SBIR-STTR Award

Years of industrial investment have yielded nickel-based, austenitic, and new ferritic alloys, which have been designed to meet the creep resistance demands, of ultrasupercritical coal-fired boilers. These developments have contributed to record high commodity prices for nickel and chrome. Now, the high operating temperatures - along with the oxidizing, corroding, and slag-deposition-induced microclimate environments - of low NOx combustion systems have generated a critical need for new cladding techniques. These new cladding techniques must be cost effective - that is, they must reduce the amount of the special creep resistant alloy materials and simultaneously improve the alloy material performance. This project will develop novel cladding processes based on the use of a high-power direct-diode laser, the smallest and most efficient laser in the world today. The diode laser will enable the welding of very thin, smooth, low-slag-adhesion clad layers of creep resistant alloys onto steel substrates, with little or no dilution, with low distortion, and at very high deposition rates.

Commercial Applications and Other Benefits as described by the awardee:
The new cladding techniques should result in improved clad material properties, reduction in coal-fired boiler costs, and increased boiler efficiencies, thereby reducing pollution and carbon dioxide emissions. For military applications, the technology should enable the laser-cladding repair of armored systems

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