the treatment of prostatecancer, whereby small gold “seeds” are irradiatedand injected into the cancer site to kill the cancer cellsby the slow release of radiation.Labware, Equipment & Related DevicesPlatinum and gold have an excellent resistance to attackfrom many substances, and as such they are used ascrucibles, electrodes, inoculating loops, ignition boats andmany other forms of labware. Since these materials arenoble, the testing method is not skewed by contaminationfrom the test equipment. Basic forms of material (wire, tube,sheet, and strip) can be fabricated into countless products asrequired for industrial use. Joaquim Bishop, a former labassistant at the University of Pennsylvania, established thefirst Pt works in the US in 1842 for the purpose of refiningPt and the production of Pt labware. His early success inthis work earned him a prestigious Franklin Institute silvermedal in 1845 for “skill and ingenuity in the manufacture ofPt scientific instruments.” Many of the complex Pt alloyfabrications have been used in the production of glassmelting “bushings” for the fiberglass industry.[6]Photographic ApplicationsPhotography’s impact on society has been vastly importantover the last 150-plus years since its discovery. During theformative period of discovery, precious metals played a keyrole in making the art a reality. At one time, the EastmanKodak Company was the single largest user of silver in theworld. Many films and photo papers used silver compoundsas the light-sensitive emulsion. Platinum and palladiumcompounds were used to make black and white printingpaper, which was and still is considered by many to be thebest paper for reproduction of the complex tonality on blackand white negatives. These prints are the most archived ofany produced because of their resistance to environmentalattack. Famed photographer Ansel Adams used gold chloridehttp://ammtiac.alionscience.com The AMMTIAC Quarterly, Volume 2, Number 1 11