Microstructural Evolution and Mechanical Properties in Yb2O3–Fluxed Silicon Nitride Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 1172-1174
Author(s):  
Gang Feng Guo ◽  
Xiao Zhan Yang ◽  
Jian Bao Li ◽  
Hong Lin ◽  
Long Liang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Nitride ◽  
Flexural Strength ◽  
Microstructural Evolution ◽  
Intergranular Fracture ◽  
Fracture Mode ◽  
Transgranular Fracture ◽  
Sintering Additive ◽  
Nitride Ceramics

Silicon nitride ceramics were fabricated with Yb2O3 as the sintering additive. The effects of the amount of Yb2O3 on the microstructure and the mechanical properties such as the flexural strength and the fracture toughness were investigated. Almost fully densified Si3N4 was obtained when only 4 wt% Yb2O3 was added. Both the flexural strength and the fracture toughness increased steadily with the Yb2O3 content. The transgranular fracture mode was observed in the specimen containing 4 wt% Yb2O3, however, the intergranular fracture mode was observed in the specimen containing 10 wt% Yb2O3.

Effects of Sintering Additives on the Microstructure and Mechanical Properties of Silicon Nitride Ceramics by GPS

2010 ◽  
Vol 105-106 ◽  
pp. 27-30 ◽  
Author(s):  
Wei Ru Zhang ◽  
Feng Sun ◽  
Ting Yan Tian ◽  
Xiang Hong Teng ◽  
Min Chao Ru ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Phase Transformation ◽  
Silicon Nitride ◽  
Porous Silicon ◽  
Flexural Strength ◽  
Relative Density ◽  
Sintering Additives ◽  
Microstructure And Mechanical Properties ◽  
Nitride Ceramics

Silicon nitride ceramics were prepared by gas pressure sintering (GPS) with different sintering additives, including La2O3, Sm2O3 and Al2O3. Effect of sintering additives on the phase-transformation, microstructure and mechanical properties of porous silicon nitride ceramics was investigated. The results show that the reaction of sintering additives each other and with SiO2 had key effects on the phase-transformation, grain growing and grain boundaries. With 9MPa N2 atmosphere pressure, holding 1h at 1850°C, adding 10wt% one of the La2O3, Sm2O3, Al2O3, porous silicon nitride was prepared and the relative density was 78%, 72%, 85% respectively. The flexural strength was less than 500MPa, and the fracture toughness was less than 4.8MPam1/2. Dropping compounds sintering additives, such as La2O3+Al2O3, Sm2O3+Al2O3 effectively improves the sintering and mechanical properties. The relative density was 99.2% and 98.7% with 10wt% compounds sintering additives. The grain ratio of length to diameter was up to 1:8. The flexural strength was more than 900MPa, and the fracture toughness was more than 8.9MPam1/2.

A Comparison between B4C-ZrB2-Al Composite and B4C-Al Composite on Microstructure and Mechanical Properties

2011 ◽  
Vol 279 ◽  
pp. 71-76 ◽  
Author(s):  
Peng Lü
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Fracture Surface ◽  
Flexural Strength ◽  
Fracture Mode ◽  
Transgranular Fracture ◽  
Aluminum Addition ◽  
Microstructure And Mechanical Properties ◽  
Al Composite ◽  
Toughness Improvement

B4C-Al and B4C-ZrB2-Al composites were fabricated by infiltrating aluminum into porous B4C and B4C-ZrB2 preforms in vacuum. The effect of ZrB2 addition on the microstucture and mechanical properties of the B4C-Al composites were investigated. The flexural strength and the fracture toughness of composite improved greatly as the result of ZrB2 addition. The ZrB2 addition inhibited the reaction between B4C and Al. The infiltrated aluminum addition was the leading reason for the fracture toughness improvement of the composites. Inter/transgranular fracture mode with many tear ridges and dimples was showing in the fracture surface of the B4C-ZrB2-Al composite. The relationships between the microstructures and the mechanical properties of the B4C-ZrB2-Al composites were discussed.

A Comparison between B4C-TiB2-Al Composite and B4C-Al Composite on Microstructure and Mechanical Properties

2011 ◽  
Vol 66-68 ◽  
pp. 255-259
Author(s):  
Peng Lü ◽  
Fang Yu ◽  
Hong Qiang Ru
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Fracture Surface ◽  
Flexural Strength ◽  
Fracture Mode ◽  
Transgranular Fracture ◽  
Aluminum Addition ◽  
Microstructure And Mechanical Properties ◽  
Al Composite ◽  
Toughness Improvement

B4C-Al and B4C-TiB2-Al composites were fabricated by infiltrating aluminum into porous B4C and B4C-TiB2preforms in vacuum. The effect of TiB2addition on the microstucture and mechanical properties of the B4C-Al composites were investigated. The flexural strength and the fracture toughness of composite improved greatly as the result of TiB2addition. The TiB2addition inhibited the reaction between B4C and Al. The infiltrated aluminum addition was the leading reason for the fracture toughness improvement of the composites. Inter/transgranular fracture mode with many tear ridges and dimples was showing in the fracture surface of the B4C-TiB2-Al composite. The relationships between the microstructures and the mechanical properties of the B4C-TiB2-Al composites were discussed.

Microstructure and Mechanical Properties of Multi-Scale Titanium Diboride Matrix Nanocomposite Ceramic Tool Materials

2010 ◽  
Vol 431-432 ◽  
pp. 523-526
Author(s):  
Han Lian Liu ◽  
Chuan Zhen Huang ◽  
Shou Rong Xiao ◽  
Hui Wang ◽  
Ming Hong
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Transgranular Fracture ◽  
Ceramic Tool ◽  
Tool Materials ◽  
Micro Scale ◽  
Multi Scale ◽  
Nano Scale ◽  
Matrix Nanocomposite

Under the liquid-phase hot-pressing technique, the multi-scale titanium diboride matrix nanocomposite ceramic tool materials were fabricated by adding both micro-scale and nano-scale TiN particles into TiB2 with Ni and Mo as sintering aids. The effect of content of nano-scale TiN and sintering temperature on the microstructure and mechanical properties was studied. The result showed that flexural strength and fracture toughness of the composites increased first, and then decreased with an increase of the content of nano-scale TiN, while the Vickers hardness decreased with an increase of the content of nano-scale TiN. The optimal mechanical properties were flexural strength 742 MPa, fracture toughness 6.5 MPa•m1/2 and Vickers hardness 17GPa respectively. The intergranular and transgranular fracture mode were observed in the composites. The metal phase can cause ductility toughening and crack bridging, while crack deflection and transgranular fracture mode could be brought by micro-scale TiN and nano-scale TiN respectively.

Effect of Iron Additive on the Sintering Behavior of Hot-Pressed ZrC-W Composites

2008 ◽  
Vol 368-372 ◽  
pp. 1764-1766 ◽  
Author(s):  
Yu Jin Wang ◽  
Lei Chen ◽  
Tai Quan Zhang ◽  
Yu Zhou
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Relative Density ◽  
Sintering Temperature ◽  
Sintering Behavior ◽  
Hot Press ◽  
Sintering Additive ◽  
Microstructure And Mechanical Properties ◽  
Hot Press Sintering

The ZrC-W composites with iron as sintering additive were fabricated by hot-press sintering. The densification, microstructure and mechanical properties of the composites were investigated. The incorporation of Fe beneficially promotes the densification of ZrC-W composites. The relative density of the composite sintered at 1900°C can attain 95.3%. W2C phase is also found in the ZrC-W composite sintered at 1700°C. The content of W2C decreases with the increase of sintering temperature. However, W2C phase is not identified in the composite sintered at 1900°C. The flexural strength and fracture toughness of the composites are strongly dependent on sintering temperature. The flexural strength and fracture toughness of ZrC-W composite sintered at optimized temperature of 1800°C are 438 MPa and 3.99 MPa·m1/2, respectively.

Microstructure and Properties of Al2O3-ZrO2 Ceramics Prepared by Microwave Sintering

2014 ◽  
Vol 633 ◽  
pp. 193-197 ◽  
Author(s):  
Yun Long Ai ◽  
Xiang Hua Xie ◽  
Wen He ◽  
Bing Liang Liang ◽  
Wei Hua Chen
Keyword(s):  
Mechanical Properties ◽  
Intergranular Fracture ◽  
Fracture Mode ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Microwave Sintering ◽  
Transgranular Fracture ◽  
Submicron Scale ◽  
Main Fracture ◽  
Sintering Processes

ZrO2 doped with 7.5% (volume percent) nanoalumina ceramics were prepared by microwave sintering processes. The effects of nanoalumina additions and various sintering temperature on densification, phase composition, microstructure and mechanical properties of Al2O3-ZrO2 ceramics were investigated. The results show that the m-ZrO2 phase transformed into t-ZrO2 during the process of microwave sintering. Relative densities between 95% and 99% were attained in the different conditions. In any cases the grain size was maintained at a submicron scale at a processing microwave sintering. The presence of Al2O3 grains had an effect of hindering grain growth of ZrO2 grains. When the microwave sintering temperature was 1500°C, 7.5Al2O3-ZrO2 composite ceramics presented excellent mechanical properties: HV=12.0 GPa, σf=715.7 Mpa, KIC=11.9 MPa·m1/2. Compared with that of pure ZrO2 ceramic, the bending strength and the fracture toughness were improved 45% and 23% at least, respectively. The fracture mode was associated with sintering temperature: when the sintering temperature was 1350°C~1450°C, the intergranular fracture and transgranular fracture coexisted; when the sintering temperature was 1500°C, intergranular fracture was the main fracture mode.

scholarly journals Influence of MXene (Ti3C2) Phase Addition on the Microstructure and Mechanical Properties of Silicon Nitride Ceramics

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5221
Author(s):  
Jaroslaw Wozniak ◽  
Mateusz Petrus ◽  
Tomasz Cygan ◽  
Artur Lachowski ◽  
Bogusława Adamczyk-Cieślak ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Phase Transformation ◽  
Silicon Nitride ◽  
Powder Processing ◽  
Sintering Process ◽  
Microstructure And Mechanical Properties ◽  
Plasma Sintering ◽  
Nitride Ceramics ◽  
Spark Plasma

This paper discusses the influence of Ti3C2 (MXene) addition on silicon nitride and its impact on the microstructure and mechanical properties of the latter. Composites were prepared through powder processing and sintered using the spark plasma sintering (SPS) technic. Relative density, hardness and fracture toughness, were analyzed. The highest fracture toughness at 5.3 MPa·m1/2 and the highest hardness at HV5 2217 were achieved for 0.7 and 2 wt.% Ti3C2, respectively. Moreover, the formation of the Si2N2O phase was observed as a result of both the MXene addition and the preservation of the α-Si3N4→β-Si3N4 phase transformation during the sintering process.

scholarly journals The Influence of Microstructure on the Mechanical Behavior of Silicon Nitride Ceramics

1992 ◽  
Vol 287 ◽  
Author(s):  
P. F. Becher ◽  
H. T. Lin ◽  
S. L. Hwang ◽  
M. J. Hoffmann ◽  
I-Wei Chen
Keyword(s):  
Fracture Toughness ◽  
Silicon Nitride ◽  
Liquid Phase ◽  
Interfacial Debonding ◽  
Considerable Improvement ◽  
Boundary Phase ◽  
Transgranular Fracture ◽  
Silicon Nitrides ◽  
Crack Wake ◽  
Nitride Ceramics

The introduction of elongated silicon nitride grains during densification in the presence of a liquid phase can impart considerable improvement to the fracture toughness. This toughening is not universally attained but depends on the activation of intergranular rather than transgranular fracture. This is reminiscent of the requirement of interfacial debonding in whiskerreinforced ceramics. In fact, additional observations such as bridging in the crack wake by elongated grains and pullout of some of these grains further suggest that the crack wake mechanisms that contribute to the toughening of whisker-reinforced ceramics can also operate in silicon nitrides containing elongated grains. Various investigators have found that, consistent with crack wake mechanisms, the fracture toughness of silicon nitrides increases with increase in the diameter of the larger elongated grains. However, little is known about the effects of the grain boundary phase(s) and their properties on the interfacial debonding/intergranular fracture in such silicon nitrides. This is critical as observations show that crack propagation in some systems exhibiting larger elongated grains occurs transgranularly and no toughening occurs.

Effect of (Ni,Mo) and (W,Ti)C on the Microstructure and Mechanical Properties of TiB2 Ceramic Tool Materials

2012 ◽  
Vol 723 ◽  
pp. 233-237 ◽  
Author(s):  
Tong Chun Yang ◽  
Chuan Zhen Huang ◽  
Han Lian Liu ◽  
Bin Zou ◽  
Hong Tao Zhu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Flexural Strength ◽  
Grain Growth ◽  
Vickers Hardness ◽  
Ceramic Tool ◽  
Tool Materials ◽  
Sintering Additive ◽  
Microstructure And Mechanical Properties

TiB2-(W,Ti)C composites with (Ni,Mo) as sintering additive have been fabricated by hot-pressing technique, and the microstructure and mechanical properties of the composites have been investigated. (Ni,Mo) promotes grain growth of the composites. In the case of 7vol.% (Ni,Mo), the grain size decreases consistently with an increase in the content of (W,Ti)C. When the proper content of (W,Ti)C is added to TiB2 composites, the growth of matrix grains is inhibited and the mechanical properties of the composites are improved. The best mechanical properties of the composites are 1084.13MPa for three-point flexural strength, 7.80MPa•m 1/2 for fracture toughness and 17.92GPa for Vickers hardness.

Effect of Hot Pressing Technology on the Microstructure and Mechanical Properties of ZrO2 Nano-Composite Ceramic Tool and Die Material

2011 ◽  
Vol 686 ◽  
pp. 396-400
Author(s):  
Ming Dong Yi ◽  
Chong Hai Xu ◽  
Jing Jie Zhang ◽  
Zhen Yu Jiang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Fracture Mode ◽  
Hot Pressing ◽  
Composite Ceramic ◽  
Ceramic Tool ◽  
Nano Composite ◽  
Die Material ◽  
Pressing Technology

A new nano-composite ceramic tool and die material was prepared by vacuum hot pressing technique. The effect of hot pressing technology on the microstructure and mechanical properties of ZrO2nano-composite ceramic tool and die material was investigated systemically, and the ceramic tool and die material with good mechanical properties was fabricated successfully. Results show that, the highest flexural strength, fracture toughness and hardness of ZrO2nano-composite ceramic tool and die material reaches 1055 MPa, 10.57 MPa∙m1/2 and 13.59 GPa, respectively by means of the vacuum hot pressing technique at 1430 °C for 60min at 35MPa. The flexural strength and fracture toughness has been improved greatly by the optimization of hot pressing technology. In the materials, the optimum sinter process could ensure the t-ZrO2stabilized till room temperature that can enhance the toughening effect of ZrO2. The microstructure of ZrO2nano-composite ceramic tool and die materials were improved by the optimization of hot pressing technology, and the fracture mode is the typical mixed trans/inter-granular fracture mode.

Sign in / Sign up

Export Citation Format

Share Document