Alumina/alumina composite with a porous zirconia interphase —Processing, properties and component testing (original) (raw)
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Oxide Ceramic Matrix Composite Materials for Aero-Engine Applications: A Literature Review
Advances in Transdisciplinary Engineering, 2021
The development of aircraft gas turbine engines has extensively been required for the development of advanced materials. This complex development process is however justified by the system-level benefits in terms of reduced weight, higher temperature capability, and/or reduced cooling, each of which increases efficiency. This is where high-temperature ceramics have made considerable progress and ceramic matrix composites (CMCs) are in the foreground. CMCs are classified into non-oxide and oxide-based ones. Both families have material types that have a high potential for use in high-temperature propulsion applications. Typical oxide-based ones are based on an oxide fiber and oxide matrix (Ox-Ox). Some of the most common oxide subcategories, are alumina, beryllia, ceria, and zirconia ceramics. Such matrix composites are used for example in combustion liners of gas turbine engines and exhaust nozzles. However, until now a thorough study on the available oxide-based CMCs for such applic...
2009
The main reasons for the attention focused on ceramics as possible structural materials are their wear resistance and the ability to operate with limited oxidation and ablation at temperatures above 2000°C. Hence, this work is devoted to the study of two classes of materials which can satisfy these requirements: silicon carbide-based ceramics (SiC) for wear applications and borides and carbides of transition metals for ultra-high temperatures applications (UHTCs). SiC-based materials: Silicon carbide is a hard ceramic, which finds applications in many industrial sectors, from heat production, to automotive engineering and metals processing. In view of new fields of uses, SiC-based ceramics were produced with addition of 10-30 vol% of MoSi 2 , in order to obtain electro conductive ceramics. MoSi 2 , indeed, is an intermetallic compound which possesses high temperature oxidation resistance, high electrical conductivity (21•10-6 Ω•cm), relatively low density (6.31 g/cm 3), high melting point (2030°C) and high stiffness (440 GPa). The SiC-based ceramics were hot pressed at 1900°C with addition of Al 2 O 3-Y 2 O 3 or Y 2 O 3-AlN as sintering additives. The microstructure of the composites and of the reference materials, SiC and MoSi 2 , were studied by means of conventional analytical techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (SEM-EDS). The composites showed a homogeneous microstructure, with good dispersion of the secondary phases and low residual porosity. The following thermo-mechanical properties of the SiC-based materials were measured: Vickers hardness (HV), Young's modulus (E), fracture toughness (K Ic) and room to high temperature flexural strength (σ). The mechanical properties of the ABSTRACT 13 composites were compared to those of two monolithic SiC and MoSi materials and resulted in a higher stiffness, fracture toughness and slightly higher flexural resistance. Tribological tests were also performed in two configurations disco-on-pin and slideron cylinder, aiming at studying the wear behaviour of SiC-MoSi 2 composites with Al 2 O 3 as counterfacing materials. The tests pointed out that the addition of MoSi 2 was detrimental owing to a lower hardness in comparison with the pure SiC matrix. On the contrary, electrical measurements revealed that the addition of 30 vol% of MoSi 2 , rendered the composite electroconductive, lowering the electrical resistance of three orders of magnitude. Ultra High Temperature Ceramics: Carbides, borides and nitrides of transition metals (Ti, Zr, Hf, Ta, Nb, Mo) possess very high melting points and interesting engineering properties, such as high hardness (20-25 GPa), high stiffness (400-500 GPa), flexural strengths which remain unaltered from room temperature to 1500°C and excellent corrosion resistance in aggressive environment. All these properties place the UHTCs as potential candidates for the development of manoeuvrable hypersonic flight vehicles with sharp leading edges. To this scope Zr-and Hf-carbide and boride materials were produced with addition of 5-20 vol% of MoSi 2. This secondary phase enabled the achievement of full dense composites at temperature lower than 2000°C and without the application of pressure. Besides the conventional microstructure analyses XRD and SEM-EDS, transmission electron microscopy (TEM) was employed to explore the microstructure on a small length scale to disclose the effective densification mechanisms. A thorough literature analysis revealed that neither detailed TEM work nor reports on densification mechanisms are available for this class of materials, which however are essential to optimize the sintering aids utilized and the processing parameters applied. Microstructural analyses, along with thermodynamics and crystallographic considerations, led to disclose of the effective role of MoSi 2 during sintering of Zrand Hf-carbides and borides. Among the investigated mechanical properties (HV, E, K Ic , σ from room temperature to 1500°C), the high temperature flexural strength was improved due to the protective and sealing effect of a silica-based glassy phase, especially for the borides.
CMCs or Ceramic Matrix Composites consist of ceramic fibers embedded in a ceramic matrix, thus forming a ceramic fiber reinforced ceramic (CFRC) material. The matrix and fibers can consist of any ceramic material, whereas carbon and carbon fibers can also be considered a ceramic material. CMCs were developed to overcome the problems associated with the conventional ceramics like alumina, silicon carbide, aluminum nitride etc – they fracture easily under mechanical or thermo-mechanical loads because of cracks initiated by small defects or scratches. Like in glass the crack resistance is very low. To increase the crack resistance or fracture toughness , particles (so-called mono crystalline whiskers or platelets ) were embedded into the matrix.The present paper throws light on the different attributes of CMCs or Ceramic Matrix Composites, their mechanical properties and utility in future gas turbines.
Ceramic and metal matrix composites: route and properties
The paper presents a brief state of the art of advanced ceramics, metal matrix and ceramic matrix composites. The attention is focused on process technologies involved, applications and future of these " potential " materials. Some experimental results are included. The future of advanced materials is related to systems solutions, economical manufacturing processing, diverse markets and new technologies. The new materials will provide the opportunity for growth to a new and healthier balance, with vibrant commercial sector delivering an improved quality of life and stronger technology base. 1. CERAMICS With technological progress, natural materials become insufficient to meet increasing demands on product capabilities and functions. There are many combinations of metallic and non-metallic atoms that can combine to form ceramic components, and also several structural arrangements are usually possible for each combination of atoms. This led scientists to invent many new ceramic materials to meet increasing requirements and demands in various application areas. Advanced furnaces and heat engines played important roles in the success of the industrial revolution, while ceramic materials were essential for thermal insulation of various types of furnaces and engines. Electrically insulating ceramic materials were developed as electrical and electronic technologies matured. As higher and higher frequencies and voltages were used, the demand on ceramic dielectrics became more stringent. Also, new specifications for the magnetic and optical properties of ceramics were developed as a part of the new electronic and electro–optical technology revolution. The technology of ceramics is a rapidly developing applied science in today's world. Technological advances result from unexpected material discoveries. On the other hand, the new technology can drive the development of new ceramics. Currently many new classes of materials have been devised to satisfy various new applications. Advanced ceramics offer numerous enhancements in performance, durability, reliability, hardness, high mechanical strength at high temperature, stiffness, low density, optical conductivity, electrical insulation and conductivity, thermal insulation and conductivity, radiation resistance, and so on. Ceramic technologies have been widely used for aircraft and
Ceramic materials for aviation technology
Refractories and Industrial Ceramics, 1993
Improving the potential and reliability of components in gas-turbine engines operating in conditions of high thermal and aerodynamic stress is closely linked with the need to improve ceramic parts used in the production of complex articles from nickel, heat-resistant alloys. The Obninsk Enterprise "Tekhnologiya" has carried out a comprehensive investigation aimed at developing thermalshock resistant refractories based on corundum-mullite materials possessing high metal resistance to heat-resistant nickel alloys, and which are used for making crucibles for precision casting of the blades of gas-turbine engines (GTE), the production of measured blanks of heat-resistant alloys, and saggers for firing rods* [1-6]. These investigations established that it is possible in theory to increase the thermal-shock resistance of high-alumina ceramics with a low porosity and sufficiently high mechanical strength. This was achieved by forming a microcracked, fragmented structure by introducing coarse-grained additions of sintered multite, electrocorundum, silicon carbide, and electrofused zirconium dioxide. It was shown that the thermal-shock resistance depends on the concentration of microcracks and the size of the fragments; and, moreover, the increase in the thermal-shock resistance is greater the more the temperature coefficient of linear expansion (TCLE) of the additive differs from that of the high-alumina matrix. The increase in the labor productivity and the quality of the engine blades, cast in vacuum induction furnaces (designate UPPF), are mainly determined by the thermal-shock resistance of the ceramic crucible and the degree of contamination, from the molten metal. Rammed crucibles that were used in this work, and which lasted (with intermediate repairs) up to 400 castings, are eroded by the chemically active alloys, and are a source of dirt and blisters, as a result of which the total loss of blades due to metal contamination reaches 60-80 %. We therefore developed corundum-mullite material TSM-323 (see ) and a production technology for changeable ceramic crucibles, height 320 mm, internal diameter about 135 ram, and wall thickness 18 mm for use in UPPF furnaces, and VIP-3 furnaces . The enhanced thermal-shock resistance of TSM-323 is due to the formation of a fragmented structure. During a final firing at 1580~ the high-alumina matrix undergoes shrinkage, and the grains of mullite prevent this. As a result, the matrix is broken into several fragments that are capable of being mutually displaced and thereby resisting thermal shock. It is found that the highest increase in thermal-shock resistance is attained by introducing into the ceramic composition sintered mullite grade with grain sizes of 0.4-0.63 mm . The phase composition of the ceramic consists of corundum (a-A1203), mullite (3A1203-2SiO2), strontium anorthite (Sr2A12Si2Os), and strontium titanate (SrTiO3). The ceramic has a high refractoriness --1740~ The crucibles were made by hot vibration-forming from thermoplastic slips. During shaping the vibration oscillations during the application of pressure prevented layering of the slip at the moment of casting up of the body, and ensured that good quality blanks were obtained with uniform density. Industrial tests on the crucibles made of TSM-323 in UPPF furnaces showed that the yield of acceptable blades after luminescence (LYuM) control testing from the first application, when alloys VZhL-8U, VZhL-12U, and ZhS-6K 'were being melted, compared with these factors with the use of rammed crucibles, increases 1.5-2 times and reaches 80-90%. The loss due to contamination is reduced by 35-45 %, and the total yield of acceptable blades is increased by 10 %. In terms of the short-*L. P. Ivanova, G. M. Ivanova, T. M. Khranovskaya, and V. A. Bevz took part in the work. Obninsk Scientific Production Enterprises "Tekhnologiya."
Mechanical Properties and Performance of Engineering Ceramics and Composites VII
Ceramic Engineering and Science Proceedings, 2012
Niobium carbide (NbC) has a high melting point (36OO0C), good electrical conductivity and high hardness. These properties encourage the investigation of zirconia-based niobium carbide composites aiming at achieving a composite with good fracture toughness, high hardness and at the same time a sufficient electrical conductivity to allow electro-discharge machining (EDM). Since the commercially available NbC powders are relatively coarse (d50 = 1-3 pm), a NbC nanopowder was prepared by carbo-thermal reduction of NbOs. The synthesis time, temperature, and C/Nb205 ratio have been optimized to obtain a NbC powder with extremely fine grain size and minimum residual carbon and oxide impurities. Carbon black and NbzO5 were mixed in different ratios and thermally treated at 1000-1450°C for 0.5-10 h. NbC powder with a dso grain size of 185 nm was obtained from a powder mixture with a carbodniobium oxide ratio of 1.88. thermally treated in vacuum (l o 5 to Pa) at 1350°C for 5 hours. Zr02-NbC-TiN (65:35:5 vol YO) composites based on the synthesized NbC powder could be fully densified by means of hot pressing at 145OOC for 1 hour at 28 MPa, resulting in a composite with an excellent hardness of 16 GPa, a fracture toughness of 5 MPa.mo5 and an electrical resistivity of 0.8 mS2.cm.
Development of Ultra High Temperature Ceramic Composites for Gas Turbine Combustors
Volume 4: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation; Education; IGTI Scholar Award, 1997
All-oxide ceramic composites as a material with potential for long life-time applications at temperatures in the 1400–1600°C range in combustion environments were studied. The properties of available polycrystalline and single crystal oxide fibres were summarised. The literature on stable weak interfaces in all-oxide composites was reviewed. Composites with single crystal fibres, a polycrystalline matrix of the same material as the fibres, and a compatible high temperature stable weak oxide interphase was suggested to be the most promising approach. Recent progress in an ongoing European project aiming at development, scale-up and property evaluation of all-oxide composites is reported. The composite will be applied to a simple prototype combustor tile and tested in a combustor rig.
Advances in Applied Ceramics, 2018
There is an increasing demand for advanced materials with enhanced temperature capability in highly corrosive environments, for instance enable space vehicles to resist several launches and re-entries. The EU-funded project C 3 HARME aims at combining the best features of CMCs and UHTCs to design, develop, manufacture and qualify a new class of Ultra-High Temperature Ceramic Matrix Composite (UHTCMCs) with self-healing capabilities. Applications selected to implement the new materials are near-zero erosion nozzles and near-zero ablation thermal protection systems. This paper aims at giving an introduction to the challenges addressed by C 3 HARME project including (i) the integration between well-established and novel techniques for CMCs and UHTCs production, (ii) the need for very high temperature characterisation, (iii) the meaning of self-healing capability for UHTCMCs, (iv) the contribution of modelling to materials development and (V) the investigation of the microstructure/ thermo-mechanical property correlations.
Emerging Applications of Ceramic and Metal Matrix Composites
Almost 500 papers were presented during the 43 sessions of the Many of these papers focused on composites, both ceramic and metal matrix, and discussed mechanical behavior, design, fibers/interfaces, processing, and applications. Potential applications under development include components for armor, nuclear energy, and automobiles. A few of these applications have reached commercialization.
All-oxide ceramic matrix composites
2001
This work has concerned the preparation and properties of all-oxide composites. The most common examples of such materials are composites of oxide particles in an oxide matrix, continuous oxide fib ...