skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Thick Thermal Barrier Coatings (TTBCs) for Low Emission, High Efficiency Diesel Engine Components

Abstract

The objective of this program was to advance the fundamental understanding of thick thermal barrier coating (TTBC) systems for application to low heat rejection diesel engine combustion chambers. Previous reviews of thermal barrier coating technology concluded that the current level of understanding of coating system behavior is inadequate and the lack of fundamental understanding may impede the application of thermal barrier coating to diesel engines.(1) Areas of TTBC technology examined in this program include powder characteristics and chemistry; bond coating composition, coating design, microstructure and thickness as they affect properties, durability, and reliability; and TTBC "aging" effects (microstructural and property changes) under diesel engine operating conditions. Fifteen TTBC ceramic powders were evaluated. These powders were selected to investigate the effects of different chemistries, different manufacturing methods, lot-to-lot variations, different suppliers and varying impurity levels. Each of the fifteen materials has been sprayed using 36 parameters selected by a design of experiments (DOE) to determine the effects of primary gas (Ar and N2), primary gas flow rate, voltage, arc current, powder feed rate, carrier gas flow rate, and spraying distance. The deposition efficiency, density, and thermal conductivity of the resulting coatings were measured. A coating with a high deposition efficiency andmore » low thermal conductivity is desired from an economic standpoint. An optimum combination of thermal conductivity and disposition efficiency was found for each lot of powder in follow-on experiments and disposition parameters were chosen for full characterization.(2) Strengths of the optimized coatings were determined using 4-point bending specimens. The tensile strength was determined using free-standing coatings made by spraying onto mild steel substrates which were subsequently removed by chemical etching. The compressive strengths of the coatings were determined using composite specimens of ceramic coated onto stainless steel substrates, tested with the coating in compression and the steel in tension. The strength of the coating was determined from an elastic bi-material analysis of the resulting failure of the coating in compression.(3) Altough initial comparisons of the materials would appear to be straight forward from these results, the results of the aging tests of the materials are necessary to insure that trends in properties remain after long term exposure to a diesel environment. Some comparisons can be made, such as the comparison between for lot-to-lot variation. An axial fatigue test to determine the high cycle fatigue behavior of TTBCs was developed at the University of Illinois under funding from this program.(4) A fatigue test apparatus has been designed and initial work performed which demonstrates the ability to provide a routine method of axial testing of coating. The test fixture replaces the normal load frame and fixtures used to transmit the hydraulic oil loading to the sample with the TTBC specimen itself. The TTBC specimen is a composite metal/coating with stainless steel ends. The coating is sprayed onto a mild steel center tube section onto which the stainless steel ends are press fit. The specimen is then machined. After machining, the specimen is placed in an acid bath which etches the mild steel away leaving the TTBC attached to the the stainless steel ends. Plugs are then installed in the ends and the composite specimen loaded in the test fixture where the hydraulic oil pressurizes each end to apply the load. Since oil transmits the load, bending loads are minimized. This test fixture has been modified to allow piston ends to be attached to the specimen which allows tensile loading as well as compressive loading of the specimen. In addition to the room temperature data, specimens have been tested at 800 Degrees C with the surprising result that at high temperature, the TTBC exhibits much higher fatigue strength. Testing of the TTBC using tension/compression cycling has been conducted using the modified test fixture. The goal of this work was to investigate the failure mechanisms of the coating and to determine if tensile and compressive fatigue damage would interact to influence the resulting life of the coating. Coating samples were run with various mean compressive loads and constant tensile loading approximately equal to 90% of the tensile strength of the coating. The results of this testing shows no interaction of failure resulting from the tensile and compressive load. The material fails in tension at the life predicted by the maximum tensile stress or in compression at the life predicted by the compressive stress. This indicates that there are two differing failure mechanisms for the TTBC in tension and compression.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Caterpillar Inc., P. O. Box 1875, Peoria, IL 61656-1875
Sponsoring Org.:
USDOE Office of Transportation Technologies - (EE-30) USDOE Office of Heavy Vehicle Technologies (OHVT) - (EE-33)
OSTI Identifier:
878132
Report Number(s):
DOE/OR/22580-1
TRN: US200712%%276
DOE Contract Number:
FC05-97OR22580
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AGING; CERAMICS; COATINGS; COMBUSTION CHAMBERS; DIESEL ENGINES; EFFICIENCY; GAS FLOW; MICROSTRUCTURE; STAINLESS STEELS; TENSILE PROPERTIES; THERMAL BARRIERS; THERMAL CONDUCTIVITY; Thermal barrier coatings, fatigue, oxidation, thermal properties, thermal conductivity, thermal diffusivity, diesel engine, piston, cylinder head, coatings, bond coatings, zirconia, mullite, calcium titanate, powder, plasma spray, aging, durability

Citation Formats

M. Brad Beardsley, Caterpillar Inc., Dr. Darrell Socie, University of Illinois, Dr. Ed Redja, University of Illinois, and Dr. Christopher Berndt, State University of New York at Stony Brook. Thick Thermal Barrier Coatings (TTBCs) for Low Emission, High Efficiency Diesel Engine Components. United States: N. p., 2006. Web. doi:10.2172/878132.
M. Brad Beardsley, Caterpillar Inc., Dr. Darrell Socie, University of Illinois, Dr. Ed Redja, University of Illinois, & Dr. Christopher Berndt, State University of New York at Stony Brook. Thick Thermal Barrier Coatings (TTBCs) for Low Emission, High Efficiency Diesel Engine Components. United States. doi:10.2172/878132.
M. Brad Beardsley, Caterpillar Inc., Dr. Darrell Socie, University of Illinois, Dr. Ed Redja, University of Illinois, and Dr. Christopher Berndt, State University of New York at Stony Brook. Thu . "Thick Thermal Barrier Coatings (TTBCs) for Low Emission, High Efficiency Diesel Engine Components". United States. doi:10.2172/878132. https://www.osti.gov/servlets/purl/878132.
@article{osti_878132,
title = {Thick Thermal Barrier Coatings (TTBCs) for Low Emission, High Efficiency Diesel Engine Components},
author = {M. Brad Beardsley, Caterpillar Inc. and Dr. Darrell Socie, University of Illinois and Dr. Ed Redja, University of Illinois and Dr. Christopher Berndt, State University of New York at Stony Brook},
abstractNote = {The objective of this program was to advance the fundamental understanding of thick thermal barrier coating (TTBC) systems for application to low heat rejection diesel engine combustion chambers. Previous reviews of thermal barrier coating technology concluded that the current level of understanding of coating system behavior is inadequate and the lack of fundamental understanding may impede the application of thermal barrier coating to diesel engines.(1) Areas of TTBC technology examined in this program include powder characteristics and chemistry; bond coating composition, coating design, microstructure and thickness as they affect properties, durability, and reliability; and TTBC "aging" effects (microstructural and property changes) under diesel engine operating conditions. Fifteen TTBC ceramic powders were evaluated. These powders were selected to investigate the effects of different chemistries, different manufacturing methods, lot-to-lot variations, different suppliers and varying impurity levels. Each of the fifteen materials has been sprayed using 36 parameters selected by a design of experiments (DOE) to determine the effects of primary gas (Ar and N2), primary gas flow rate, voltage, arc current, powder feed rate, carrier gas flow rate, and spraying distance. The deposition efficiency, density, and thermal conductivity of the resulting coatings were measured. A coating with a high deposition efficiency and low thermal conductivity is desired from an economic standpoint. An optimum combination of thermal conductivity and disposition efficiency was found for each lot of powder in follow-on experiments and disposition parameters were chosen for full characterization.(2) Strengths of the optimized coatings were determined using 4-point bending specimens. The tensile strength was determined using free-standing coatings made by spraying onto mild steel substrates which were subsequently removed by chemical etching. The compressive strengths of the coatings were determined using composite specimens of ceramic coated onto stainless steel substrates, tested with the coating in compression and the steel in tension. The strength of the coating was determined from an elastic bi-material analysis of the resulting failure of the coating in compression.(3) Altough initial comparisons of the materials would appear to be straight forward from these results, the results of the aging tests of the materials are necessary to insure that trends in properties remain after long term exposure to a diesel environment. Some comparisons can be made, such as the comparison between for lot-to-lot variation. An axial fatigue test to determine the high cycle fatigue behavior of TTBCs was developed at the University of Illinois under funding from this program.(4) A fatigue test apparatus has been designed and initial work performed which demonstrates the ability to provide a routine method of axial testing of coating. The test fixture replaces the normal load frame and fixtures used to transmit the hydraulic oil loading to the sample with the TTBC specimen itself. The TTBC specimen is a composite metal/coating with stainless steel ends. The coating is sprayed onto a mild steel center tube section onto which the stainless steel ends are press fit. The specimen is then machined. After machining, the specimen is placed in an acid bath which etches the mild steel away leaving the TTBC attached to the the stainless steel ends. Plugs are then installed in the ends and the composite specimen loaded in the test fixture where the hydraulic oil pressurizes each end to apply the load. Since oil transmits the load, bending loads are minimized. This test fixture has been modified to allow piston ends to be attached to the specimen which allows tensile loading as well as compressive loading of the specimen. In addition to the room temperature data, specimens have been tested at 800 Degrees C with the surprising result that at high temperature, the TTBC exhibits much higher fatigue strength. Testing of the TTBC using tension/compression cycling has been conducted using the modified test fixture. The goal of this work was to investigate the failure mechanisms of the coating and to determine if tensile and compressive fatigue damage would interact to influence the resulting life of the coating. Coating samples were run with various mean compressive loads and constant tensile loading approximately equal to 90% of the tensile strength of the coating. The results of this testing shows no interaction of failure resulting from the tensile and compressive load. The material fails in tension at the life predicted by the maximum tensile stress or in compression at the life predicted by the compressive stress. This indicates that there are two differing failure mechanisms for the TTBC in tension and compression.},
doi = {10.2172/878132},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Mar 02 00:00:00 EST 2006},
month = {Thu Mar 02 00:00:00 EST 2006}
}

Technical Report:

Save / Share:
  • Thermal efficiencies of 54% have been demonstrated by single cylinder engine testing of advanced diesel engine concepts developed under Department of Energy funding. In order for these concept engines to be commercially viable, cost effective and durable systems for insulating the piston, head, ports and exhaust manifolds will be required. The application and development of new materials such as thick thermal barrier coating systems will be key to insulating these components. Development of test methods to rapidly evaluate the durability of coating systems without expensive engine testing is a major objective of current work. In addition, a novel, low costmore » method for producing thermal barrier coated pistons without final machining of the coating has been developed.« less
  • Cummins Inc., in partnership with the Department of Energy, has developed technology for a new highly efficient, very low emission, diesel engine for light trucks and sport utility vehicles. This work began in April 1997, and started with very aggressive goals for vehicles in the 5751 to 8500 pound GCW weight class. The primary program goals were as follows: (1) EMISSIONS NOx = 0.50 g/mi PM = 0.05 g/mi CO = 2.8 g/mi NMHC = 0.07 g/mi California decided to issue new and even tougher LEV II light truck regulations late in 1999. EPA also issued its lower Tier 2more » regulations late in 2000. The net result was that the targets for this diesel engine project were lowered, and these goals were eventually modified by the publication of Federal Tier 2 emission standards early in 2000 to the following: NOx = 0.07 g/mi PM = 0.01 g/mi (2) FUEL ECONOMY The fuel economy goal was 50 percent MPG improvement (combined city/highway) over the 1997 gasoline powered light truck or sport utility vehicle in the vehicle class for which this diesel engine is being designed to replace. The goal for fuel economy remained at 50 percent MPG improvement, even with the emissions goal revisions. (3) COOPERATIVE DEVELOPMENT Regular design reviews of the engine program will be conducted with a vehicle manufacturer to insure that the concepts and design specifics are commercially feasible. (DaimlerChrysler has provided Cummins with this design review input.) Cummins has essentially completed a demonstration of proof-of-principle for a diesel engine platform using advanced combustion and fuel system technologies. Cummins reported very early progress in this project, evidence that new diesel engine technology had been developed that demonstrated the feasibility of the above emissions goals. Emissions levels of NOx = 0.4 g/mi and PM = 0.06 g/mi were demonstrated for a 5250 lb. test weight vehicle with passive aftertreatment only. These results were achieved using the full chassis dynamometer FTP-75 test procedure that allowed compliance with the Tier 2 Interim Bin 10 Standards and would apply to vehicles in MY2004 through MY2007 timeframe. In further technology development with active aftertreatment management, Cummins has been able to report that the emissions goals for the Tier 2 Bin 5 standards were met on an engine running the full FTP-75 test procedure. The fuel economy on the chassis tests was measured at over 59 percent MPG improvement over the gasoline engines that are offered in typical SUVs and light trucks. The above demonstration used only in-cylinder fueling for management of the aftertreatment system.« less
  • Cummins Inc., in partnership with the Department of Energy, has developed technology for a new highly efficient, very low emission, diesel engine for light trucks and sport utility vehicles. This work began in April 1997, and started with very aggressive goals for vehicles in the 5751 to 8500 pound GCW weight class. The primary program goals were as follows: (1) EMISSIONS NOx = 0.50 g/mi PM = 0.05 g/mi CO = 2.8 g/mi NMHC = 0.07 g/mi California decided to issue new and even tougher LEV II light truck regulations late in 1999. EPA also issued its lower Tier 2more » regulations late in 2000. The net result was that the targets for this diesel engine project were lowered, and these goals were eventually modified by the publication of Federal Tier 2 emission standards early in 2000 to the following: NOx = 0.07 g/mi PM = 0.01 g/mi (2) FUEL ECONOMY The fuel economy goal was 50 percent MPG improvement (combined city/highway) over the 1997 gasoline powered light truck or sport utility vehicle in the vehicle class for which this diesel engine is being designed to replace. The goal for fuel economy remained at 50 percent MPG improvement, even with the emissions goal revisions. (3) COOPERATIVE DEVELOPMENT Regular design reviews of the engine program will be conducted with a vehicle manufacturer to insure that the concepts and design specifics are commercially feasible. (DaimlerChrysler has provided Cummins with this design review input.) Cummins has essentially completed a demonstration of proof-of-principle for a diesel engine platform using advanced combustion and fuel system technologies. Cummins reported very early progress in this project, evidence that new diesel engine technology had been developed that demonstrated the feasibility of the above emissions goals. Emissions levels of NOx = 0.4 g/mi and PM = 0.06 g/mi were demonstrated for a 5250 lb. test weight vehicle with passive aftertreatment only. These results were achieved using the full chassis dynamometer FTP-75 test procedure that allowed compliance with the Tier 2 Interim Bin 10 Standards and would apply to vehicles in MY2004 through MY2007 timeframe. In further technology development with active aftertreatment management, Cummins has been able to report that the emissions goals for the Tier 2 Bin 5 standards were met on an engine running the full FTP-75 test procedure. The fuel economy on the chassis tests was measured at over 59 percent MPG improvement over the gasoline engines that are offered in typical SUVs and light trucks. The above demonstration used only in-cylinder fueling for management of the aftertreatment system.« less
  • Cummins Inc., in partnership with the Department of Energy, has developed technology for a new highly efficient, very low emission, diesel engine for light trucks and sport utility vehicles. This work began in April 1997, and started with very aggressive goals for vehicles in the 5751 to 8500 pound GCW weight class. The primary program goals were as follows: (1) EMISSIONS NOx = 0.50 g/mi PM = 0.05 g/mi CO = 2.8 g/mi NMHC = 0.07 g/mi California decided to issue new and even tougher LEV II light truck regulations late in 1999. EPA also issued its lower Tier 2more » regulations late in 2000. The net result was that the targets for this diesel engine project were lowered, and these goals were eventually modified by the publication of Federal Tier 2 emission standards early in 2000 to the following: NOx = 0.07 g/mi PM = 0.01 g/mi (2) FUEL ECONOMY The fuel economy goal was 50 percent MPG improvement (combined city/highway) over the 1997 gasoline powered light truck or sport utility vehicle in the vehicle class for which this diesel engine is being designed to replace. The goal for fuel economy remained at 50 percent MPG improvement, even with the emissions goal revisions. (3) COOPERATIVE DEVELOPMENT Regular design reviews of the engine program will be conducted with a vehicle manufacturer to insure that the concepts and design specifics are commercially feasible. (DaimlerChrysler has provided Cummins with this design review input.) Cummins has essentially completed a demonstration of proof-of-principle for a diesel engine platform using advanced combustion and fuel system technologies. Cummins reported very early progress in this project, evidence that new diesel engine technology had been developed that demonstrated the feasibility of the above emissions goals. Emissions levels of NOx = 0.4 g/mi and PM = 0.06 g/mi were demonstrated for a 5250 lb. test weight vehicle with passive aftertreatment only. These results were achieved using the full chassis dynamometer FTP-75 test procedure that allowed compliance with the Tier 2 Interim Bin 10 Standards and would apply to vehicles in MY2004 through MY2007 timeframe. In further technology development with active aftertreatment management, Cummins has been able to report that the emissions goals for the Tier 2 Bin 5 standards were met on an engine running the full FTP-75 test procedure. The fuel economy on the chassis tests was measured at over 59 percent MPG improvement over the gasoline engines that are offered in typical SUVs and light trucks. The above demonstration used only in-cylinder fueling for management of the aftertreatment system.« less
  • Cummins Inc., in partnership with the Department of Energy, has developed technology for a new highly efficient, very low emission, diesel engine for light trucks and sport utility vehicles. This work began in April 1997, and started with very aggressive goals for vehicles in the 5751 to 8500 pound GCW weight class. The primary program goals were as follows: (1) EMISSIONS NOx = 0.50 g/mi PM = 0.05 g/mi CO = 2.8 g/mi NMHC = 0.07 g/mi California decided to issue new and even tougher LEV II light truck regulations late in 1999. EPA also issued its lower Tier 2more » regulations late in 2000. The net result was that the targets for this diesel engine project were lowered, and these goals were eventually modified by the publication of Federal Tier 2 emission standards early in 2000 to the following: NOx = 0.07 g/mi PM = 0.01 g/mi (2) FUEL ECONOMY The fuel economy goal was 50 percent MPG improvement (combined city/highway) over the 1997 gasoline powered light truck or sport utility vehicle in the vehicle class for which this diesel engine is being designed to replace. The goal for fuel economy remained at 50 percent MPG improvement, even with the emissions goal revisions. (3) COOPERATIVE DEVELOPMENT Regular design reviews of the engine program will be conducted with a vehicle manufacturer to insure that the concepts and design specifics are commercially feasible. (DaimlerChrysler has provided Cummins with this design review input.) Cummins has essentially completed a demonstration of proof-of-principle for a diesel engine platform using advanced combustion and fuel system technologies. Cummins reported very early progress in this project, evidence that new diesel engine technology had been developed that demonstrated the feasibility of the above emissions goals. Emissions levels of NOx = 0.4 g/mi and PM = 0.06 g/mi were demonstrated for a 5250 lb. test weight vehicle with passive aftertreatment only. These results were achieved using the full chassis dynamometer FTP-75 test procedure that allowed compliance with the Tier 2 Interim Bin 10 Standards and would apply to vehicles in MY2004 through MY2007 timeframe. In further technology development with active aftertreatment management, Cummins has been able to report that the emissions goals for the Tier 2 Bin 5 standards were met on an engine running the full FTP-75 test procedure. The fuel economy on the chassis tests was measured at over 59 percent MPG improvement over the gasoline engines that are offered in typical SUVs and light trucks. The above demonstration used only in-cylinder fueling for management of the aftertreatment system.« less