In-situ 14H-LPSO reinforced GW93 alloy prepared from the recycling of discard components by rapid-solidification plus hot press sintering technique

Author(s):  
Yiyi Feng ◽  
Jianli Wang ◽  
Fei Li ◽  
Hongbo Duan ◽  
Zhong Yang ◽  
...  
Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 422
Author(s):  
Kuai Zhang ◽  
Yungang Li ◽  
Hongyan Yan ◽  
Chuang Wang ◽  
Hui Li ◽  
...  

An Fe/FeAl2O4 composite was prepared with Fe-Fe2O3-Al2O3 powder by a hot press sintering method. The mass ratio was 6:1:2, sintering pressure was 30 MPa, and holding time was 120 min. The raw materials for the powder particles were respectively 1 µm (Fe), 0.5 µm (Fe2O3), and 1 µm (Al2O3) in diameter. The effect of sintering temperature on the microstructure and mechanical properties of Fe/FeAl2O4 composite was studied. The results showed that Fe/FeAl2O4 composite was formed by in situ reaction at 1300 °C–1500 °C. With the increased sintering temperature, the microstructure and mechanical properties of the Fe/FeAl2O4 composite showed a change law that initially became better and then became worse. The best microstructure and optimal mechanical properties were obtained at 1400 °C. At this temperature, the grain size of Fe and FeAl2O4 phases in Fe/FeAl2O4 composite was uniform, the relative density was 96.7%, and the Vickers hardness and bending strength were 1.88 GPa and 280.0 MPa, respectively. The wettability between Fe and FeAl2O4 was enhanced with increased sintering temperature. And then the densification process was accelerated. Finally, the microstructure and mechanical properties of the Fe/FeAl2O4 composite were improved.


2014 ◽  
Vol 602-603 ◽  
pp. 488-493 ◽  
Author(s):  
Bao Xin Zhu ◽  
Yu Jun Zhang ◽  
Hong Sheng Wang ◽  
Chong Hai Wang ◽  
Shuang Shuang Yue

SiC-TiB2/B4C composites were fabricated by hot-press sintering B4C with silicon powder and tetrabutyl titanate (precursor of TiO2) as sintering and reinforcement agents. The influence of additives on hot-press sintering densification, microstructure and properties of composites were studied. The results showed that TiB2 and SiC generated by chemical reaction between additives and B4C matrix reinforced the sintering activity of the mixed powders and accelerated significantly the hot-press sintering densification rate of B4C from 1200 °C to 1700 °C. According to the SEM observation, the second phase of TiB2 and SiC particles synthetized in situ sited along the grain boundaries of B4C, meanwhile, those SiC particles of nanoscale size embedded into the B4C grains, and thereby, intra/inter-type ceramics formed. The maximum relative density of 98.1% was obtained with 9wt.% TiO2. The typical valus of Vickers hardness, bending strength and fracture toughness can reach 26.7 GPa, 580 MPa and 5.0 MPam1/2, respectively.


2006 ◽  
Vol 317-318 ◽  
pp. 653-656 ◽  
Author(s):  
Jun Yoshikawa ◽  
Yuji Katsuda ◽  
Naohito Yamada ◽  
Hiroaki Sakai

Electrically conductive AlN ceramics were fabricated by the addition of a small amount of B4C and sintering aid, and hot-press sintering in a nitrogen atmosphere. The electrical resistivity of AlN ceramics decreased remarkably from 1014 cm to the range of 100 to 102 cm by a minimum of 2.3 wt% of B4C addition. This resistivity decrease was caused by forming three-dimensional networks composed of boron carbonitride (B-C-N) platelets synthesized during sintering. To produce the networks of B-C-N platelets, two-step sintering with a heat-treatment step at 1600°C before the densification step at 2000°C was needed.


Author(s):  
B Nikfar ◽  
H Ghiabakloo ◽  
H R M Hosseini ◽  
A V Mohammadi

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1428
Author(s):  
Heng Luo ◽  
Chen Li ◽  
Lianwen Deng ◽  
Yang Li ◽  
Peng Xiao ◽  
...  

In situ grown C0.3N0.7Ti and SiC, which derived from non-oxide additives Ti3SiC2, are proposed to densify silicon nitride (Si3N4) ceramics with enhanced mechanical performance via hot-press sintering. Remarkable increase of density from 79.20% to 95.48% could be achieved for Si3N4 ceramics with 5 vol.% Ti3SiC2 when sintered at 1600 °C. As expected, higher sintering temperature 1700 °C could further promote densification of Si3N4 ceramics filled with Ti3SiC2. The capillarity of decomposed Si from Ti3SiC2, and in situ reaction between nonstoichiometric TiCx and Si3N4 were believed to be responsible for densification of Si3N4 ceramics. An obvious enhancement of flexural strength and fracture toughness for Si3N4 with x vol.% Ti3SiC2 (x = 1~20) ceramics was observed. The maximum flexural strength of 795 MPa for Si3N4 composites with 5 vol.% Ti3SiC2 and maximum fracture toughness of 6.97 MPa·m1/2 for Si3N4 composites with 20 vol.% Ti3SiC2 are achieved via hot-press sintering at 1700 °C. Pull out of elongated Si3N4 grains, crack bridging, crack branching and crack deflection were demonstrated to dominate enhance fracture toughness of Si3N4 composites.


2008 ◽  
Vol 591-593 ◽  
pp. 493-497 ◽  
Author(s):  
Rosa Maria da Rocha ◽  
Francisco Cristóvão Lourenço de Melo

Boron carbide (B4C) and silicon carbide (SiC) are materials with high hardness and low density what make them very useful in various applications, such armor plates. Hot press sintering of B4C-SiC composites was studied. The powder mixture was obtained in situ by carbothermal reduction using B2O3, SiO2 and carbon black as precursors. Seeds of commercial B4C and SiC were used to accelerate the synthesis reaction. Compositions were prepared to obtain powders after carbothermal reduction with 10, 30 and 50 wt% of SiC. Carbothermal reaction was conducted in argon atmosphere at temperatures up to 1700 °C. The synthesized powders were analyzed by DRX and SEM. Hot pressing at 1850 °C/30 min (20 MPa) in argon atmosphere was applied. Densities higher than 93% of theoretical density and microhardness of 34 GPa were achieved for hot pressed samples.


2006 ◽  
Vol 532-533 ◽  
pp. 25-28 ◽  
Author(s):  
Qing Zhang ◽  
Jun Ting Luo ◽  
Kai Feng Zhang

Si3N4- Si2N2O composites were fabricated with amorphous nano-sized silicon nitride powders by the hot press sintering(HPS). The Si2N2O phase was generated by an in-situ reaction 2Si3N4(s)+1.5O2(g)=3Si2N2O(s)+N2(g). The content of Si2N2O phase up to 60% was accepted when the sintering temperature was 1650°C and decreased whether the sintering temperature was increased or not, which indicated that the reaction was reversible. The mass loss, relative density and average grain size increased with raising of sintering temperature. The average grain size was less than 500nm if the sintering temperature was below 1700°C. The sintered body crystaled completely at 1600°C . The microstructure crystaled in 1600°C indicated that most of the grain size was in 150-250nm. The aspect ratio of some grains reached 1.5. The superplastic deep-drawing forming could be undertaken at 1550°C with a forming velocity of 0.2mm/min. The complex-shape gears could be formed by a sinter-forging technology when the sintering temperature was 1600°C and the superplastic forging temperature was 1550°C.


Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 204
Author(s):  
Kuai Zhang ◽  
Yungang Li ◽  
Chuang Wang ◽  
Hongyan Yan ◽  
Hui Li ◽  
...  

The Fe/FeAl2O4 cermet was prepared with Fe-Fe2O3-Al2O3 powder by a hot press sintering method at 1400 °C. The raw materials for the powder particles were respectively 2 µm (Fe), 0.5 µm (Fe2O3), and 0.5 µm (Al2O3) in diameter, the sintering pressure was 30 MPa, and the holding time was 120 min. The effects of different Fe mass ratios on the microstructure and mechanical properties of Fe/FeAl2O4 cermet were studied. The results showed that a new ceramic phase FeAl2O4 could be formed by an in situ reaction during the hot press sintering. When the Fe mass ratio was increased, the microstructure and mechanical properties of the Fe/FeAl2O4 cermet showed a change law that initially became better and then became worse. The best microstructure and mechanical properties were obtained in the S2 sample, where the mass ratio of Fe-Fe2O3-Al2O3 was 6:1:2. In this Fe mass ratio, the relative density was about 94%, and the Vickers hardness and bending strength were 1.21 GPa and 210.0 MPa, respectively. The reaction mechanism of Fe in the preparation process was the in situ synthesis reaction of FeAl2O4 and the diffusion reaction of Fe to FeAl2O4 grains. The increase of the Fe mass ratio improved the wettability of Fe and FeAl2O4, which increased the diffusion rate of Fe to FeAl2O4 grains, which increased the influence on the structure of FeAl2O4.


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