Electron Microscopy Techniques for the Microstructural Characterization of Silicon Nitride

1988 ◽  
Author(s):  
Kerry N. Siebein ◽  
Russell L. Yeckley
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Nitride ◽  
Microstructural Characterization ◽  
Ceramic Materials ◽  
Processing Parameters ◽  
Bend Strength ◽  
Fracture Origin ◽  
Microscopy Techniques

It is well known that the mechanical properties of ceramic materials are directly dependent upon their microstructure with respect to the size, crystallinity, distribution and composition of the phases present. Our understanding of the microstructural details of silicon nitride was enhanced through the application of scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM). The SEM and STEM are necessary for analyzing the microstructure of silicon nitride because it is a fine grained material. The SEM is used to analyze the etched microstructure and fracture surfaces of bulk silicon nitride samples. Relationships between the grain size distribution, aspect ratio of the grains and fracture toughness of the material are summarized, as well as fracture origin identity and bend strength data. STEM is employed to analyze the crystallinity, distribution and composition of the phases present in a material. These features are related to the processing parameters, fracture toughness and bend strength of silicon nitride. This paper presents a short description of the microscopy techniques employed to characterize silicon nitride, the results obtained using the various techniques and the relationship between the microstructural features and mechanical properties.

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.

Effects of TiN Content on Mechanical Properties and Microstructure of ATN Materials

2013 ◽  
Vol 589-590 ◽  
pp. 590-593 ◽  
Author(s):  
Min Wang ◽  
Jun Zhao
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Fracture Toughness ◽  
Vickers Hardness ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Ceramic Materials ◽  
Hot Press ◽  
Hot Press Sintering ◽  
Tin Content

In order to investigate the effects of TiN content on Al2O3/TiN ceramic material (ATN), the ATN ceramic materials were prepared of TiN content in 30%, 40%, 50%, 60% in the condition of hot press sintering. The sintering temperature is 1700°C, the sintering press is 32MPa, and the holding time are 5min, 10min, 15min. The effects of TiN content on mechanical properties and microstructure of ATN ceramic materials were investigated by analyzing the bending strength, hardness, fracture toughness. The results show that ATN50 has the best mechanical property, its bending strength is 659.41MPa, vickers hardness is 13.79GPa, fracture toughness is 7.06MPa·m1/2. It is indicated that the TiN content has important effect on microstructure and mechanical properties of ATN ceramic materials.

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.

scholarly journals Synthesis of "in situ" reinforced silicon nitride composites

2004 ◽  
Vol 69 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Aleksandra Vuckovic ◽  
Snezana Boskovic ◽  
Ljiljana Zivkovic
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Nitride ◽  
Pressureless Sintering ◽  
Sintering Additives ◽  
Sintering Time

The objective of this work was to investigate the effect of two different sintering additives (CeO2 and Y2O3 + Al2O3), sintering time and amount of ?-Si3N4 seeds on the densification, mechanical properties and microstructure of self-reinforced Si3N4 based composites obtained by pressureless sintering. Preparation of ?-Si3N4 seeds, also obtained by a pressureless sintering procedure, is described. Samples without seeds were prepared for comparison. The results imply that self-reinforced silicon nitride based composites with densities close to the theoretical values and with fracture toughness of 9.3MPa m1/2 can be obtained using a presureless sintering procedure.

scholarly journals Mechanical properties of microwave sintered Si3N4-based ceramics

2002 ◽  
Vol 34 (3) ◽  
pp. 223-229 ◽  
Author(s):  
O.I. Getman ◽  
V.V. Holoptsev ◽  
V.V. Panichkina ◽  
I.V. Plotnikov ◽  
V.K. Soolshenko
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Bending Strength ◽  
Normal Pressure ◽  
Ceramic Materials ◽  
Particle Sizes ◽  
Phase Measurements ◽  
Ceramic Samples ◽  
Mean Size ◽  
The Mean

The mechanical properties and microstructure formation processes in Si3N4+3% AI2O3+5% Y2O3(Yb2O3) ceramic compacts sintered under microwave heating (MWH) and under traditional heating (TH) were investigated. The initial ceramic materials were powder blends of silicon nitride with oxides. The mean powder particle sizes were 0.5-1.0 mim. The content of alfa-phase in the Si3N4 powder was more than 95 %. The samples were sintered at 1800BC in nitrogen at normal pressure, the heating rate in all experiments was 60BC/min. The Vickers hardness (HV), fracture toughness (K1C) and bending strength (on) were determined. The microstructures of fracture surfaces of samples were studied by SEM. Quantitative microstructure analysis was carried out. It was shown that the values of HV and Kic of ceramic samples sintered under MWH at 1800BC rose steadily with the sintering time. This caused an increase in density, which reached maximum as fast as after 30 min of the MWH sintering; the mass loss at that time amounted to 3-4 %. The porosity of sintered samples with an addition of yttria was less than 1 %, that of ytterbia was greater, 2.4 %. For similar values of relative density, the hardness and fracture toughness of ceramic samples produced under MWH were higher as compared with those of samples sintered under TH. The microstructure of samples had the form of elongated grains in a matrix of polyhedral grains of the beta-Si3N4 phase. Measurements showed the mean size of grains in samples produced by MWH to be greater that in samples produced by TH. A larger number of elongated grains were formed. It was concluded that for sintering under MWH of Si3N4-based ceramics the growth of elongated beta-Si3N4 grains and formation of a "reinforced" microstructure were promoted and thereby improved the mechanical properties of such ceramics.

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.

Development and Characterization of New Ti-25Ta-Zr Alloys for Biomedical Applications

2021 ◽  
Vol 1016 ◽  
pp. 137-144
Author(s):  
Pedro Akira Bazaglia Kuroda ◽  
Fernanda de Freitas Quadros ◽  
Mycaela Vieira Nascimento ◽  
Carlos Roberto Grandini
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Elastic Modulus ◽  
Biomedical Applications ◽  
Solution Heat Treatment ◽  
High Hardness ◽  
Microstructural Characterization ◽  
Β Phase ◽  
Cp Ti ◽  
Microscopy Techniques

This paper deals with the study of the development, structural and microstructural characterization and, selected mechanical properties of Ti-25Ta-50Zr alloy for biomedical applications. The alloy was melted in an arc furnace and various solution heat treatments were performed to analyze the influence of the temperature and time on the structure, microstructure, microhardness and elastic modulus of the samples. The structural and microstructural results, obtained by X-ray diffraction and microscopy techniques, showed that the solution heat treatment performed at high temperatures induces the formation of the β phase, while solution heat treatment performed at low temperatures induces the formation of the α” and ω metastable phases. Regarding the effect of time, samples subjected to heat treatment for 6 hours have only the β phase, indicating that lengthy treatments suppress the α” phase. Regarding the hardness and elastic modulus, the alloy with the α” and ω phases, after treatment performed at a temperature of 500 °C, has a high hardness value and elastic modulus due to the presence of the ω phase that hardens and weakens alloys. The titanium alloys developed in this study have excellent mechanical properties results for use in the orthopedic area, better than many commercial materials such as cp-Ti, stainless steel and Co-Cr alloys.

scholarly journals Silicon Nitride-Based Composites with the Addition of CNTs—A Review of Recent Progress, Challenges, and Future Prospects

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2799
Author(s):  
Awais Qadir ◽  
Péter Pinke ◽  
Ján Dusza
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Carbon Nanotube ◽  
Silicon Nitride ◽  
Wear Rate ◽  
Recent Progress ◽  
Bending Strength ◽  
Microstructure Development ◽  
Future Prospects ◽  
Microstructure Characteristics

In this overview, the results published to date concerning the development, processing, microstructure characteristics, and properties of silicon nitride/carbon nanotube (Si3N4 + CNTs) composites are summarized. The influence of the different processing routes on the microstructure development of the Si3N4 + CNTs is discussed. The effects of the CNTs addition on the mechanical properties—hardness, bending strength and fracture toughness—and tribological characteristics—wear rate and coefficient of friction—are summarized. The characteristic defects, fracture origins, toughening and damage mechanisms occurring during the testing are described. The influence of the CNTs’ addition on the thermal and functional properties of the composites is discussed as well. New trends in the development of these composites with significant potential for future applications are outlined.

scholarly journals Effect of Different Cooling Regimes on the Mechanical Properties of Cementitious Composites Subjected to High Temperatures

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Jiangtao Yu ◽  
Wenfang Weng ◽  
Kequan Yu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
High Temperature ◽  
Significant Influence ◽  
Microstructural Characterization ◽  
Cementitious Composite ◽  
Engineered Cementitious Composite ◽  
Before And After ◽  
Scanning Electron

The influence of different cooling regimes (quenching in water and cooling in air) on the residual mechanical properties of engineered cementitious composite (ECC) subjected to high temperature up to 800°C was discussed in this paper. The ECC specimens are exposed to 100, 200, 400, 600, and 800°C with the unheated specimens for reference. Different cooling regimens had a significant influence on the mechanical properties of postfire ECC specimens. The microstructural characterization was examined before and after exposure to fire deterioration by using scanning electron microscopy (SEM). Results from the microtest well explained the mechanical properties variation of postfire specimens.

Sign in / Sign up

Export Citation Format

Share Document