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1.
Zewen Chen Zhenhua Wang Boxiang Wang Juntang Yuan Lei Huang Zengbin Yin 《International Journal of Applied Ceramic Technology》2021,18(6):2010-2019
In this study, WC-8Co cemented carbides were prepared by spark plasma sintering. When the samples sintered at 1300℃ were cooled to room temperature, the samples were sintered multiple times at 1250℃. The changes in microstructure and mechanical properties of WC-8Co cemented carbides prepared by multiple spark plasma sintering were studied. The hardness of cemented carbides increased in the first two sintering, reaching 16.5 GPa. However, the hardness decreased seriously in the last two sintering. The attenuation rates of hardness were 6.2% and 2.5% due to the abnormal coarse grains. Furthermore, the crack path along the grain boundary was almost straight, causing a decrease in the indentation fracture toughness of cemented carbides. Additionally, the grains of cemented carbides were abnormally coarsened, and the morphologies of grains became unstable due to multiple sintering. 相似文献
2.
Mingdan Chen Zengbin Yin Juntang Yuan Weiwei Xu Jiadong Ye Shiyu Yan 《Ceramics International》2018,44(13):15370-15377
A kind of B4C/SiC composite ceramic toughened by graphene platelets and Al was fabricated by spark plasma sintering. The effects of graphene platelets and Al on densification, microstructure and mechanical properties were studied. The sintering temperature was decreased about 125–300?°C with the addition of 3–10?wt% Al. Al can also improve fracture toughness but decrease hardness. The B4C/SiC composite ceramic with 3?wt%Al and 1.5?wt% graphene platelets sintered at 1825?°C for 5?min had the optimal performances. It was fully densified, and the Vickers hardness and fracture toughness were 30.09?±?0.39?GPa and 5.88?±?0.49?MPa?m1/2, respectively. The fracture toughness was 25.6% higher than that of the composite without graphene platelets. The toughening mechanism of graphene platelets was also studied. Pulling-out of graphene platelets, crack deflection, bridging and branching contributed to the toughness enhancement of the B4C-based ceramic. 相似文献
3.
《Ceramics International》2023,49(8):11921-11925
In this work, spark plasma sintering of La2Mo2O9 powder was used to achieve dense ceramics of La7Mo7O30 and explore their thermoelectric properties. SPS sintering of La2Mo2O9 powder at 973 K for 10 min under 90 MPa leads to a bicoloured sample with white and black faces. XRD patterns of white and black faces are attributed to La2Mo2O9 and La7Mo7O30 phases, respectively. These experimental conditions allow observing the in-situ reduction of La2Mo2O9 during the SPS process. With a longer sintering time of 30 min, a ceramic of La7Mo7O30 is obtained. Its electrical conductivity exhibits a semiconducting behaviour and reaches a value of 1000 Sm-1 at 1000 K. The negative Seebeck coefficient show a n-type conduction in this phase. La7Mo7O30 exhibits a very low thermal conductivity, less than 1 Wm−1K−1 from room temperature up to 1000 K, similar to the values reported for La2Mo2O9. A figure of merit of 0.04 is reached at 1000 K. 相似文献
4.
《Ceramics International》2017,43(11):8190-8194
Bulk boron carbide (B4C) ceramics was fabricated from a boron and carbon mixture by use of one-step reactive spark plasma sintering (RSPS). It was also demonstrated that preliminary high-energy ball milling (HEBM) of the B+C powder mixture leads to the formation of B/C composite particles with enhanced reactivity. Using these reactive composites in RSPS permits tuning of synthesized B4C ceramic microstructure. Optimization of HEBM + RSPS conditions allows rapid (less than 30 min of SPS) fabrication of B4C ceramics with porosity less than 2%, hardness of ~35 GPa and fracture toughness of ~ 4.5 MPa m 1/2 相似文献
5.
Vaclav Tyrpekl Marco Cologna Michael Holzhäuser Petr Svora 《Journal of the American Ceramic Society》2021,104(2):793-802
Electric field-assisted sintering (FAST) is a rapidly growing scientific and engineering domain. In the present paper, we describe the process of flash sintering (FS) in a configuration of classical spark plasma sintering (SPS) (graphite punch and boron nitride (BN) die), also called flash spark plasma sintering (FSPS). The densification process of Gd0.1Ce0.9O2-x powder is studied in detail with a focus on the transition from FAST to FS. We discuss the electrical, geometrical, and thermal evolution of the process and the characteristics of the final compacts. Low electrical fields are sufficient for the onset of FS. Ceria is a material difficult to sinter by FAST techniques due to its known mechanochemical transformations. We observed the disintegration of pellets after experiments with well-pronounced flash event. 相似文献
6.
《Journal of the European Ceramic Society》2014,34(10):2169-2175
B4C based ceramics were fabricated with different Fe3Al contents as sintering aids by spark plasma sintering at relatively low temperature (1700 °C) in vacuum by applying 50 MPa pressure and held at 1700 °C for 5 min. The effect of Fe3Al additions (from 0 to 9 wt%) on the microstructure and mechanical properties of B4C has been studied. The composition and microstructure of as-prepared samples were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe microanalyzer (EPMA) equipped with WDS (wavelength dispersive spectrometry) and EDS. The mixtures of B4C and Fe3Al underwent a major reaction in which the metal borides and B4C were encountered as major crystallographic phases. The sample with 7 wt% of Fe3Al as a sintering aid was found to have 32.46 GPa Vickers hardness, 483.40 MPa flexural strength, and 4.1 MPa m1/2 fracture toughness which is higher than that of pure B4C. 相似文献
7.
Titanium carbide (TiC) has been widely used as reinforcement in metal matrix composites and is known to exist over a wide range of stoichiometry. In this study, the effect of C/Ti ratio on the densification kinetics, grain size, lattice parameter, hardness and elastic modulus of TiCx prepared by reactive spark plasma sintering (RSPS) is presented. Commercial purity titanium was ball milled with 5, 7.5, 10, 12.5, 15 and 17.5 wt% carbon black powder for 5 h and subjected to RSPS to prepare TiCx samples with different C/Ti ratio. Dense TiCx samples with ‘x′ ranging from 0.34 to 0.78 could be prepared by RSPS at 1400 °C. Increasing C/Ti ratio was found to increase the activation energy thereby reducing the rate of sintering and also resulted in finer grain size. The lattice parameter and the ratio of intensities of (200) to (111) peaks were correlated with the C/Ti ratio. The hardness and elastic modulus were shown to increase significantly with increase in C/Ti ratio. 相似文献
8.
《Ceramics International》2023,49(2):2073-2080
Based on good thermomechanical and electromagnetic properties of silicon nitride (Si3N4), barium aluminosilicate (BaO–BaTiO3–SiO2 or BAS), and boron nitride (BN), a novel combination of Si3N4/BAS/BN composites was fabricated by spark plasma sintering (SPS) after traditional powder mixing process. The effect of different amounts of BN (3–9 wt%) on the mechanical properties of composite was studied. The phases were observed by X-ray diffraction, and the microstructures were identified by scanning electron microscopy (SEM). The optimal sample is the one containing 3 wt% of BN and is sintered under a final pressure of 50 MPa. This sample has a hardness of 9.03 GPa, a flexural strength of 418.75 MPa, an elastic modulus of 934.46 MPa, and a loss tangent of less than 0.002 in 38% of the X-band frequencies. The optimal sample thickness was determined via the Nicolson-Ross-Weir (NRW) technique considering the mechanical strength limits. 相似文献
9.
《Journal of the European Ceramic Society》2022,42(5):2004-2014
Homogenous distribution of whiskers in the ceramic matrix is difficult to be achieved. To solve this problem, B4C-SiCw powder mixtures were freeze dried from a slurry dispersed by cellulose nanofibrils (CellNF) in this work. Dense B4C ceramics reinforced with various amounts of SiCw up to 12 wt% were consolidated by spark plasma sintering (SPS) at 1800 °C for 10 min under 50 MPa. During this process, CellNF was converted into carbon nanostructures. As iron impurities exist in the starting B4C and SiCw powders, both thermodynamic calculations and microstructure observations suggest the dissolution and precipitation of SiCw in the liquids composed of Fe-Si-B-C occurred during sintering. Although not all the SiCw grains were kept in the final ceramics, B4C-9 wt% SiCw ceramics sintered at 1800 °C still exhibit excellent Vickers hardness (35.5 ± 0.8 GPa), flexural strength (560 ± 9 MPa) and fracture toughness (5.1 ± 0.2 MPa·m1/2), possibly contributed by the high-density stacking faults and twins in their SiC grains, no matter in whisker or particulate forms. 相似文献
10.
Wirat Lerdprom Salvatore Grasso Doni Daniel Jayaseelan Michael J. Reece William E. Lee 《应用陶瓷进展》2017,116(6):307-315
Porcelain powder was consolidated using spark plasma sintering (SPS) at a constant heating rate of 100°C?min?1 to peak temperatures ranging from 1000 to 1200°C and was observed to sinter at relatively low temperature ~920°C under the SPS conditions while conventional sintering requires ~1050°C. SPS produced densification rates about 10 times greater than conventional sintering. The dwelling step at the optimal peak temperature was negligible due to rapid flow of the molten glass assisted by applied pressure. SPSed samples exhibited denser microstructures, resulting in improved physico-mechanical properties compared with conventionally sintered samples such as apparent bulk density improved from 2.38 to 2.48?g?cm?3, Vickers hardness improved from 3–5 to 6–7?GPa, and fracture toughness improved from 2–3 to 4–6?MPa?m1/2. 相似文献
11.
《Ceramics International》2022,48(20):30376-30383
In this study, α/β-Si3N4 composite ceramics with high hardness and toughness were fabricated by adopting two different novel ternary additives, ZrN–AlN–Al2O3/Y2O3, and spark plasma sintering at 1550 °C under 40 MPa. The phase composition, microstructure, grain distribution, crack propagation process and mechanical properties of sintered bulk were investigated. Results demonstrated that the sintered α/β-Si3N4 composite ceramics with ZrN–AlN–Al2O3 contained the most α phase, which resulted in a maximum Vickers hardness of 18.41 ± 0.31 GPa. In the α/β-Si3N4 composite ceramics with ZrN–AlN–Y2O3 additives, Zr3AlN MAX-phase and ZrO phase were found and their formation mechanisms were explained. The fracture appearance presented coarser elongated β-Si3N4 grains and denser microstructure when 20 wt% TiC particles were mixed into Si3N4 matrix, meanwhile, exhibited maximum mean grain diameter of 0.98 ± 0.24 μm. As a result, the compact α/β-Si3N4 composite ceramics containing ZrN–AlN–Y2O3 additives and TiC particles displayed the optimal bending strength and fracture toughness of 822.63 ± 28.75 MPa and 8.53 ± 0.21 MPa?m1/2, respectively. Moreover, the synergistic toughening of rod-like β-Si3N4 grains and TiC reinforced particles revealed the beneficial effect on the enhanced fracture toughness of Si3N4 ceramic matrix. 相似文献
12.
Dong Wang Yifan Bai Bo Qiu Hongtao Yu Zhibao Li 《International Journal of Applied Ceramic Technology》2023,20(3):1420-1431
A microstructure evolution model for the ceramic materials was constructed, and the spark plasma sintering parameters were optimized using the model to shorten the designing period and reduce the consumption of the material. Based on the optimized sintering parameters, the ceramic tool material with a composition of Al2O3, TiB2, and TiC proved to be a success. It verified that the materials prepared under the optimized sintering parameters exhibited excellent mechanical properties. The results showed when sintered at 1600°C, under the pressure of 40 MPa and with the holding period of 7 min, the materials with 70% Al2O3, 20% TiB2, and 10% nano-TiC possess the relatively best performance, with the hardness, fracture toughness, and flexure strength being 20.3 GPa, 10.5 MPa/m2, and 839.5 MPa, respectively. 相似文献
13.
Xiang Zhang Mahdieh Khedmati Yong-Rak Kim Hyu-Soung Shin Jangguen Lee Young-Jae Kim Bai Cui 《Journal of the American Ceramic Society》2020,103(2):899-911
A spark plasma sintering (SPS) process has been explored to densify FJS-lunar soil simulants for structural applications in space explorations. The effect of SPS conditions, such as temperature and pressure, on the densification behavior, phase transformation, microstructural evolution, and mechanical properties of FJS-1 have been examined by conducting the X-ray diffraction analysis, electron microscopy imaging, and nano/micro indentation testing. Test analysis results were also compared to results from the FJS-1 powder and sintered samples without pressure. The FJS-1 powder was composed of sodian anorthite, augite, pigeonite, and iron titanium oxide. When FJS-lunar soil simulants were sintered without pressure, the main phase evolved from sodian anorthite to the intermediate sodian anorthite, jadeite and glass, and iron titanium oxide at 1000°C, which were further transformed into filiform and feather-shaped augite and schorlomite at 1100°C. Most densification processes in pressureless sintering occurred at 1050°C-1100°C. During the SPS process, the main phases were sodian anorthite, pigeonite, and iron titanium oxide at 900°C. These phases were transformed to sodian anorthite, glass, and feather-shaped augite at 1000°C and 1050°C, with the nucleation of dendritic schorlomite at 1050°C. Significant densification by SPS can be observed as low as 900°C, which indicates that the application of pressure can substantially lower the sintering temperature. The SPSed samples showed higher Vickers microhardness than the pressureless sintered samples. The mechanical properties of the local phases were represented by the contour maps of elastic modulus and nanohardness. Multiscale mechanical test results along with the microstructural characteristics further imply that the SPS can be considered a promising in-situ resource utilization (ISRU) method to densify lunar soils. 相似文献
14.
《Ceramics International》2016,42(13):14463-14468
The development of reliable joining technology is of great importance for the full use of SiC. Ti3SiC2, which is used as a filler material for SiC joining, can meet the demands of neutron environment applications and can alleviate residual stress during the joining process. In this work, SiC was joined using different powders (Ti3SiC2 and 3Ti/1.2Si/2C/0.2Al) as filler materials and spark plasma sintering (SPS). The influence of the joining temperature on the flexural strength of the SiC joints at room temperature and at high temperatures was investigated. Based on X-ray diffraction and scanning electron microscopy analyses, SiC joints with 3Ti/1.2Si/2C/0.2Al powder as the filler material possess high flexural strengths of 133 MPa and 119 MPa at room temperature and at 1200 °C, respectively. The superior flexural strength of the SiC joint at 1200 °C is attributed to the phase transformation of TiO2 from anatase to rutile. 相似文献
15.
《Ceramics International》2022,48(21):31952-31964
In this paper, a novel nuclear shielding material capable of shielding neutrons and gamma rays, WB-reinforced Al (WB/Al) composites, was prepared by spark plasma sintering (SPS) process. The microstructure of the composites was characterized, and the effects of WB content, heat treatment and matrix type on the properties of the composites were discussed. The results demonstrate that the WB particles are uniformly dispersed in the aluminum matrix and formed a good binding interface with the matrix. WAl12 as an interfacial reaction product is identified, and segregation of Si and Mg elements at the reinforcement/matrix interface occurs. The mechanical properties of the WB/Al composites are sensitive to the WB content. The hardness, elastic modulus and bending strength of the composites increase monotonously as the WB volume fraction increasing, up to 234%, 107% and 91.6% higher respectively than those of the monolithic 6061Al. However, the tensile strength reaches a peak point when the volume fraction is 20%. The effects of T6 treatment and matrix type are not pronounced, especially for the composites with high WB content. The thermal neutron and gamma ray shielding properties of the composites both increase with the increase of material thickness and WB content. The WB/Al composites developed in this work show good application prospects in the field of nuclear radiation protection, due to their good mechanical properties and well neutron and gamma-ray shielding performance. 相似文献
16.
《Journal of the European Ceramic Society》2023,43(2):419-427
The 30%LiFePO4-55%Li1.5Al0.5Ge1.5(PO4)3-15%C composite electrodes were successfully prepared by spark plasma sintering, and the microstructure and electrochemistry performance were investigated. As sintered at 550 °C, the phase structure of the composite electrode remained unchanged. With the sintering temperature increasing, the Li1.5Al0.5Ge1.5(PO4)3 were decomposed and transformed into nanocrystals and impurity phases of AlPO4 and GeO2. The 3D-microstructure showed that abundant pores existed in the composite electrodes. The volume fraction and connectivity of these pores decreased with the sintering temperature. The initial discharge capacity of the composite electrode was 138 mAh·g?1 as sintered at 550 ℃, while it decreased monotonously with the sintering temperature. The decrease was related with the formation of impurities and closed pores. Moreover, the composited electrode sintered at 550 ℃ had severely capacity fading during electrochemistry cycles. By the EIS and postmortem analyses, it was determined that the capacity fading was due to the ion transport failure caused by the cracking during cycles. 相似文献
17.
Barak Ratzker Avital Wagner Maxim Sokol Sergey Kalabukhov Moshe P. Dariel Nachum Frage 《Journal of the European Ceramic Society》2019,39(8):2712-2719
Transparent alumina was fabricated from untreated commercial powder by high-pressure spark plasma sintering (HPSPS) at temperatures of 1000, 1050 and 1100 °C under pressures of 250-800 MPa. It was established that transparency strongly depends on the HPSPS parameters. At all temperatures, there was a certain point when increasing the pressure led to decreasing transparency. At 1100 °C, relatively high pressure led to excessive grain growth, as well as the formation of creep-induced porosity at the center of the samples. Hardness values decreased with pressure due to grain growth, correlated with the Hall-Petch relationship. The optimal combination of optical and mechanical properties (68% in-line transmittance at a wavelength of 640 nm and a hardness value of about 2300 HV2) was achieved after sintering at 1050 °C under 600 MPa. 相似文献
18.
Maxime Schwertz Sébastien Lemonnier Elodie Barraud Adele Carradò Marie‐France Vallat Michel Nardin 《应用聚合物科学杂志》2014,131(18)
This article presents two high‐temperature thermoplastic powders which were sintered by spark plasma sintering in order to get homogeneous mechanical properties. Dense polyimide (PI) and polyetheretherketone (PEEK) specimens were obtained at temperatures as low as 320°C for PI and 200°C for PEEK, respectively. Relative densities higher than 99% were reached for both materials. In order to characterize their properties, in situ measurements with compression and hardness tests were carried out on sintered samples. This method allowed to obtain polymeric materials with improved mechanical properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40783. 相似文献
19.
20.
Daimeng Chen Kuibao Zhang Jianjun Zeng Haiyan Guo Bo Li 《International Journal of Applied Ceramic Technology》2022,19(4):1949-1955
Spark plasma sintering (SPS) is an advanced sintering technique because of its fast sintering speed and short dwelling time. In this study, TiB2, Y2O3, Al2O3, and different contents of B4C were used as the raw materials to synthesize TiB2-B4C composites ceramics at 1850°C under a uniaxial loading of 48 MPa for 10 min via SPS in vacuum. The influence of different B4C content on the microstructure and mechanical properties of TiB2-B4C composites ceramics are explored. The experimental results show that TiB2-B4C composite ceramic achieves relatively good comprehensive properties and exceptionally excellent flexural strength when the addition amount of B4C reaches 10 wt.%. Its relative density, Vickers hardness, fracture toughness, and flexural strength reach to 99.20%, 24.65 ± .66 GPa, 3.16 MPa·m1/2, 730.65 ± 74.11 MPa, respectively. 相似文献