Laser heating was used to study the rates and trajectories of carbon black during the earliest stages of annealing. A commercial carbon black, Regal 250 (R250 Cabot Corporation) was heated with a Q-switched Nd:YAG laser and a continuous wave CO2 laser. Structural transformations were observed with transmission electron microscopy. Micrographs were processed with in-house codes for the purpose of extracting distributions of fringe length, tortuosity (curvature), and number of lamellae per stack. Time-temperature-histories with nanosecond temporal resolution and temperature reproducibility within tens of degrees Celsius were determined by spectrally resolving the laser induced incandescence signal and applying multi-wavelength pyrometry. The Nd:YAG laser fluences include: 25, 50, 100, 200, 300, and 550 mJ/cm2. The maximum observed temperature ranged from 2400 °C to the C2 sublimation temperature of 4180 °C. The CO2 laser was used to collect a series of isothermal (2600 °C) heat treatments versus time (100 ms–20 s). Laser heated samples are compared against R250 annealed in a furnace at 2600 °C. The material transformation trajectory of Nd:YAG laser heated R250 was different than the traditional furnace heating. The traditional furnace annealing pathway is followed for CO2 laser heating as based upon equivalent end structures.
All Science Journal Classification (ASJC) codes
- Materials Science(all)