Denkena / Rienäcker / Knoll Microstructuring of Thermo-Mechanically Highly Stressed Surfaces

Final Report of the DFG Research Group 576
1. Auflage 2014
ISBN: 978-3-319-09692-6
Verlag: Springer International Publishing
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, 190 Seiten

Reihe: Lecture Notes in Production Engineering

The fuel consumption of a modern combustion engine is one of the most important purchase criteria in contemporary society. Increasing oil prices and exhaust emissions taxes force the automotive industry to continuously improve the vehicle engines. The fuel consumption is closely related to the frictional losses of an engine. New material pairings or constructive modifications of the piston group can reduce such losses. Another innovative concept to lower the frictional forces is the micro-structuring of thermo-mechanically highly stressed surfaces. Within an interdisciplinary research group sponsored by the German Research Foundation, scientists at the Leibniz Universität Hannover and Universität Kassel have been working together to investigate this research topic. This final report presents their findings and offers scope for further discussion.

This contributed volume presents the final research results of the DFG Research Group 576, which is a joint initiative of five different institutes of the Leibniz Universität Hannover and the Universität Kassel, Germany. The research of the DFG Research Group 576 focuses on improving the tribological behavior of thermomechanically highly stressed surfaces, particularly on cylinder liner for combustion engines. The target audience primarily comprises researchers and experts in the field but the book may also be beneficial for graduate students who want to specialize in the field.

Autoren/Hrsg.

Denkena, Berend

Rienäcker, Adrian

Knoll, Gunter

Bach, Friedrich-Wilhelm

Maier, Hans Jürgen

Reithmeier, Eduard

Re, Eduard

Dinkelacker, Friedrich

Inhaltsverzeichnis

1;Preamble;6
2;Acknowledgement;7
3;Contents;8
4;Formula symbols and abbreviations;10
4.1;Formula Symbols;10
4.2;Symbols;13
4.3;Abbreviations;14
5;1 Introduction;16
6;2 Project overview;17
6.1;2.1 Consortium;17
6.2;2.2 Starting situation and need for action;19
6.3;2.3 Summary of main results;22
7;3 Methods and models for the design of microstructures;24
7.1;3.1 Objective and approach;24
7.2;3.2 Comparison between Computational Fluid Dynamics and the Reynolds equation;24
7.3;3.3 Investigation of dimple geometry and arrangement;26
7.3.1;Cross section geometry;26
7.3.2;Lateral dimple position;29
7.3.3;Dimple distance L2;30
7.3.4;Inlet length L1 and exit length L3;30
7.3.5;Study of 3D dimple cross section geometry;32
7.4;3.4 Simulation model for piston ring friction coefficient test rig;33
7.5;3.5 Design and validation of a test engine simulation model;35
7.5.1;Theoretical foundation;35
7.5.2;Simulation model;38
7.5.3;Effect of liner roughness on piston ring dynamics;39
7.5.4;Surface topology effects on oil consumption;41
7.6;3.6 Conclusion;42
8;4 Microstructuring by means of cutting processes;43
8.1;4.1 Objective and approach;43
8.2;4.2 Experimental set-up fly-cutting tests;44
8.2.1;Test materials;44
8.2.2;Test tools;45
8.2.3;Formation of chip roots by means of a quick-stop device;45
8.2.4;Highly dynamic cutting force measuring method;47
8.3;4.3 High-quality cutting of micro-dimples;48
8.3.1;Cutting edge: mechanisms;48
8.3.2;Influence of cutting speed on quality characteristics and chip formation;50
8.3.3;Tool-specific parameters influencing the quality of the micro-dimples and the chip formation process;51
8.3.4;Material-specific separation mechanisms;58
8.3.5;Model for the prediction of burr dimensions;59
8.4;4.4 Inner structuring of rotationally symmetrical components;61
8.4.1;Process development for load-specific inner structuring of rotationally symmetrical surfaces;61
8.4.2;Process / tool design and process limits;62
8.4.3;Kinematic parameters influencing micro dimple geometry;63
8.4.4;Geometrical kinematic parameters influencing micro dimple geometry;65
8.4.5;Loadand speed-specific structuring of cylinder liners;66
8.4.6;Microstructuring tools for machining of cylinder liners;67
8.4.7;Creation of hybrid cylinder liners;69
8.5;4.5 Conclusion;71
9;5 Microstructured thermally sprayed surfaces;73
9.1;5.1 Objective;73
9.2;5.2 Experimental;73
9.3;5.3 Outer coating of rotationally symmetric components;75
9.3.1;Spray material Fe/Mo 50-50;75
9.3.2;Spray material FeCr13;83
9.4;5.4 Inner coating of rotationally symmetric components;89
9.4.1;Spray material FeCr13;90
9.4.2;Spray material FeCr13/Mo 50-50;92
9.4.3;Spray material Mo/NiCrBSi 75-25;100
9.5;5.5 Tribological testing of the inner coating of cylinder liners;104
9.6;5.6 Conclusion;106
10;6 Surface characterisation based on optical metrology;108
10.1;6.1 Objective and approach;108
10.2;6.2 Measurement techniques;109
10.2.1;White light interferometer;109
10.2.2;Chromatic sensor;110
10.3;6.3 Measurement of machined micro-dimples;112
10.3.1;Data preprocessing stitching;112
10.3.2;Data preprocessing form and waviness;113
10.3.3;Segmentation methods for the identification of micro-dimples;114
10.3.4;Data processing region detection;116
10.3.5;Data processing micro-dimple characteristics;118
10.4;6.4 Measurement of thermal sprayed surfaces;124
10.4.1;Data processing micro pore characteristics;124
10.5;6.5 Multi-measurement methods;126
10.5.1;Undercut detection;126
10.5.2;Data processing undercut detection;126
10.5.3;3D morphological-thinning;129
10.6;6.6 Conclusion;131
11;7 Tribological mechanisms of microstructures;134
11.1;7.1 Tribological mechanisms of machined micro-dimples under planar contactconditions;134
11.1.1;Ring-on-disc tribometer tests;134
11.1.2;Functioning of machined micro-dimples;136
11.1.3;Influence of micro-dimple ratio on friction coefficient and minimum friction coefficient;137
11.1.4;Influence of micro-dimple arrangement on friction coefficient and minimum friction coefficient;139
11.1.5;Influence of micro-dimple dimensions on friction coefficient and minimum friction coefficient;140
11.1.6;Influence of micro-dimple geometry on friction coefficient and minimum friction coefficient;142
11.1.7;Conclusion;143
11.2;7.2 Tribological mechanisms of microstructured thermally sprayed surfaces;144
11.2.1;Pin-on-disc experiments;144
11.2.2;Tribological properties of the Fe/Mo 50-50 coatings;145
11.2.3;Tribological properties of the FeCr13 coatings;148
11.2.4;Tribological properties of the FeCr13/Mo 50-50 coatings;149
11.2.5;Tribological properties of Mo/NiCrBSi:;153
11.2.6;Conclusion;155
11.3;7.3 Tribological mechanisms of microstructured surfaces under dragged conditions;156
11.3.1;Piston ring friction results for hybrid cylinder liners;156
11.3.2;Tribological test results for structured and coated cylinder liners;156
11.3.3;Wear investigations;158
11.3.4;Derivation of a wear model;159
11.3.5;Conclusion;160
12;8 Test of cylinder liner under fired engine conditions;161
12.1;8.1 Objective and approach;161
12.2;8.2 Engine test bench and cylinder liners;161
12.2.1;1. Temperature;163
12.2.2;2. Pressure (relative);164
12.2.3;3. Operating fluids;164
12.2.4;4. Further boundary conditions;164
12.3;8.3 Methods to measure friction losses and oil emissions;164
12.4;8.4 Measurement uncertainty;165
12.5;8.5 Validation of the measuring method;166
12.5.1;Deviation;166
12.5.2;Reproducibility;167
12.5.3;Influence of engine assembling;168
12.6;8.6 Results: frictional losses;169
12.6.1;Comparison between the reference liners: plateau and fine honed;170
12.6.2;Microstructures in dead centre areas;171
12.6.3;Microstructures in areas of hydrodynamic lubrification;173
12.6.4;Influence of the structure density on friction;174
12.6.5;Thermal spray coatings;175
12.7;8.7 Results: oil emission;177
12.8;8.8 Conclusion;179
13;9 Own publications;182
14;10 Quoted literature;185