Microstructure and Mechanical Properties of Hot-Pressed and Pressureless Sintered WC-Al2O3 Ceramic Composites

1993 ◽  
Vol 327 ◽  
Author(s):  
Hidehiro Endo ◽  
Masanori Ueki
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Composite System ◽  
Ceramic Composites ◽  
Pressureless Sintering ◽  
Sintering Aid ◽  
Al2o3 Ceramic ◽  
Remarkable Improvement

AbstractFully densified WC-A12O3 composites were successfully consolidated by both hot-pressing and pressureless sintering. The optimum hot-pressing condition for the composites was 1700°C for 2h under a pressure of 40MPa. A remarkable improvement in mechanical properties was achieved in the composite system, especially in WC-30 and -70vol%A12O3, compared to the monolithic WC and A12O3 ceramics. The addition of MgO as a sintering aid had a great effect on the properties of the composites. WC-30vol%A12O3 composite with 1.Owt% MgO addition exhibited flexural strength higher than 1000MPa up to 1200°C, fracture toughness; KIC≥7MPa√m, and hardness; HV ≥2450. In pressureless sintering with the addition of MgO as a sintering aid and subsequent HIP treatment, the WC-30vol%A12O3 composite exhibited the flexural strength higher than 900MPa up to 1200°C.

Effect of BN Short Fiber Content on Mechanical Properties of ZrB2-SiC UHTCs

2012 ◽  
Vol 512-515 ◽  
pp. 706-709 ◽  
Author(s):  
Chang Ling Zhou ◽  
Yan Yan Wang ◽  
Zhi Qiang Cheng ◽  
Chong Hai Wang ◽  
Rui Xiang Liu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Scanning Electron Microscopy ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Ceramic Composites ◽  
Short Fiber ◽  
Hot Pressing Sintering ◽  
Scanning Electron

ZrB2-20%volSiC ceramic composites with different volume of BN short fiber were fabricated by the hot-pressing sintering under 2000°C. The content of BN short fiber changed from 0 to 15vol%. The density, flexural strength, fracture toughness and thermal expansions coefficient were studied. The microstructures of the samples were observed by scanning electron microscopy. The results show that the introducing of BN short fiber into the ZrB2-20%volSiC lead to a serious of change to the mechanical properties of the ceramic. When the content of the BN short fiber is 10vol%, the flexural strength and fracture toughness reach 422.1MPa and 6.15 MPa•m 1/2 respectively. And the mechanism of the increasing toughness was studied.

Microstructure and Mechanical Properties of Hot Pressed ZrC-SiC-ZrB2 Composites

2010 ◽  
Vol 434-435 ◽  
pp. 173-177 ◽  
Author(s):  
Bao Xia Ma ◽  
Wen Bo Han ◽  
Xing Hong Zhang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Ceramic Composites ◽  
Strong Function ◽  
Slight Tendency ◽  
Microstructure And Mechanical Properties

Ternary ZrC-SiC-ZrB2 ceramic composites were prepared by hot pressing at 1900 °C for 60 min under a pressure of 30 MPa in argon. The influence of ZrB2 content on the microstructure and mechanical properties of ZrC-SiC-ZrB2 composites was investigated. Examination of SEM showed that the microstructure of the composites consisted of the equiaxed ZrB2, ZrC and SiC grains, and there was a slight tendency of reduction for grain size in ZrC with increasing ZrB2 content. The hardness increased considerably from 23.3 GPa for the ZS material to 26.4 GPa for the ZS20B material. Flexural strength was a strong function of ZrB2 content, increasing from 407 MPa without ZrB2 addition to 627 MPa when the ZrB2 content was 20vol.%. However, the addition of ZrB2 has little influence on the fracture toughness, ranging between 5.5 and 5.7 MPam1/2.

Mechanical Properties of NanoSiC Reinforced ZrB2-Based Ceramic Composite

2013 ◽  
Vol 745-746 ◽  
pp. 560-564
Author(s):  
Wen Bo Han ◽  
Peng Wang ◽  
Yang Hou
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Ceramic Composite ◽  
Ceramic Materials ◽  
Ceramic Composites

ZrB2-based ceramic composites were prepared through hot-pressing at a temperature of 1880°C. An intragranular microstructure was achieved because of the existence of nanoSiC. In this paper, the mechanical properties of ceramic materials of ZrB2-SiC-G were studied, and the influence of intragranular microstructure on the mechanical properties was analyzed. The values of flexural strength and fracture toughness of ZrB2-20vol%SiCnp-15vol%G reached 551.9MPa and 5.25MPa·m1/2, respectively. Compared to ZrB2-20vol%SiC-15vol%G with micro-SiC, the fracture toughness was improved.

Effect of Sintering Temperature on Microstructure and Mechanical Properties of Al2O3-TiC-ZrO2 Ceramic Composites

2012 ◽  
Vol 476-478 ◽  
pp. 1031-1035
Author(s):  
Wei Min Liu ◽  
Xing Ai ◽  
Jun Zhao ◽  
Yong Hui Zhou
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Relative Density ◽  
Sintering Temperature ◽  
Ceramic Composites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

Al2O3-TiC-ZrO2ceramic composites (ATZ) were fabricated by hot-pressed sintering. The phases and microstructure of the composites were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The relative density and mechanical properties (flexural strength, fracture toughness and Vicker’s hardness) of the composites were tested. The results show that the microstructure of the composites was the gray core-white rim. With the increase of sintering temperature, the relative density and mechanical properties of the composites increased first and then decreased. The composite sintered at 1705°C has the highest synthetical properties, and its relative density, flexural strength, fracture toughness and Vickers hardness are 98.3%,970MPa,6.0 MPa•m1/2and 20.5GPa, respectively.

scholarly journals Nano-(Ta, Zr)C Precipitates at Multigrain Conjunctions in TaC Ceramic with 10 mol% ZrC and 5 mol% Cu as Sintering Aid

2018 ◽  
Vol 2018 ◽  
pp. 1-5
Author(s):  
Lianbing Zhong ◽  
Guihong Geng ◽  
Yujin Wang ◽  
Feng Ye ◽  
Limeng Liu
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Glassy Matrix ◽  
Sintering Aid ◽  
Uniform Dispersion ◽  
New Type

A fully dense TaC ceramic was prepared by hot pressing using 10 mol% ZrC plus 5 mol% Cu as a sintering aid. Formation of (Ta, Zr)C solid solution (ss) by reaction between TaC and ZrC facilitated densification. Addition of Cu refined the microstructure and consequently improved flexural strength of the TaC ceramics. TEM investigation found ubiquitous precipitation of nanocrystallites at multigrain conjunctions. The nanocrystallites were (Ta, Zr)C solid solution with uniform dispersion in an oxygen-rich glassy matrix. Although formation of nanoprecipitates may not much affect the mechanical properties of the TaC ceramic, the structure suggested a new type of nanoceramic worth further research.

Microstructure and Mechanical Properties of SiC Whisker-Reinforced ZrB2 Ultra-High Temperature Ceramic

2008 ◽  
Vol 368-372 ◽  
pp. 1730-1732 ◽  
Author(s):  
Ping Hu ◽  
Xing Hong Zhang ◽  
Jie Cai Han ◽  
Song He Meng ◽  
Bao Lin Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Temperature ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Room Temperature ◽  
Pressing Temperature ◽  
Sintering Time ◽  
Microstructure And Mechanical Properties ◽  
Ultra High Temperature

SiC whisker-reinforced ZrB2 matrix ultra-high temperature ceramic were prepared at 2000°C for 1 h under 30MPa by hot pressing and the effects of whisker on flexural strength and fracture toughness of the composites was examined. The flexural strength and fracture toughness are 510±25MPa and 4.05±0.20MPa⋅m1/2 at room temperature, respectively. Comparing with the SiC particles-reinforced ZrB2 ceramic, no significant increase in both strength and toughness was observed. The microstructure of the composite showed that the SiC whisker was destroyed because the SiC whisker degraded due to rapid atom diffusivity at high temperature. The results suggested that some related parameters such as the lower hot-pressing temperature, a short sintering time should be controlled in order to obtain SiC whiskerreinforced ZrB2 composite with high properties.

Reactive Synthesis and Mechanical Properties of ZrB2-SiC-ZrC Composites

2008 ◽  
Vol 368-372 ◽  
pp. 1758-1760 ◽  
Author(s):  
Wen Wen Wu ◽  
Guo Jun Zhang ◽  
Yan Mei Kan ◽  
Pei Ling Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Raw Materials ◽  
Reactive Synthesis ◽  
Reactive Hot Pressing

ZrB2-SiC based composites with 0,5 and 15 vol% addition of ZrC were synthesized via reactive hot pressing at 1800°C using Zr, Si and B4C as raw materials. The mechanical properties of the composites were investigated. The composite of ZSC15 that contained 15 vol% of ZrC has the highest hardness. ZSC5 with 5 vol% of ZrC owns a most homogenous microstructure and the highest fracture toughness and flexural strength.

Mechanical Properties and Machinability of Si3N4/hBN Composites Prepared by Pressureless Sintering

2006 ◽  
Vol 510-511 ◽  
pp. 1014-1017 ◽  
Author(s):  
Won Seung Cho ◽  
Ki Ju Lee ◽  
Myeong Woo Cho ◽  
Jae Hyung Lee ◽  
Woon Suk Hwang
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Ceramic Composites ◽  
Pressureless Sintering ◽  
Si3n4 Ceramic ◽  
Cutting Resistance ◽  
Axis Parallel ◽  
Si3n4 Ceramics

The effects of hBN content on microstructure, mechanical properties, and machinability of the pressureless-sintered Si3N4 ceramics were investigated. Flexural strength, Young’s modulus, and hardness decreased with increasing h-BN content. The mechanical properties are decreased mainly because of increased porosity of composite, and the much lower Young's modulus of BN compared to that of Si3N4. Pressureless-sintered Si3N4/hBN composites exhibit strong texture of BN grains oriented with the c-axis parallel to the cold-pressing direction. Cutting resistance of Si3N4 ceramic composites with more than 10 vol% hBN decreased with increasing hBN content, demonstrating a good machinability of the composites. The residual pores can be attributed to improved machinability of pessureless-sintered Si3N4-BN composite.

Microstructure and properties of pressureless sintered ZrC-based materials

2008 ◽  
Vol 23 (7) ◽  
pp. 1882-1889 ◽  
Author(s):  
Laura Silvestroni ◽  
Diletta Sciti
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Flexural Strength ◽  
Room Temperature ◽  
Pressureless Sintering ◽  
Secondary Phases ◽  
Sintering Aid ◽  
Mean Particle Size ◽  
Dense Bodies ◽  
Similar Materials

ZrC-based composites were produced by pressureless sintering thanks to the addition of MoSi2 as sintering aid. After preliminary tests, a baseline ZrC material and two mixed ZrC–HfC and ZrC–ZrB2 composites with 20 vol% MoSi2 were densified at 1900 to 1950 °C reaching final relative densities of 96%–98%. Mean particle size of the dense bodies ranged from 5 to 9 μm. Secondary phases were found to form during sintering, such as SiC and Zr–Mo–Si-based compounds. Room-temperature mechanical properties were in the range of the values reported in the literature for similar materials densified by pressure-assisted techniques. The flexural strength was tested at room temperature, 1200 and 1500 °C.

Si3N4/BN Composite Ceramics with Nd2O3-Al2O3-Y2O3 Ternary Additives by Pressureless Sintering

2010 ◽  
Vol 434-435 ◽  
pp. 106-108
Author(s):  
Ping Liu ◽  
Yong Feng Li ◽  
Xiang Dong Wang ◽  
Hai Yun Jin ◽  
Guan Jun Qiao
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Phase Transformation ◽  
Flexural Strength ◽  
Pressureless Sintering ◽  
Sintering Process ◽  
Composite Ceramics ◽  
Fracture Toughness Testing ◽  
Β Phase ◽  
Toughness Testing

Si3N4/BN composite ceramics with 25vol% h-BN were prepared by pressure-less sintering process with Nd2O3/Al2O3/Y2O3 as sintering additives. The effects of these ternary additives on the densification behaviors and mechanical properties were investigated. XRD and FESEM were used to investigate the α-β phase transformation and microstructure. The XRD results showed that α-Si3N4 has transformed to β-Si3N4 completely in all the samples during the pressureless sintering process. The line shrinkage increased with the Nd2O3 contents increasing, and the highest line shrinkage (7.75%) was observed when 4wt% Nd2O3 was added, then decreased. The same trends were observed in flexural strength and fracture toughness testing. The ternary additives of Y2O3-Al2O3-Nd2O3 could improve the density, strength and fracture toughness of the material effectively.

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