Advances in High Temperature Ceramic Matrix Composites and Materials for Sustainable Development

Mrityunjay Singh, Tatsuki Ohji, Shaoming Dong, Dietmar Koch, Kiyoshi Shimamura, Bernd Clauss, Bernhard Heidenreich, Jun Akedo, Mrityunjay Singh, Tatsuki Ohji, Shaoming Dong, Dietmar Koch, Kiyoshi Shimamura, Bernd Clauss, Bernhard Heidenreich, Jun Akedo

• Publisher: Wiley-American Ceramic Society
• Year: 2017
• Print ISBN: 9781119406433
• eBook ISBN: 9781119407287
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Global population growth and tremendous economic development has brought us to the crossroads of long-term sustainability and risk of irreversible changes in the ecosystem. Energy efficient and ecofriendly technologies and systems are critically needed for further growth and sustainable development. While ceramic matrix composites were originally developed to overcome problems associated with the brittle nature of monolithic ceramics, today the composites can be tailored for customized purposes and offer energy efficient and ecofriendly applications, including aerospace, ground transportation, and power generation systems. The 9th International Conference on High Temperature Ceramic Matrix Composites (HTCMC 9) was held in Toronto, Canada, June 26-30, 2016 to discuss challenges and opportunities in manufacturing, commercialization, and applications for these important material systems.

The Global Forum on Advanced Materials and Technologies for Sustainable Development (GFMAT 2016) was held in conjunction with HTCMC 9 to address key issues, challenges, and opportunities in a variety of advanced materials and technologies that are critically needed for sustainable societal development.

This Ceramic Transactions volume contains a collection of peer reviewed papers from the 16 below symposia that were submitted from these two conferences

• Design and Development of Advanced Ceramic Fibers, Interfaces, and Interphases in Composites- A Symposium in Honor of Professor Roger Naslain
• Innovative Design, Advanced Processing, and Manufacturing Technologies
• Materials for Extreme Environments: Ultrahigh Temperature Ceramics (UHTCs) and Nano-laminated Ternary Carbides and Nitrides (MAX Phases)
• Polymer Derived Ceramics and Composites
• Advanced Thermal and Environmental Barrier Coatings: Processing, Properties, and Applications
• Thermomechanical Behavior and Performance of Composites
• Ceramic Integration and Additive Manufacturing Technologies
• Component Testing and Evaluation of Composites
• CMC Applications in Transportation and Industrial Systems
• Powder Processing Innovation and Technologies for Advanced Materials and Sustainable Development
• Novel, Green, and Strategic Processing and Manufacturing Technologies
• Ceramics for Sustainable Infrastructure: Geopolymers and Sustainable Composites
• Advanced Materials, Technologies, and Devices for Electro-optical and Medical Applications
• Porous Ceramics for Advanced Applications Through Innovative Processing
• Multifunctional Coatings for Sustainable Energy and Environmental Applications

Thermomechanical
Behavior and Performance
of Composites

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THERMAL ABLATION PERFORMANCE OF C_F-HFB₂ COMPOSITES WITH AND WITHOUT A C MATRIX DEPOSITED BY CVI

Rubio V, Ramanujam P, Ramachandran D K, D’Angio’ A and Binner J G P

School of Metallurgy and Materials, University of Birmingham, Birmingham, UK

ABSTRACT

C_f-HfB₂-based composites have been produced using a vacuum impregnation route with half of the samples being further densified by the inclusion of a carbon matrix using CVI. Both composites, C_f-HfB₂ and C_f-HfB₂/C, were characterised by oxyacetylene torch testing to determine the effect of the carbon matrix on the thermo-ablative performance. The mass loss of the samples revealed what whilst the C_f-HfB₂ samples performed slightly better when tested for 60 s due to the presence of a surface layer of HfB₂ powder, the C_f-HfB₂/C composites were significantly superior when tested at nearly 3000^oC for 300 s. The reason is believed to be related to the fact that the molten hafnia formed during testing was more absorbed by the C_f-HfB₂ samples, which remained very porous. It is the presence of the viscous molten hafnia that is believed to offer the protection in this system.

INTRODUCTION

Thermal protection systems (TPS) for hypersonic applications and re-entry vehicles into Earth’s atmosphere should be able to resist temperatures of at least 2000°C⁽¹⁾ combined with the intense thermal shock⁽²⁾ arising from high heat fluxes due to the speed they travel. These result in severe oxidation and thermo-mechanical stress, which causes severe ablation during the time of flight⁽³⁾. Carbon fibre-based composites are potential candidate materials since they show good damage tolerance⁽⁴⁾ and can withstand severe mechanical stresses; however, they offer poor resistance to erosion and oxidation at temperatures above ~600°C^(5,6). Over the last decade, researchers have been tailoring carbon fibre composites with different ultra-high temperature ceramics (UHTC) such as HfB₂, ZrB₂^(7,8) and their derivatives^(9-11) as a dispersed phase since these materials possess very high melting points and exhibit superior thermal properties when compared to other covalently bonded materials. The performance of the UHTC composites is greatly influenced by the process route used. For instance, hot pressing or spark plasma sintering have been used to consolidate UHTC composites ⁽¹²⁾, but these techniques involve the use of high pressures and temperatures which can severely damage the fibres and hence limit the physical properties. Other processes, including reactive melt infiltration (RMI), polymer infiltration & pyrolysis (PIP) and vacuum impregnation/chemical vapour infiltration have also been investigated. The RMI process involves depositing a carbon matrix in a 2D or 3D C_f preform, usually by CVI, and then infiltrating with a molten metal (e.g. Zr, Hf, Si, Ti) via capillary pressure between the fibre tows where it reacts to form a metal carbide^(13,14). The resulting stoichiometry and potential damage to the carbon fibres are both concerns since they could have negative effects on the thermal performance. The PIP process is primarily used for SiC-based composites^(15-17) where polymers such as polycarbosilane are infiltrated into fibre preforms and heat treated to form SiC at elevated temperatures; this step typically needs repeating 4 to 5 times to improve the final density of the composite. Chemical vapour infiltration relies on the decomposition of a gaseous phase at elevated temperature to deposit a matrix within a fibre preform; the latter typically consists of carbon or silicon carbide fibres. To speed up the process by filling the larger initial pores in the preform, powders are often impregnated into the preform first, usually using vacuum impregnation^(8,18-19), and a low temperature pyrolysis is required to burn off the organics^(8,18-19). The advantages of this route are the ability to manipulate particle size distribution to improve the packing fraction of particles in the matrix as well as the ability to select independently the composition of the fibre, powder and matrix phases to tailor the final composite performance.

In the current work, vacuum impregnation^(20,21) has been used to fabricate C_f-HfB₂ composites with an homogenous powder distribution. Half of the samples also had a carbon matrix deposited within the residual porosity using chemical vapour infiltration (CVI). The effects of the carbon matrix on the thermo-ablation resistance have been evaluated using an oxyacetylene test facility. The resultant samples were characterised using a range of analytical methods and the results are discussed.

EXPERIMENTAL

40 × 26 × 12.5 mm thick rectangular samples of 2.5D needled carbon fibre, C_f, preforms containing 23 vol% fibres and having a bulk density of 0.37 g cm^-3 were obtained from Surface Transforms plc, UK. The structure of the preforms consisted of layers of fabric stacked in an arrangement of random/0°/random/90°/random orientation fibres, w...

Table of contents

• Cover
• Title Page
• Copyright
• Preface
• Design and Development of Advanced Ceramic Fibers, Interfaces, and Interphases in Composites
• Innovative Design, Advanced Processing, and Manufacturing Technologies
• Advanced Thermal and Environmental Barrier Coatings
• Thermomechanical Behavior and Performance of Composites
• Component Testing and Applications of Composites
• Multifunctional Coatings for Sustainable Energy and Environmental Applications
• Ceramics for Sustainable Infrastructure
• Advanced Materials, Technologies, and Devices for Electro-Optical and Medical Applications
• EULA