Laser Applications in Materials Technology (II): Laser Materials Processing
Sponsored by: MS&T Organization
Program Organizers: Stephen Copley, Penn State
Monday 2:00 PM
October 17, 2011
Room: E161A
Location: Greater Columbus Convention Center
Session Chair: Stephen Copley, Penn State University/Applied Research Laboratory
2:00 PM
Solid Free Form or Joining by Gas Phase Laser Oxide Deposition: Clayton Weiss1; Harris Marcus1; 1Institute of Materials Science-University of Connecticut
Selective area laser deposition of oxide ceramics is performed for the purpose of making a free form shape or a monolithic oxide joint. By using a combination of precursor gasses it is possible to achieve a desired final oxide deposit. Precursors are selected that provide tailored compositions, which are converted to gasses for the deposition process. By using a highly focused laser spot size as the thermal decomposition source, a high degree of spatial resolution is possible. The deposition can freeform objects or can be used to join the oxide materials.
2:20 PM
Microstructural Analysis of Laser Sustained Nitrogen Plasma Interaction with Titanium: Amber Black1; Ravindra Akarapu1; Stephen Copley1; Judith Todd1; 1Penn State
The effects of laser sustained plasma (LSP) on a commercially pure titanium substrate were investigated employing a carbon dioxide laser with the beam oriented parallel to the substrate surface. In this arrangement the LSP interacts with the substrate but there is no direct melting of substrate by the laser beam. The morphological features after interaction with the plasma were assessed visually. Scanning electron microscopy and energy dispersive spectroscopy were employed to further elucidate the nitrided features. Regions were identified containing hyper-stoichiometric titanium nitride, as well as faceted titanium nitride crystals with an epitaxial surface phase. The distance between the substrate surface and the laser beam was determined to be a critical factor influencing surface morphology.
2:40 PM
On CO2 Laser Nitriding of Titanium: Abdalla Nassar1; Ravindra Akarapu1; Stephen Copley1; Judith Todd1; 1Penn State
Laser-sustained plasma and CCD imaging of reactant species were employed to investigae the role of near-surface plasma in CO2 laser nitriding of titanium in open atmosphere. Using these investigative techniques, insights were gained regarding the role of plasma absorption and reactive nitriding species in laser nitriding. A low scanning speed limit to the formation of titanium nitride without surface oxidation was found and important parametric regions in the nitriding process were identified. It was found that heat unput to a nitride sample is about the same whether surface plasma is present or not. Evidence for a reaction between titanium and nitrogen within the plasma is presented.
3:00 PM
Use of Two Photon Polymerization for Additive Fabrication of Small-Scale Medical Devices: R. Narayan1; Anand Doraiswamy2; Shaun Gittard1; Aleksandr Ovsianikov3; Boris Chichkov3; 1Univ of North Carolina & North Carolina State Univ; 2Advanced Vision Science, Inc.; 3Laser Zentrum Hannover
Two photon polymerization involves nearly simultaneous absorption of two photons within a small volume in a photosensitive resin, which induces chemical reactions between photoinitiator molecules and monomers. We have examined use of two photon polymerization for fabrication of small-scale medical devices out of acrylate polymers and organically-modified ceramic materials. For example, we have shown that two photon polymerization is able to create hollow microneedles with in-plane and out-of-plane geometries, which exhibit a larger range of geometries than conventional fabrication methods. In vitro testing of two photon polymerization-fabricated microneedles with cadaveric porcine skin has been demonstrated. In addition, small prostheses and tissue engineering scaffolds have been prepared using photon polymerization. Furthermore, the use of soft lithography for high fidelity replication of two photon polymerization-fabricated structures has been evaluated. These results indicate that two photon polymerization is an attractive additive fabrication approach for processing small-scale medical devices.
3:20 PM Break
3:40 PM
The Effects of Laser Machining on Structure and Mechanical Properties of Micro-Channel Heat Exchangers Alloys: Hossein Lavvafi1; John Lewandowski1; Mark Lewandowski2; David Schwam1; John Lewandowski1; 1CWRU; 2other
The trend towards miniaturization of products coupled with high-precision production is posing new challenges for manufacturing technologies. Some materials are not easy to machine using traditional techniques. In recent years ways to improve the quality of cutting and micromachining of different materials using lasers have been developed. For instance, ablation with Nd:YAG laser marking systems permits much greater detail in the machined pattern than conventional machining . This study will employ a pulsed Nd:YAG laser to machine micro-channels in plates of heat exchangers. The thermal interaction of the laser with heat resistant alloys such as 316 stainless steel will be investigated. The effect of microstructural changes on the fatigue resistance of the alloys will be determined.
4:00 PM
Plasma/Laser Assisted Template Free Synthesis of ZnO Pillars: Raj Siman Ugapathy1; Raghavender Tummala1; Ramesh Kumar Guduru1; Pravansu Mohanty1; 1Univ of Michigan
Patterned structures of ZnO are usually synthesized via elaborate template assisted/lithography/ vapor deposition based techniques. A rapid technique to obtain ZnO pillars without the use of templates/catalysts will be presented in this paper. The pillar morphology is achieved via pulsed lasing of plasma synthesized ZnO coatings. The growth of ZnO pillars is believed to originate from hydrodynamic phenomena and its mechanism will be reported in detail. The ZnO patterned surfaces were characterized in terms of topology, optical and electrical properties. The phase and crystallinity was confirmed by X – ray diffraction. Optical transmission of the patterned ZnO was observed to be uniform throughout the ultraviolet – visible range; however, the as-sprayed plasma coatings of ZnO showed decreasing transmittance with increasing the energy of photon radiation. Further, laser patterned ZnO showed better electrical properties compared to the untreated coatings.
4:20 PM
Diode Laser Surface Treatment of Structural Aluminum Alloys 7075, 2024, 5456 and 6061: Microstructure and Corrosion Properties: Samar Kalita1; 1Advanced Engineered Materials Center, University of North Dakota
Corrosion mitigation is essential to extend service life of structural aluminum alloys (AA) used in aerospace and defense. This research investigated the effects of diode laser treatment on corrosion performance of AA 7075-T6, 2024-T351, 5456-H116 and 6061-T6. Microstructure and composition were analyzed by optical/electron microscopy and energy dispersive spectroscopy. Corrosion properties were evaluated in a NaCl solution using immersion and electrochemical techniques (open circuit potential, cyclic polarization and polarization resistance). Hardness was determined using a Hysitron-TI950 NanoIndenter. The melt region demonstrated epitaxially grown columnar grains. A thick planar boundary was observed around the edges of the melted region. Immersion test results demonstrated no pitting in laser melted regions, while large pits were observed in parent alloys. Corrosion current was marginally reduced in AA 2024, 5456 and 7075. A 270 mV improvement in the pit nucleation resistance of AA 5456-H116 was attained. Laser treatment improved resistance to pit-growth in some alloys.
4:40 PM
Localized Measurements of the Coefficient of Thermal-Expansion at Micron-Scale Spatial Resolution: Changdong Wei1; Peng Zhao1; Siwei Cao1; Xuan Zheng2; Ji-Cheng Zhao1; 1The Ohio State University; 2Seagate Technology
A newly developed time-domain probe beam deflection (TD-PBD) method was utilized to evaluate the coefficient of thermal expansion (CTE) as a function of composition for several binary alloy systems: Fe-Co, Co-Cr, Co-Ni, Pt-Ni, Pt-Cr, Pt-Pd and Pt-Rh. The systematic measurements were made on diffusion-multiple samples that were used to generate composition variations for these binary systems. The micron-scale spatial resolution of the TD-PBD method allows localized CTE measurements to be performed on diffusion multiples to establish the CTE-composition relationships without the need of making individual alloys. The CTE results from our high-throughput method were compared with available literature data for some of these binary systems and the good agreements demonstrate the high accuracy of the TD-PBD method and the power of systematic property measurements.
5:00 PM
Composition-Dependent Thermal Conductivity of Several Binary Systems: Siwei Cao1; Xuan Zheng2; Ji-Cheng Zhao1; 1The Ohio State University; 2Seagate Technology
Time-domain thermoreflectance (TDTR) measurements using a pump-and-probe femtosecond laser system are employed to rapidly evaluate thermal conductivity-composition relationships in several binary systems. Composition variations in solid-solution phases are generated in diffusion multiples via long-term interdiffusion. Localized thermal conductivity measurements with micron-scale resolution are made using TDTR on the diffusion multiple samples. Electron probe microanalysis (EPMA) is then performed to correlate the measurement locations with compositions. Such measurements can obtain composition-dependent thermal conductivity data much more effectively than using individual aIloy samples. The results of the following binary systems will be presented: Cr-Ni, Cr-Pd, Cr-Pt, Pd-Pt, Pd-Rh, and Pt-Rh. The effects of point defects on thermal conductivity will be discussed.
5:20 PM Cancelled
Property Change during Nanosecond Pulse Laser Annealing of Amorphous NiTi Thin Film: noushin yasavol1; Khatiboleslam Sadrnezhaad2; Mansoureh Ganjali3; 1tarbiat modares univ; 2Sharif university; 32Materials and Energy Research Center
Nanosecond lasers of different intensities were pulsed into sputter-deposited amorphous thin films of near equiatomic Ni/Ti composition to produce partially crystallized highly sensitive R-phase spots surrounded by amorphous region. Scanning electron microscopy with secondary and back-scattered electrons, field emission scanning electron microscopy, optical microscopy and x-ray diffraction patterns were used to characterize the laser treated spots. Effect of nanosecond pulse lasering on microstructure, morphology, thermal diffusion and inclusion formation was investigated. Increasing beam intensity and laser pulse-number promoted amorphous to R-phase transition. Lowering duration of the pulse incidence reduced local film oxidation and film/substrate interference.