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1.
ABSTRACTThis research focuses on the cutting performance of Al2O3 and Si3N4 ceramic cutting tools in up-milling plywood, the results of which are as follows. First, whether the tool material is Al2O3 or Si3N4 ceramic, the cutting forces at low-speed cutting were less than those at high-speed cutting, and the machining quality at low-speed cutting was greater than that at high-speed cutting. Then, whether at low- or high-speed cutting, the cutting forces of Al2O3 cutting tools were higher than those of Si3N4 cutting tools, and the machining quality of plywood milled by Al2O3 ceramic cutting tools was poorer than that milled by Si3N4 ceramic cutting tools. Finally, Si3N4 ceramic cutting tools were more suitable to machine the wooden productions with much glue content than Al2O3 ceramic cutting tools for the better machined quality. 相似文献
2.
Ming Huang Zhihang Peng Wen Zhang Yang Xiang Feng Cao 《International Journal of Applied Ceramic Technology》2022,19(5):2916-2924
Fused silica ceramic has become one of the most widely used radome materials in the world since the 1970s. But its poor mechanical properties restricted its application to some extent. To improve the mechanical properties of the fused silica ceramic and keep its characteristic for radome materials, silicon nitride (Si3N4) whisker-reinforced fused silica ceramics were prepared by a slip-casting method in the work. The influence of Si3N4 whisker contents on the properties of the slurry was studied, indicating that the preferable pH values of the slurry were 4–6 and whisker contents were 10 wt.%. The flexural strength of as-prepared Si3N4w/SiO2 ceramic was about 74.35 MPa, exhibiting an increase of 7.75% over that of the pure silica sample. Its dielectric constant in the range from 8 to 12 GHz and tanδ under 10 GHz were, respectively, 3.37 and .0011. It is of great interest to find that Si3N4w/SiO2 has excellent oxidization resistance and its mass maintains even at 1270°C. 相似文献
3.
Equiaxed β–Si3N4 ceramics prepared by rapid reaction‐bonding and post‐sintering using TiO2–Y2O3–Al2O3 additives
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Li‐Xiang Wu Wei‐Ming Guo Ling‐Yong Zeng Hua‐Tay Lin 《Journal of the American Ceramic Society》2017,100(12):5353-5357
Sintered reaction‐bonded Si3N4 ceramics with equiaxed microstructure were prepared with TiO2–Y2O3–Al2O3 additions by rapid nitridation at 1400°C for 2 hours and subsequent post‐sintering at 1850°C for 2 hours under N2 pressure of 3 MPa. It was found that α–Si3N4, β–Si3N4, Si2N2O, and TiN phases were formed by rapid nitridation of Si powders with single TiO2 additives. However, the combination of TiO2 and Y2O3–Al2O3 additives led to the formation of 100% β–Si3N4 phase from the nitridation of Si powders at such low temperature (1400°C), and the removal of Si2N2O phase. As a result, dense β–Si3N4 ceramics with equiaxed microstructure were obtained after post‐sintering at high temperature. 相似文献
4.
Beiyue Ma Yandong Tang Chengji Deng 《International Journal of Applied Ceramic Technology》2022,19(5):2523-2532
Silicon nitride (Si3N4) ceramics doped with two different sintering additive systems (Al2O3–Y2O3 and Al2O3–Yb2O3) were prepared by hot-pressing sintering at 1800℃ for 2 h and 30 MPa. The microstructures, nano-indentation test, and mechanical properties of the as-prepared Si3N4 ceramics were systematically investigated. The X-ray diffraction analyses of the as-prepared Si3N4 ceramics doped with the two sintering additives showed a large number of phase transformations of α-Si3N4 to β-Si3N4. Grain size distributions and aspect ratios as well as their effects on mechanical properties are presented in this study. The specimen doped with the Al2O3–Yb2O3 sintering additive has a larger aspect ratio and higher fracture toughness, while the Vickers hardness is relatively lower. It can be seen from the nano-indentation tests that the stronger the elastic deformation ability of the specimens, the higher the fracture toughness. At the same time, the mechanical properties are greatly enhanced by specific interlocking microstructures formed by the high aspect ratio β-Si3N4 grains. In addition, the density, relative density, and flexural strength of the as-prepared Si3N4 ceramics doped with Al2O3–Y2O3 were 3.25 g/cm3, 99.9%, and 1053 ± 53 MPa, respectively. When Al2O3–Yb2O3 additives were introduced, the above properties reached 3.33 g/cm3, 99.9%, and 1150 ± 106 MPa, respectively. It reveals that microstructure control and mechanical property optimization for Si3N4 ceramics are feasible by tailoring sintering additives. 相似文献
5.
Li-Juan Yuan Peng-Jie Zhang Fei Zuo Rui-Xin Luo Zhao-Liang Guo Kevin Plucknett Bei-Bei Jiang Guang-Lin Nie Fan Meng Víctor Valcárcel-Juárez Alexandre Maître Hua-Tay Lin 《Journal of the European Ceramic Society》2021,41(1):706-718
The densification behavior, microstructural development, toughening and strengthening mechanisms of Al2O3 whisker-reinforced 3Y-TZP and 12Ce-TZP composites were systematically and comparatively investigated with varying whisker lengths. Compared with 3Y-TZP/Aw composites, the presence of a Ce-Al-Si-O amorphous phase, caused by the addition of Al2O3 whiskers, promoted the densification and grain growth of 12Ce-TZP/Aw composites. Crack deflection and bridging are proposed as the primary toughening mechanisms for 3Y-TZP/Aw composites, while the t-m martensitic transformation would dominate the toughening and strengthening processes of 12Ce-TZP/Aw composites. Changes in Al2O3 whisker length would vary the distributions of internal stress and amorphous phase within the ceria-stabilized ZrO2 matrix, and hence affect the toughening and strengthening results. It indicates that effective toughening and strengthening of the Al2O3 whisker-reinforced TZP composites can be achieved by taking advantage of collaborative engineering control on the reinforcement morphology and the interface chemistry/structure. 相似文献
6.
《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
7.
《Journal of the European Ceramic Society》2006,26(6):1059-1067
The densification behaviors (include α–β transformation) and high-temperature characteristics (especially oxidation resistance and high-temperature strength properties) of Si3N4 sintered bodies using Al2O3–Yb2O3 based sintering additive are investigated.Densification and α–β transformation behaviors were investigated by varying the compositions of Al2O3–Yb2O3 additives. In terms of the influence of the Y2O3/Al2O3 ratio on densification behavior, a greater Yb2O3/Al2O3 ratio tends to inhibit densification. The α–β transformation tended to be delayed in sintered bodies with a small additive amount of 3.4 mass%. Compared with the transformation behaviors of the sintered bodies using Al2O3–Y2O3 additives, those using Al2O3–Yb2O3 additives exhibited a narrower temperature zone for α–β transformation, which attributed to the finer structure for the sintered body using Al2O3–Yb2O3 additives. This is affected by the difference in solubility of Si3N4 in the two kinds of glass phase.High room temperature strength of 900–1000 MPa was obtained for sintered bodies with a 10.0 mass% addition of additives, and this is considered to be due to the finer micro-structure. Precipitation of a Yb4Si2N2O7 phase at the grain boundary glass phase, as induced by crystallization processing, enables the improvement of 1300 °C strength to about 650–720 MPa. Crystallization processing resulted in a 30% reduction in the amount of weight change during oxidation (from 3.42 to 2.46 mg/cm2), demonstrating the effectiveness in improving oxidation resistance. 相似文献
8.
《Ceramics International》2017,43(13):10224-10230
Whiskers and nanoparticles are usually used as reinforcing additives of ceramic composite materials due to the synergistically toughening and strengthening mechanisms. In this paper, the effects of TiC nanoparticle content, particle size and preparation process on the mechanical properties of hot pressed Al2O3-SiCw ceramic tool materials were investigated. The results showed that the Vickers hardness and fracture toughness of the materials increased with the increasing of TiC content. The optimized flexural strength was obtained with TiC content of 4 vol% and particle size of 40 nm. The particle size has been found to have a great influence on flexural strength and small influence on hardness and fracture toughness. It was concluded that the flexural strength increased remarkably with the decreasing of the TiC particle size, which was resulted from the improved density and refined grain size of the composite material due to the dispersion of the smaller TiC particle size. SEM micrographs of fracture surface showed the whiskers to be mainly distributed along the direction perpendicular to the hot-pressing direction. The fracture toughness was improved by whisker crack bridging, crack deflection and whisker pullout; the TiC nanoparticles in Al2O3 grains caused transgranular fracture and crack deflection, which improved the flexural strength and fracture toughness with whiskers synergistically. Uniaxial hot-pressing of SiC whisker reinforced Al2O3 ceramic composites resulted in the anisotropy of whiskers’ distribution, which led to crack propagation differences between lateral crack and radical crack. 相似文献
9.
《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
10.
《Journal of the European Ceramic Society》2005,25(1):19-28
Sintering additives containing Y2O3 influence the microstructure and the crystalline-state of Si3N4-ceramics produced via pressureless sintering, and determine their response towards oxidation. Y2SiO5 and Y2Si2O7 were formed after sintering and oxidation, respectively. The superficial layers formed after oxidation are thinner and formed faster on the surface of the compositions 90Si3N4–5Y2O3–5Al2O3 and 90Si3N4–5Y2O3–5AlN than on 90Si3N4–5Y2O3–2.5Al2O3–2.5AlN (in wt.%). The 90Si3N4–5Y2O3–5Al2O3/liquid Al interface features strong interfacial adhesion while mild diffusion should govern the interfacial interactions. Compounds, whose formation results from the yttria-containing sintering aids, such as yttrium aluminates, should act as diffusion barriers at the ceramic/liquid metal interface. The experimental results indicate attractive features for applications in both Al-foundry industry and production of Si3N4–Al composites. 相似文献
11.
《Ceramics International》2023,49(13):22022-22029
The in-situ controllable synthesis of AlN–SiC solid solution reinforcement in large-sized Al–Si3N4–Al2O3 composite refractory by two-steps nitriding sintering was examined. In the first step, a dynamic Al@AlN structure was constructed in the composite by pre-nitriding at 580 °C. During the subsequent sintering process, it cracked above ∼900 °C, and micronized Al cluster (mixture of droplets and vapor) was extracted out gradually. As a result, multiple AlN mesophases were formed through different reaction paths, including i) initial AlN shell formed by solid Al with N2, ii) reaction of Al cluster with N2, and iii) reaction of Al cluster with Si3N4 from 900 °C to 1500 °C. The Si3N4 precursor serves as both a solid nitrogen source and an active Si source, and the controllable reaction between Al and Si3N4 leading to uniformly distributed AlN and Si mesophases. AlN–SiC solid solution is significantly formed when liquid Si appears. The shell, granule and whisker SiC–AlN solid solution were observed mainly depending on the dynamic AlN mesophase. The SiC–AlN solid solution reinforced Al2O3 materials is a novel promising refractory for large-scale blast furnace lining. 相似文献
12.
Kundan Kumar Mi-Ju Kim Hyeon-Myeong Oh Young-Jo Park Ha-Neul Kim Ho Jin Ma Jae-Wook Lee Jae-Woong Ko 《Journal of the American Ceramic Society》2022,105(7):4669-4680
Dense Si3N4 ceramics were fabricated by pressureless sintering at a low temperature of 1650°C with a short holding period of 1 h under a nitrogen atmosphere. The role of ternary oxide additives (Y2O3–MgO–Al2O3, Y2O3–MgO–SiO2, Y2O3–MgO–ZrO2) on the phase, microstructure, and mechanical properties of Si3N4 was examined. Only 5 wt.% of Y2O3–MgO–Al2O3 additive was sufficient to achieve >98% of theoretical density with remarkably high biaxial strength (∼1200 MPa) and prominent hardness (∼15.5 GPa). Among the three additives used, Y2O3–MgO–Al2O3 displayed the finest grain diameter (0.54 μm), whereas Y2O3–MgO–ZrO2 produced the largest average grain diameter (∼0.95 μm); the influence was seen on their mechanical properties. The low additive content Si3N4 system is expected to have superior high-temperature properties compared to the system with high additive content. This study shows a cost-effective fabrication of highly dense Si3N4 with excellent mechanical properties. 相似文献
13.
《应用陶瓷进展》2013,112(1):20-24
AbstractAbstractLow temperature sintering of α‐Si3N4 matrix ceramics was developed in the present study using 4?wt‐%MgO together with Al2O3 or AlPO4 as the sintering additives and spark plasma sintering technique. The results suggested that α‐Si3N4 ceramics could be densified at low sintering temperature by adjusting both the sintering temperature and sintering additive content. For low temperature sintered α‐Si3N4 ceramics, using MgO and Al2O3 as the sintering additives, the densification is not complete at a temperature lower than 1600°C, and the mechanical strength is <200?MPa. When MgO and AlPO4 were used as the sintering additives, the increase in AlPO4 content not only declines the sintering temperature but also promotes the mechanical property of the sintered Si3N4 ceramics. It was the AlPO4 phosphate binder that played a significant role in low temperature sintering of Si3N4 ceramics. 相似文献
14.
Hanqin Liang Yongfeng Xia Kaihui Zuo Dongxu Yao Jinwei Yin Yuping Zeng 《International Journal of Applied Ceramic Technology》2018,15(3):653-659
Si3N4 ceramics with different BaTiO3 contents have been fabricated by pressureless sintering in a N2 atmosphere at 1680°C for 2 h. Al2O3 and Nd2O3 were used as sintering additives to promote the densification of Si3N4 ceramics. The effect of BaTiO3 addition on the densification, mechanical properties, phase compositions, microstructure, and dielectric properties of Si3N4 ceramics was investigated. The relative density and flexural strength of Si3N4 ceramics increased with the addition of BaTiO3 up to 15 wt% and then decreased, while the dielectric constant increased continuously as the BaTiO3 contents increased. The dielectric constant of Si3N4 ceramics can be tailored in the range from 8.42 to 12.96 by the addition of 5 wt%‐20 wt% BaTiO3. Meanwhile, these Si3N4 ceramics all had flexural strength higher than 500 MPa. 相似文献
15.
《Journal of the European Ceramic Society》1999,19(1):61-65
A novel approach for in-situ incorporation of Al2O3 and Y2O3 additives into Si3N4 powder by a combustion technique is described. A suspension is made by mixing an alcoholic solution of Al/Y nitrates and citric acid with Si3N4 powder. The suspension forms a gray precipitate upon heating at 60°C. This precipitate undergoes a combustion reaction upon heating at 200°C and produces an amorphous phase of Al5Y3O12 (YAG) on the Si3N4 powder. The amorphous YAG phase shows a homogeneous distribution on the Si3N4 powder. Pellets of the composite powder are fabricated by cold isostatic pressing and sintered at 1750°C for 2 h at 5 bar of nitrogen pressure. The microstructure of the sintered body prepared by this method reveals a high density, the fracture toughness (K1C) is increased by 13·4%, compared to that of a sintered Si3N4 body formed with identical amounts of alumina and yttria additives prepared by planetary milling. 相似文献
16.
《Ceramics International》2021,47(18):25491-25496
In this study, we developed a novel method for synthesising Al2OC-AlNss using a solid nitrogen source: a Si3N4 mesophase. The two-step sintered Al–Al2O3 and Si3N4–Al–Al2O3 samples were prepared under an atmosphere of nitrogen to investigate the effect of Si3N4 on the formation of Al2OC-AlNss in resin-bonded Al–Al2O3 composites. The samples were investigated via XRD and SEM. The results indicated that the synthesis of Al2OC-AlNss with different morphologies was achieved via the Si3N4 mesophase, and its morphology was influenced by the source of AlN. Both Al2OC-AlNss and Al4O4C were formed in the two-step sintered Al–Al2O3 sample, whereas only Al2OC-AlNss was formed in the two-step sintered Si3N4–Al–Al2O3 sample. Induced by the AlN formed by the nitridation of Al, needle-like Al2OC-AlNss was generated. Compared to that formed by the nitridation of Al, more AlN nuclei were provided by the reaction between Si3N4 and Al. Subsequently, columnar and granular Al2OC-AlNss were formed. Furthermore, fibre-like Al2OC-AlNss was also generated via the VS and VLS mechanism. The reaction model was established in this study. 相似文献
17.
《Journal of the European Ceramic Society》1999,19(10):1903-1909
Si3N4 ceramic matrix composites reinforced by nearly unidirectionally aligned SiC whiskers have been prepared by extrusion and hot pressing. Unlike the case in traditional Si3N4 ceramic matrix composites reinforced by random SiC whiskers, the mechanical properties of the composites exhibit a significant dependence on whisker orientation. In the direction of whisker alignment for SiC(w)/Si3N4 composites, increments in bending strength and fracture toughness of 200 MPa and 3 MPa·m1/2 are obtained respectively, compared to the values in the direction perpendicular to whisker alignment. Based on microscopic fractographic observation and micromechanics analyses, the effects of whisker orientation on toughening mechanisms are discussed. The results indicate that the whisker orientation, θ, is a decisive factor for the essential toughening mechanisms of whiskers. Only in the case of small θ and weak interface can whisker pullout occur, and whisker has maximum toughening effect. The results show that effects of whisker strengthening and toughening can be improved simultaneously through whisker oriented alignment. © 相似文献
18.
Yuhan Ren Biao Zhang Junda Shao Jian Ye Qiang Liu Ye Gao Haoqian Zhang Zhaoxin Zhong Yang Wang Feng Ye 《International Journal of Applied Ceramic Technology》2022,19(5):2489-2499
Ceramics from porous Si3N4 and its derivatives SiAlON and Si2N2O were once considered the most promising high-temperature wave-transmitting materials. However, their large-scale application in the field of radomes is greatly restricted due to their poor oxidation resistance, high preparation costs, and expensive raw materials. Therefore, the development of low-cost porous oxide ceramics remains of significant interest to the field of high-temperature wave transmission. Surprisingly, mullite ceramics, which are representative of the Al2O3-SiO2-system of ceramics, are ultra-low-cost materials with the potential to replace ceramics from Si3N4 and its derivatives. In this paper, integrated porous Al2O3-SiO2-system ceramics were successfully prepared for load-bearing/wave-transmitting applications, using inexpensive calcined kaolin and alumina powder as the main raw materials. Calcined kaolin can provide seeds for the growth and development of mullite crystals in the ceramic system. High-strength and high-porosity ceramics were obtained with the mullite morphology controlled through the molar ratio of Al2O3 to SiO2 and the resulting content of mullite seeds. With increasing of mullite seed content, the length and radial width of mullite whiskers with “interlocking structure” gradually change from rod-shaped “long and thick” to needle-like “short and thin.” The prepared porous Al2O3-SiO2 ceramics have high flexural strength, fracture toughness, and good dielectric properties. 相似文献
19.
《Journal of the European Ceramic Society》2022,42(5):2146-2156
Si3N4 whisker (Si3N4w) reinforced composites were prepared by a near-net shaping process, i.e., gel-casting of the Si3N4w preform followed by polymer infiltration and pyrolysis (PIP) densification using polysilazane as precursor. The densification process by PIP was described mathematically, after which several key parameters affecting densification efficiency were discussed. The small pore size (0.04 ~ 1 μm) of Si3N4w preform can cause filtration effect (low permeability of precursor with a molecular size bigger than pore size), which resulted in the density gradient of the composites. Porosity (P) dependence of flexural strength and elastic modulus of Si3N4w/Si3N4 followed a power law of (1 – P). With increasing density, the response of Si3N4w when confronting cracks transformed from whisker debonding to whisker fracture, which was supposed to be due to the increase of whisker/matrix interface strength. The Si3N4w/Si3N4 developed by us achieved a good balance between high strength and low dielectric constant, making it promising for high-temperature wave-transparent application. 相似文献
20.
Wei‐Ming Guo Shang‐Xian Gu Yang You Qiang‐Guo Jiang Shang‐Hua Wu Hua‐Tay Lin 《Journal of the American Ceramic Society》2015,98(12):3651-3654
Densification and thermal stability of hot‐pressed Si3N4–ZrB2 ceramics with and without additives were investigated in N2 atmosphere. The addition of MgO–Yb2O3, MgO–Y2O3, and Al2O3–Yb2O3 resulted in significant increase in relative density of the ceramics hot‐pressed at 1500°C from 48.5% to 98.0%, 97.3%, and 95.6%, respectively. There was weak reaction of ZrB2 with N2 to form ZrN in hot‐pressed ceramics. Then heat treatment at 1550°C resulted in the further reactions to produce ZrN, ZrSi2, and BN. The Si3N4–ZrB2 ceramics with MgO–Yb2O3 showed much better thermal stability as compared to the ceramics with Al2O3–Yb2O3. The small difference in density led to the obvious difference in thermal stability. Therefore, Si3N4–ZrB2 ceramics should be densified to full density, to obtain high thermal stability. 相似文献