共查询到20条相似文献,搜索用时 31 毫秒
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(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
3.
4.
《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
5.
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
6.
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
7.
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
8.
《Journal of the European Ceramic Society》2023,43(6):2376-2387
Chemical-vapor-infiltrated (CVI) SiC/SiC composites with Sylramic?-iBN SiC fibers and CVI carbon, BN, and a combination of BN/C interface coating were heat treated in 0.1-MPa argon or 6.9-MPa N2 at temperatures to 1800 °C for exposure times up to 100 hr. The effects of thermal treatment on constituent microstructures, in-plane tensile properties, in-plane and through-the-thickness thermal conductivities, and creep behavior of the composites were investigated. Results indicate that heat treatment affected stoichiometry of the CVI SiC matrix and interface coating microstructure, depending on the interface coating composition and heat treatment conditions. Heat treatment of the composites with CVI BN interface in argon caused some degradation of in-plane properties due to the decrease in interface shear strength, but it improved creep resistance significantly. In-plane tensile property loss in the composites can be avoided by modifying the interface composition and heat treatment conditions. 相似文献
9.
《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
10.
ZrB2–SiC composites were prepared by hot pressing with different sources of SiC to study the effect of SiC with different morphology on densification, microstructure, phase composition and mechanical properties like hardness, fracture toughness and tribological properties (namely, scratch resistance, wear parameters) and thermal behaviour of the composites. Three different ZrB2–SiC composites, i.e. ZrB2–SiCP (polycarbosilane derived SiC), ZrB2–SiCC (SiC from CUMI, India) and ZrB2–SiCH (SiC from H. C. Starck, Germany), were studied. It is found that ZrB2–SiCC composite shows highest hardness (19·13 GPa) and fracture toughness (5·30 MPa m1/2 at 1 kgf load) in comparison with other composites. Interconnected network, better contiguity between grains of ZrB2–SiC composites and impurity content in starting powders can play significant roles for achieving high mechanical, tribological and thermal properties of the composites. Coefficient of friction and wear parameters of all ZrB2–SiC composites are very low, and thermal conductivity of ZrB2–SiC composites varied from 52·71 to 65·53 W (m K)?1 (ZrB2–SiCP), 54·30 to 71·55 W (m K)?1 (ZrB2–SiCC) and 64·25 to 88·02 W (m K)?1 (ZrB2–SiCH), respectively and also calculate the interfacial resistance of all the composites. 相似文献
11.
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
12.
《Journal of the European Ceramic Society》2022,42(8):3383-3394
The influence of high-temperature argon heat-treatment on the microstructure and room- temperature in-plane tensile properties of 2D woven CVI and 2D unidirectional MI SiC/SiC composites with Hi-Nicalon?-S SiC fibers was investigated. The 2D woven CVI SiC/SiC composites were heat-treated between 1200 and 1600 °C for 1- and 100-hr, and the 2D unidirectional MI SiC/SiC composites between 1315 and 1400 °C for up to 2000 hr. In addition, the influence of temperature on fast fracture tensile strengths of these composites was also measured in air. Both composites exhibited different degradation behaviors. In 2D woven CVI SiC/SiC composites, the CVI BN interface coating reacted with Hi-Nicalon?-S SiC fibers causing a loss in fast fracture ultimate tensile strengths between 1200 and 1600 °C as well as after 100-hr isothermal heat treatment at temperatures > 1100 °C. In contrast, 2D unidirectional MI SiC/SiC composites showed no significant loss in in-plane tensile properties after the fast fracture tensile tests at 1315 °C. However, after isothermal exposure conditions from 1315° to 1400°C, the in-plane proportional limit stress decreased, and the ultimate tensile fracture strain increased with an increase in exposure time. The mechanisms of strength degradation in both composites are discussed. 相似文献
13.
Dan Zhu Mingxia Gao Hongge Pan Yongfeng Liu Xiaodong Wang Yi Pan Filipe J. Oliveira Joaquim M. Vieira 《Ceramics International》2013,39(4):3831-3842
A reactive infiltration processing of SiC/Fe–Si composites using preforms made of coked rice husks (RHs) and SiC powder in different ratios is reported, in which FeSi2 alloy was used as infiltrant. The preforms were heat-treated at 1550 °C for 6 h prior to the infiltration. The coked RHs, which are composed of SiO2 and C, were converted to SiC and poorly crystallized C by carbothermal reduction during the heat treatment. The study of the microstructure and mechanical properties of the composites shows that molten Fe–Si alloy had good wetting of the heat-treated preforms and adequate infiltration properties. Free carbon in the preform reacted with Si in the molten FeSi2 during infiltration forming new SiC, the composition of the intermetallic liquid being moved towards that of FeSi. As a result, the infiltrated composites are composed of SiC, FeSi2 and FeSi phases. Vickers hardness, elastic modulus, three-point flexural strength and indentation fracture toughness of the composites are found to increase with SiC additions up to 30% w/w in the preforms, reaching the values of 18.2 GPa, 290 GPa, 213 MPa and 4.9 MPa m1/2, respectively. With the SiC addition further raised to 45% w/w, the elastic modulus, flexural strength and fracture toughness of the composite turned down probably due to high residual stress and hence the more intense induction of microcracks in the composite. De-bonding of SiC particles pulled out of the Fe–Si matrix, transgranular fracture of part of the SiC particles and in the Fe–Si matrix, and crack bridging all exist in the fracture process of the composites. 相似文献
14.
《Ceramics International》2016,42(10):11611-11618
SiC crystal growth using the top seeded solution growth (TSSG) method involves the precipitation of solid SiC from carbon that is dissolved in a silicon melt. The growth rate of SiC is strongly influenced by the solubility of C in liquid Si, which is quite low. In this study, the dissolution of C from graphite to the Si melt was explored by observing the formation of an SiC interlayer at a graphite – Si liquid interface. The SiC interlayer was observed to become thickened during the several hours needed to reach a certain thickness at 1500 °C. Assuming that the SiC interlayer is a direct C source, a pre-formed SiC layer was coated on the graphite crucible to evaluate its effect on the concentration of C in the Si melt. As a result, the concentration of C in the Si melt increased within a short time, especially at low temperatures. By applying the SiC coated crucible to the TSSG process for SiC crystal growth, we confirmed that the development of a pre-formed SiC layer enhanced the growth rate of SiC crystals, especially at the initial stage of crystal growth at low temperatures. 相似文献
15.
Continuous SiC fiber reinforced SiC matrix composites (SiC/SiC) have been considered as candidates for heat resistant and nuclear materials. Three-dimensional (3D) SiC/SiC composites were fabricated by the polymer impregnation and pyrolysis (PIP) method with a consolidation process, mechanical properties of the composites were found to be significantly improved by the consolidation process. The SiC/SiC composites were then heat treated at 1400 °C, 1600 °C and 1800 °C in an inert atmosphere for 1 h, respectively. The effect of heat treatment temperature on the mechanical properties of the composites was investigated, the mechanical properties of the SiC/SiC composites were improved after heat treatment at 1400 °C, and conversely decreased with increased heat treatment temperature. Furthermore, the effect of heat treatment duration on the properties of the SiC/SiC composites was studied, the composites exhibited excellent thermal stability after heat treatment at 1400 °C within 3 h. 相似文献
16.
《Ceramics International》2019,45(16):20155-20164
In this paper, Ni–SiC nanocomposites were deposited on Q235 steel substrates by magnetic pulse electrodeposition (MPED) technique. Microstructures, compositions and microhardness values of obtained composites were determined by scanning electron microscopy (SEM), scanning probe microscopy (SPM), X-ray diffraction (XRD), and triboindenter in-situ nanomechanical testing. Results showed S-30 nanocomposites with fine, compact and uniform structures consisting of fine nickel grains (average size: 381.7 nm) and SiC nanoparticles (average size: 34.2 nm). For SiC particle size of 30 nm, diffraction peaks of Ni and SiC appeared wide with low intensity, indicating S-30 nanocomposites with small sized Ni grains and SiC nanoparticles. Largest TiN content reaching 10.59 wt% was embedded in S-30 nanocomposites prepared at SiC particle size of 30 nm. Final depths of S-30 and S-200 composites were estimated to 15.1 μm and 24.8 μm, respectively. Wear and corrosion properties of Ni–SiC nanocomposites were then investigated. After corrosion testing for 24 h, the weight losses of S-200, S-80 and S-30 composites were recorded as 1.67, 1.44 and 0.95 mg, respectively. Under the same wear experimental conditions, S-200 composite presented the highest mass loss while S-80 composites displayed the lowest mass loss. By comparison, wear mass loss of S-30 nanocomposites was only 37.1 mg. 相似文献
17.
《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
18.
《应用陶瓷进展》2013,112(3):166-173
Polymeric liquid ceramic precursors for the production of multi-component ZrC–SiC ceramics were prepared by reactive blending of polyzirconoxanesal, phenylacetylene-terminated polysilane and bisphenol-A type benzoxazine. The polymeric liquid precursors of ZrC–SiC ceramic have the processing capability of Precursor-Infiltration-and-Pyrolysis technique in ceramic composites fabrication. The thermal cure reactions included by the catalytic polymerisation of ethynyl groups, the ring opening polymerisation of benzoxazine rings, and the condensation of zirconate with phenolic hydroxyl and Si–H at 200–350°C. The monolithic ceramics were formed upon pyrolysis at 1000, 1200 and 1600°C in a yield of 65, 62 and 40%, respectively. X-ray diffraction and SEM–EDS results revealed that almost pure, elemental, uniformly distributed ZrC–SiC multi-component ceramic monolith was obtained through pyrolysis at 1600°C via carbothermal reduction of ZrO2. 相似文献
19.
MoSi2–25 wt.%SiC nanocomposite powder was successfully synthesized by ball milling Mo, Si and graphite powders. The effect of milling time and annealing temperature were investigated. Changes in the crystal structure and powder morphology were monitored by XRD and SEM, respectively. The microstructure of powders was further studied by peak profile analysis and TEM. MoSi2 and SiC were synthesized after 10 h of milling. Both high and low temperature polymorphs (LTP and HTP) of MoSi2 were observed at the short milling times. Further milling led to the transformation of LTP to HTP. On the other hands, an inverse HTP to LTP transformation took place during annealing of 20 h milled powder at 900 °C. Results of peak profile analysis showed that the mean grain size and strain of the 20 h milled powder are 31.8 nm and 1.19% that is in consistent with TEM image. 相似文献
20.
Xin Qi Xudong Luo Ling Zhang Shaoyang Wang Jialiang Zhao 《International Journal of Applied Ceramic Technology》2022,19(5):2723-2733
Adding SiC directly to MgO–C refractories possesses the disadvantages of low dispersion and interfacial bonding strength. Herein, the in situ synthesized SiC was introduced into the MgO–SiC–C refractories to maintain the original excellent performance of MgO–C refractories and reduce the carbon dissolution in molten steel. With the increase of Si and C content in raw materials, the morphology of SiC changed from whisker to network, whose growth mechanism was vapor–solid and vapor–liquid–solid. The network structure and uniform distribution of SiC improved the thermal shock resistance of MgO–SiC–C refractories. According to the analysis of molecular dynamics simulation by Materials Studio software, SiC strengthened the relationship between periclase and graphite to enhance the structure of the compound. 相似文献