CONTENTS

Preface

Advanced Ceramics and Composites for Gas Turbine Engines

DAMAGE OF CERAMIC MATRIX COMPOSITES (CMCs) DURING MACHINING OPERATIONS
1. ABSTRACT
2. INTRODUCTION
3. EXPERIMENTAL
4. EVALUATION WITH FOCUS VARIATION AND IMAGE PROCESSING
5. RESULTS
6. CONCLUSION
7. ACKNOWLEDGEMENT
8. LITERATURE
CMCS: THE KEY FOR AFFORDABLE ACCESS TO SPACE
1. ABSTRACT
2. INTRODUCTION
3. CMCS FOR SSTO ENGINE APPLICATION
4. MECHANICAL PROPERTIES TESTING FOR ESCAPE DYNAMICS SPECIMENS
5. DISCUSSION
6. CONCLUSIONS
7. REFERENCES
NUMERICAL DETERMINATION OF EFFECTS OF TEMPERATURE ON INFILTRATION DYNAMICS OF LIQUID-COPPER AND TITANIUM/SOLID-CARBON SYSTEM
1. ABSTRACT:
2. INTRODUCTION
3. NUMERICAL PROCEDURE
4. RESULTS AND DISCUSSION
5. CONCLUSIONS
6. REFERENCES
OXIDATION AND HIGH TEMPERATURE RESISTANCE OF SiC/SiC COMPOSITES BY NITE-METHOD
1. ABSTRACT
2. INTRODUCTION
3. NITE PROCESS FOR SiC/SiC COMPOSITE FABRICATION
4. EXPERIMENTAL PROCEDURE
5. RESULTS AND DISCUSSION
6. CONCLUSIONS
7. ACKNOWLEDGEMENTS
8. REFERENCES
HIGH PERFORMANCE SiC/SiC COMPONENT BY NITE-METHOD AND ITS APPLICATION TO ENERGY AND ENVIRONMENT
1. ABSTRACT
2. INTRODUCTION
3. RECENT EFFORTS ON HEAT RESISTANT SiC/SiC R & D
4. CYCLIC WATER QUENCHING TEST (CWQT)
5. CONCLUSIONS
6. ACKNOWLEDGEMENTS
7. REFERENCES
CERAMIC MATRIX COMPOSITES: CONCURRENT DEVELOPMENT OF MATERIALS AND CHARACTERIZATION TOOLS
1. ABSTRACT
2. INTRODUCTION
3. BACKGROUND
4. THROUGH THICKNESS MODULUS
5. NONDESTRUCTIVE ANALYSIS
6. FUTURE WORK
7. ACKNOWLEDGMENTS
8. REFERENCES
FABRICATION OF EBC SYSTEM WITH OXIDE EUTECTIC STRUCTURE
1. ABSTRACT
2. INTRODUCTION
3. EXPERIMENT
4. RESULTS AND DISCUSSION
5. CONCLUSIONS
6. ACKNOWLEDGMENT
7. REFERENCES

Advanced Refractory Ceramic Materials and Technologies

THE USE OF ADVANCED CERAMIC MATERIALS IN OIL AND GAS APPLICATIONS
1. ABSTRACT
2. INTRODUCTION
3. CARBON-GRAPHITE MATERIALS FOR SEAL AND BEARING APPLICATIONS
4. CERAMIC MATERIALS FOR USE IN EROSIVE ENVIRONMENTS
5. CONCLUSION
6. REFERENCES
MICROSTRUCTURE AND ELASTIC PROPERTIES OF HIGHLY POROUS MULLITE CERAMICS PREPARED WITH WHEAT FLOUR
1. ABSTRACT
2. INTRODUCTION
3. THEORETICAL
4. EXPERIMENTAL
5. RESULTS AND DISCUSSION
6. CONCLUSIONS
7. ACKNOWLEDGEMENT
8. REFERENCES
THE USE OF ADVANCED REFRACTORY CERAMIC MATERIALS TO ADDRESS INDUSTRIAL ENERGY EFFICIENCY CHALLENGES
1. ABSTRACT
2. INTRODUCTION
3. DISCUSSION
4. CONCLUSION
5. ACKNOWLEDGEMENTS
6. REFERENCES
AN APPROACH FOR MODELING SLAG CORROSION OF LIGHTWEIGHT Al₂O₃-MgO CASTABLES IN REFINING LADLE
1. ABSTRACT
2. INTRODUCTION
3. MATHEMATICAL MODEL
4. RESULTS AND DISCUSSION
5. CONCLUSIONS
6. ACKNOWLEDGEMENT
7. REFERENCES
MICROSTRUCTURE, ELASTIC PROPERTIES AND HIGH-TEMPERATURE BEHAVIOR OF SILICA REFRACTORIES
1. ABSTRACT
2. INTRODUCTION
3. PHASE COMPOSITION AND ELASTIC PROPERTIES OF SILICA MATERIALS
4. EXPERIMENTAL
5. RESULTS AND DISCUSSION
6. CONCLUSIONS
7. ACKNOWLEDGEMENT
8. REFERENCES
CEMENT FREE MAGNESIA BASED CASTABLES VERSUS MAGNESIA-SPINEL BRICKS IN CEMENT ROTARY KILNS
1. ABSTRACT
2. INTRODUCTION
3. PART I – THERMO-MECHANICAL BEHAVIOR
4. EXPERIMENTAL SET UP
5. RESULTS AFTER PREFIRING
6. RESULTS AFTER THERMAL SHOCK TEST
7. INTERMEDIATE CONCLUSION PART I
8. PART II – COMPARED INTRISIC PROPERTIES LINKED TO THERMO-CHEMICAL REQUIREMENTS
9. EXPERIMENTAL SET UP
10. EXPERIMENTAL RESULTS
11. CONCLUSION AND PERSPECTIVES
12. REFERENCES
EVALUATION OF REOXIDATION TENDENCY OF REFRACTORY MATERIALS IN STEEL METALLURGY BY A NEW TEST METHOD BASED ON CARRIER GAS HOT EXTRACTION
1. ABSTRACT
2. INTRODUCTION
3. METHODS AND MATERIALS
4. RESULTS Thermodynamic
5. DISCUSSION
6. OUTLOOK
7. ACKNOWLEDGMENT
8. REFERENCES
CERAMIC AND METAL-CERAMIC COMPONENTS WITH GRADED MICROSTRUCTURE
1. ABSTRACT
2. INTRODUCTION
3. EXPERIMENTAL PROCEDURES
4. RESULTS AND DISCUSSION
5. CONCLUSION
6. ACKNOWLEDGEMENT
7. REFERENCES

Energy Efficient Wear Resistant Materials

HIGH SPEED FORMATION OF FINE CERAMIC LAYERS BY NANOPARTICLES FILLER ROD THERMAL SPRAYING
1. ABSTRACT
2. INTRODUCTION
3. EXPERIMENTAL PROCEDURE
4. RESULTS AND DISCUSSION
5. CONCLUSIONS
6. REFERENCES
DEVELOPMENT OF SILICON NITRIDE BEARING COMPONENTS BY POWDER INJECTION MOLDING USING A NOVEL BINDER SYSTEM
1. ABSTRACT
2. INTRODUCTION
3. EXPERIMENTAL PROCEDURE
4. RESULTS & DISCUSSION
5. TOOL DESIGN
6. INJECTION MOULDING
7. INJECTION PRESSURE
8. INJECTION TEMPERATURE
9. OTHER PARAMETERS
10. TEST PART REPRODUCIBILITY
11. DESIGN OF THE DEBINDING PROCESS
12. THE SINTERING PROCESS
13. CONCLUSIONS
14. ACKNOWLEDGEMENT
15. REFERENCES

Advanced Coatings

STABILITY OF α-ALUMINA PHOTONIC STRUCTURES FORMED AT LOW TEMPERATURES UTILIZING CHROMIA-SEEDING
1. ABSTRACT
2. INTRODUCTION
3. EXPERIMENTAL
4. RESULTS AND DISCUSSION
5. CONCLUSIONS
6. ACKNOWLEDGEMENTS
7. REFERENCES
POLYMER DERIVED GLASS CERAMIC LAYERS FOR CORROSION PROTECTION OF METALS
1. ABSTRACT
2. INTRODUCTION
3. EXPERIMENTAL
4. RESULTS AND DISCUSSION
5. CONCLUSIONS
6. ACKNOWLEDGMENTS
7. REFERENCES

Author Index

EULA

List of Illustrations

Chapter 1

Fig. 1 Test machine DMG Ultrasonic 55-5 linear with basic parameters
Fig. 2 Machining set up for drilling experiments
Fig. 3 Analyses with focus variation from Alicona
Fig. 3 Comparison of the mechanical damage characteristics when drilling - Left side: 2d-C-SiC - Right side: OFC-1 CMC
Fig. 4 Effect of feed rate on the Edge chipping factor for CF226 P75
Fig. 5 Effect of cutting speed on the Edge chipping factor for CF226 P75
Fig. 6 Effect of feed rate on fiber fraying for OFC-P1
Fig. 7 Effect of cutting speed on fiber frying for OFC-P1

Chapter 2

Figure 1. Artist’s impression of Spaceplane1.
Figure 2. Example of CMC Heat Exchanger Tubes².
Figure 3. Specific Strength Comparison of Materials³.
Figure 4. Complete propulsion system. The gyrotrons track and follow the vehicle all the way to orbit beaming through microwaves the energy collected from the grid².
Figure 5. Specific Impulse of Various Propulsion Systems².
Figure 6. Escape Dynamics C/SiC CMC sample.
Figure 7. Test Specimen in scissor-grip fixture
Figure 8. Test specimen dimensions in mm following ASTM standard⁶.
Figure 9. Young’s modulus measured from eleven specimens with mean and standard deviation. The mean value is 1,485 MPa.
Figure 10. Test results for ultimate tensile strength for the 11 specimens (out of the 14 tested) that broke in the gage area. The mean is 111 MPa.
Figure 11. Stress-strain curve test data for specimen R252-2 together with linear fit.

Chapter 3

Figures 1. The different angles of contact are illustrated for wetting and non-wetting liquids.
Figure 2. Theoretical (a) Cu-17.5%wt. Ti and (b) Cu-28%wt. Ti system infiltration profiles in capillaries of initial radii (r₀ = 15 pm); based on diffusion-limited (Eq. 10) capillary rise with variable θand r.

Chapter 4

Fig. 1: Oxidation and High Temperature Resistance Tests in OASIS
Fig. 2: Outline of DEMO-NITE Process
Fig. 3: Helium leak tightness improvement of NITE-SiC/SiC
Fig. 4: Thermal Shock Test Set-up
Fig. 5: Surface appearance after TSTWQ
Fig. 6: DEMO-NITE SiC after TSTWQ at 500 C
Fig. 7: DEMO-NITE SiC/SiC after TSTWQ at 1000 C
Fig. 8: Microstructure of intra fiber bundle of SiC/SiC after TSTWQ
Fig. 9: Stress-strain relation of DEMO-NITE SiC
Fig. 10: Stress-strain relation of DEMO-NITE SiC/SiC
Fig. 11: Effects of TSTWQ temperature on three point bending properties
Fig. 12: Effect of TSTWQ Temperature on Fracture Behavior for SiC
Fig. 13: Effect of TSTWQ Temperature on Fracture Behavior for SiC SiC/SiC

Chapter 5

Fig. 1: On-going NITE-SiC R & D in OASIS, Muroran
Fig. 2: Flame Exposure Test under Gas-Generator Advanced Turbo Ram Jet Engine
Fig. 3: Surface appearance after the exposure test
Fig. 4: R & D Status of SiC Rotating Target for “DeeMe” Project environment, no realistic material exists except DEMO-NITE SiC/SiC.
Fig. 5: High Temperature Steam Test at ORNL
Fig. 6: Surface Morphology Changes by High Temperature Steam Test at ORNL
Fig. 7: “In-Situ” Plasma Exposure Test in LHD at NIFS
Fig. 8: Damage Analysis of W-SiC/SiC by US Inspection
Fig. 9: Cyclic Water Quenching Test
Fig. 10: Brief Summary of the C-WQT
Fig. 10: Fracture Surface after 3PBT for CREST-ACE SiC/SiC
Fig. 11: Fracture Surface of DEMO-NITE SiC after 3 cycles of WQT
Fig. 12: Surface Appearance of DEMO-NITE SiC/SiC after 10 & 50 cycles of WQT
Fig. 13: Surface Appearance of DEMO-NITE SiC/SiC 3 PBT
Fig. 14: Surface Appearance of DEMO-NITE SiC/SiC after 3 PBT

Chapter 6

Figure 1. Gas Turbine Engine highlighting initial areas for CMC insertion
Figure 2. Tensile Strength versus Engine Test Duration in Terms of Tactical Aircraft Cycles (4300 TACS = engine life / efficient strength based on seal coat thickness removed from area [5-7])
Figure 3. Schematic of CMC panel showing orthogonal axes
Figure 4. Through Thickness Modulus (E₃₃) versus Temperature for 2 CMCs
Figure 5. Cross section showing highlighted porosity within the fiber tow (Porosity shaded in red for one tow (circled in green))
Figure 6. Micro-structural Cross Sections of S200 of different manufactured thicknesses
Figure 7. “Creep” Curved of S200 at two different temperatures (same stress) (samples did not fail, testing was stopped at 100 hours)
Figure 8. Pulse-Echo Thermography of 8 HS Balance Symmetric Coupons
Figure 9. SEM and Oxygen Element Map of Samples at 649°C and 982°C
Figure 10. Thermography Results from Interlaminar Tensile Coupons (prior to testing)
Figure 11. Thermal Diffusivity (via Thermography) versus Interlaminar Tensile Strength (at multiple processing steps)

Chapter 7

Figure 1. The X-ray diffraction patterns of (a) before and (b) after the light focusing⁹, K. Seya et al., Mater. Sci. Technol. Jpn. 52, 31-35 (2015). © 2015, Materials Science Society of Japan.
Figure 2. The schematic illustration for preparation process of eutectic EBC film.
Figure 3. The powder X-ray diffraction pattern of the deposited powder on inner wall of quartz tube⁹, K. Seya et al., Mater. Sci. Technol. Jpn. 52, 31-35 (2015). © 2015, Materials Science Society of Japan.
Figures 4. The X-ray diffraction pattern (a) and SEM image (b) from the surface of solidified EBC film⁹, K. Seya et al., Mater. Sci. Technol. Jpn. 52, 31-35 (2015). © 2015, Materials Science Society of Japan.
Figure 5. Cross section SEM image of the EBC film⁹, K. Seya et al., K. Seya et al., Mater. Sci. Technol. Jpn. 52, 31-35 (2015). © 2015, Materials Science Society of Japan.
Figures 6. Line analysis for the intermediate layer⁹, K. Seya et al., Mater. Sci. Technol. Jpn. 52, 31-35 (2015). © 2015, Materials Science Society of Japan.

Chapter 8

Figure 1. Representative wet sliding friction and wear results for all-carbon (left) and metal-impregnated carbon (right).
Figure 2. Dry abrasion test results
Figure 3. Slurry abrasion test results

Chapter 9

Figure 1. Microstructure of mullite foams prepared from suspensions with wheat flour with 0.1, 2 and 8 h of shaking after partial sintering at 1600 °C (SEM micrographs with scale bar 500 μm).
Figure 2. Microstructure of mullite foams prepared from suspensions with wheat flour with 4 h of shaking after partial sintering at 1600 °C (SEM micrographs with scale bars 100 and 5 μm).
Figure 3. Comparison of the porosity related to the foams cells (determined by microscopic image analysis / MIA) and the total porosity (both are equal for foams with porosity 88 %).
Figure 4. Correlation of interface density and mean curvature integral density of mullite foams versus their total porosity; determined by stereology-based image analysis (Equations 2 and 3).
Figure 5. Correlation of pore size and distance measures (mean chord length, Jeffries size, mean distance) of mullite foams versus their total porosity; determined by stereology-based image analysis (Equations 4, 5 and 6).
Figure 6. Pore throat size distributions (intrusion curves) of mullite foams measured via mercury porosimetry (total intrusion volumes transformed to open porosities via the true density).
Figure 7. Porosity dependence of the effective Poisson ratio of mullite foams.

Chapter 11

Figure 1. The schematic of geometric model
Figure 2. Schematic of the computational domains.
Figure 3. The slag penetration at time (a) 2 s, (b) 4 s, (c) 6 s, and (d) 8.8 s.
Figure 4. The penetration of slag into the aggregates at time (a) 0.1 s, (b) 0.2 s, and (c) 0.3 s.
Figure 5. The slag corrosion product layer in the aggregates.
Figure 6. The effect of average pore sizes of the aggregates on slag penetration: (a) 0.5 μm, (b) 0.7 μm, and (c) 1 μm.

Chapter 12

Figure 1. Poisson ratio of dense isotropic polycrystalline cristobalite-tridymite composites (model systems for silica refractories), calculated from the sigmoidal average of the upper and lower Hashin-Shtrikman bounds of the Young’s modulus, shear modulus and bulk modulus.
Figure 2. Microstructure of silica refractories, showing white cristobalite grains in a tridymite matrix with coloring impurities; sample of batch A (smaller grain size, l.h.s.), sample of batch D (larger grain size, r.h.s.); optical micrographs of diamond-cut surfaces (scale bar 1 mm).
Figure 3. Young’s moduli of silica refractories (bar-shaped and plate-shaped samples), compared to (from top to bottom) the Voigt bound (dotted), upper Hashin-Shtrikman bound (dashed), power-law prediction (full) and exponential prediction (bold full curve).
Figure 4. Poisson ratio of silica refractories (plate-shaped samples), compared to (from bottom to top) the linear approximation (dotted), the power-law approximation and the exponential approximation.
Figure 5. Temperature dependence of the Young’s modulus and relative length change (dilatation curve) of silica refractories, measured for a bar-shaped sample of batch A (porosity 16.0 %, average cristobalite grain size 293 ± 43 μm).
Figure 6. Temperature dependence of the Young’s modulus and relative length change (dilatation curve) of silica refractories, measured for a bar-shaped sample of batch D (porosity 13.2 %, average cristobalite grain size 407 ± 44 μm).
Figure 7. Pore (throat) size distributions of samples of bacthes A and D, measured via mercury porosimetry.

Chapter 13

Figure 1 Sum up of stresses origins on refractories used in cement kiln
Figure 2 Temperature Variation in the Burning Zone Refractories During Kiln Rotation
Figure 3 Distortion of the Kiln Shell, Refractory Lining during the Kiln Rotation & resulting bricked lining damages
Fig. 4: modulus of rupture after prefing at 1600°C.
Fig. 5: Young’s modulus after pre-firing at 1600°C.
Fig. 6: σ²/E after pre-firing at 1600°C in function of addition percentage.
Fig. 7: residual M.o.R after thermal shock resistance (%)
Fig. 8: residual Young’s modulus after thermal shock resistance (%)
Figure 9 : alkali bursting and resulting stresses (links) & visual appearance of post mortem brick and lab tested castable (right)
Figure 10 : determination of permeability to gas according Darcy’s law, by measurement of gas flow versus applied pressure P1.
Figure 11 : illustration of capillary suction test procedure
Figure 12 : illustration of Jurin’s law permitting to assess the speed of penetration and equivalent capillary radius.
Figure 13 : evolution of air flow through a 30mm thick sample versus air pressure applied.
Figure 14 : Evolution of oil weight penetrating samples due to capillary suction versus elapsed time.
Figure 15. Speed of liquid penetration under capillary suction and equivalent pore radius of tested samples
Fig 15 : Preparation (anchors welding / dilatation joins) of an iron pellet firing kiln before installation of castable by Shotcreeting (left) – Detail of the tyre section (UTZ area) of a cement kiln lined with castable (right).
Figure 16 : Illustration of high installations speed of bricks thanks use of laying machines (left) versus complexity in radially or axially deformed areas (right)

Chapter 14

Figure 1: Calculated equilibrium phases for reaction of graphite with periclase in presence of tin flux.
Figure 2: Calculated solid equilibrium phases for reaction of graphite with quartz in presence of tin flux.
Figure 3: Thermodynamic stability of the tested oxides according to the Ellingham diagram.
Figure 4: Matrix structure of the unaffected area in the alumina-chamotte model material after crucible test (x350).
Figure 5: Matrix structure of alumina-chamotte model material at the interface to the steel melt after crucible test (x300).
Figure 6: Matrix structure of alumina model material at the interface to the steel melt after crucible test (x400).

Chapter 15

Figure 1. Pattern of tape casting equipment with carrier foil (1), cast suspension (2), and suspension reservoir (3).
Figure 2. Detailed pattern of tape casting equipment with carrier foil (1), suspension (2) suspension reservoir (3), and doctor blade (4).
Figure 3. Pattern of lamination with a hand roller (4) to join a single tape (3) with a multilayer (1) by using joining suspension (2)
Figure 4. Pattern of lamination of single tapes (3) to a multilayer (1) between a pair of rolls (5) by using joining suspension (2).
Figure 5. Cross section of homogenous 5-layer-CaAl-multilayer without PFA, overview.
Figure 6. Cross section of one layer in a homogenous CaAl-multilayer without PFA, detail.
Figure 7. Cross section of homogenous 5-layer-CaAl-multilayer with 12wt.-% PFA, overview.
Figure 8. Cross section of one layer in a homogenous CaAl-multilayer with 12wt.-% PFA, detail.
Figure 9. Porosity vs. amount of PFA for CaAl-multilayers, characterized by analyzing SEM-images of cross sections.
Figure 10. Pore size distribution within CaAl-multilayer, characterized by mercury porosimetry.
Figure 11. Cross section of homogenous 7-layer-MgO-PSZ-multilayer without PFA, overview.
Figure 12. Cross section of a layer of MgO-PSZ-multilayer without PFA, detail.
Figure 13. Cross section of homogenous 7-layer-MgO-PSZ-multilayer with 4wt.-% PFA, overview.
Figure 14. Cross section of homogenous 9-layer-MgO-PSZ-multilayer with 8wt.-% PFA, overview.
Figure 15. Cross section of 8-layer-MgO-PSZ-multilayer with 12wt.-% PFA, overview.
Figure 16. Cross section of a layer of MgO-PSZ-multilayer with 12wt.-% PFA, detail.
Figure 17. Porosity vs. amount of PFA for MgO-PSZ-multilayers, characterized by analyzing SEM-images of cross sections.
Figure 18. Continuous graded 6-layer-CaAl-multilayer with a dense layer at the bottom and increasing porosity to the top after sintering.
Figure 19. Continuous graded 3-layer-CaAl-multilayer with a dense layer at the bottom and increasing porosity to the top after sintering.
Figure 20. Discontinuous graded 5-layer-CaAl-multilayer with a dense layer in the middle and increasing porosity to the top and bottom after sintering.
Figure 21. Discontinuous graded 5-layer-CaAl-multilayer with a repeating change between dense and porous layers after sintering.
Figure 22. Discontinuously graded 7-layer-MgO-PSZ-multilayer with a repeating change between dense and porous layers after sintering, overview.
Figure 23. Discontinuously graded MgO-PSZ-multilayer with a repeating change between dense and porous layers after sintering, detail.
Figure 24. Discontinuously graded 7-layer-MgO-PSZ-multilayer with a high porous layer in the middle and decreasing porosity to the top and bottom after sintering
Figure 25. Discontinuously graded 7-layer-MgO-PSZ-multilayer with a dense layer in the middle and increasing porosity to the top and bottom after sinterins
Figure 26 Discontinuously graded 3-layer-steel-zirconia-steel multilayer, overview.
Figure 27 Interface between a steel-layer (bottom) and a zirconia-layer (top).

Chapter 16

Fig. 1 A schematic illustration of solid rod feeding toward Rokide flame gun. Nanoparticles dispersed resins can be introduced to realize higher deposition rate.
Fig. 2 An schematic illustration of experimental setup on spectroscopic measurements of terahertz wave reflectance from ceramics coated samples.
Fig. 3 The appearance photograph of the acrylic resin rod with the alumina nanoparticles dispersion at 40 vol. % fabricated by injection molding and thermal polymerization.
Fig. 4 X-ray diffraction patterns of the alumina particles sprayed from the gas flame gun. The particles were collected by a water bath fixed in front of the flame gun.
Fig. 5 A surface microstructure of the alumina particles sprayed from the flame nozzle and collected by the water bath. Crystal grain boundaries can be observed in the micro bulk.
Fig. 6 A microstructure of the alumina layer formed on the stainless steel substrate by the thermal nanoparticles spraying technique using filler rods feeding. The fine coated layer without micro cracks or pores can be obtained.

Chapter 17

Figure 1. The cavity cross-section of the one-cavity tool
Figure 2. The ball and the runner
Figure 3. The relationship between the density of the green body and the injection pressure
Figure 4. The mass variation of injected balls
Figure 5. The initial-to-final stage of binder removal
Figure 6. The relationship between the density of sintered balls and the sintering temperature

Chapter 18

Figure 1. SEM micrographs of the unseeded alumina inverse opal surface after heating at 500 °C (a), 1200 °C (c), and 1400 °C (e) for 1 h. Micrographs of the inverse opal with chromia-seeding after heating at 500 °C (b), 1200 °C (d), and 1400 °C (f) for 1 h. The a-chromia seeds are observable in the sample cross-section (b).
Figure 2. X-ray diffractograms of the unseeded (dashed line) and chromia-seeded (solid line) alumina inverse opals as a function of temperature. Peak locations for pure a-alumina and α-chromia are indicated with symbols for reference.
Figure 3. Specular reflectance spectra of the unseeded and chromia-seeded alumina inverse opals after heating for 1 h at 500, 1200, and 1400 °C.

Chapter 19

Fig. 1: Processing flow chart of preparation of aluminosilicate-zirconate glass microspheres.
Fig. 2: Processing flow chart of preparation of coating systems.
Fig. 3: XRD patterns of the glass microspheres.
Fig. 4: The results of DSC analysis of glass microspheres.
Fig. 5: Particle size distribution of the prepared glass microspheres.
Fig. 6: SEM micrographs of glass microspheres a) SAZ_M_80-10-10, b) SAZ_M_60-30-10.
Fig. 7: SEM micrographs a) uncoated stainless steel sheet, b) bond coated steel sheet
Fig. 8: The average thickness of coatings of various compositions.
Fig. 9: XRD patterns of composite top coatings.
Fig. 10: SEM micrographs of top coat a) C 80-10-10, b) C 60-30-10, c) cross-section of C 60-30-10
Fig. 11: SEM micrographs of top coat after corrosion after 8 days a) uncoated steel sheet, b) C 80-10-10

DAMAGE OF CERAMIC MATRIX COMPOSITES (CMCs) DURING MACHINING OPERATIONS

R. Goller, A. Rösiger

Department of Composites Process Technology, University of Applied Sciences, Augsburg, Germany

ABSTRACT

Machining is for many products the ultimate operation in a complex manufacturing process with the goal to give the final shape to a part and to reach the required tolerances. If this process damages the part a big economic loss is the consequence. However during those operations mechanical damage can occur which only lead to a degradation of the material. In the case of ceramic matrix composites, which already play an important role in components like turbine vanes, combustion chambers and brake disks, the damage often cannot be identified. In this paper special machining operations for different CMC materials are compared with respect to influence on part quality. A new method for quantifying the damage using an optical focus variation and image processing is presented.

INTRODUCTION

Ceramic matrix composites are a group of materials, in which ceramic matrices and ceramic or carbon fibers are combined. These materials have typically a high temperature resistance, a high fracture toughness and compared to high temperature resistant metal alloys, a low density. These combination of properties make them interesting for many different applications e.g. turbine vanes and combustion chambers for gas turbines as well as brake and clutch applications [1, 2]. However the market success in the future will depend on further progress in cost reduction combined with reliable prediction of the performance and lifetime. The final machining operation is a challenging process, with high cost and high quality risk. In the past some experimental work regarding drilling of CMC with diamond grinding bits have been published [3, 4]. The experiments presented in this paper were done with diamond tools with determined diamond cutting edges, which is a new approach to machine CMCs. The results will be presented on two different CMCs materials, 2d-Ox/Ox and 2d C-SiC. For the quantitative evaluation a special optical method combined with a 3d digital imaging software was used. The results show two different damage mechanisms of the to materials and a significant influence of the machining parameters on the finish quality.

EXPERIMENTAL

MATERIAL

Two fiber reinforced ceramic composite materials were used in the present investigation:

1) A 2d-C-SiC material (Product name CF226 P75), produced by Schunk Kohlenstofftechnik, Heuchelheim, Germany and

2) a 2d Ox-Ox material (product name OFC-P1), produced by University of Bayreuth, Germany.

The CF226 P75 [5] is a 2d-C/C-SiC ceramic matrix composite material produced by the so called PCI process (pack cementation and capillary infiltration), a liquid silicon infiltration process used for industrial production. For composition 8 layers of 0/90° woven fabric were laminated. The resulting composite had a thickness of 3 mm, a fiber content of up to 60%, a silicon carbide content of up to 10 vol.-% and a total porosity of 6 vol.-%.

OFC-P1 is also a 2d laminate based on woven 0/90° fabrics of 3M^TM Nextel^TM alumina (Al₂O₃) fibers. The investigated composite consists of a lay-up of twelve 0/90° layers. The composite was infiltrated with a pre-ceramic slurry and then sintered resulting in a fiber content of up to 40 vol.-% and a porosity of 30 vol.-%. The laminate thickness was 4 mm. The low density also leads to a low ILT strength.

TOOLING

Polycrystalline Diamond (PCD) 8 mm diameter twisted drills with massive PCD tip, 120° point angle, 25° rake angle, 15° clearance angle, 50° wedge angle (producer: Hufschmied GmbH, Bobingen) were used.

MACHINE

DMG Ultrasonic 55-5, linear (Fig. 1) was used for all experiments. The machining environment was 8% cooling liquid at 23 bar applied through flexible ducts directly onto the tool tip.

images — Fig. 1 Test machine DMG Ultrasonic 55-5 linear with basic parameters

The machining setup for drilling operation is schematically shown in Fig. 2.

EVALUATION WITH FOCUS VARIATION AND IMAGE PROCESSING

Digital image analysis to determine delamination after drilling composites was applied by Davim et.al. [6] on fibre reinforces plastics. In our case the method of focus variation, which describes a procedure, where a microscope is scanning in 3 axis the surface of a specimen was applied on CMCs. The digital pictures of single stacks were arranged by a special software tool to create a 3d digital image. These images represent the surface and the surface near zones, which could be reached by the microscope and from these pictures surfaces and volumes were calculated. In Fig. 3 the measurement and digital imaging process is explained.

The introduction of the dimensionless chipping factor F_Chip,L is described in a previous paper [7]. Eq. 1-3 describe the calculation of the edge chipping factor F_Chip,L.

(1)

(2)

(3)

A _Chip,I Single sheet element area

A₀ Nominal hole area

t Specimen thickness

t_Chip,I Thickness of single sheet elements

V_0,L Nominal hole volume

V_Chip,L Calculated chipping volume

To evaluate the OFC-1 material the chipping factor could not be used, because the damage did not show any chipping, but fraying. The quantitative evaluation of fraying length or fraying area did not show any consistent result. Therefore it was decided to use a qualitative evaluation. The problem of this evaluation method is that it depends on the experience of the observer’s eye. Nevertheless 3 levels of fraying have been defined:

Plenty = the whole area shows fraying traces

Moderate = only partial fraying

Low = very little or no fraying

RESULTS

As a result of the drilling operation 2 fundamentally different damage mechanisms were seen. While the C-SiC material showed brittle fracture behavior in the case of Ox-Ox a kind of fiber pull-out was observed. In the microscopic pictures of Fig. 4 the two mechanisms are compared. We called the brittle behavior “edge chipping” and the fiber pull out (non cut fiber residuals respectively) “fiber fraying”. This leads to the hypothesis, that the different fiber/matrix bonding of the two materials causes also different cutting behavior. In the C-SiC case much better bonding than in the OFC case. At the same time density (matrix porosity respectively) can be related to the inter-laminar shear/tensile strength (ILS). Especially the porous Matrix properties of the Ox-Ox lead to low ILS [8]. Looking at the resulting images the link between porosity, fiber content and machining behavior can be explained. To further find out, if there is also an influence of the machining parameters on chipping and fraying intensity, these were varied according to Tab. 1.

Tab. 1 Machining parameters

Run	1	2	3	4	5	6
Feed [mm/rev]	0.01	0.01	0.01	0.05	0.10	0.20
Speed [m/min]	175	300	425	175	175	175

In Figure 5 the effect of feed rate on the edge chipping factor F_Chip,L of the 2d-C-SiC shows that increasing feed rate increases the chipping. At 0,2 mm/rev the chipping factor is with 2 % two times the value at 0,01 mm/rev. The scatter also increases significantly.

Keeping the feed rate at a lowest point (with lowest chipping result), the increase of cutting speed shows, that F_Chip,L depends much more on the cutting speed (Fig. 6). At 175 m/min cutting speed the chipping factor was only at 1%. At 300 m/min an increase to 8% was observed and the worst result showed the experiment at 425 m/min with a factor of 32%.

In Fig. 7 the qualitative analysis of 0FC-P1 material shows, that the combination of low constant speed of 175 m/min and low feed rate gives lowest fraying. Increasing feed rate increases the fraying. In all cases fraying occurs mostly at the hole exit, which also can be seen in the images below,

On the other hand cutting speed seems not to have a strong influence on fraying in the case of the OFC-P1. The results in Fig. 8 do not show significant differences between low and high speed. Also entrance and exit of the hole show no difference in this case.

CONCLUSION

Two ceramic composite materials have been investigated regarding their damage behavior through a drilling operation using diamond tipped tools with defined cutting edges and varying feed rate and cutting speed.

The results show two different damage mechanisms of the two materials. Where C-SiC shows chipping of edges in surface and volume, the Ox/Ox Composite shows fiber fraying mainly at the exit of the holes.

C-SiC shows a small increase of chipping with increasing feed rate, at constant cutting speed. However a strong effect of cutting speed on chipping can be observed. One explanation for this behavior could be the strong fiber/matrix bonding of the C-SiC and the micro cracked micro-structure of this laminate. This leads to the chipping of material from the matrix. At higher speed more cutting power is introduced into the material and leads therefore to more damage. Depending on the final requirements this is a clear indication that the cutting speed cannot be increased over a certain limit, which is on the one hand given by the tool stability and on the other hand by the micro structural bonding of fiber and matrix.

In contrast to the chipping of the 2d-C-SiC, the Ox-Ox material behaves completely different. In this case no chipping but fraying of alumina fibers can be observed. One explanation could be the much lower fiber matrix bonding between alumina fibers and alumina matrix, which leads to more fiber pull out. No direct influence of the cutting speed but significant more fraying by increasing the feed rate. Low feed rate give in this case low fraying even at high cutting speed.

The experiments and investigations will be continued to find out, how the damage will influence the mechanical performance of the part and to find an optimum tool/machine/parameter configuration. As inter-laminar damage can be expected, further research has to be done on shape, type and detection of those damages.

ACKNOWLEDGEMENT

The authors thank Hufschmied GmbH, Bobingen for providing the tools and the machining capacity, Schunk Group for offering the C-SiC material and University of Bayreuth for offering Ox-Ox material.

LITERATURE

[1] Krenkel, W. (ed.): Ceramic Matrix Composites Fibre Reinforced Ceramics and their Applications. Weinheim: WILEY-VCH Verlag GmbH & Co KGaA, 2008.
[2] Krenkel, W. (ed.): Keramische Verbundwerkstoffe. Weinheim: WILEY-VCH Verlag GmbH & Co KGaA, 2003.
[3] D. Biermann, T. Jansen, M. Feldhoff, Faserverstärkte Keramik effizient bearbeiten, MM-Maschinenmarkt. Das Industrie Magazin 11 (2009) 28–31.
[4] K. Weinert, T. Jansen, Machining Aspects for the Drilling of C/C-SiC Materials, in: W. Krenkel (Ed.), Ceramic Matrix Composites, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany 2008, pp. 287–301.
[5] Weiss, R.: Carbon Fibre Reinforced CMCs: Manufacture, Properties, Oxidation Protection, in: W. Krenkel (Ed.), High Temperature Ceramic Matrix Composites, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany 2001, pp. 440–456.
[6] J. Davim, J. Rubio, A. Abrao, A novel approach based on digital image analysis to evaluate the delamination factor after drilling composite laminates, Composites Science and Technology 67 (2007) 1939–1945.
[7] Rösiger, A.; Goller, R.: Damage evaluation of CMCs after drilling with geometrically defined cutting edges. In: Proceedings of the 20th Symposium on Composites, 2015, pp. 271-278.
[8] Wamser, T.; Scheler, S.; Martin, B.; Krenkel, W.: Novel oxide fiber composites by freeze casting. In Journal of the European Ceramic Society 34 (2014) 3827–3833.

Advanced and Refractory
Ceramics for Energy
Conservation and Efficiency

Ceramic Transactions, Volume 256

A Collection of Papers Presented
at CMCEE-11,
June 14–19, 2015,
Vancouver, BC, Canada