共查询到20条相似文献,搜索用时 35 毫秒
1.
Ahmad Zahirani Ahmad AzharHasmaliza Mohamad Mani Maran RatnamZainal Arifin Ahmad 《International Journal of Refractory Metals and Hard Materials》2011,29(4):456-461
The mechanical properties, microstructure and wear performance of zirconia-toughened alumina (ZTA) cutting inserts with Magnesia (MgO) in different particle sizes as additives was investigated. The MgO particle sizes were varied from 80 nm to 7000 nm. The alumina (Al2O3), yittria stabilized zirconia (YSZ) and MgO powders were mixed, compacted and sintered at 1600 °C using the solid-state sintering method. The mechanical and physical properties of the samples such as wear resistance, Vickers hardness, fracture toughness, microstructure and density were analyzed. Commercially available stainless steel (316L) was used as the workpiece for the wear resistance study. It was observed that smaller MgO particle sizes induce better wear performance and mechanical properties for the cutting inserts. Wear resistance analysis showed that the cutting insert with nano-sized MgO (particle size 80 nm) had the lowest wear area of 0.019 mm². The same cutting insert also possessed the highest Vickers hardness value of 1740 Hv compared to the other samples. Furthermore, microstructural observations show that the Al2O3 grain size depends on the particle size of MgO, and is directly related to its hardness property. 相似文献
2.
The objective of this work is to produce Al2O3-ZrO2 composite from nano-sized powders processed by coprecipitation method. Al2O3 and mixture of Al2O3 + 10 wt.% ZrO2 precipitated successfully by chemical route from aluminum sulfate and zirconium sulfate were pressed under uniaxial compression of 170 MPa and sintered at 1600 °C for 1 h. SEM investigations revealed that, pure alumina sample has a microstructure with coarse grains which anisotropically grown up to 30-40 μm in size. In alumina-zirconia composite, the structure consists of very fine equiaxed grains of typically 2 μm in which zirconia precipitates were uniformly dispersed. By adding zirconia to alumina, hardness and indentation fracture toughness were increased from 11.6 GPa to 16.8 GPa and from 3.2 MPa m1/2 to 4.9 MPa m1/2, respectively. Improvement in fracture toughness was attributed to bridging effects of zirconia particles as well as transformation toughening. 相似文献
3.
I. Khobta O. PetukhovO. Vasylkiv Y. SakkaA. Ragulya 《Journal of Alloys and Compounds》2011,509(5):1601-1606
The simultaneous synthesis and densification of TiN/TiB2 ceramic composites via reactive spark plasma sintering (RSPS) was investigated. Different component ratios (TiH2/BN (TiN, B)) and heating rates (112.5-300 °C/min) were used to initiate the chemical reaction for TiN/TiB2 synthesis. The omit RSPS process was revealed to have three stages, which are described separately. The relationships between the RSPS conditions, the microstructure and the properties of sintered ceramic composites were established. A Vickers hardness of 16-25 GPa and a fracture toughness of 4-6.5 MPa m1/2 were measured for various compositions. Sintered ceramic composites containing 36 wt% TiB2 with the highest relative density of 97.4 ± 0.4% and an average grain size of 150-550 nm have been obtained. 相似文献
4.
Bulk WC-Al2O3 composites prepared by spark plasma sintering 总被引:1,自引:0,他引:1
Donghai ZhengXiaoqiang Li Xuan AiChao Yang Yuanyuan Li 《International Journal of Refractory Metals and Hard Materials》2012,30(1):51-56
WC and WC-Al2O3 materials without metallic binder addition were densified by spark plasma sintering in the range of 1800-1900 °C. The densification behavior, phase constitution, microstructure and mechanical properties of pure WC and WC-Al2O3 composite were investigated. The addition of Al2O3 facilitates sintering and increases the fracture toughness of the composites to a certain extent. An interesting phenomenon is found that a proper content of Al2O3 additive helps to limit the formation of W2C phase in sintered WC materials. The pure WC specimen possesses a hardness (HV10) of 25.71 GPa, fracture toughness of 4.54 MPa·m1/2, and transverse fracture strength of 862 MPa, while those of WC-6.8 vol.% Al2O3 composites are 24.48 GPa, 6.01 MPa·m1/2, and 1245 MPa respectively. The higher fracture toughness and transverse fracture strength of WC-6.8 vol.% Al2O3 are thought to result from the reduction of W2C phase, the crack-bridging by Al2O3 particles and the local change in fracture mode from intergranular to transgranular. 相似文献
5.
Nanopowders of Ni and ZrO2 (11 nm and 90 nm, respectively) were synthesized from NiO and Zr by high energy ball milling. A highly dense nanostructured 2Ni-ZrO2 composite was consolidated at low temperature by high-frequency induction heat sintering within 2 min of the mechanical synthesis of the powders (Ni-ZrO2) with horizontal milled NiO + Zr powders under 500 MPa pressure. This process allows very quick densification to near theoretical density and prohibits grain growth in nano-structured materials. The grain sizes of Ni and ZrO2 in the composite were calculated. Finally, the average hardness and fracture toughness values of nanostructured 2Ni-ZrO2 composites were investigated. 相似文献
6.
A. Nevarez-Rascon A. Aguilar-Elguezabal E. Orrantia M.H. Bocanegra-Bernal 《International Journal of Refractory Metals and Hard Materials》2009,27(6):962-970
In this work the influence of pressureless sintering on the Vickers hardness and fracture toughness of ZrO2 reinforced with Al2O3 particles (ATZ) and Al2O3 reinforced with ZrO2 particles (ZTA) has been investigated. The ceramic composites were produced by means of uniaxial compacting at 50 MPa and the green compacts were heated to 1250 °C using a heating rate of 10 °C min−1, then to 1500 °C at 6 °C min−1 and maintained at this temperature during 2 h. After sintering, relative density over 94%, hardness values between 9.5 and 21.9 GPa, and fracture toughness as high as 3.6 MPa m1/2 were obtained. The presence of TZ-3Y particles on the grain boundaries suggests that they inhibit notably the alumina grain growth. The grain sizes of pure Al2O3 and TZ-3Y as well as Al2O3 and TZ-3Y in the 20 wt% Al2O3+80 wt% TZ-3Y composite were 1.27 ± 0.51 μm, 0.57 ± 0.12 μm, 0.65 ± 0.19 μm and 0.41 ± 0.14 μm, respectively. The 20 wt% Al2O3 + 80 wt% ZrO2 + 3 mol% Y2O3 (TZ-3Y) composite showed a hardness of 16.05 GPa and the maximum fracture toughness (7.44 MPa m1/2) with an average grain size of 0.53 ± 0.17 μm. On the other side, the submicron grain size and residual porosity seem to be responsible for the high hardness and fracture toughness obtained. The reported values were higher than those obtained by other authors and are in concordance with international standards that could be suitable for dental applications. 相似文献
7.
A. Nevarez-Rascon A. Aguilar-ElguezabalE. Orrantia M.H. Bocanegra-Bernal 《International Journal of Refractory Metals and Hard Materials》2011,29(3):333-340
The aim of this investigation was to study the variability in compressive strength, fracture toughness and microhardness applying the well-known Weibull statistics and to be able to provide a wide spectrum of mechanical properties in Al2O3 whisker reinforced alumina toughened zirconia (ATZ) and zirconia toughened alumina (ZTA) nanocomposites for possible dental applications. Uniaxial compression tests at room temperature of samples 6.35 ± 0.03 mm in diameter and 12.50 ± 0.63 mm in length and Vickers hardness measurements on polished surfaces were carried out. The indentation fracture toughness (KIC) was derived from the average crack length. Weibull analysis was performed on the data. The ATZ2 (18.0 wt.% Al2O3 + 2.0 wt.%(w) + 80.0 wt.% ZrO2 (TZ-3Y)) nanocomposite reported the highest average compressive load of 1200 MPa, the highest value of characteristic strength, σo, of 1340 MPa with Weibull modulus of 3.25 and relatively high fracture toughness (4.7 ± 0.7 MPa m1/2), suggesting that with the wide range of mechanical properties obtained in our work, different dental applications could be offered without lead to premature failure. 相似文献
8.
Mehdi Rahimian Naser Ehsani Nader Parvin Hamid reza Baharvandi 《Journal of Materials Processing Technology》2009,209(14):5387-5393
Al2O3 is a major reinforcement in aluminum-based composites, which have been developing rapidly in recent years. The aim of this paper is to investigate the effect of alumina particle size, sintering temperature and sintering time on the properties of Al–Al2O3 composite. The average particle size of alumina were 3, 12 and 48 μm. Sintering temperature and time were in the range of 500–600 °C for 30–90 min. A correlation is established between the microstructure and mechanical properties. The investigated properties include density, hardness, microstructure, yield strength, compressive strength and elongation to fracture. It has been concluded that as the particle size of alumina is reduced, the density is increased followed by a fall in density. In addition, at low particle size, the hardness and yield strength and compressive strength and elongation to fracture were higher, compared to coarse particles size of alumina. The variations in properties of Al–Al2O3 composite are dependent on both sintering temperature and time. Prolonged sintering times had an adverse effect on the strength of the composite. 相似文献
9.
Ming He Shuren ZhangXiaohua Zhou Bo LiJing Wan 《Journal of Alloys and Compounds》2011,509(11):4260-4263
The behavior of dielectric and microwave properties against sintering temperature has been carried out on CaO-SiO2-B2O3 ceramic matrix composites with ZrO2 addition. The results indicated that ZrO2 addition was advantageous to improve the dielectric and microwave properties. X-ray diffraction (XRD) patterns show that the major crystalline β-CaSiO3 and a little SiO2 phase existed at the temperature ranging from 950 °C to 1050 °C. At 0.5 wt% ZrO2, CaO-SiO2-B2O3 ceramic matrix composites sintered at 1000 °C possess good dielectric properties: ?r = 5.85, tan δ = 1.59 × 10−4 (1 MHz) and excellent microwave properties: ?r = 5.52, Q · f = 28,487 GHz (11.11 GHz). The permittivity of Zr-doped CaO-SiO2-B2O3 ceramic matrix composites exhibited very little temperature dependence, which was less than ±2% over the temperature range of −50 to 150 °C. Moreover, the ZrO2-doped CaO-SiO2-B2O3 ceramic matrix composites have low permittivity below 5.5 over a wide frequency range from 20 Hz to 1 MHz. 相似文献
10.
J.K. SonberR.K. Fotedar A.K. Suri 《International Journal of Refractory Metals and Hard Materials》2011,29(1):21-30
This paper presents the results of experimental investigations carried out on the synthesis of pure ZrB2 by boron carbide reduction of ZrO2 and densification with the addition of HfB2 and TiSi2. Process parameters and charge composition were optimized to obtain pure ZrB2 powder. Monolithic ZrB2 was hot pressed to full density and characterized. Effects of HfB2 and TiSi2 addition on densification and properties of ZrB2 composites were studied. Four compositions namely monolithic ZrB2, ZrB2 + 10% TiSi2, ZrB2 + 10% TiSi2 + 10% HfB2 and ZrB2 + 10% TiSi2 + 20% HfB2 were prepared by hot pressing. Near theoretical density (99.8%) was obtained in the case of monolithic ZrB2 by hot pressing at 1850 °C and 35 MPa. Addition of 10 wt.% TiSi2 resulted in an equally high density of 98.9% at a lower temperature (1650 °C) and pressure (20 MPa). Similar densities were obtained for ZrB2 + HfB2 mixtures also with TiSi2 under similar conditions. The hardness of monolithic ZrB2 was measured as 23.95 GPa which decreased to 19.45 GPa on addition of 10% TiSi2. With the addition of 10% HfB2 to this composition, the hardness increased to 23.08 GPa, close to that of monolithic ZrB2. Increase of HfB2 content to 20% did not change the hardness value. Fracture toughness of monolithic sample was measured as 3.31 MPa m1/2, which increased to 6.36 MPa m1/2 on addition of 10% TiSi2. With 10% HfB2 addition the value of KIC was measured as 6.44 MPa m1/2, which further improved to 6.59 MPa m1/2 with higher addition of HfB2 (20%). Fracture surface of the dense bodies was examined by scanning electron microscope. Intergranular fracture was found to be a predominant mode in all the samples. Crack propagation in composites has shown considerable deflection indicating high fracture toughness. An oxidation study of ZrB2 composites was carried out at 900 °C in air for 64 h. Specific weight gain vs time plot was obtained and the oxidized surface was examined by XRD and SEM. ZrB2 composites have shown a much better resistance to oxidation as compared to monolithic ZrB2. A protective glassy layer was seen on the oxidized surfaces of the composites. 相似文献
11.
R. PazhaniH. Padma Kumar Angeo VargheseA. Moses Ezhil Raj Sam SolomonJ.K. Thomas 《Journal of Alloys and Compounds》2011,509(24):6819-6823
Phase pure zirconium oxide powders have been synthesized using the single step auto-ignition combustion method, the particles were nanometer sized (20 nm) and the size distribution was very narrow (3.4 nm). Systematic structural characterization revealed the t-ZrO2 and indexed for its tetragonal structure (a = 3.5975 Å and c = 5.1649 Å). Calculated microstrain in most of the plane indicated the presence of compressive stress (65-288 MPa) along various planes of the particles. Observed space group (P42/nmc) revealed the presence of cations in the 8e positions (0.75, 0.25, 0.75) and the anions in the 16 h positions (0.25, 0.25, 0.4534). The metal-oxide (Zr-O) band observed at the low wavenumber region further confirmed the phase purity of the as-prepared ZrO2 nanopowders. Peaks at the binding energy positions 2.042 and 0.525 keV in the energy dispersive X-ray spectrum revealed oxygen deficient zirconia. The particle size estimated by TEM was in good agreement with the results obtained through X-ray line broadening (20.81 nm) measurements. The nanopowders were sintered to above 98% of the theoretical density by using vacuum sintering technique at a relatively low temperature of 1300 °C. Stable tetragonal ZrO2 experimentally yield the permittivity value of about 28 at 10 MHz. 相似文献
12.
Chuncheng Wei Xinghong ZhangPing Hu Wenbo HanShuang Li 《International Journal of Refractory Metals and Hard Materials》2012,30(1):173-176
Laminated ZrB2-SiC ceramics with ZrO2 interface layers were successfully prepared by tape casting, laminating and hot pressing. The flexural strength and fracture toughness are 561 ± 20 MPa and 14.4 ± 0.3 MPa m1/2 for parallel direction, and 432 ± 18 MPa and 5.8 ± 0.3 MPa m1/2 for perpendicular direction. The fracture toughness for parallel direction is improved significantly compared to monolithic ZrB2-SiC ceramics. The toughening mechanism was attributed to the deflection and branch of the crack and the new microcracks, which would increase the propagation path and fracture work. 相似文献
13.
X.Q. OuM. Song T.T. ShenD.H. Xiao Y.H. He 《International Journal of Refractory Metals and Hard Materials》2011,29(2):260-267
The ultrafine grained WC-10Co-0.45Cr3C2-0.25VC alloys were fabricated through planetary ball milling and low pressure sintering. The effects of the cobalt particle size, milling speed and sintering temperature on the microstructure, hardness and fracture toughness of the ultrafine grained alloys were investigated using optical microscopy, scanning electron microscopy and mechanical testing. The results showed that the mechanical properties of the low pressure-sintered alloys substantially depend on the milling speed and sintering temperature. At the same time, the hardness and fracture toughness of the samples can be increased from 1703 MPa and 8.90 MN m−3/2 to 1789 MPa and 11.21 MN m−3/2, respectively, when the cobalt particle size is reduced from 17 μm to 1.4 μm. 相似文献
14.
S.A. Sajjadi M. Torabi PariziH.R. Ezatpour A. Sedghi 《Journal of Alloys and Compounds》2012,511(1):226-231
Aluminum/alumina composites are used in automotive and aerospace industries due to their low density and good mechanical strength. In this study, compocasting was used to fabricate aluminum-matrix composite reinforced with micro and nano-alumina particles. Different weight fractions of micro (3, 5 and 7.5 wt.%) and nano (1, 2, 3 and 4 wt.%) alumina particles were injected by argon gas into the semi-solid state A356 aluminum alloy and stirred by a mechanical stirrer with different speeds of 200, 300 and 450 rpm. The microstructure of the composite samples was investigated by Optical and Scanning Electron Microscopy. Also, density and hardness variation of micro and nano composites were measured. The microstructure study results revealed that application of compocasting process led to a transformation of a dendritic to a nondendritic structure of the matrix alloy. The SEM micrographs revealed that Al2O3 nano particles were surrounded by silicon eutectic and inclined to move toward inter-dendritic regions. They were dispersed uniformly in the matrix when 1, 2 and 3 wt.% nano Al2O3 or 3 and 5 wt.% micro Al2O3 was added, while, further increase in Al2O3 (4 wt.% nano Al2O3 and 7.5 wt.% micro Al2O3) led to agglomeration. The density measurements showed that the amount of porosity in the composites increased with increasing weight fraction and speed of stirring and decreasing particle size. The hardness results indicated that the hardness of the composites increased with decreasing size and increasing weight fraction of particles. 相似文献
15.
Haizhou Yu Yong Zheng Wenjun Liu Jianzhi Zheng Weihao Xiong 《International Journal of Refractory Metals and Hard Materials》2010
Five series of Mo2FeB2 based cermets with Mn addition between 0 and 10 wt% in 2.5 wt% increments were prepared by reaction sintering process. The effect of Mn content on the microstructure and crystalline phases was investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD). Hardness (HRA) and transverse rupture strength (TRS) were also measured. Mn addition improved the wettability of the Fe binder phase on the Mo2FeB2 hard phase, which resulted in a decrease in porosity and Mo2FeB2 grain size and an increase in phase uniformity. No Fe–Mn intermetallic compounds or other intermetallic compounds were detected with increasing Mn content. The TRS increased with increasing Mn content until it reached the maximum value at 10.0 wt% Mn addition. The hardness slightly increased with increasing Mn content firstly and then turned to decrease with increasing Mn content. The highest hardness was obtained for cermets with 5.0 wt% Mn addition. 相似文献
16.
通过2TiC-Ti-1.2Al体系的原位热压反应制备了Ti3AlC2陶瓷,然后以59.2Ti-30.8Al-10Ti3AlC2(wt%)为反应体系,采用放电等离子烧结技术制备出Ti2AlC/TiAl基复合材料。借助XRD、SEM分析了产物的相组成和微观结构,并测量了其室温力学性能。结果表明:原位热压烧结产物由Ti3AlC2和TiC相组成,Ti3AlC2呈典型的层状结构,TiC颗粒分布在其间。SPS法制备的Ti2AlC/TiAl基复合材料主要由TiAl、Ti3Al和Ti2AlC相组成,Ti2AlC增强相主要分布于基体晶界处,表现为晶界/晶内强化作用。力学性能测试表明:Ti2AlC/TiAl基复合材料的密度、维氏硬度、断裂韧性和抗弯强度分别为3.85 g/cm3、5.37 GPa、7.17 MPa?m1/2和494.85 MPa。 相似文献
17.
J. Echeberria J. Ollo M.H. Bocanegra-Bernal A. Garcia-Reyes C. Domínguez-Rios A. Aguilar-Elguezabal A. Reyes-Rojas 《International Journal of Refractory Metals and Hard Materials》2010
This work describes the microstructure and fracture toughness of zirconia toughened alumina (ZTA) nanocomposite in which multi-wall carbon nanotubes (MWCNTs) and nanosized ZrO2 particles were used as reinforcement. The ZTA nanocomposites with additions of 0, 0.005, and 0.01 wt.% MWCNTs and 2 wt.% nanosized ZrO2 particles were pressureless sintered in an anti-oxidant sagger with graphite powder bed at 1520 °C during 1 h in air and then HIPed at 1475 °C in argon atmosphere 1 h at a pressure of 150 MPa. Relative densities ranging 94–98% were reached. In HIPed composites the hardness and fracture toughness values were increased up to ∼17% and ∼37%, respectively, compared to the “as sintered” composites free of carbon nanotubes. A combined fracture mode, crack deflection, pull-outs of a small amount of carbon nanotubes, and bridging effect were the mechanisms leading to the improvement in fracture toughness. 相似文献
18.
通过放电等离子烧结技术制备了添加不同W含量(1%,3%和5%,体积分数,下同)的ZrB2-SiC复合材料,研究了烧结过程中复合材料的致密化行为,分析了添加W对复合材料微观组织演化、相组成、力学性能和氧化行为的影响。结果表明:W的添加使复合材料的微观组织表现出核壳结构,以ZrB2晶粒为核,原位形成的(Zr, W)B2固溶体为壳,有效地促进了复合材料的致密化和晶粒细化。对比不含W的复合材料,含W复合材料的维氏硬度、抗弯曲强度和断裂韧性显著提高,W添加含量在3%时力学性能最优,复合材料表现出最佳的硬度、强度和韧性。随着W添加量从0%增加到5%,复合材料的氧化增重和氧化层厚度逐渐减小。当W添加量为5%时,复合材料的SiC贫化层消失。最后,详细说明了W的添加对复合材料性能的影响机制。 相似文献
19.
Effects of sintering additives on microstructure and mechanical properties of TiB2-WC ceramic-metal composite tool materials 总被引:1,自引:0,他引:1
Jinpeng SongChuanzhen Huang Bin ZouHanlian Liu Lin LiuJun Wang 《International Journal of Refractory Metals and Hard Materials》2012,30(1):91-95
TiB2-WC ceramic-metal composite tool materials were fabricated using Co, Ni and (Ni, Mo) as sintering additives by vacuum hot-pressing technique. The microstructure and mechanical properties of the composite were investigated. The composite was analyzed by the observations of scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectrometry (EDS). The microstructure of TiB2-WC ceramic-metal composites consisted of the fine WC grains and uniform TiB2 grains. The brittle phase of Ni3B4 and a few pores were found in TiB2-WC-Ni ceramic-metal composite. A lot of pores and brittle phases such as W2CoB2 and Co2B were formed in TiB2-WC-Co ceramic-metal composite. The liquid phase of Co was consumed by the reaction which led to the formation of the pores and the coarse grains of TiB2. The pores, brittle phases and coarse grains of TiB2 were harmful to the improvement of the mechanical properties of the composite. The sintering additive of (Ni, Mo) had a significant effect on the density and the mechanical properties of TiB2-WC ceramic-metal composite. The formation of intermetallic compound of MoNi4 inhibited the consumption of liquid phase of (Ni, Mo). The liquid phase of (Ni, Mo) not only inhibited the formation of the pores and the coarse grains of TiB2 but also strengthened the interface energy between WC and TiB2 grains. The grain size was fine and the average relative density of TiB2-WC-(Ni, Mo) ceramic-metal composite reached 99.1%. The flexural strength, fracture toughness and Vickers hardness of TiB2-WC-(Ni, Mo) ceramic-metal composite were 1307.0 ± 121.4 MPa, 8.19 ± 0.29 MPa m1/2 and 22.71 ± 0.82 GPa, respectively. 相似文献
20.
F. SamanipourM.R. Bayati H.R. ZargarF. Golestani-Fard T. TroczynskiM. Taheri 《Journal of Alloys and Compounds》2011,509(38):9351-9355
Micro arc oxidation (MAO) and electrophoretic deposition (EPD) processes were simultaneously employed to grow ZrO2-HAp-TiO2 porous layers on titanium substrates under different conditions. Influence of the electrolyte composition and the growth time on surface morphology, topography, phase structure, and stoichiometry of the layers was investigated. The utilized electrolytes consisted of β-glycerophosphate, calcium acetate, sodium phosphate, and micron sized yttria-stabilized zirconia with different concentrations. AFM and SEM evaluations revealed a rough surface with a porous structure with a pores size of 50-750 nm. The pores size increased with the time and the electrolyte concentration. Based on the XRD and XPS results, the layers consisted of anatase, hydroxyapatite, monoclinic ZrO2, tetragonal ZrO2, ZrO, CaTiO3, and α-TCP phases whose fractions were observed to change depending on the synthesis conditions. The average crystalline size of the HAp phase was determined as ∼54 nm. The nano-sized zirconia particles (d = 20-60 nm) were dispersed not only on surface, but also in depth of the layers. Utilizing thicker electrolytes and prolonging the growth time resulted in decomposition of hydroxyapatite as well as tetragonal ZrO2 to monoclinic ZrO2. EDX results also showed that the zirconium wt% in the layers increased with the time. EPD-enhanced MAO (EEMAO) technique was expressed as an efficient route to fabricate ZrO2-HAp-TiO2 multiphase systems within short times and only in one step. 相似文献