CANCELLED - Manufacturing of High Temperature Brazed Burners for Stationary Gas Turbines - Simulation Versus Experiment

Welding of relevant safety components, carrying combustible material for burners in stationary gas turbines is state of the art. Based on many years of experience in welding components of burners there exists a huge amount of empirically determined data for the design of weld joints. The need to increase functionality and efficiency of burner components in stationary gas turbines as well as in jet engines, together with the commonly rising cost pressure lead to higher requirements in joining technology. High temperature brazing is one alternative to welding. However the replacement of welding technology often fails because of missing criteria for design for high temperature brazing. This practice-oriented article provides first development results for high temperature brazing of components for burners in combustion turbines.

In addition to the experimental trials of brazed burner components the lecture shows first development results concerning simulation tools supporting high strength braze joints. A joint approach of simulation and experiment was chosen to determine the process window in terms of brazing time and temperature. A systematic design of experiment supported the simulation work in order to keep the experimental effort low. Prediction of thermodynamics and kinetic processes were made by means of the CALPHAD software Thermo-Calc and the diffusion solver DICTRA. Based on an economical high temperature brazing method for 16Mo3 heat resisting steel in combination with nickel based braze alloy Ni 660 the time for isothermal solidification was determined over temperature. As result on that, a process window was calculated and experimentally validated. Additionally, the process robustness in terms of joint widths variations was determined and experimentally confirmed. The end of the lecture reveals how practical braze trials in combination with the described simulation tools deliveres the best practice procedure for brazed burner components in stationary gas turbines.