Microfabricated Silicon Carbide Microengine Structures

1998 ◽  
Vol 546 ◽  
Author(s):  
Kevin A. Lohner ◽  
Kuo-Shen Chen ◽  
Arturo A. Ayon ◽  
S. Mark Spearing
Keyword(s):  
Silicon Carbide ◽  
Elevated Temperatures ◽  
Development Program ◽  
Chemical Vapor ◽  
Turbine Engine ◽  
Specific Strength ◽  
Develop Technology ◽  
Etched Silicon ◽  
Biaxial Mechanical Testing ◽  
Silicon Silicon

AbstractA research and development program is underway to develop technology for a MEMS-based microgas turbine engine. The thermodynamic requirements of power-generating turbomachinery drive the design towards high rotational speeds and high temperatures. To achieve the specified performance requires materials with high specific strength and creep resistance at elevated temperatures. The thermal and mechanical properties of silicon carbide make it an attractive candidate for such an application. Silicon carbide as well as silicon-silicon carbide hybrid structures are being designed and fabricated utilizing chemical vapor deposition of relatively thick silicon carbide layers (10–100 μm) over time multiplexed deep etched silicon molds. The silicon can be selectively dissolved away to yield high aspect ratio silicon carbide structures with features that are hundreds of microns tall.Research has been performed to characterize the capabilities of this process. Specimens obtained to date show very good conformality and step coverage with a fine (≈0.1 μm dia.) columnar microstructure. Surface roughness (Rq) of the films is on the order of 100 nm, becoming rougher with thicker deposition. Residual stress limits the achievable thickness, as the strain energy contained within the compressive film increases its susceptibility to cracking. Room temperature biaxial mechanical testing of CVD silicon carbide exhibits a reference strength of 724 MPa with a Weibull modulus, m =16.0.

Process Development of Silicon-Silicon Carbide Hybrid Micro-Engine Structures

2001 ◽  
Vol 687 ◽  
Author(s):  
Dongwon Choi ◽  
Robert J. Shinavski ◽  
Wayne S. Steffier ◽  
Skip Hoyt ◽  
S.Mark Spearing
Keyword(s):  
Silicon Carbide ◽  
Residual Stresses ◽  
Elevated Temperatures ◽  
Process Development ◽  
High Stress ◽  
Development Program ◽  
High Strength ◽  
Operating Conditions ◽  
Source Power ◽  
Silicon Silicon

AbstractA MEMS-based gas turbine engine is being developed for use as a button-sized portable power generator or micro-aircraft propulsion source. Power densities expected for the micro- engine require high combustor exit temperatures (1300-1700K) and very high rotor peripheral speeds (300-600m/s). These harsh operating conditions induce high stress levels in the engine structure, and thus require refractory materials with high strength. Silicon carbide has been chosen as the most promising material for use in the near future due to its high strength and chemical inertness at elevated temperatures. However, techniques for microfabricating single- crystal silicon carbide to the level of high precision needed for the micro-engine are not currently available. To circumvent this limitation and to take advantage of the well-established precise silicon microfabrication technologies, silicon-silicon carbide (SiC) hybrid turbine structures are being developed using chemical vapor deposition of poly-SiC on silicon wafers and wafer bonding processes. Residual stress control of SiC coatings is of critical importance to all the silicon-silicon carbide hybrid structure fabrication steps since a high level of residual stresses causes wafer cracking during the planarization, as well as excessive wafer bow, which is detrimental to the subsequent planarization and bonding processes. The origins of the residual stresses in CVD SiC layers have been studied. SiC layers (as thick as 30µm) with low residual stresses (on the order of several tens of MPa) have been produced by controlling CVD process parameters such as temperature and gas ratio. Wafer-level SiC planarization has been accomplished by mechanical polishing using diamond grit and bonding processes are currently under development using interlayer materials such as silicon dioxide or poly-silicon. These process development efforts will be reviewed in the context of the overall micro-engine development program.

SiC Fiber Reinforced Ceramic Matrix Composites for Turbine Engine Applications

2000 ◽  
Author(s):  
Kenneth Hatton ◽  
Dennis Landini ◽  
Stan Hemstad ◽  
R. Craig Robinson
Keyword(s):  
Silicon Carbide ◽  
Ceramic Matrix Composite ◽  
Chemical Vapor ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Chemical Vapor Infiltration ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Turbine Engine ◽  
Nozzle Guide

Honeywell Advanced Composites Inc. (ACI) has been working with OEM’s to develop, fabricate, and test ceramic matrix composite (CMC) materials for partial and full replacement of hot section turbine engine components. Using Chemical Vapor Infiltration (CVI) technology, silicon carbide fiber reinforced silicon carbide matrix parts, such as full annular combustion liners and inserts for leading edges on nozzle guide vanes have been fabricated and tested.

scholarly journals Characterization of nano-bio silicon carbide

2020 ◽  
Vol 23 (04) ◽  
pp. 346-354
Author(s):  
S.I. Vlaskina ◽  
◽  
G.N. Mishinova ◽  
I.L. Shaginyan ◽  
P.S. Smertenko ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Chemical Vapor Deposition ◽  
Luminescence Spectrum ◽  
Bias Voltage ◽  
Vapor Deposition ◽  
Deep Level ◽  
Chemical Vapor ◽  
Conductive Substrate ◽  
Develop Technology ◽  
Dielectric Ceramics

Plasma-enhanced chemical vapor deposition, reactive magnetron sputtering, hot-wire chemical vapor deposition and radio frequency plasma-enhanced chemical vapor deposition were used to develop technology for preparation of nano-bio silicon carbide coating of ceramic materials for dental applications. The effect of the bias voltage applied to the ceramic prostheses and dental crowns on the crystallization processes have been recognized. The optimal bias voltage applied to conductive substrate was –200 V, whereas for dielectric substrate the bias voltage Vbias did not affect the properties of SiC coating. The analysis of CVCs and spectroscopic diagnostics as the methods for studying the mechanism of interfacial rearrangements to investigate SiC phase transition in nano silicon carbide coatings were used. The conductivity of the SiC coating coincided with the conductivity on the dielectric (µn0 = 1012…1013 сm–1·s–1·V–1). The conductive substrate had a significant effect on the properties of the coating and thus depended on the bias voltage Vbias. The conductivity increased by three-four orders of magnitude (µn0 = 3·1017 сm–1·s–1·V–1), if the bias voltage Vbias = –200 V. The increase of the bias voltage (Vbias = –600 V) led to a decrease in the conductivity (µn0 = 1011…1012 сm–1·s–1·V–1). It was found that there was the double injection regime with bimolecular recombination in this structure with the dependence I = V3/2 for CVCs of SiC. The luminescence spectrum of SiC coating on non-dielectric ceramics (if Vbias = – 200 V during deposition) was significantly different from the luminescence spectrum of SiC coating on dielectric ceramics. Increasing the applied voltage to the substrate Vbias during deposition led to increasing the fraction of hexagonal polytypes. Directions in the crystal lattice according to the photoluminescence spectra were identified from the comparing the values of the width of the non-phonon parts of stacking faults and deep level spectra in the low-temperature photoluminescence with arrangements of atoms in the SiC lattice structure. The displacement of each atom participating in photoluminescence allowed to find the correlation with technology of SiC deposition and to develop technology of SiC coating on the dental materials.

TEM of grain growth and phase transformations during creep of SCS-6 silicon carbide fibers

1995 ◽  
Vol 53 ◽  
pp. 350-351
Author(s):  
L. A. Giannuzzi ◽  
C. A. Lewinsohn ◽  
C. E. Bakis ◽  
R. E. Tressler
Keyword(s):  
Silicon Carbide ◽  
Creep Rate ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Primary Creep ◽  
Excess Carbon ◽  
Silicon Carbide Fibers ◽  
Sic Fiber ◽  
Carbon Core ◽  
Grain Width

The SCS-6 SiC fiber is a 142 μm diameter fiber consisting of four distinct regions of βSiC. These SiC regions vary in excess carbon content ranging from 10 a/o down to 5 a/o in the SiC1 through SiC3 region. The SiC4 region is stoichiometric. The SiC sub-grains in all regions grow radially outward from the carbon core of the fiber during the chemical vapor deposition processing of these fibers. In general, the sub-grain width changes from 50nm to 250nm while maintaining an aspect ratio of ~10:1 from the SiC1 through the SiC4 regions. In addition, the SiC shows a <110> texture, i.e., the {111} planes lie ±15° along the fiber axes. Previous has shown that the SCS-6 fiber (as well as the SCS-9 and the developmental SCS-50 μm fiber) undergoes primary creep (i.e., the creep rate constantly decreases as a function of time) throughout the lifetime of the creep test.

Sputter‐etched Silicon Carbide by AES

1994 ◽  
Vol 3 (3) ◽  
pp. 182-186
Author(s):  
June M. Epp
Keyword(s):  
Silicon Carbide ◽  
Etched Silicon

Modeling of silicon carbide chemical vapor deposition in a vertical reactor

1999 ◽  
Vol 61-62 ◽  
pp. 172-175 ◽  
Author(s):  
A.N. Vorob’ev ◽  
Yu.E. Egorov ◽  
Yu.N. Makarov ◽  
A.I. Zhmakin ◽  
A.O. Galyukov ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor

Mechanical behaviour of silicon-silicon carbide composites

1996 ◽  
Vol 16 (7) ◽  
pp. 703-712 ◽  
Author(s):  
E. Scafè ◽  
G. Giunta ◽  
L. Fabbri ◽  
L. Di Rese ◽  
G. De Portu ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Mechanical Behaviour ◽  
Silicon Silicon

Fracture behavior of 3-d Braided Nicalon/Silicon Carbide Composite

1988 ◽  
Vol 120 ◽  
Author(s):  
J.-M. Yang ◽  
J.-C. Chou ◽  
C. V. Burkland
Keyword(s):  
Fracture Toughness ◽  
Silicon Carbide ◽  
Thermal Shock Resistance ◽  
Fracture Behavior ◽  
Ceramic Composite ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Fiber Architecture ◽  
Structural Ceramic ◽  
Shock Resistance

AbstractThe fracture behavior of a 3-D braided Nicalon fiber-reinforced SiC matrix composite processed by chemical vapor infiltration (CVI) has been investigated. The fracture toughness and thermal shock resistance under various thermomechanical loadings have been characterized. The results obtained indicate that a tough and durable structural ceramic composite can be achieved through the combination of 3-D fiber architecture and the low temperature CVI processing.

Sign in / Sign up

Export Citation Format

Share Document