Chemical vapour deposition of SiC and some of its properties

Motojima, Seiji; Yagi, Hideki; Iwamori, Noriyuki

doi:10.1007/bf01671419

Cited by 21 publications

(8 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…21 Si-H-containing PSZs were also crosslinked using organoaluminum derivatives.424 '425 In addition, HMDZ426 and l,3,5-trimethyl-l,3,5-tri-vinylcyclotrisilazane427-429 have been investigated as ceramic precursors, and ceramic films have been reported from hexachlorodisilane. 430 The high molecular weight linear polymers prepared by Soum and co-workers348'349 431 by anionic or cationic ring-opening polymerization of cyclodisilazanes gave high char yields in the case of vinylsubstituted precursors. Treatment of PSZs, obtained from disilane residues, with NaNEL in liquid ammonia has led to useful preceramic polymers,432 and PSs containing permethylsilazane and cyclodisilazane units were prepared by sodium polycondensation.…”

Section: Psz Resinsmentioning

confidence: 98%

Comprehensive Chemistry of Polycarbosilanes, Polysilazanes, and Polycarbosilazanes as Precursors of Ceramics

Birot¹,

Pillot²,

Dunoguès³

1995

Chem. Rev.

501

324

View full text Add to dashboard Cite

Section: Psz Resinsmentioning

confidence: 98%

Comprehensive Chemistry of Polycarbosilanes, Polysilazanes, and Polycarbosilazanes as Precursors of Ceramics

Birot¹,

Pillot²,

Dunoguès³

1995

Chem. Rev.

501

324

View full text Add to dashboard Cite

“…The reaction rate constant is given by k1 = k ~ exp (-EA/RT) [5] with k ~ = 262 cm/s and EA = 120 k J/mole, a typical value for thermal decomposition of hydrocarbons. The boundary conditions in the pore are given by C* (r*, z* = 0) = 1, T*g(r*,z*=0)= 1 [6] 0T*g aC* (r*, z* 1) = 0,…”

Section: Mtms D~176 T Ot*mentioning

confidence: 99%

“…At the boundary between regions 1 and 2, equality of concentration and temperature as well as of heat and mass fluxes is enforced. During densification, region 1 continuously decreases necessitating the periodic elimination of computational elements along with remeshing and reinterpolation of the [2], and [6][7][8][9][10][11][12], even for the isothermal situation. Given the boundary conditions and the deforming shape of the domain, Galerkin's finite element method coupled with an explicit time-integration scheme is used.…”

Section: Mtms D~176 T Ot*mentioning

confidence: 99%

“…AS a result and more recently, trichloromethylsilane (TMS) has been extensively used as a single source for the production of SiC matrices in a range of temperatures (600~176 In a typical CVl operation, dry carbon preforms are predensified in a CVD reactor by pyrocarbon in order to achieve 0.25-0.40 residual porosity. The preforms currently used in laboratory scale are usually cylindrical with diameter of 8-25 mm, height of 2-20 mm, and pore diameters ranging between i and 100 p.m (2,3,6).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Densification of Porous Materials by Chemical Vapor Infiltration

Gupte

Tsamopoulos

1989

J. Electrochem. Soc.

View full text Add to dashboard Cite

A mathematical model that describes the combined diffusion and reaction of trichloromethylsilane in a porous preform under typical chemical vapor infiltration (CVI) conditions is presented. The model utilizes a single pore to demonstrate the importance of the pore geometry, totalgaseous pressure, temperature, and imposed temperature gradient on the degree of achieved densification. By focusing attention on a single pore, it is possible to account for changes in the pore shape that occur during deposition of silicon carbide on the pore boundaries. Process conditions for operation in the reaction-controlled regime in order to attain complete densification are quantitatively identified even for the longer pores and the relatively higher temperatures used.Composite materials are becoming increasingly important in the aerospace, automobile, nuclear, solar energy, and manufacturing industries. Carbon fibers imbedded in a carbon matrix exhibit significant advantages, including low density to strength ratio, and excellent behavior towards friction and ablation at even high temperatures. Moreover, the use of multidirectional reinforcement leads to a quasi-isotropic behavior. However, carbon-carbon composites exhibit a few drawbacks, most important of which is their poor resistance towards oxidation at relatively low temperatures (500~176 On the other hand, monolithic ceramics (silicon carbide, silicon nitride, alumina) combine good strength and resistance to oxidation. Their main disadvantage is their sensitivity to crack propagation and poor resistance to mechanical and thermal shocks. In order to combine the advantages of both classes of materials and overcome their weaknesses, it has been suggested to even partially replace the carbon matrix, by a refractory material. More specifically, silicon carbide (SIC) and titanium carbide (TIC) are compatible with carbon and have improved mechanical properties and good oxidation resistance at high temperatures due to a protective oxide formed on their surfaces (1-3).Typical fabrication stages of fiber-reinforced ceramics include, among others, extrusion, hot-pressing, and sintering. However, during these processes the fibers may be chemically or mechanically damaged and the final product is often not of high purity but of high porosity. A most promising alternative is to subject a fibrous preform of the desired shape to the comparatively low-stress and lowtemperature process of chemical vapor infiltration (CVI) of appropriate chemical precursors and subsequent deposition of the desired product on the fibers until complete densification is achieved. Extreme care must be taken so that the deposition process is uniform and complete filling of the voids is achieved, rather than simple overcoating. To this end, the combined diffusion and reaction process must be limited by the chemical reaction allowing for indepth diffusion. Due to this requirement, the overall process is extremely slow and 300-600h of operation have been required for the full densification of laboratory-scale sampl...

show abstract

“…Considering that other research concerning the mechanical properties of ZrC showed hardness values in the range of 25 GPa and elastic moduli of approximately 355 GPa, our structure possessed a higher hardness and lower elastic modulus. The reason for this result is considered to be due to the deposited substrate, the different compositions, and roughness of the deposited ZrC [22,23]. In particular, by comparing the mechanical properties obtained at the various temperatures, the ZrC films deposited at 1500 1C, which have the best stoichiometric composition and the smoothest roughness, demonstrated a maximum hardness of 44 GPa.…”

Section: Resultsmentioning

confidence: 97%