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A D V A N C E D M A T E R I A L S & P R O C E S S E S | F E B R U A R Y / M A R C H 2 0 1 8 2 8 takeoff [1] . New materials for modern jets can withstand a maximum TET of 1100°C (2010°F) for 1000 h creep life at 137 MPa (20 ksi). However, turbine ma- terials are expected to withstand tem- peratures up to 1200°C (2190°F), leaving a gap of 100°C (180°F). Y 2 O 3 stabilized ZrO 2 thermal barri- er coatings (TBCs) on turbine blades en- able withstanding 165° to 300°C (300° to 540°F) higher TET, enabling operation at higher temperatures in new gener- ation aircraft [1] . Coatings are typically applied via plasma spray and electron beam physical vapor deposition. Lower metal surface temperature due to TBCs increases the creep life of turbine ma- terial. A temperature decrease of 60° to 70°C (110° to 125°F) leads to a tenfold in- crease in turbine-blade creep life at the same pressure; a decrease from 1000° to 870°C results in a 100-fold increase in creep rupture life. An increase of 20°C (36°F) in TET leads to approximately 0.5% improvement in fuel efficiency [10] . PREDICTING LIFE SPAN Accurate assessment of the re- maining useful life (RUL) of critical components is essential to enable any remedial action necessary for LCI. The predicted time at which a sys- tem or component will no longer per- form its intended function becomes the RUL, which is an important con- cept in decision-making for repair or replace. Improved nondestructive evaluation and life monitoring en- ables setting higher tolerable defect sizes and thus more RUL. Nondestruc- tive sensing techniques to monitor wear and microstructure are used for RUL determination in condition-based maintenance. LCI of critical components can save energy of 10.42 quadrillion Btu and cor- responding CO 2 emission by 2080 bil- lion metric tons [1] . LCI by five folds of a 1-ton steel component can save 4 tons of steel. This savings can conserve 5.6 tons of iron ore, 3.2 tons of coal, 1.2 tons of limestone, and 0.48 tons of recycled steel plus 80 GJ energy for steel produc- tion in an integrated steel plant [11] . Life cycle improvement in the use, maintenance, and reuse of components leads to increased useful life by several folds [2] , which saves significant amounts of nonrenewable resources and energy, enhances sustainability, improves GDP, and negates anthropological changes in ecology and climate [1,12] . ~AM&P For more information: Ramnarayan Chattopadhyay is an adviser, consul- tant, and honorary professor, Simon Bo- livar University, Caracas, Venezuela. He is available in the U.S. a fewmonths per year. ramchattopadhyay@gmail.com . References 1. R. Chattopadhyay, Green Tribology, Green Surface Engineering and Global Warming, ASM International, 2014. 2. R. Chattopadhyay, Advanced Ther- mally Assisted Surface Engineering Pro- cesses, Springer, N.Y., 2004. 3. J. Farmer, High-Velocity Laser- Accelerated Deposition, S&TR, Oct/Nov 2012 ,https://str.llnl.gov/OctNov12/pdfs/ 10.12.2.pdf. 4. R. Chattopadhyay, High Silt Wear of Hydroturbine Runners, Intl. Conf. on Wear of Matls. , ASME, p 1040-1044, April 1993. 5. R.J.K. Wood, Tribology and Cor- rosion Aspects of Wind Turbines, Wind Energy-Challenges for Materials, Mech- anics and Surface Science, IOP, 2010. 6. E.T. Vitche, High Temperature Fa- tigue Test of Automotive Valve Steels, Fatigue at High Temperature , ASTM STP520, ASTM, p 231-241, 1973. 7. R. Chattopadhyay and P.A. Kam- mer, Study of Dilutions in High Alloy Overlays, 3rd Intl. Conf. on Trends in Welding Research, ASM Intl. and AWS, p 455-460, 1992. 8. R. Chattopadhyay, Surface Wear, Analysis, Treatment and Prevention, ASM Intl., 2001. 9. R. Chattopadhyay, Rail Wheel Con- tact Wear, Intl. Symp. on Tribol., Beijing , 1993. 10. L. Reade, Extending the Life of Jet Engines, Mater. World, p 16-19, May 2009. 11. World Steel Organization, fact sheet, www.worldsteel.org/en/dam/ jcr:140482e9-5875-4c2d-abc4-19767ed 48437/fact_raw+materials_2016.pdf. 12. R. Chattopadhyay and Mandira Chatterjee, Global Warming: Origin, Significance, and Management, Global Vision Publishing, New Delhi, 2012.