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1.
《Journal of the European Ceramic Society》1999,19(13-14):2285-2296
The creep behavior of SiC/C/SiC microcomposites at 1200–1400 °C and 140–450 MPa was investigated in the presence and absence of matrix cracking. The microcomposites consisted of single Hi Nicalon or Carborundum fibers coated with a CVD carbon interlayer and a CVD SiC matrix. Since the fibers and matrix had been examined by the identical experimental technique, direct comparisons of the creep of the composite and of the constituents were performed. The creep of uncracked microcomposites was successfully modeled using a simple rule of mixtures algorithm. When matrix cracks were present, the microcomposites were modeled using a series composite consisting of intact microcomposite, exposed fiber at the matrix crack, and the debonded region in between. Trends for behavior with respect to the various mechanical and structural parameters that control creep are presented. 相似文献
2.
《Journal of the European Ceramic Society》1999,19(9):1789-1793
A SiC–AlN composite was fabricated by mechanical mixing of SiC and AlN powders, hot pressed under 40 MPa at 1950°C in Ar atmosphere. The object of this attempt was to achieve full density and a little solid solution formation. Fine microstructure and crack deflection behaviour are to improve the mechanical properties of the SiC–AlN composite. The bending strength and fracture toughness were achieved 800 MPa and 7·6 MPa m1/2 at room temperature, respectively. The fracture toughness of the SiC–AlN composite shows minimal change between room temperature and 1400°C. Post-HIP improves the surface densification of the SiC–AlN composite resulting in an increase of the strength and the ability to resist oxidization. The bending strength of SiC–AlN composite increases from 800 to 1170 MPa after HIP treatment for 1 h under 187 MPa at 1700°C in N2 atmosphere. 相似文献
3.
《Ceramics International》2017,43(13):9934-9940
Continuous silicon carbide fiber–reinforced silicon carbide matrix (SiCf/SiC) composites have developed into a promising candidate for structural materials for high–temperature applications in aerospace engine systems. This is due to their advantageous properties, such as low density, high hardness and strength, and excellent high temperature and oxidation resistance. In this study, SiCf/SiC composites were fabricated via polymer infiltration and pyrolysis (PIP) with the lower–oxygen–content KD–II SiC fiber as the reinforcement; a mixture of 2,4,6,8–tetravinyl–2,4,6,8–tetramethylcyclotetrasiloxane (V4) and liquid polycarbosilane (LPCS), known as LPVCS, was used as the precursor; while pyrolytic carbon (PyC) was used as the interface. The effects of oxidation treatment at different temperatures on morphology, structure, composition, and mechanical properties of the KD–II SiC fibers, SiC matrix from LPVCS precursor conversion, and SiCf/SiC composites were comprehensively investigated. The results revealed that the oxidation treatment greatly impacted the mechanical properties of the SiC fiber, thereby significantly influencing the mechanical properties of the SiCf/SiC composite. After oxidation at 1300 °C for 1 h, the strength retention rates of the fiber and composite were 41% and 49%, respectively. In terms of the phase structure, oxidation treatment had little effect on the SiC fiber, while greatly influencing the SiC matrix. A weak peak corresponding to silica (SiO2) appeared after high–temperature treatment of the fiber; however, oxidation treatment of the matrix led to the appearance of a very strong diffraction peak that corresponds to SiO2. The analysis of the morphology and composition indicated cracking of the fiber surface after oxidation treatment, which was increasingly obvious with the increase in the oxidation treatment temperature. The elemental composition of the fiber surface changed significantly, with drastically decreased carbon element content and sharply increased oxygen element content. 相似文献
4.
《Journal of the European Ceramic Society》1999,19(12):2155-2163
This work summarises the influence of the original particle-size of the SiC powder on the mechanical properties of silicon infiltrated SiC (SiC-Si) composite. These composites are based on a defined SiC particle-size structure. Using α-SiC powders with a mean particle-size of 12·8, 6·4, 4·5 and 3 μm, a clear linear enhancement of the bending strength with decrease of SiC-particle-size was observed. However, a further decrease of the SiC particle-size (from 3 to 0·5 μm) brought no increase of the strength and toughness, respectively. © 相似文献
5.
《Ceramics International》2020,46(7):9225-9232
Corundum–mullite–SiC composites were synthesised using a carbothermal reduction method. The effects of SiC nanoparticles and sintering temperatures on the phase transformation of the composites and the synthesis of SiC whiskers were studied by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Results indicated that corundum, mullite, and SiC whiskers were produced as final products at 1600–1650 °C. SiC whiskers were formed through the vapor–solid mechanism. The added SiC nanoparticles worked as nucleating agents to facilitate the carbothermal reduction of aluminosilicates and formation of SiC whiskers. The sample with the added SiC nanoparticles exhibited a high yield of β-SiC of 17.1%. Furthermore, the SiC nanoparticles decreased the formation temperature of SiC whiskers from the original 1600 °C to 1500 °C, and the porosity of the composites was increased from 56.7% to 64.7% by increasing the partial pressure of SiO gas. This study provides an insight into the more efficient synthesis of composites with SiC whiskers through the carbothermal reduction of aluminosilicates. 相似文献
6.
Soheila Faraji Afidah Abdul Rahim Norita Mohamed Coswald Stephen Sipaut 《Journal of Coatings Technology and Research》2012,9(1):115-124
In this work, Cu–P–SiC composite coatings were deposited via electroless plating with the addition of sodium hypophoshite
(NaH2PO2) as a reducing agent. The coating compositions deposited were determined by using energy dispersive X-ray spectroscopy (EDX).
The surface morphology of the coatings that were analyzed using scanning electron microscopy (SEM) showed that SiC particles
were uniformly distributed by virtue of surfactant addition and mechanical stirring. The anti-corrosion properties of Cu–P
and Cu–P–SiC coatings in NaCl and HCl solutions were investigated by the weight loss and potentiodynamic polarization techniques.
The results showed that the corrosion resistance of Cu–P–SiC coatings was superior to that of electroless Cu–P coatings and
carbon steel substrates in various concentrations of NaCl and HCl solutions. 相似文献
7.
《Journal of the European Ceramic Society》2002,22(13):2357-2363
Silicon carbide green bodies with and without carbon-fibre reinforcement have been infiltrated with MoSi2–Si–X in order to produce high-temperature resistant materials. X is Cr, Ti, Al or B respectively. By adding silicon and one of these components to MoSi2 the melting point is lowered dramatically. The composites therefore could be gained by melt infiltration at max. 1600 °C. During infiltration the additives react within the infiltrated body with carbon or silicon to form high-temperature resistant carbides or silicides. Thermodynamic calculations have been performed to analyse the reactions during infiltration. The infiltration parameters have been studied with respect to the resulting microstructure and properties. By fitting the amount of additives to the quantity of carbon in the SiC-body (or vice versa) no decrease in strength could be observed up to 1500 °C. The fracture toughness can be increased by the use of high-modulus carbon fibres. The most promising X-element for a high-temperature resistant material is titanium. 相似文献
8.
Sandan Kumar Sharma B. Venkata Manoj Kumar Kwang-Young Lim Young-Wook Kim S.K. Nath 《Ceramics International》2014
Dense silicon carbide (SiC) ceramics were prepared with 0, 10, 30 or 50 wt% WC particles by hot pressing powder mixtures of SiC, WC and oxide additives at 1800 °C for 1 h under a pressure of 40 MPa in an Ar atmosphere. Effects of alumina or SiC erodent particles and the WC content on the erosion performance of sintered SiC–WC composites were assessed. Microstructures of the sintered composites consisted of WC particles distributed in the equi-axed grain structure of SiC. Fracture surfaces showed a mixed mode of fracture, with a large extent of transgranular fracture observed in SiC ceramics prepared with 30 wt% WC. Crack bridging by WC enhanced toughening of the SiC ceramics. A maximum fracture toughness of 6.7 MPa*m1/2 was observed for the SiC ceramics with 50 wt% WC, whereas a high hardness of 26 GPa was obtained for the SiC ceramics with 30 wt% WC. When eroded at normal incidence, two orders of magnitude less erosion occurred when SiC–WC composites were eroded by alumina particles than that eroded by SiC particles. The erosion rate of the composites increased with increasing angle of SiC particle impingement from 30° to 90°, and decreased with WC reinforcement up to 30 wt%. A minimum erosion wear rate of 6.6 mm3/kg was obtained for SiC–30 wt% WC composites. Effects of mechanical properties and microstructure on erosion of the sintered SiC–WC composites are discussed, and the dominant wear mechanisms are also elucidated. 相似文献
9.
Gabriella Roventi Tiziano Bellezze Romeo Fratesi 《Journal of Applied Electrochemistry》2013,43(8):839-846
Zn–SiC composite coatings were obtained on mild steel substrate by electrodeposition technique with high-current efficiency. A slightly acidic chloride bath, containing SiC nanoparticles and gelatine as additive, was used. The electrodeposition was carried out under galvanostatic control with pulsed direct current; the effect of experimental parameters (temperature, average current density and particles concentration) on composition, morphology and structure of the deposit was studied. Coatings were characterized by means of scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffractometry and Vickers microhardness measurements. Zn–SiC electrodeposits with the best characteristics were obtained by performing electrodepositions at 45 °C, with 20 g L?1 SiC in the bath and with average current density in the range 100–150 mA cm?2. Under these experimental conditions, homogeneous and compact coatings, with low-grain size and SiC content ranging from 1.7 to 2.1 wt%, were found to be electrodeposited. Microhardness measurements showed for these deposits an increase of about 50 % with respect to those without nanoparticles obtained in the same experimental conditions. 相似文献
10.
《Ceramics International》2020,46(10):16249-16256
In this study, silicon carbide-lanthanum hexaboride (SiC–LaB6) and silicon carbide–lanthanum hexaboride–zirconium boride (SiC–LaB6–ZrB2) ceramics were fabricated by spark plasma sintering at 1900 °C, and their ablation resistance was tested under plasma flames over 2300 °C. The results indicate that the SiC–LaB6–ZrB2 ceramic exhibits better ablation resistance than the SiC–LaB6 ceramic. After ablation under the plasma flame for 60 s, the mass and linear ablation rates of the SiC–LaB6 ceramic were 15.83 μg/s and 1.08 μm/s, respectively, while those of SiC–LaB6–ZrB2 were -8.42 μg/s and -0.27 μm/s. With the addition of ZrB2, SiC–LaB6–ZrB2 ceramic attained a high density and fewer inner oxygen diffusion channels. Moreover, the ZrO2–La2O3–SiO2 oxide scale with good self-healing ability and excellent stability was formed in the ablation centre, which can retard the further oxidation during ablation. 相似文献
11.
The literature suggests that MgAl2O4 can accelerate SiC oxidation in Al2O3–MgAl2O4–SiC–C refractory castables. Thus, in this work thermodynamic calculations have been carried out using FactSage® software in order to explore, search for and understand the role of MgAl2O4 on the SiC oxidation. According to the thermodynamic predictions, at 1500 °C and under a reducing atmosphere, there is no evidence that spinel might directly affect SiC oxidation. The increase of SiC content in an Al2O3–SiC–C (AL) castable composition was mainly related to the reaction between mullite and carbon. On the other hand, the SiC generation in the Al2O3–MgAl2O4–SiC–C (SP) composition was a result of the reaction involving liquid SiO2 and carbon from the refractory. Therefore, the lower SiC content in the SP castable resulted from the refractory's phase transformations. It was also suggested that the samples thermally treated 15 times at 1500 °C did not reach the equilibrium condition, which explains the differences between experimental and thermodynamic results. 相似文献
12.
《Ceramics International》2020,46(1):156-164
Spark plasma sintering (SPS) route was employed for preparation of quadruplet ZrB2–SiC–ZrC–Cf ultrahigh temperature ceramic matrix composites (UHTCMC). Zirconium diboride and silicon carbide powders with a constant ZrB2:SiC volume ratio of 4:1 were selected as the baseline. Mixtures of ZrB2–SiC were co-reinforced with zirconium carbide (ZrC: 0–10 vol%) and carbon fiber (Cf: 0–5 vol%), taking into account a constant ratio of 2:1 for ZrC:Cf components. The sintered composite samples, processed at 1800 °C for 5 min and 30 MPa punch press under vacuumed atmosphere, were characterized by densitometry, field emission scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry as well as mechanical tests such as hardness and flexural strength measurements. The results verified that the composite co-reinforced with 5 vol% ZrC and 2.5 vol% Cf had the optimal characteristics, i.e., it reached a relative density of 99.6%, a hardness of 18 GPa and a flexural strength of 565 MPa. 相似文献
13.
Yuan Tian Xin Long Changwei Shao Yingde Wang 《Journal of the American Ceramic Society》2023,106(3):1981-1992
Continuous ceramic fibers with ultrahigh-temperature stability are in high demand for applications in advanced space propulsion and thermal protection systems. In this study, SiC nanograins stabilized Si–C–B–N ceramic fibers were prepared using chemically modified polyborosilazane via a polymer-derived method. The fabricated Si–C–B–N fibers exhibited a rather high tensile strength of approximately 1.8 GPa and a high strength retention of approximately 90% after annealing at 2100°C for 0.5 h under a nitrogen atmosphere. The ultrahigh-temperature stability can be contributed to the presence of thermodynamically stable SiC nanograins and the encapsulation of SiC nanograins by the BN(C) phase and amorphous Si–C–B–N matrix. Our work offers a convenient strategy for preparing Si-based ceramic fibers with ultrahigh-temperature stability at beyond 2000°C. 相似文献
14.
The oxidation resistance of SiC–BN composites with different BN content hot-pressed from Si3N4, B4C and C was investigated. The oxidized products of SiC and BN were identified to be SiO2, C and B2O3, N2. SiO2 and B2O3 could further form a borosilicate glass which covered the surfaces of the samples and withstood oxidation because of its flowability and self-healing. The oxidation resistance of the SiC–BN composites in static air atmosphere deteriorated with the increase of temperature as well as of the BN content. 相似文献
15.
In the present study, the effect of SiC addition on properties of basalt base glass–ceramic coating was investigated. SiC reinforced glass–ceramic coating was realized by atmospheric air plasma spray coating technique on AISI 1040 steel pre-coated with Ni + 5 wt.%Al bond coat. Composite powder mixture consisted of 10%, 20% and 30% SiC by weight were used for coating treatment. Controlled heat treatment for crystallization was realized on pre-coated samples in argon atmosphere at 800 °C, 900 °C and 1000 °C which determined by differential thermal analysis for 1–4 h in order to obtain to the glass–ceramic structure. Microstructural examination showed that the coating performed by plasma spray coating treatment and crystallized was crack free, homogeneous in macro-scale and good bonded. The hardness of the coated samples changed between 666 ± 27 and 873 ± 32 HV0.01 depending on SiC addition and crystallization temperature. The more the SiC addition and the higher the treatment temperature, the harder the basalt base SiC reinforced glass–ceramic coating became. X-ray diffraction analysis showed that the coatings include augeite [(CaFeMg)–SiO3], diopside [Ca(Mg0.15Fe0.85)(SiO3)2], albite [(Na,Ca)Al(Si,Al)3O8], andesine [Na0.499Ca0.492(Al1.488Si2.506O8] and moissanite (SiC) phases. EDX analyses support the X-ray diffraction analysis. 相似文献
16.
《硅酸盐学报》2016,(9)
以煅烧铝矾土、棕刚玉、板状刚玉、鳞片石墨、碳化硅粉为原料,单质Si粉为添加剂,酚醛树脂为结合剂,制备出Al_2O_3–Si C–C耐火材料。研究了不同热处理温度对材料显微结构及性能的影响。结果表明:在埋碳条件下,1 000℃烧成后样品中有柱状莫来石物相生成;1 400℃烧成后柱状莫来石长径比增大,同时还有Si C晶须生成。热处理温度从1 000℃升高到1 400℃时,样品显气孔率和常温耐压强度变化不明显,但常温抗折强度提高54.73%,达到8.17 MPa,载荷位移量增大近20%。3次热震后残余耐压强度保持率从54.36%(200℃烧成后)提高到89.10%(1 400℃烧成后)。原位生成的Si C晶须和发育良好的柱状莫来石显著提高了样品常温抗折强度、断裂韧性和抗热震性。 相似文献
17.
通过在1680℃热压烧结,氮和氩2种气氛下制备了SiC–Si3N4–Y2O3陶瓷材料样品,并采用X射线衍射仪分析了样品的相组成。结果表明:在SiC–Si3N4–Y2O3样品的系统中,除了SiC和Si3N4共存外,还生成了Si3N4·Y2O3(M),Si2N2O·Y2O3(K)和Si2N2O·2Y2O3(J)相。SiC和Si3N4都分别同这3相共存。Si2N2O组分的引入使系统扩大成为SiC–Si3N4–Si2N2O–Y2O3四元系。在此四元系统中分别确定了3个相容性四面体,即,SiC–M–K–J,SiC–M–J–Y2O3,SiC–Si3N4–M–K(N2气氛)或SiC–Si3N4–M–J(Ar气氛)。随着样品中配置粉料的氧含量和高温氛围氧分压的影响,SiC和Si3N4将依含氧量由低到高的顺序M,K,J,Y2O3,分别有选择性地与三相处于平衡。提出了SiC–Si3N4–Y2O3三元系统和SiC–Si3N4–Si2N2O–Y2O3四元系统亚固相图。 相似文献
18.
《Journal of the European Ceramic Society》2000,20(14-15):2601-2606
The feasibility of synthesising AlN–SiC solid solution ceramics by combustion synthesis (CS) reaction is demonstrated through igniting the mixtures of aluminium, silicon and carbon black under different nitrogen pressure values. The effects of the nitrogen pressure and the atomic ratio of (Si+C)/Al on the crystalline phases formed in the reaction product and on the characteristics of combustion behaviour were investigated. Combining thermodynamic analysis and the combustion characteristics, the reaction sequence and the formation of AlN–SiC solid solution by CS were explained. 相似文献
19.
《Ceramics International》2001,27(2):123-133
The substantial densification, that occurred in the SiC–Al–Y–O system was explained in the present work by analysing possible chemical reactions and their dependence on initial particle associations, i.e. homogeneity of mixing, the physical and chemical state of additives, pressurised sintering environment over the reactants and temperature of sintering. Hydroxyhydrogel powder precursors were found to be better than mechanically mixed SiC–YAG powder and pre-forming of YAG by holding the specimens at the temperature of 1400°C for 2 h were found to be the best. Decomposition reactions within the system could be controlled by using finer SiC and applying gas pressure over the reactants. 相似文献
20.
《Journal of the European Ceramic Society》2003,23(1):1-8
The vaporization behaviour of pure Al2O3, Y2O3 and SiC as well as SiC–Al2O3 and SiC–Al2O3/Y2O3 mixtures has been analysed by thermodynamic calculations in an open system. Pure Al2O3 and Y2O3 evaporate congruently in the 1200–2300 K temperature range. Pure SiC vaporizes in a non-congruent manner leading to graphite formation as by-product. A SiC–Al2O3 mixture evaporates congruently according to the main vaporization reaction, 2 SiC(s) + Al2O3(s) +Al2O(g) ⇆ 2 SiO(g) + 2 CO(g) +4 Al(g), but the overall composition changes: for SiC rich samples, the mixture tends towards pure SiC in time, and for Al2O3 rich samples towards pure Al2O3. A SiC–Al2O3/Y2O3 mixture shows similar behaviour. 相似文献