Lecture 08


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Lecture 08

  1. 1. Today’s objectives-Advanced processing and Optical Fibers <ul><li>Concepts and applications of three of the following </li></ul><ul><ul><li>Powder processing </li></ul></ul><ul><ul><li>Sol-gel </li></ul></ul><ul><ul><li>Bio mimetic </li></ul></ul><ul><ul><li>Cements </li></ul></ul><ul><ul><li>Single crystals </li></ul></ul><ul><ul><li>Thermal oxidation </li></ul></ul><ul><ul><li>Sputtering </li></ul></ul><ul><ul><li>PLD </li></ul></ul><ul><ul><li>CVD </li></ul></ul><ul><ul><li>MEMS </li></ul></ul><ul><li>Optical Fiber Processing </li></ul><ul><ul><li>Initial tube </li></ul></ul><ul><ul><li>CVD of core </li></ul></ul><ul><ul><li>Sintering and annealing </li></ul></ul><ul><ul><li>coating </li></ul></ul><ul><ul><li>applications </li></ul></ul>
  2. 2. HPT Airfoil Material Advances Material advances allow the use of higher metal temperatures and/or less cooling air. Ceramic layer Metallic layer Ni or Co base Gary Chaplin, Pratt & Whitney
  3. 3. PW4000 Material Technologies Ceramic outer air seals are combined with abrasive coated blade tips to create an abradable system that reduces turbine operating tip clearance. Shown below is the continuously graded ceramic outer airseal segments that have been successfully cut by a sprayed abrasive blade tip system. Brush seals can significantly reduce leakage relative to KE seals. The static seal’s cobalt alloy brush wires are in constant contact with a ceramic coated rotating seal land. Brush wear is determined by the interference load & the surface speed & temperature. Gary Chaplin, Pratt & Whitney
  4. 4. Space Port to be Built in New Mexico A core group of 100 “founders’ have paid the initial $200,000 cost of a flight up front. Flights will begin in late 2008 or early 2009. Spaceport construction should begin in early 2007. Virgin Galactic’s Richard Branson has a deal with Burt Rutan to build 5 space craft Gary Chaplin, Pratt & Whitney
  5. 5. Thermal Oxidation <ul><li>Heat it up, usually around 600C for less than a minute. </li></ul><ul><li>Oxidize the surface. </li></ul><ul><li>Oxide extends into the sample depending on time and temperature (diffusion). </li></ul><ul><li>Possible with N as well. </li></ul><ul><ul><li>Most commonly used for SiO 2 formation. </li></ul></ul><ul><ul><li>NOT LINE OF SIGHT </li></ul></ul>http://www.memsnet.org/mems/beginner/deposition.html
  6. 6. Sputtering <ul><li>Bombard a target with inert ions </li></ul><ul><li>Sputters target ions into the vacuum. </li></ul><ul><li>Substrate coated with target ions. </li></ul><ul><li>Common industrial process. </li></ul><ul><ul><li>Line of sight. </li></ul></ul>http://www.angstromsciences.com/technology/sputtering.htm http://www.gencoa.com/tech/whatsputtering.html
  7. 7. PLD <ul><li>Incredible control is possible. </li></ul><ul><li>Substrate temp can be lower than other techniques. </li></ul><ul><li>Atomic layers/second or minute can be grown. </li></ul><ul><ul><li>Common research lab process. </li></ul></ul><ul><ul><li>Commonly used for pure epitaxial growth. </li></ul></ul><ul><ul><li>Line of sight. </li></ul></ul><ul><li>Laser vaporizes target with heating rates up to 100 degrees/s </li></ul>Pamir Alpay, UConn MSE A B C A B C B A B C C B A B C A B C A
  8. 8. CVD <ul><li>Start with gaseous molecules (precursor) </li></ul><ul><li>Expose to a substrate </li></ul><ul><li>Molecules adsorb </li></ul><ul><li>Molecules decompose and chemically bond to the surface </li></ul><ul><li>Byproducts desorb back into gas phase </li></ul><ul><li>Film growth can be carefully controlled. </li></ul><ul><ul><li>Common industrial process. </li></ul></ul><ul><ul><li>NOT line of sight. </li></ul></ul><ul><ul><li>Often an ‘imperfect’ layer is grown. </li></ul></ul><ul><ul><li>Substrate should be at about 600C, ultimately down to 350C but quality is sacrificed. </li></ul></ul><ul><li>Used for </li></ul><ul><ul><li>IC’s, optoelectronics, and sensors </li></ul></ul><ul><ul><li>Catalyst deposition </li></ul></ul><ul><ul><li>Powder preparation </li></ul></ul><ul><ul><li>Protective coatings </li></ul></ul>http://www.memsnet.org/mems/beginner/deposition.html
  9. 9. Lithography Steps <ul><li>Design </li></ul><ul><li>Coat </li></ul><ul><li>Mask </li></ul><ul><li>Expose </li></ul><ul><li>Develop </li></ul><ul><li>Fabricate </li></ul><ul><ul><li>Oxidize </li></ul></ul><ul><ul><li>Deposit (industrially usually sol-gel or cvd) </li></ul></ul><ul><ul><li>Etch (for MEMS, deep reactive ion etch, “RIE”) </li></ul></ul><ul><li>Lift-off </li></ul><ul><li>Repeat to complete multiple layers if necessary </li></ul><ul><li>Bonding of dissimilar parts if necessary </li></ul>UV cross-linked
  10. 10. MicroElectroMechanicalSystems (MEMS, NEMS) <ul><li>MEMS provide sensors and actuators that act as &quot;eyes&quot; and &quot;arms“ of current and future devices that interact with their environment. They are usually made using standard Si technology, allowing incredible functionality, reliability, repeatability, and sophistication at a relatively low cost. </li></ul><ul><li>Si has limits, though, so some MEMS are being made of ceramics like SiN </li></ul><ul><ul><li>Increased operating temperatures </li></ul></ul><ul><ul><li>Less sensitive to water or oxygen </li></ul></ul><ul><ul><li>Tougher </li></ul></ul>http://www.sandia.gov/mstc/index.html
  11. 11. MEMS processing <ul><li>Design </li></ul><ul><li>Masking </li></ul><ul><li>Etching (deep reactive ion etch, “RIE”) </li></ul><ul><li>Oxidizing </li></ul><ul><li>Coating (usually sol-gel or cvd). </li></ul><ul><li>Repeat to complete multiple layers if necessary </li></ul><ul><li>Bonding of dissimilar parts if necessary </li></ul>
  12. 12. MEMS applications <ul><li>Applied in several products on the market today: </li></ul><ul><ul><li>Biotech (lab on a chip) </li></ul></ul><ul><ul><li>Chemical threat detectors </li></ul></ul><ul><ul><li>Communications (optical switching) </li></ul></ul><ul><ul><li>Accelerometers </li></ul></ul><ul><ul><li>Mechanically adaptive optics (AO) </li></ul></ul>www.NASA.gov Astronomers use AO to straighten out star light that bends and distorts as it travels through the atmosphere. This effect of air turbulence on light makes us see the twinkling in stars. In the human eye, disease and vision problems also cause light rays to distort, resulting in blurred vision. Scientists are developing miniature versions of adaptive optics systems used in observatories to improve patient care. The Planet Neptune with and without AO Image from earth of a star with and without AO.
  13. 13. MEMS at work <ul><li>Chain gears rotating Up to 5000 rpm </li></ul><ul><li>Transmission up to 60000 rpm </li></ul><ul><li>Mirror raised/lowered up to 100000 rpm </li></ul>http://www.sandia.gov/mstc/technologies/micromachines/movies/index.html
  14. 14. SUMMARY <ul><li>Concepts and applications of three of the following </li></ul><ul><ul><li>Powder processing </li></ul></ul><ul><ul><li>Sol-gel </li></ul></ul><ul><ul><li>Bio mimetic </li></ul></ul><ul><ul><li>Cements </li></ul></ul><ul><ul><li>Single crystals </li></ul></ul><ul><ul><li>Thermal oxidation </li></ul></ul><ul><ul><li>Sputtering </li></ul></ul><ul><ul><li>PLD </li></ul></ul><ul><ul><li>CVD </li></ul></ul><ul><ul><li>MEMS </li></ul></ul><ul><li>Optical Fiber Processing </li></ul><ul><ul><li>Initial tube </li></ul></ul><ul><ul><li>CVD of core </li></ul></ul><ul><ul><li>Sintering and annealing </li></ul></ul><ul><ul><li>coating </li></ul></ul><ul><ul><li>applications </li></ul></ul>Reading for next class Optical Fibers details (download from web site)