scholarly journals Research of properties of protective coating applied to the surface of reaction-sintered ceramic materials

2021 ◽  
Vol 1 (101) ◽  
pp. 22-27
Author(s):  
Vasiliy Kovbashyn ◽  
Igor Bochar
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Protective Coating ◽  
Diffusion Processes ◽  
Molybdenum Disilicide ◽  
Ceramic Materials ◽  
Sharp Change ◽  
Sintered Ceramic ◽  
Cyclic Changes ◽  
Almost All

The study describes the properties of the protective coating deposited on the surface of the reaction-sintered silicon carbide and molybdenum disilicide. The technology of increasing the protective ability of the coating of products deposited on the surface on the basis of reactive sintered carbide of silicon and molybdenum disilicide, which operate in an oxidizing environment at high temperature and a sharp change of thermal regime, is investigated. The obtained results showed that the presence of a protective slip layer significantly increases the stability of the deposited silicoboride coating, thus blocking the interaction of silicon hexaboride with the environment, slowing down almost all diffusion processes at the transition of the interaction of diffusion. It has been established that the simultaneous use of both diffusion and slurry coatings enables maximum protection of reaction-sintered ceramic materials based on silicon carbide and molybdenum disilicide against high-temperature gas corrosion. The developed coating ensures maximum resistance to repeated changes in temperature conditions, while cyclic changes destroy products of silicon carbide and molybdenum disilicide without applied protective coating. The proposed protective coating can be recommended for the protection of reaction-sintered ceramic materials operated in high temperatures.

Silicon carbide fibers and whiskers for ceramic matrix composites (review)

2021 ◽  
Vol 87 (8) ◽  
pp. 51-63
Author(s):  
A. M. Shestakov
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
High Temperature ◽  
Composite Materials ◽  
Ceramic Matrix Composites ◽  
Ceramic Materials ◽  
Ceramic Composites ◽  
Silicon Compounds ◽  
Reinforcing Fillers ◽  
Operating Temperatures

An increase the operating temperature range of structural elements and aircraft assemblies is one of the main goals in developing advanced and new models of aerospace equipment to improve their technical characteristics. The most heat-loaded aircraft structures, such as a combustion chamber, high-pressure turbine segments, nozzle flaps with a controlled thrust vector, must have a long service life under conditions of high temperatures, an oxidizing environment, fuel combustion products, and variable mechanical and thermal loads. At the same time, modern Ti and Ni-based superalloys have reached the limits of their operating temperatures. The leading world aircraft manufacturers — General Electric (USA), Rolls-Royce High Temperature Composite Inc. (USA), Snecma Propulsion Solide (France) — actively conduct fundamental research in developing ceramic materials with high (1300 – 1600°C) and ultrahigh (2000 – 2500°C) operating temperatures. However, ceramic materials have a number of shortcomings attributed to the high brittleness and low crack resistance of monolithic ceramics. Moreover, manufacturing of complex configuration and large-sized ceramic parts faces serious difficulties. Nowadays, ceramic composite materials with a high-temperature matrix (e.g., based on ZrC-SiC) and reinforcing filler, an inorganic fiber, (e.g., silicon carbide) appeared most promising for operating temperatures above 1200°C and exhibited enhanced energy efficiency. Ceramic fibers based on silicon compounds possess excellent mechanical properties: the tensile strength more than 2 GPa, modulus of elasticity more than 200 GPa, and thermal resistance at a temperature above 800°C, thus making them an essential reinforcing component in metal and ceramic composites. This review is devoted to silicon carbide core fibers obtained by chemical vapor deposition of silicon carbide onto a tungsten or carbon core, which makes it possible to obtain fibers a 100 – 150 μm in diameter to be used in composites with a metal matrix. The coreless SiC-fibers with a diameter of 10 – 20 μm obtained by molding a polymer precursor from a melt and used mainly in ceramic composites are also considered. A comparative analysis of the phase composition, physical and mechanical properties and thermal-oxidative resistance of fibers obtained by different methods is presented. Whiskers (filamentary crystals) are also considered as reinforcing fillers for composite materials along with their properties and methods of production. The prospects of using different fibers and whiskers as reinforcing fillers for composites are discussed.

scholarly journals CVD of Silicon Carbide on Structural Fibers: Microstructure and Composition

1991 ◽  
Vol 250 ◽  
Author(s):  
Lisa C. Veitch ◽  
Francis M. Terepka ◽  
Suleyman A. Gokoglu
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Cross Sections ◽  
Electron Microprobe ◽  
Ceramic Materials ◽  
Careful Analysis ◽  
Deposition Rates ◽  
Different Temperatures ◽  
Concentrated Source ◽  
Environmental Attack

AbstractStructural fibers are currently being considered as reinforcements for intermetallic and ceramic materials. Some of these fibers, however, are easily degraded in a high temperature oxidative environment. Therefore, coatings are needed to protect the fibers from environmental attack.Silicon carbide (SiC) was chemically vapor deposited (CVD) on Textron's SCS6 fibers. Fiber temperatures ranging from 1350 to 1500 °C were studied. Silane (SiH4) and propane (C3H8.) were used for the source gases and different concentrations of these source gases were studied. Deposition rates were determined for each group of fibers at different temperatures. Less variation in deposition rates were observed for the dilute source gas experiments than the concentrated source gas experiments. A careful analysis was performed on the stoichiometry of the CVD SiC-coating using electron microprobe. Microstructures for the different conditions were compared. At 1350°C, the microstructures were similar;however, at higher temperatures, the microstructure for the more concentrated source gas group were porous and columnar in comparison to the cross sections taken from the same area for the dilute source gas group.

Design and Development of a Low-Cost, High Temperature Silicon Carbide Micro-Channel Recuperator

2005 ◽  
Author(s):  
Merrill A. Wilson ◽  
Kurt Recknagle ◽  
Kriston Brooks
Keyword(s):  
Heat Transfer ◽  
Silicon Carbide ◽  
High Temperature ◽  
Heat Exchanger ◽  
Thermal Efficiency ◽  
Heat Exchangers ◽  
Ceramic Materials ◽  
Micro Channel ◽  
Micro Channels ◽  
Micro Turbine

Typically, ceramic micro-channel devices are used for high temperature heat exchangers, catalytic reactors, electronics cooling, and processing of corrosive streams where the thermomechanical benefits of ceramic materials are desired. These benefits include: high temperature mechanical and corrosion properties and tailorable material properties such as thermal expansion, electrical conductivity and thermal conductivity. In addition, by utilizing Laminated Object Manufacturing (LOM) methods, inexpensive ceramic materials can be layered, featured and laminated in the green state and co-sintered to form monolithic structures amenable to mass production. In cooperation with the DOE and Pacific Northwest National Labs, silicon carbide (SiC) based micro-channel recuperator concepts are being developed and tested. The performance benefits of a high temperature, micro-channel heat exchanger are realized from the improved thermal efficiency of the high temperature cycles and the improved effectiveness of micro-channels for heat transfer. In designing these structures, the heat and mass transfer within the micro-channels are being analyzed with heat transfer models, computational fluid dynamics models and validated with experimental results. As an example, a typical micro-turbine cycle was modified and modeled to incorporate this ceramic recuperator and it was found that the overall thermal efficiency of the micro-turbine could be improved from about 27% to over 40%. Process improvements require technical advantages and cost advantages. These LOM methodologies have been based on well-proven industry standard processes where labor, throughput and capital estimates have been tested. Following these cost models and validation at the prototype scale, cost estimates were obtained. For the micro-turbine example, cost estimates indicate that the high-temperature SiC recuperator would cost about $200 per kWe. The development of these heat exchangers is multi-faceted and this paper focuses on the design optimization of a layered micro-channel heat exchanger, its performance testing, and fabrication development through LOM methodologies.

Oxidation of Porous HfB2–SiC Ultra-High-Temperature Ceramic Materials Rich in Silicon Carbide (65 vol %) by a Supersonic Air Flow

2020 ◽  
Vol 65 (4) ◽  
pp. 606-615 ◽  
Author(s):  
E. P. Simonenko ◽  
N. P. Simonenko ◽  
A. N. Gordeev ◽  
A. F. Kolesnikov ◽  
A. S. Lysenkov ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Air Flow ◽  
Ceramic Materials ◽  
Ultra High Temperature

Structural Ceramic Materials Under Development

1975 ◽  
Author(s):  
F. F. Lange
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Silicon Nitride ◽  
Stress Analysis ◽  
Structural Design ◽  
Hot Pressing ◽  
Ceramic Materials ◽  
Reaction Sintering ◽  
Structural Ceramic ◽  
Conventional Sintering

A variety of different promising high temperature structural materials exist under the generic names of silicon nitride (Si3N4) and silicon carbide (SiC). Each of these materials are fabricated by a different method and thus, each develop different microstructures and different properties. The relations between fabrication, microstructure and properties will be reviewed for both Si3N4 and SiC fabricated by (a) reaction-sintering, (b) conventional sintering, and (c) hot-pressing. The object of this review is to allow the engineer to obtain a better understanding of the different materials that are becoming available for high temperature structural design applications. An Appendix presents the properties of these materials required for stress analysis.

Reaction Bonded Silicon Carbide and Silicon Nitride for Gas Turbine Applications

1972 ◽  
Author(s):  
R. A. Alliegro ◽  
S. H. Coes
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Silicon Nitride ◽  
Thermal Shock ◽  
Gas Turbine ◽  
Thermal Shock Resistance ◽  
Casting Process ◽  
Ceramic Materials ◽  
Machining Process ◽  
Shock Resistance

Two unique ceramic materials offer the gas turbine designer the opportunity to substitute uncooled high temperature components for the presently cooled metal and alloy ones. Recrystallized silicon carbide made by a casting process and reaction bonded silicon nitride shaped by a simple machining process before firing, offer not only high temperature materials capable of living in the gas turbine environment, but also an intricacy of shape consistent with combustor, shroud and associated high temperature component needs. Silicon carbide’s 3200 F capability and its thermal shock resistance makes it a sound choice; silicon nitride’s low expansion coefficient, thermal shock resistance, and 2900 F capability make it a material of real merit. The properties of these materials are discussed in detail along with potential areas of application and design capabilities.

Phase transformation and layer evolution in molybdenum disilicide-silicon carbide nanolayered coatings

1994 ◽  
Vol 52 ◽  
pp. 538-539
Author(s):  
H. Kung ◽  
T. R. Jervis ◽  
J.-P. Hirvonen ◽  
M. Nastasi ◽  
T. E. Mitchell ◽  
...  
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Oxidation Resistance ◽  
Elevated Temperatures ◽  
Matrix Material ◽  
Molybdenum Disilicide ◽  
High Temperature Strength ◽  
Cross Sectional ◽  
Good Oxidation Resistance ◽  
Structural Applications

MoSi2 is a potential matrix material for high temperature structural composites due to its high melting temperature and good oxidation resistance at elevated temperatures. The two major drawbacksfor structural applications are inadequate high temperature strength and poor low temperature ductility. The search for appropriate composite additions has been the focus of extensive investigations in recent years. The addition of SiC in a nanolayered configuration was shown to exhibit superior oxidation resistance and significant hardness increase through annealing at 500°C. One potential application of MoSi2- SiC multilayers is for high temperature coatings, where structural stability ofthe layering is of major concern. In this study, we have systematically investigated both the evolution of phases and the stability of layers by varying the heat treating conditions.Alternating layers of MoSi2 and SiC were synthesized by DC-magnetron and rf-diode sputtering respectively. Cross-sectional transmission electron microscopy (XTEM) was used to examine three distinct reactions in the specimens when exposed to different annealing conditions: crystallization and phase transformation of MoSi2, crystallization of SiC, and spheroidization of the layer structures.

DURALCAN F3S.xxS

Alloy Digest ◽  
1994 ◽  
Vol 43 (10) ◽  
Keyword(s):  
Fracture Toughness ◽  
Silicon Carbide ◽  
Compressive Strength ◽  
Aluminum Alloy ◽  
High Temperature ◽  
Base Alloy ◽  
Alloy Matrix ◽  
Reinforced Composite ◽  
Temperature Performance ◽  
Aluminum Alloy Matrix

Abstract Duralcan F3S.xxS is a heat treatable aluminum alloy-matrix gravity composite. The base alloy is similar to Aluminum 359 (Alloy Digest Al-188, July 1969); the discontinuously reinforced composite is silicon carbide. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive strength as well as fracture toughness and fatigue. It also includes information on high temperature performance. Filing Code: AL-329. Producer or source: Alcan Aluminum Corporation.

Sign in / Sign up

Export Citation Format

Share Document