Novel Diode Laser Cladding of High Temperature Alloys for Used in Ultrasupercritical Coal-Fired Boilers

The future use of coal, which is projected to remain a mainstay of energy consumption well into the 21st century, will require efficient, low emission ultra-supercritical coal-fired boilers. The high operating temperature, along with the oxidizing, corroding, and slag-deposition-induced microclimate environment of these systems have generated a critical need for new cladding techniques. Due to the high cost of the alloys used for cladding, this project will develop reduced-thickness cladding materials that maintain their high temperature corrosion resistance. Phase I developed and demonstrated a high-power diode laser cladding process that yielded low-dilution high-performance alloy clads that were less than 750microns (0.030¿) in thickness. Very thin and smooth low-slag-adhesion clad layers of alloy C22 were welded onto supercritical tube components at economical deposition rates. Phase II will develop laser cladding processes for ultra-supercritical alloys (IN72, IN52, Alloy 33), test these corrosion resistant alloys at temperatures exceeding 760°C, and code-certify the processes for pressure tubing and water wall panels. Manufacturability will be enhanced via improvements to the laser cladding nozzle and power feeder, laser cladding optics, and overall laser system robustness. Commercial Applications and other Benefits as described by the awardee: For supercritical coal-fired boilers, the technology should satisfy the demand for cladding of super heater and reheater pipe, tubes and panels, and upper and lower water wall components. These techniques also should find use in critical nuclear power plant infrastructure, military combat and transportation vehicle engines, and drive train components for our war fighters and peacekeepers