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1.
《Ceramics International》2019,45(13):16504-16511
The aim of this study was to improve the mechanical properties of Al2O3 ceramics by the addition of Y2O3-stabilized ZrO2 whiskers (designated as Al2O3/YSZW composite) through the flux method and hot-pressing technology. The effect of YSZW content on their microstructure, phase composition and transformability, mechanical properties, and wear resistance was systematically investigated. The Al2O3/YSZW composites containing 10 wt% YSZW exhibited the best mechanical performance, including the highest content of YSZW tetragonal phase and transformability as well as the largest values in their relative density (99.5%), hardness (1969 HV), fracture toughness (9.57 MPa m1/2) and flexural strength (855 MPa). The strengthening and toughening of the Al2O3/YSZW composites were attributed to the YSZW tetragonal-monoclinic phase transformation as well as the whiskers reinforcing effect. Furthermore, the Al2O3/YSZW composites also showed the highest friction and wearing properties. 相似文献
2.
《Journal of the European Ceramic Society》2020,40(15):5305-5315
In this study, three-dimensional silicon nitride fiber-reinforced silicon nitride matrix (3D Si3N4f/BN/Si3N4) composites with a boron nitride (BN) interphase were fabricated through chemical vapor infiltration. Through comparing the changes of microstructure, thermal residual stress, interface bonding state, and interface microstructure evolution of composites before and after heat treatment, the evolution of mechanical and dielectric properties of Si3N4f/BN/Si3N4 composites was analyzed. Flexural strength and fracture toughness of composites acquired the maximum values of 96 ± 5 MPa and 3.8 ± 0.1 MPa·m1/2, respectively, after heat treatment at 800 °C; however, these values were maintained at 83 ± 6 MPa and 3.1 ± 0.2 MPa·m1/2 after heat treatment at 1200 °C, respectively. The relatively low mechanical properties are mainly attributed to the strong interface bonding caused by interfacial diffusion of oxygen and subsequent interfacial reaction and generation of turbostratic BN interphase with relatively high fracture energy. Moreover, the Si3N4f/BN/Si3N4 composites also displayed moderate dielectric constant and dielectric loss fluctuating irregularly around 5.0 and 0.04 before and after heat treatment, respectively. They were mainly determined based on the intrinsic properties of materials system and complex microstructure of composites. 相似文献
3.
《Journal of the European Ceramic Society》2021,41(14):6905-6914
The fabrication of three-dimensional silicon nitride (Si3N4) fiber-reinforced silicon nitride matrix (3D Si3N4f/BN/Si3N4) composites with a boron nitride (BN) interphase through precursor infiltration and pyrolysis (PIP) process was reported. Heat treatment at 1000–1200 °C was used to analyze the thermal stability of the Si3N4f/BN/Si3N4 composites. It was found after heat treatment the flexural strength and fracture toughness change with a pattern that decrease first and then increase, which are 191 ± 13 MPa and 5.8 ± 0.5 MPa·m1/2 respectively for as-fabricated composites, and reach the minimum values of 138 ± 6 MPa and 3.9 ± 0.4 MPa·m1/2 respectively for composites annealed at 1100 °C. The influence mechanisms of the heat treatment on the Si3N4f/BN/Si3N4 composites include: (Ⅰ) matrix shrinkage by further ceramization that causes defects such as pores and cracks in composites, and (Ⅱ) prestress relaxation, thermal residual stress (TRS) redistribution and a better wetting at the fiber/matrix (F/M) surface that increase the interfacial bonding strength (IBS). Thus, heat treatment affects the mechanical properties of composites by changing the properties of the matrix and IBS, where the load transfer efficiency onto the fibers is fluctuating by the microstructural evolution of matrix and gradually increasing IBS. 相似文献
4.
《Ceramics International》2019,45(10):13308-13314
The Si3N4 coating and Si3N4 coating with Si3N4 whiskers as reinforcement (Si3N4w-Si3N4) were prepared by chemical vapor deposition (CVD) on two-dimensional silicon nitride fiber reinforced silicon nitride ceramic matrix composites (2D Si3N4f/Si3N4 composites). The effects of process parameters of as-prepared coating including the preparation temperature and volume fraction of Si3N4w on the microstructure and mechanical properties of the composites were investigated. Compared with Si3N4 coating, Si3N4w-Si3N4 coating shows more significant effect on the strength and toughness of the composites, and both strengthening and toughening mechanism were analyzed. 相似文献
5.
Effect of hBN addition on the fabrication,mechanical and tribological properties of Sialon materials
《Ceramics International》2022,48(6):7715-7722
This work aims to investigate the effect of hBN on the friction and wear resistance of Sialon composite. Sialon and its composite with 10 wt% hBN were fabricated by SPS sintering. The effect of hBN additive on the phase composition, microstructure, densification behavior, mechanical and dry sliding tribological properties of Sialon material was studied. Being sintered at 1600 °C for 10 min, compared to monolithic Sialon, Sialon-hBN composite has more refined β-Sialon grains with smaller aspect ratios and slightly declined relative density. The hardness of the Sialon-hBN composite was reduced due to the weak bonding between Sialon and hBN grains. Nevertheless, its fracture toughness increased ascribing to the toughening mechanisms, including crack deflection and crack bridging. hBN had an essential impact on the tribological performances of the composite due to its lower friction coefficient and good lubrication action. Under the same densification level (i.e., with a relative density of around 97.5%), the friction and wear resistance of Sialon-hBN composite were much better than monolithic Sialon. The main wear mechanisms were tribolayer formation, oxidized wear, and abrasive wear. 相似文献
6.
《Ceramics International》2022,48(24):36853-36859
Copper/graphite composites and copper/graphite/Ti2SnC composites were fabricated through the process of ball-milling, pressing and sintering. The effects of Ti2SnC as the second lubrication component on the mechanical properties, wear resistance and lubrication properties of copper/graphite composites were studied in this paper. The results showed that copper/graphite/Ti2SnC composites had better hardness, impact toughness, wear resistance and lubrication performance than copper/graphite composites. The optimum values of hardness, impact toughness, friction coefficient and wear rate of copper/graphite/Ti2SnC composites were, respectively, 56 HSD, 1.8J/cm2, 0.15, 9.126 × 10?6 mm3/N·m, while these were only 45 HSD, 1.2 J/cm2, 0.17, 3.534 × 10?4 mm3/N·m of copper/graphite composites. 相似文献
7.
《Journal of the European Ceramic Society》2020,40(4):1532-1538
Dense Al2O3/Ti(C,N) composite ceramics reinforced with GNPs/nano-ZrO2 were fabricated by hot-press sintering. The effects of nano-ZrO2 content on the microstructure and mechanical properties of the prepared Al2O3/Ti(C,N)/GNPs/ZrO2 composites were investigated. Results showed that nano-ZrO2 inclusions refined the matrix grains significantly and resulted in the formation of intra-granular structure. Excellent comprehensive mechanical properties were achieved via addition of combined GNPs and nano-ZrO2. In particular, the fracture toughness of composites incorporating GNPs (0.4 wt%)/ZrO2 (1 wt%) exceeded 11 MPa m1/2, which was increased by more than 86 % compared with that of Al2O3/Ti(C,N) ceramic composites without GNPs/ZrO2. The main toughening mechanisms have been identified as stress-induced phase transformation, crack bridging, deflection and pull-out of GNPs. The toughening effects originated from GNPs were enhanced with the introduction of nano-ZrO2 because of not only the residual stress resulted from phase transformation but also the formation of intra-granular structure with uneven surface around GNPs. 相似文献
8.
《Journal of the European Ceramic Society》2022,42(3):869-876
Monolithic B4C, B4C–TiB2, and B4C–TiB2–graphene nanoplatelets (GNPs) were fabricated by hot pressing (HP) at 1900 °C for 1 h under an axial pressure of 30 MPa. The microstructures and mechanical and electrical properties of the B4C composites were investigated. The results show that the GNPs are distributed homogeneously in B4C-based ceramic composites. Compared with monolithic B4C, the TiB2–GNPs-containing B4C composite exhibits an approximately 68 % increase in flexural strength and a 169 % increase in fracture toughness due to the synergistic effects of TiB2 particles and GNPs. The toughening mechanisms mainly include TiB2 crack deflection, crack branching, transgranular fracture and GNPs crack deflection, crack bridging, and GNPs pull-out. Additionally, the electrical conductivity of the B4C composite reinforced with dual fillers is three orders of magnitude higher than that of monolithic B4C due to the establishment of a conductive network. The addition of GNPs can efficiently connect the isolated conductive TiB2 particles in the B4C matrix and provides an additional channel for electron migration. 相似文献
9.
《Journal of the European Ceramic Society》2023,43(2):370-377
To solve the shortcomings of traditional layered structure for broadband wave-transmitting applications, a novel porosity gradient structure is proposed. The precise turning of the relative permittivity of each layer and their simultaneous shrinkage during sintering are the keys to design and fabrication. Porous BN/Si3N4 composites with different porosities were prepared by incorporation of pore former, tape casting and gas pressure sintering. Results show that the obtained composites with different porosities exhibit low and similar shrinkage after sintering at 1900 °C, which is mainly due to the bridging effect between rapidly growing β-Si3N4 rod. When the porosity increases from 33.2% to 59.4%, the relative permittivity decreases from 4.00 to 2.38. Moreover, the composites with different porosities have excellent mechanical properties, with bending strength and fracture toughness of 180 ± 10–36 ± 4 MPa and 3.2 ± 0.30–0.85 ± 0.10 MPa·m?1/2, respectively, which is attributed to the bridging and pull-out strengthening effects of the elongated β-Si3N4 grains. 相似文献
10.
《Ceramics International》2020,46(6):7879-7887
In this study, boron carbide (B4C)-graphene nanoplatelets (GNPs) composites, with enhanced strength and toughness, were fabricated by hot pressing at 1950 °C under a pressure of 30 MPa for 1 h. Microstructure analysis revealed that the GNPs are homogenously dispersed within the B4C matrix. Raman spectroscopy and electron microscopy showed the orientation of the GNPs in the composites. The effects of the amount of GNPs on the microstructure and mechanical properties of the composites were also investigated. The optimal mechanical properties were achieved using 1 wt% GNPs. The relative density, Vickers hardness, flexure strength, and fracture toughness of the B4C-GNPs composite ceramic were found to be 99.12%, 32.8 GPa, 508 MPa, and 4.66 MPa m1/2, respectively. The main toughening mechanisms included crack deflection in three dimensions, GNPs pull-out, and crack bridging. The curled and semi-wrapped GNPs encapsulated individual B4C grains to resist GNPs pull-out and to deflect propagating cracks. 相似文献
11.
Monika Tatarková Peter Tatarko Alexandra Kovalčíková Ivo Dlouhý Ján Dusza Pavol Šajgalík 《Journal of the European Ceramic Society》2021,41(10):5115-5126
Fully dense Si3N4 materials with 1 wt.% (~ 1.5 vol.%) and 2 wt.% (~ 3.0 vol.%) h-BN nanosheets were prepared by spark plasma sintering at 1750 °C with the dwell of 7 min under a pressure of 50 MPa in a vacuum. BN nanosheets with different dimensions were prepared by ultrasound-assisted liquid phase exfoliation of h-BN powder, followed by centrifugation at different speeds (1000 rpm and 3000 rpm). The addition of BN nanosheets hindered the particle rearrangement stage of sintering, which resulted in the delayed α→β phase transformation of Si3N4. To study a direct effect of BN nanosheets on the mechanical properties of Si3N4, the results were compared to the monolithic Si3N4 with similar grain size and α/β-Si3N4 ratio. The addition of 2 wt.% h-BN nanosheets (1000 rpm) increased both the fracture toughness (~ 26 %) and the strength (~ 45 %) of Si3N4, when compared to the monolithic Si3N4 with similar microstructure. 相似文献
12.
Feng Gong Jun Zhao Zuoli Li Jialin Sun Xiuying Ni Guanming Hou 《Ceramics International》2018,44(3):2941-2951
A type of multidimensional graded ceramic tool materials (MGTMs) was designed and fabricated by vacuum hot-pressing sintering technology. The microstructure and compositional distribution of tool simultaneously changed in two different directions. The tool-chip and tool-workpiece contact regions were designed to have high hardness, and metal phases Mo and Ni were added to produce a gradual increase in toughness from the outer layer to core layer. The effect of orientation angle, thickness ratio and sintering parameters on the mechanical properties and microstructure were investigated. The experimental results showed that the composites, sintered at 1700 °C for 15 min, with the orientation angle of 30° and a thickness ratio of 0.4, had the optimal comprehensive mechanical properties. In addition, the crack propagation paths were observed to analyze the toughening mechanisms for the multidimensional graded ceramic tool materials. It was found that there is a crack resistance behavior when the crack extended from the outer layer to transition layer. The effect of the angle between the crack and graded interface on crack propagation paths was also investigated and the results indicated that the small angle was favorable for the crack deflection when the cracks passed through the graded interface. The residual thermal stress contributed to the occurrence of the crack bridging and transgranular fracture inside the Al2O3 grains, while the intergranular fracture and crack deflection were observed around the TiC grains. 相似文献
13.
《Ceramics International》2016,42(12):13497-13506
Si3N4/(W, Ti)C graded nano-composite ceramic tool materials with different thickness ratios and number of layers were fabricated by hot pressing technology. The flexural strength, fracture toughness and hardness of the sintered composites were tested and the microstructure and indention cracks were observed. The experiment results showed that the five-layer graded nano-composites with a thickness ratio of 0.2, which were sintered under a pressure of 30 MPa at 1700 °C in vacuum condition for 45 min, had the optimum comprehensive mechanical properties with a flexural strength of 1080.3 MPa, a hardness of 17.64 GPa, and a fracture toughness of 10.87 MPa·m1/2. The formation of elongated β-Si3N4 grains contributes to the favorable mechanical properties. The graded structure can induce residual compressive stress in the surface layer and enhance the mechanical properties. The strengthening and toughening mechanisms are a synergistic effect of intergranular and transgranular fracture, crack bridging and deflection. 相似文献
14.
《Journal of the European Ceramic Society》2020,40(4):1139-1148
The boron nitride (BN) interphase of silicon nitride (Si3N4) fiber-reinforced BN matrix (Si3N4f/BN) composites was prepared by chemical vapor deposition (CVD) of liquid borazine, and the microstructure, growth kinetics and crystallinity of the BN coating were examined. The effects of coating thickness on the mechanical strength and fiber/matrix interfacial bonding strength of the composites were then investigated. The CVD BN coating plays a key role in weakening the interfacial bonding condition that improves the mechanical properties of the composites. The layering structure of the BN coating promotes crack propagation within the coating, which leads to a variety of toughening mechanisms including crack deflection, fiber bridging and fiber pull out. Single-fiber push-out experiments were performed to quantify the fiber/matrix bonding strength with different coating thicknesses. The physical bonding strength due to thermal mismatch was discussed. 相似文献
15.
《Ceramics International》2022,48(6):7897-7904
High-performance B4C-PrB6 composites were prepared via hot-pressing sintering with matrix phase B4C and with 2–5 wt% Pr6O11 as additive. The effects of different sintering processes and Pr6O11 content on the microstructure and mechanical properties of the composites were studied in detail. It is found that increasing sintering temperature and pressure will contribute to the densification of B4C-PrB6 composites. Coarse grains are formed in B4C without additives at high temperature conditions, resulting in the decrease of the densification. Pr6O11 can effectively hinder the formation of coarse grains and finally promote the densification of the composites. The main toughening mechanisms of composites was crack deflection. The composites with 4 wt% Pr6O11 prepared at 2050 °C and 25 MPa had the best comprehensive mechanical properties. The relative density, hardness, flexural strength and fracture toughness reached to 98.9%, 37.6 GPa, 339 MPa and 4.4 MP am1/2, respectively. 相似文献
16.
《Ceramics International》2020,46(7):8845-8852
Al2O3-SiCw toughened ceramic tools play vital role in high-speed machining of nickel-based superalloys due to their superior mechanical properties. Herein, owing to synergistic toughening mechanism, α-Si3N4 particles are employed as reinforcement phase into Al2O3-SiCw ceramic composite to optimize mechanical properties of Al2O3-SiCw ceramic tools. Moreover, the influence of Si3N4 content and sintering parameters on microstructure and mechanical properties of Al2O3-20 vol%SiCw ceramic tool material is systematically investigated. Results reveal that appropriate amount of Si3N4 particles is required to effectively increase the density of Al2O3-SiCw ceramic composites. The presence of Si3N4 particles leads to formation of novel β-sialon phase during hot-press sintering, which effectively enhances fracture toughness and flexural strength of Al2O3-SiCw ceramic composites. It is observed that grain size of newly formed β-sialon phase is extremely sensitive to hot-pressing sintering conditions. The degree of chemical transformation of α-Si3N4 into Si6-zAlzOzN8-z (β-sialon) and z-value of Si6-zAlzOzN8-z are significantly influenced by sintering temperature. Overall, Al2O3-20 vol%SiCw-15 vol%Si3N4 ceramic tool material, with 1.5 vol%Y2O3-0.5 vol%La2O3-0.5 vol%CeO2 (YLC) sintering additive, rendered optimal mechanical properties after sintering at 1600 °C under 32 MPa for 30 min. Improved mechanical performance can be ascribed to synergistic toughening and strengthening influence of whiskers and particles. 相似文献
17.
《Ceramics International》2020,46(6):7170-7177
This paper introduce the formation of alumina matrix composites reinforced with multilayered graphene, graphene oxide and nickel-phosphorus coated multilayered graphene. The powder metallurgy technique followed by the Spark Plasma Sintering (SPS) method were utilized to fabricate the specimens. The influence of graphene-family material additions on microstructure was investigated, and correlated with measurements of mechanical properties. The emphasis of the research has been placed on the tribological performance conducted with the use of the ball-on-disc method under loads of 10 N and 30 N. Both the wear tracks of composites and the corresponding counterparts were carefully analysed, to evaluate the combined influence of mechanical properties and tribofilm formation on the measured wear rates. All results were compared to pure alumina as a reference specimen. 相似文献
18.
《Journal of the European Ceramic Society》2017,37(9):3195-3202
In order to overcome intrinsic brittleness and poor mechanical properties of fused silica (FS), boron nitride nanosheets (BNNSs) as a novel reinforcement were employed for fabrication of BNNSs/fused silica composites. BNNSs with micron lateral size were homogeneously dispersed with FS powder using a surfactant-free flocculation method and then consolidated by hot pressing. The flexural strength and fracture toughness of the composite with the addition of only 0.5 wt.% BNNSs increased by 53% and 32%, respectively, compared with those of pure FS. However, for higher BNNSs contents the improvement in mechanical properties was limited. Microstructural analyzes have shown that the toughening mechanisms are combinations of the pull-out, crack bridging, and crack deflection mechanisms. 相似文献
19.
Xuchao Wang Jun Zhao Enzhao Cui Shiping Song Hao Liu Weitian Song 《Ceramics International》2019,45(8):10321-10329
The low fracture toughness of Al2O3-based ceramics limited their practical application in cutting tools. In this work, graphene was chosen to reinforce Al2O3-WC-TiC composite ceramic tool materials by hot pressing. Microstructure, mechanical properties and toughening mechanisms of the composite ceramic tool materials were investigated. The results indicated that the more refined and denser composite microstructures were obtained with the introduction of graphene. The optimal flexural strength, Vickers hardness, indentation fracture toughness were 646.31?±?20.78?MPa, 24.64?±?0.42?GPa, 9.42?±?0.40?MPa?m1/2, respectively, at 0.5?vol% of graphene content, which were significantly improved compared to ceramic tool material without graphene. The main toughening mechanisms originated from weak interfaces induced by graphene, and rugged fractured surface, grain refinement, graphene pull-out, crack deflection, crack bridging, micro-crack and surface peeling were responsible for the increase of fracture toughness values. 相似文献
20.
Dan Luo Jie Fei Chao Zhang Hejun Li Lijie Zhang Jianfeng Huang 《Ceramics International》2018,44(13):15393-15401
The multi-scale reinforcements of ZnO nanorods/carbon fabric with different morphologies were obtained using a simple water bath method via controlling the concentration of growth solution for a new application in wet friction materials. The ZnO nanorods/carbon fabric were characterized via X-ray diffraction, Scanning electron microscopy, Fourier transform infrared spectroscopy and Raman spectra. As a result, the ZnO nanorods/carbon fabric/resin composite (sample CP3) possesses the maximum bending and tensile strength of 62.7?MPa and 170.0?MPa, which increases by 40.2% and 59.1% compared with that of bare carbon fabric/resin composite due to the best mechanical interlocking and chemical adhesion at the interfacial region of the composite. Meanwhile, the wear rate of the sample CP3 decreases obviously by 81.5% together with stable friction coefficient under various friction condition. From view point of material design, it is necessary to control the morphologies of ZnO nanorods to optimize mechanical and tribological properties of ZnO nanorods/carbon fabric/resin composites. 相似文献