共查询到20条相似文献,搜索用时 15 毫秒
1.
《Journal of the European Ceramic Society》2017,37(14):4297-4306
Al2O3/SiC composites containing different volume fractions (3, 5, 10, 15, and 20 vol%) of SiC particles were produced by conventional mixing of alumina and silicon carbide powders, followed by hot pressing at 1740 °C for 1 h under the pressure of 30 MPa in the atmosphere of Ar. The influence of the volume fraction and size of SiC particles (two different powders with the mean size of SiC particles 40 and 200 nm were used), and final microstructure on mechanical properties and dry sliding wear behaviour in ball-on-disc arrangement were evaluated. The properties of the composites were related to a monolithic Al2O3 reference. Microstructure of the composites was significantly affected by the volume fraction of added SiC, with the mean size of alumina matrix grains decreasing with increasing content of SiC particles. The addition of SiC moderately improved the Vickers hardness. Fracture toughness was lower with respect to monolithic Al2O3, irrespective of the volume fraction and size of SiC particles. Al2O3/SiC nanocomposites conferred significant benefits in terms of wear behaviour under the conditions of mild dry sliding wear. Wear resistance of the alumina reference was poor, especially at the applied load of 50 N. The wear rates of composites markedly decreased with increasing volume fraction of SiC. Wear of the composites was also influenced by the material of counterparts, especially their hardness, with softer counterparts resulting in lower wear rates. All composites wore by a combination of grain pull-out with plastic deformation associated with grooving and small contribution of mechanical wear (micro-fracture). No influence of SiC particle size on wear rate or mechanism of wear was observed in the materials with identical volume fractions of SiC. 相似文献
2.
《Journal of the European Ceramic Society》2006,26(7):1273-1279
Dry ceramic block-on-steel ring wear tests were performed at high loads in several Al2O3/20 vol.% SiC composites as a function of the SiC grain size, which ranged from 0.2 to 4.5 μm in d50. The wear resistance of the monolithic alumina was radically improved by the addition of the SiC particles, reducing down to one order of magnitude wear rate. Two different behaviours were identified according to the microstructural observations on the worm surfaces: intergranular fracture and grain pull-out in the monolithic Al2O3, and plastic deformation and surface polishing in the composites. The wear resistance of the Al2O3/SiC composites increased with the SiC grain size due to their fracture toughness enhancement. 相似文献
3.
《Journal of the European Ceramic Society》2004,24(10-11):3279-3284
The friction and wear behavior of self-mated Si3N4, SiC and Al2O3 in water were investigated by varying the test conditions of applied load and sliding speed. It was found that, for self-mated Si3N4 and SiC ceramics, the tribochemical reaction resulted in surface smoothening with low friction coefficient at high load and high speed condition. Al2O3 shows high friction coefficient, but better wear rate (10−11 mm2/N) than other ceramic materials. 相似文献
4.
《Ceramics International》2017,43(11):8411-8417
The effect of nano-sized carbon black on densification behavior, microstructure, and mechanical properties of zirconium diboride (ZrB2) – silicon carbide (SiC) ceramic was studied. A ZrB2-based ceramic matrix composite, reinforced with 20 vol% SiC and doped with 10 vol% nano-sized carbon black, was hot pressed at 1850 °C for 1 h under 20 MPa. For comparison, a monolithic ZrB2 ceramic and a ZrB2–20 vol% SiC composite were also fabricated by the same processing conditions. By adding 20 vol% SiC, the sintered density slightly improved to ~93%, compared to the relative density of ~90% of the monolithic one. However, adding 10 vol% nano-sized carbon black to ZrB2–20 vol% SiC composite meaningfully increased the sinterability, as a relatively fully dense sample was obtained (RD=~100%). The average grain size of sintered ZrB2 was significantly affected and controlled by adding carbon black together with SiC acting as effective grain growth inhibitors. The Vickers hardness, flexural strength and fracture toughness of SiC reinforced and carbon black doped composites were found to be remarkably higher than those of monolithic ZrB2 ceramic. Moreover, unreacted carbon black additives in the composite sample resulted in the activation of some toughening mechanisms such as crack deflections. 相似文献
5.
Manish Patel V.V. Bhanu Prasad Vikram Jayaram 《Journal of the European Ceramic Society》2013,33(10):1615-1624
Thermal diffusivity and conductivity of hot pressed ZrB2 with different amounts of B4C (0–5 wt%) and ZrB2–SiC composites (10–30 vol% SiC) were investigated experimentally over a wide range of temperature (25–1500 °C). Both thermal diffusivity and thermal conductivity were found to decrease with increase in temperature for all the hot pressed ZrB2 and ZrB2–SiC composites. At around 200 °C, thermal conductivity of ZrB2–SiC composites was found to be composition independent. Thermal conductivity of ZrB2–SiC composites was also correlated with theoretical predictions of the Maxwell–Eucken relation. The dominated mechanisms of heat transport for all hot pressed ZrB2 and ZrB2–SiC composites at room temperature were confirmed by Wiedemann–Franz analysis by using measured electrical conductivity of these materials at room temperature. It was found that electronic thermal conductivity dominated for all monolithic ZrB2 whereas the phonon contribution to thermal conductivity increased with SiC contents for ZrB2–SiC composites. 相似文献
6.
Al2O3–SiC micro–nanocomposites are much more resistant materials than monolithic alumina regarding some mechanical properties. In order to study the possibility of obtaining creep resistant alumina/SiC micro–nanocomposites using inexpensive forming methods, alumina 1 and 5 vol% SiC materials were produced by slip-casting and pressureless sintering. Well-densified alumina–SiC pressureless sintered materials were obtained at 1700 °C for 2 h and attained 97–99% of the theoretical density. The microstructure, hardness and toughness were examined and 4-point flexure creep tests were performed at 1200 °C and 100 MPa in air. Compared with pure alumina materials, the creep resistance, toughness and hardness were enhanced drastically in materials containing 5 vol% of SiC. 相似文献
7.
Babak Mohammadpour Zohre Ahmadi Mohammadreza Shokouhimehr Mehdi Shahedi Asl 《Ceramics International》2019,45(4):4262-4267
This research presents the influence of Al addition on microstructure and mechanical behavior of ZrB2–SiC ultra-high temperature ceramic matrix composite (UHTCMC) fabricated by spark plasma sintering (SPS). A 2.5?wt% Al-doped ZrB2–20?vol% SiC UHTCMC was produced by SPS method at 1900?°C under a pressure of 40?MPa for 7?min. The microstructural and phase analysis of the composite showed that aluminum-containing compounds were formed in-situ during the SPS as a result of chemical reactions between Al and surface oxide films of the raw materials (i.e. ZrO2 and SiO2 on the surfaces of ZrB2 and SiC particles, respectively). The Al dopant was completely consumed and converted to the intermetallic Al3Zr and Al4Si compounds as well as Al2O3 and Al2SiO5. A relative density of 99.8%, a hardness (HV5) of 21.5?GPa and a fracture toughness (indentation method) of 6.3?MPa?m1/2 were estimated for the Al-doped ZrB2–SiC composite. Crack bridging, branching, and deflection were identified as the main toughening mechanisms. 相似文献
8.
Zhihui Lü Dongliang Jiang Jingxian Zhang Qingling Lin Zhengren Huang 《Journal of the European Ceramic Society》2012,32(7):1435-1439
The oxidation behavior for ZrB2–20 vol% SiC (ZS20) and ZrB2–30 vol% SiC (ZS30) ceramics at 1500 °C was evaluated by weight gain measurements and cross-sectional microstructure analysis. Based on the oxidation results, laminated ZrB2–30 vol% SiC (ZS30)/ZrB2–25 vol% SiC (ZS25)/ZrB2–30 vol% SiC (ZS30) symmetric structure with ZS30 as the outer layer were prepared. The influence of thermal residual stress and the layer thickness ratio of outer and inner layer on the mechanical properties of ZS30/ZS25/ZS30 composites were studied. It was found that higher surface compressive stress resulted in higher flexural strength. The fracture toughness of ZS30/ZS25/ZS30 laminates was found to reach to 10.73 MPa m1/2 at the layer thickness ratio of 0.5, which was almost 2 times that of ZS30 monolithic ceramics. 相似文献
9.
Jaroslav Sedl
ek Duan Galusek Peter van
rek Ralf Riedel Alan Atkinson Xin Wang 《Journal of the European Ceramic Society》2008,28(15):2983-2993
The response of Al2O3, Al2O3–SiC–(C) and Al2O3–C nanocomposites to grinding was investigated in terms of changes of quality of ground surfaces and of the weight losses with time. The study used monolithic polycrystalline aluminas as references, and alumina-based composites with nanosized SiC and C inclusions and with alumina matrix grain size varying from submicrometer to approximately 4 μm. The studied materials can be roughly divided into two groups. Materials with submicrometer alumina matrix grains (Group 1) wear predominantly by plastic deformation and grooving. Coarse-grained materials (Group 2) wear by mixed wear mechanism involving crack initiation and interlinking accompanied by grain pull-out, plastic deformation and grooving. The wear rate of composites increases with increasing volume fraction of SiC. The Group 2 materials wear much faster then those with submicron microstructure. In all cases (with one exception) the wear resistance of composites was higher than that of pure aluminas of comparable grain sizes used as reference materials. 相似文献
10.
Gaoyuan Ouyang Pratik K Ray Matthew J Kramer Mufit Akinc 《Journal of the American Ceramic Society》2016,99(3):808-813
The effect of AlN substitution on oxidation of ZrB2–SiC was evaluated at 1600°C up to 5 h. Replacement of ZrB2 by AlN, with 30 vol% SiC resulted in improved oxidation resistance with a thinner scale and reduced oxygen affected area. On the other hand, substitution of AlN for SiC resulted in a deterioration of the oxidation resistance with an abnormal scale and significant recession. The effect of SiC content was also studied, and was found to be consistent with the literature for the composites without AlN additions. A similar effect was observed when AlN was added, with the higher SiC content materials showing improved oxidation resistance. X‐ray photoelectron spectroscopy showed the presence of Al2O3 and SiO2 on the surface, which could possibly lead to a modification in the viscosity of the glassy oxide scale. Possibly, the oxidation behavior of ZrB2–SiC composites can be improved with controlled AlN additions by adjusting the Al:Si ratios. 相似文献
11.
《Ceramics International》2023,49(5):7987-7995
Monolithic Al2O3 and Al2O3-graphene-SiC hybrid composites were prepared by spark plasma sintering (SPS) under vacuum atmosphere. The results show that the hybrid composites were almost completely dense (>97%). SiC content has a significant effect on the microstructure of the composites. With the increase of SiC content, the average grain size of alumina decreased gradually. The addition of SiC to alumina changed fracture mode from inter-granular fracture to mixed fracture mode of inter-granular fracture and trans-granular fracture. The Al2O3-0.4 wt%graphene-5 wt% SiC hybrid composite has the highest bending strength and hardness, which were 57% and 19.22% higher than those of the monolithic alumina, respectively. The room temperature (RT) thermal conductivity of the monolithic Al2O3 (25.5 W/m·K) was the highest. The thermal conductivity and thermal diffusivity coefficient of the composites decreased with the increase in temperature, while the specific heat of monolithic alumina and composites increased with the increase in temperature and additives. These properties were related to the microstructure of materials and the possible transport mechanisms were discussed. 相似文献
12.
B.V. Manoj KumarYoung-Wook Kim Dae-Soon LimWon-Seon Seo 《Ceramics International》2011,37(8):3599-3608
Fully densified SiC ceramics were developed from commercially available β-SiC powders using small amount (3 wt%) of AlN-Sc2O3 or AlN-Y2O3 additives by hot pressing at 2050 °C for 6 h in nitrogen atmosphere, and their wear properties were investigated by subjecting to self-mated sliding at different loads (1, 6 and 13 N) under unlubricated conditions. SiC ceramics prepared with 3 wt% AlN-Y2O3 additives consisted of mostly large equi-axed grains with amorphous grain boundary phase of ∼1.2 nm thickness, whereas SiC ceramics sintered with 3 wt% AlN-Sc2O3 additives showed duplex microstructure of elongated and fine equi-axed grains with clean grain boundary. As the load was increased, the steady state coefficient of friction reduced from ∼0.6 to ∼0.2, and wear rate increased from 10−6 to 10−5 mm3/N·m. It was observed that the friction did not depend on the additive composition, while less wear was observed for the SiC ceramics sintered with 3 wt% AlN-Sc2O3 additives consisting of clean grain boundary. The material loss was increased with the increased amount of sintering additive to 10 wt%. The worn surface morphology revealed that the material was primarily removed via surface grooving and microcracking at 1 N load, while tribochemical wear dominated at 6 and 13 N loads. 相似文献
13.
《Ceramics International》2016,42(3):4498-4506
The effects of processing variables on densification behavior of hot pressed ZrB2-based composites, reinforced with SiC particles and short carbon fibers (Csf), were studied. A design of experiment approach, Taguchi methodology, was used to investigate the characteristics of ZrB2–SiC–Csf composites concentrated upon the hot pressing parameters (sintering temperature, dwell time and applied pressure) as well as the composition (vol% SiC/vol% Csf). The analysis of variance recognized the sintering temperature and SiC/Csf ratio as the most effective variables on the relative density of hot pressed composites. The microstructural investigations showed that Csf can act as a sintering aid and eliminate the oxide impurities (e.g. B2O3, ZrO2 and SiO2) from the surfaces of raw materials. A fully dense composite was achieved by adding 10 vol% Csf and 20 vol% SiC to the ZrB2 matrix via hot pressing at 1850 °C for 30 min under a pressure of 16 MPa. Moreover, the in-situ formation of interfacial ZrC, which also improves the sinterability of ZrB2-based composites, was studied by energy-dispersive X-ray spectroscopy analysis and verified thermodynamically. 相似文献
14.
Derek S. King Jeremy L. Watts Kathleen S. Cissel Ali H. Kadhim Gregory E. Hilmas William G. Fahrenholtz 《Journal of the American Ceramic Society》2018,101(9):4331-4339
A silicon carbide‐based ceramic, containing 50 vol% SiC, 35 vol% ZrB2, and 15 vol% ZrC was plasma arc welded to produce continuous fusion joints with varying penetration depth. The parent material was preheated to 1450°C and arc welding was successfully implemented for joining of the parent material. A current of 138 A, plasma flow rate of ~1 L/min or ~0.5 L/min, and welding speed of ~8 cm/min were utilized for repeated joining, with full penetration fusion zones along the entire length of the joints. Solidification was determined to occur through the crystallization of β‐SiC (3C), then the simultaneous solidification of SiC and ZrB2, and lastly through the simultaneous solidification of SiC, ZrB2, and ZrC through a ternary eutectic reaction. The ternary eutectic composition was determined to be 35.3 ± 2.2 vol% SiC, 39.3 ± 3.8 vol% ZrB2, and 25.4 ± 3.0 vol% ZrC. A dual fusion zone microstructure was always observed due to convective melt pool mixing. The SiC content at the edge of the fusion zone was 57 vol%, while SiC content at the center of the fusion zone was 42 vol% although the overall SiC content was still nominally 50 vol% throughout the entire fusion zone. 相似文献
15.
《Journal of the European Ceramic Society》2023,43(13):5413-5424
The tribological behavior of ultra-high temperature ceramic matrix composites (UHTCMCs) was investigated to understand these materials in friction applications. Samples consisting of pitch-based randomly orientated chopped carbon fiber (CF) reinforced ZrB2-10 vol% SiC were prepared (ZS). The tribological behavior was tested on a self-designed dynamometer, coupling the UHTCMC pads with either carbon fiber reinforced carbon−silicon carbide (C/C-SiC) or steel disks, with two applied contact pressures (1 and 3 MPa) and the surface microstructures were analyzed to unravel the wear mechanisms. Even at high mechanical stresses, tests against the C/C-SiC disk showed stable braking performance and wear. The abraded material from a steel disk formed a stable friction film by fusing together harder pad particles with abraded steel, which reduced wear and stabilized the braking performance. The high values of coefficient of friction obtained (0.5–0.7), their stability during the braking and the acceptable wear rate make these materials appealing for automotive brake applications. 相似文献
16.
《Journal of the European Ceramic Society》2003,23(2):323-329
Sand blasting nozzle is the most critical part in the sand blasting equipment. Ceramics being with high wear resistance have great potentials as the sand blasting nozzle materials. In this paper, monolithic B4C and Al2O3/(W,Ti)C ceramic composite were developed to be used as nozzle materials. The wear behavior of nozzles made from these ceramic materials was compared by determining the cumulative mass loss and the erosion rates. Effect of the factors that influence the nozzle wear was investigated. Results showed that the hardness of the nozzles plays an important role with respect to its erosion wear in sand blasting processes. The monolithic B4C nozzles being with high hardness exhibited lower erosion rates, while the Al2O3/(W,Ti)C nozzles with relative low hardness showed higher erosion rates under the same test conditions. Studies of the worn surface of the ceramic nozzles demonstrated that monolithic B4C nozzles exhibited a brittle fracture induced removal process, while Al2O3/(W,Ti)C nozzles showed mainly a plowing type of material removal mode. 相似文献
17.
《Ceramics International》2016,42(15):16474-16479
A series of ZrB2-ZrC-SiC composites with various SiC content from 0 to 20 vol% were prepared by reactive hot-pressing using Zr, B4C and SiC as raw materials. Self-propagating high-temperature synthesis (SHS) occurred, and ZrC grains connected each other to form a layered structure when the SiC content is below 20 vol%. The evolution of microstructure has been discussed via reaction processes. The composite with 10 vol% SiC presents the most excellent mechanical properties (four-point bending strength: 828.6±49.9 MPa, Vickers hardness: 19.9±0.2 GPa) and finest grain size (ZrB2: 1.52 µm, ZrC: 1.07 µm, SiC: 0.79 µm) among ZrB2-ZrC-SiC composites with various SiC content from 0 to 20 vol%. 相似文献
18.
《Journal of the European Ceramic Society》2020,40(14):4901-4908
Nano-mechanical and wear characteristics of ZrB2 + Al2O3:Cr3+,Nd3+ (Al2O3 co-doped with Cr3+ and Nd3+ ions) luminescent ceramic composites have been investigated using nanoindentation and tribological tests. Nanoindentation was carried out using a Berkovich diamond tip applying continuous stiffness measuring (CSM) mode with a maximum depth of 200 nm. The wear behaviour was studied during dry sliding in the air with a SiC counter body at applied loads of 5 and 50 N, and sliding speed of 0.1 m/s. The nanohardness of the ZrB2 and Al2O3 are very similar with mean values of 34.2 GPa and 32.6 GPa, respectively The Young modulus for ZrB2 is higher with a mean value of 555.6 GPa in comparison to the Young modulus of alumina with mean value of 473.8 GPa. Pop – in effect was found during the indentation of ZrB2 grains at indentation loads from 0.2–8.0 mN. The lowest coefficient of friction was measured for ZrB2 + 8%Al2O3:Cr3+,Nd3+ at 5 N load with value of approximately 0.5. The wear rate of the system ZrB2 + 32 % Al2O3:Cr3+,Nd3+ at 5 N is significantly lower in comparison to the wear rate of ZrB2 + 8% Al2O3:Cr3+,Nd3+ but at a load of 50 N the wear of the systems is very similar approximately 1. 10−5 mm3/N.m. Tribolayer formation connected with debris origin, oxidation and tribochemical reactions were characteristic for both composites with similar chemical composition but different size and thickness of tribolayers. 相似文献
19.
Junjie Xu Yanbo Liu Zhuang Ma Shizhen Zhu Yijin Wang Haikun Chen Kangzhi Ma 《Ceramics International》2021,47(1):400-408
To improve the emissivity of ZrB2/SiC coatings for serving in more serious environment, ZrB2/SiC coatings with varying contents of high emissivity Sm2O3 were fabricated using atmospheric plasma spraying. The microstructure, infrared radiative performance and anti-ablation behaviour of the modified coatings were investigated. The results showed that as the content of Sm2O3 increased, the density of the coatings increased because of the low melting point of Sm2O3. When the content of Sm2O3 was 10 vol%, the coating had the highest emissivity in the 2.5–5 μm band at 1000 °C, up to 0.85, because of the oxygen vacancies promoting additional electronic transitions. Due to the high emissivity, the surface temperature of the coating modified with 10 vol% Sm2O3 decreased by 300 °C, which led to little volatilisation of the sealing phase. Further, the mass ablation ratio of the above coating was 3.19 × 10?4 g/s, decreasing 31% compared to that of a ZrB2/SiC coating. The formed dense surface structure of the coatings showed considerable oxygen obstructive effects. These findings indicate that the modified coatings show considerable anti-ablation performance, which provides effective anti-ablation protection for the C/C composite substrate. 相似文献
20.
Raphael E. P. Salem Carlos F. Guitérrez-González Amparo Borrell Maria Dolores Salvador Adilson L. Chinelatto Adriana S. A. Chinelatto Eliria M. J. A. Pallone 《International Journal of Applied Ceramic Technology》2019,16(3):1265-1273
This work presents the initial results of the dry-sliding wear behavior of 3 mol% yttria-stabilized zirconia reinforced with 5 vol% alumina-niobium carbide (3Y-TZP/5 vol% Al2O3-NbC) nanocomposites sintered by conventional sintering and spark plasma sintering methods in the temperature range of 1350-1450°C. The reinforcement of 3Y-TZP matrix with hard nanoparticles aimed to improve wear strength of the composites. Wear tests were performed by the ball-on-disc method using alumina (Al2O3) and tungsten carbide with 6 wt% cobalt cermet (WC-6%Co) balls as counter-materials, a load of 15 N, a sliding distance of 2000 m, and a sliding speed of 0.1 m/s. Wear behavior was evaluated in terms of wear rate and FE-SEM micrograph analysis of the wear tracks. The nanocomposite sintered at 1450°C by conventional sintering exhibited the least wear when tested with the WC-6%Co ball. Generally, the wear mechanism showed evidence of severe wear regime with both counter-materials. 相似文献