Integrated Fabrication of TEGs using Thermal Spray and           Laser Micromachining

Introduction and MOTIVATION

Vehicle transportation is responsible for 60% of the annual oil consumption in the U.S., yet less than 30% of the fuel energy is converted into mechanical power in a vehicle, with the balance lost as waste heat. Thermoelectric generators (TEGs) are devices that can convert heat directly into usable electricity. The successful development of TEGs for automotive applications requires:

  • Abundant, low cost, and efficient thermoelectric (TE) materials
  • Industry-scalable material synthesis and device fabrication process
  • Low cost , efficient and reliable integration into existing vehicle systems

We are proposing an innovative manufacturing solution to addresses these requirements and to develop marketable, cost-effective TEGs by directly fabricating the functional TE layers onto exhaust pipes in a rapid, economical, and industrially scalable manner.

LASER ASSISTED TEG MANUFACTURING

Process flow of integrated TEG device fabrication using thermal spray (TS) and laser machining (LM).

  1. exhaust component with integrated heat sink
  2. TS electrically insulating layer,
  3. TS bottom metallization and LM to form lower TE conductors,
  4. TS deposition of n and p type TE material,
  5. LM to electrically separate,
  6. TS and LM gap-fill and top metallization and patterning,
  7. TS electrically insulating layer
  8. attach annular water cooled heat exchanger to complete device.

Thermal Spray

Thermal spray involves the use of a torch to heat a material, in powder or wire form, to a molten or near-molten state, and the use of a gas injected through a nozzle to propel the material to the target substrate, creating a completely new surface. 

LASER PROCESSING

Laser ablation is an efficient and versatile means of material removal. Different feature sizes can be achieved by varying laser parameters.

RESULTS

Patterns made by pulsed GM30-527 green laser (200ns pulse width, 2.5mJ/pulse and 3kHz PRR) by Photonics Industries.

Masks machined from aluminum on CNC machine to spray P and N type Legs

Granular material mixed with water soluble binder is used to fill the gaps.

Thermal spray of P and N type TE Legs on patterned substrate/ Top View and Side View