scholarly journals Improved mechanical properties of dense β-Si3N4 ceramics fabricated by spark plasma sintering with Al2O3-YSZ additives

2018 ◽  
Vol 12 (4) ◽  
pp. 313-318
Author(s):  
Yang Li ◽  
Weiqin Ao ◽  
Jihua Gao ◽  
Chaohua Zhang ◽  
Fusheng Liu ◽  
...  

In this work the influence of sintering conditions on structure and mechanical properties of Si3N4 ceramics was investigated. Nearly full dense ?-Si3N4 ceramics with excellent mechanical properties and interlock microstructure of elongated grains was fabricated using Al2O3 and yttria-stabilized zirconia (YSZ with 3mol% Y2O3) as sintering additives by spark plasma sintering (SPS) at relatively low temperature of 1600?C for 15min. X-ray diffraction analysis shows that the SPSed sample is pure ?-Si3N4 phase without any secondary crystalline phase. The elements Al, Zr, Y and O of the additive can diffuse into Si3N4 lattice forming ?-Si3N4- based solid solution. The residual additive formed an amorphous phase at the ?-Si3N4 grain boundaries. The ?-Si3N4 ceramics obtained by SPS using 6.0wt.% Al2O3 and 6.0 wt.% YSZ as additives shows interlock elongated ?-Si3N4 grains of 500 nm in width and 3000 nm in length, high density of 3.29 g/cm3, Vickers hardness of 16.15GPa and high fracture toughness KIC of 6.75MPam1/2.

2016 ◽  
Vol 704 ◽  
pp. 183-189
Author(s):  
Yong Jun Su ◽  
Yi Feng Zheng ◽  
De Liang Zhang ◽  
Fan Tao Kong

TiAl alloy with a composition of Ti-43Al-5V-4Nb-Y (at.%) was prepared by spark plasma sintering (SPS). The TiAl powders were sintered between 650°C and 1300°C for 5 min under different loads. With the increasing of the temperature, the diffusion of the elements can be observed. Full compaction is achieved in a short period of time and the overall processing duration does not exceed 30 min. A fully lamellar structure was seen in the TiAl alloy after heat treatment. The microstructures of the samples were determined by X-ray diffraction and scanning electron microscopy. Their mechanical properties were evaluated by tensile tests performed at room temperature


2020 ◽  
Author(s):  
Xingheng Yan ◽  
Xingui Zhou ◽  
Honglei Wang

Abstract B4C-TiB2 composite ceramics with ultra-high fracture toughness were successfully prepared via spark plasma sintering at 1900℃ using B4C and Ti3SiC2 as raw materials. The results show that compared with pure B4C ceramics sintered by SPS, the hardness of B4C-TiB2 composite ceramics is decreased, but the flexural strength and fracture toughness are significantly improved, especially the fracture toughness has been improved by leaps and bounds. When the content of Ti3SiC2 is 30vol.%, the B4C-TiB2 composite ceramic has the best comprehensive mechanical properties: hardness, bending strength and fracture toughness are 27.28 GPa, 405.11 MPa and 18.94 MPa·m1/2, respectively. The fracture mode of the B4C-TiB2 composite ceramics is a mixture of transgranular fracture and intergranular fracture. Two main two reasons for the ultra-high fracture toughness are the existence of lamellar graphite at the grain boundary, and the formation of a three-dimensional interpenetrating network covering the whole composite.


2012 ◽  
Vol 512-515 ◽  
pp. 932-935
Author(s):  
Ying Peng ◽  
Zhi Jian Peng ◽  
Xiao Yong Ren ◽  
Hui Yong Rong ◽  
Cheng Biao Wang ◽  
...  

TiCN-based cermets with different amounts of SiC nano-whiskers were prepared by spark plasma sintering. The microstructure and mechanical properties of the as-prepared cermets were investigated. X-ray diffraction revealed that there were no SiC peaks detected, turning out some peaks of new carbide and silicate hard phases. Scanning electron microscopy indicated that there were more and more pores in the cermets with increasing amount of SiC whisker added, and the fracture mechanism of the cermets was mainly inter-granular fracture. With increasing addition amount of nano-SiC whisker, the hardness and flexural strength of the cermets increased first and decreased then, presenting the highest hardness (2170 HV) and flexural strength (750 MPa), respectively, when the addition content of nano-whiskers is 2.5 wt%.


Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1378
Author(s):  
Tomasz Mościcki ◽  
Rafał Psiuk ◽  
Joanna Radziejewska ◽  
Maria Wiśniewska ◽  
Dariusz Garbiec

To enhance the properties of tungsten diboride, we have synthesized and characterized solid solutions of this material with chromium, molybdenum, rhenium and zirconium. The obtained materials were subsequently deposited as coatings. Various concentrations of these transition metal elements, ranging from 0.0 to 24.0 at.%, on a metals basis, were made. Spark plasma sintering was used to synthesize these refractory compounds from the pure elements. Elemental and phase purity of both samples (sintered compacts and coatings) were examined using energy dispersive X-ray spectroscopy and X-ray diffraction. Microindentation was utilized to measure the Vickers hardness. X-ray diffraction results indicate that the solubility limit is below 8 at.% for Mo, Re and Zr and below 16 at.% for Cr. Above this limit both diborides (W,TM)B2 are created. Addition of transition metals caused decrease of density and increase of hardness and electrical conductivity of sintered compacts. Deposited coatings W1−xTMxBy (TM = Cr, Mo, Re, Zr; x = 0.2; y = 1.7–2) are homogenous, smooth and hard. The maximal hardness was measured for W-Cr-B films and under the load of 10 g was 50.4 ± 4.7 GPa. Deposited films possess relatively high fracture toughness and for WB2 coatings alloyed with zirconium it is K1c = 2.11 MPa m1/2.


Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4616
Author(s):  
Xingheng Yan ◽  
Xingui Zhou ◽  
Honglei Wang

B4C–TiB2 composite ceramics with ultra-high fracture toughness were successfully prepared via spark plasma sintering (SPS) at 1900 °C using B4C and Ti3SiC2 as raw materials. The results showed that compared with pure B4C ceramics sintered by SPS, the hardness of B4C–TiB2 composite ceramics was decreased, but the flexural strength and fracture toughness were significantly improved; the fracture toughness especially was greatly improved. When the content of Ti3SiC2 was 30 vol.%, the B4C–TiB2 composite ceramic had the best comprehensive mechanical properties: hardness, bending strength and fracture toughness were 27.28 GPa, 405.11 MPa and 18.94 MPa·m1/2, respectively. The fracture mode of the B4C–TiB2 composite ceramics was a mixture of transgranular fracture and intergranular fracture. Two main reasons for the ultra-high fracture toughness were the existence of lamellar graphite at the grain boundary, and the formation of a three-dimensional interpenetrating network covering the whole composite.


2020 ◽  
Vol 405 ◽  
pp. 396-401
Author(s):  
Marek Vojtko ◽  
Alexandra Kovalcikova ◽  
Viktor Puchý ◽  
Ondrej Milkovič

In the present study, bulk 10 % cerium stabilized zirconia was prepared by spark plasma sintering technique. Various time temperatures regimes were used and prepared sample were subjected to microstructure observation by electron microscopy and X-ray diffraction and mechanical testing by nanoindentations. It was shown, that conditions of spark plasma sintering process can strongly influence properties of resultant sample, mainly grain size which warried from some tens or hundreds of nanometre to approximately 100 micrometres. Also some structure changes in the sintering process were observed resulted to phase changes and decomposition.


2016 ◽  
Vol 881 ◽  
pp. 307-312
Author(s):  
Luis Antonio C. Ybarra ◽  
Afonso Chimanski ◽  
Sergio Gama ◽  
Ricardo A.G. da Silva ◽  
Izabel Fernanda Machado ◽  
...  

Tungsten carbide (WC) based composites are usually produced with cobalt, but this binder has the inconvenience of shortage, unstable price and potential carcinogenicity. The objective of this study was to develop WC composite with intermetallic Fe3Al matrix. Powders of WC, iron and aluminum, with composition WC-10 wt% Fe3Al, and 0.5 wt% zinc stearate were milled in a vibration mill for 6 h and sintered in a SPS (spark plasma sintering) furnace at 1150 °C for 8 min under pressure of 30 MPa. Measured density and microstructure analysis showed that the composite had significant densification during the (low-temperature, short time) sintering, and X-ray diffraction analysis showed the formation of intermetallic Fe3Al. Analysis by Vickers indentation resulted in hardness of 11.2 GPa and fracture toughness of 24.6 MPa.m1/2, showing the feasibility of producing dense WC-Fe3Al composite with high mechanical properties using the SPS technique.


2010 ◽  
Vol 654-656 ◽  
pp. 819-822
Author(s):  
Genki Kikuchi ◽  
Hiroshi Izui ◽  
Yuya Takahashi ◽  
Shota Fujino

In this study, we focused on the sintering performance of Ti-4.5Al-3V-2Mo-2Fe (SP-700) and mechanical properties of SP-700 reinforced with titanium boride (TiB/SP-700) fabricated by spark plasma sintering (SPS). TiB whiskers formed in titanium by a solid-state reaction of titanium and TiB2 particles were analyzed with scanning electron microscopy and X-ray diffraction. The TiB/SP-700 was sintered at temperatures of 1073, 1173, and 1273 K and a pressure of 70 MPa for 10, 30, and 50 min. The volume fraction of TiB ranged from 1.7 vol.% to 19.9 vol.%. Tensile tests of TiB/SP-700 were conducted at room temperature, and the effect of TiB volume fraction on the tensile properties was investigated.


2021 ◽  
Vol 1016 ◽  
pp. 1790-1796
Author(s):  
Maxim Syrtanov ◽  
Egor Kashkarov ◽  
Tatyana Murashkina ◽  
Nahum Travitzky

This paper describes the influence of sintering temperature on phase composition and microstructure of paper-derived Ti3AlC2 composites fabricated by spark plasma sintering. The composites were sintered at 100 MPa pressure in the temperature range of 1150-1350 °C. Phase composition and microstructure were analyzed by X-ray diffraction and scanning electron microscopy, respectively. The multiphase structure was observed in the sintered composites consisting of Ti3AlC2, Ti2AlC, TiC and Al2O3 phases. The decomposition of the Ti3AlC2 phase into Ti2AlC and TiC carbide phases was observed with temperature rise. The total content of Ti3AlC2 and Ti2AlC phases was reduced from 84.5 vol.% (1150 °C) to 69.5 vol.% (1350 °C). The density of composites affected by both the content of TiC phase and changes in porosity.


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