ENGINEERING RESEARCH EXAMPLES Dr. Adonyi SUMMARY • Can you walk, think and chew gum at the same time? Categories of research mixed • TE module R&D examples • Ho is ‘&D ei g pe fo ed? odus ope a di • Is R&D a business or a non-profit endeavor? • Conclusions Types of Research, reminder 1. 2. 3. Fundamental: Thinking General: No specific industry Blue-sky, mostly analytical No lea deli e a les, o ly i pa t Applied: Walking Specific industry targeted Mostly experimental Clear deliverables Industrial/commercial: Chewing gum Company specific, implementation Timing of Engineering Research, TE elements 1. Strategic, long-term, PhD - II-VI: high temperature stability of interfaces, improved Figure of Merit 2. Tactical, medium-term, MSc - Marlow/II-VI: microwave welding, improve life 3. Immediate, short-term, BSc - Marlow: NDE of modules Example: TE Research Methodology Surface Energy Calculations Wettability Test Surface Roughness Test Contact Angle Optimal Coatings, Atmosphere and Roughness Metal Flow Characteristics Microwave Welding 1000°C Operating Temperature Welded Interface PROBLEM STATEMENT: BSc+MSc+PhD Project Goal • Raise operating temperature of The oele t i Modules TEM s to 1000°C • Improve the efficiency and pe fo a e fo all TEM s • Replace soldered & brazed joints • Model and validate ceramic-tometal interface phenomena • Optimize joining technology for future JOINT GEOMETRIES Example PhD level: Wettability Test • Samples prepped using methanol • Surface roughness recorded using profilometer • Heated in Gleeble at 300 °C for 30 seconds • Data collected using optical and thermal cameras • Contact angle found using imaging software You g s E uatio • γSG=γSL+γLGcosθ – γSG= Interfacial energy between solid and gas – γSL = Interfacial energy between solid and gas – γLG = Interfacial energy between solid and gas Diffusion Background • Material transport by atomic motion • Types – Interdiffusion – Self-diffusion – Impurity diffusion • Mechanisms – Vacancy diffusion – Interstitial diffusion • Fi k s se o d2 la �� � � =� 2 �� �� COMSOL Modeling Verification Diffusion of Ni into n-type Bi2Te3 Concentration Ni 0.50 0.40 0.30 Diffusion Equation COMSOL 0.20 Experimental Data 0.10 0.00 0.00 2.00 4.00 6.00 Distance from Interface (µm) Example: Level MSc Microwave Welding Outline • Dielectric Heating • High Frequency Induction Heating • Heat Transfer Equations • Filler Metal Selection • Waveguide Purpose • Develop Microwave Welding as a viable process for fabrication of thermoelectric devices • Theory – Simultaneous heating methods to account for varying material properties • Dielectric Heating in TE material • High Frequency heating in metallic coating\filler metal – Significantly shorter period at elevated temperature than oven soldering Verifying Heating in Waveguide • Both Al paste and Ni coated TE elements heated • No arcing occurred • Demonstrated the need for optimizing waveguide – Heating rate too low – Damage to TE elements Dielectric Heating Principles • Ionic Polarization – Electric field causes displacement between ions – Movement in oscillating field generates heat • ̇ E=2πfε0ε 2 effE Ionic Polarization of Sodium Chloride High Frequency Heating Principles • Le z s La – Current opposes changing emf • Joule effect – P=I2R • Heat Generation – ̇ H=2πfμ0μ • Skin Effect � = 503 � �� � effE 2 Frequency • Skin Depth at 2.5GHz – 1.7µm • Average particle size Skind Depth (μm) – 22.2µm Skin Depth vs Frequency 3.0 2.5 2.0 1.5 1.0 0.5 0.0 Aluminum Nickel Cobalt Copper 1 10 Frequency (GHz) 100 Gold Heat Transfer • Heat Generation – Dielectric Heating • ̇ E=2πfε0ε effE 2 – HFI Heating • ̇ H=2πfμ0μ 2 effH • Heat Transfer Out – – Metallic Filler Metallic Coating ̇H ̇H ̇E conv=h(Ts -T∞) 4-(T )4] =εσ[(T ) rad s ∞ TE Material Short Term Projects May 20, 2011 NVG TEM Eddy Current Testing • Orientation of Elements within Module – Elements not oriented in the same direction – Scanning is difficult due to orientation NVG TEM Eddy Current Testing • Semi-Automated Setup – Simple G-code written – 2 in/min velocity – 1 MHz probe I peda e s a , Bad odule NVG TEM Dest u ti e Testi g, Bad module Solder overflow PRELIMINARY CONCLUSIONS • The three levels of R&D can (and should be) performed simultaneously • There is a continuous improvement cycle and interaction between them • Funding mechanism varies: academic credit, retainer, unrestricted accounts, dedicated accounts How is R&D being perfomed? 1 • Networking, RFP (Request for Proposal) listing, NSF, THECB 2 • Writing Proposal, peer review, gnashing of teeth, budgets 3 • Initial approval, budget and deadline adjustments. Managing R&D Deliver on time and within budget Stage Setting up teams, training, etc Hiring researchers, purchasing equipment Time Spent CONCLUSIONS • R&D is like any other business: if it does not grow, it dies! • R&D has to be led and managed like any other business • R&D does not produce profit, but generates overhead • R&D has two outputs: quality research and quality graduates