Superplastic Sinter-Forging of Fine-Grained Si3N4-Si2N2O Composite at Low Temperature

2007 ◽  
Vol 551-552 ◽  
pp. 487-490 ◽  
Author(s):  
Jun Ting Luo ◽  
Qing Zhang
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Complex Shape ◽  
Sintering Temperature ◽  
Xrd Analysis ◽  
Liquid Phase Sintering ◽  
Sintered Body ◽  
Fine Grained ◽  
Sinter Forging ◽  
Average Grain Size

The Si3N4- Si2N2O composites are fabricated with amorphous nano-sized silicon nitride powders by the liquid phase sintering (LPS) method. XRD analysis shows sintered body consists of β-Si3N4 and Si2N2O. SEM experiment conforms that the average grain size of sintered body is less than 300nm. The complex-shape gears can be formed by a sinter-forging technology when the sintering temperature is 1600°C and the superplastic forging temperature is only 1550°C. Rod-shaped grains aligned along the perpendicular direction of pressure and the mechanical properties increase about 10% after the materials were forged.

Superplasticity and Sinter-Forging of Fine-Grained Si3N4-Si2N2O Composite

2005 ◽  
Vol 475-479 ◽  
pp. 2987-2990 ◽  
Author(s):  
Jun Ting Luo ◽  
Kai Feng Zhang ◽  
Guo Feng Wang ◽  
Wen Bo Han
Keyword(s):  
Grain Size ◽  
Complex Shape ◽  
Sintering Temperature ◽  
Xrd Analysis ◽  
Liquid Phase Sintering ◽  
Sintered Body ◽  
Fine Grained ◽  
Sinter Forging ◽  
Average Grain Size ◽  
Cavitation Failure

The Si3N4- Si2N2O composites are fabricated with amorphous nano-sized silicon nitride powders by the liquid phase sintering(LPS) method in this article. XRD analysis shows that the sintered body consists of β-Si3N4 and Si2N2O. SEM experiment conforms that the average grain size of sintered body is less than 300nm. The superplastic deep-drawing forming can be proceed at a low temperature of 1550°C with a forming velocity of 0.2mm/min. There are only a few small sintered defects before forming, but there are a lot of cavity groups after forming. Cavitation failure occurs by nucleation, growth and interlinkage of cavities. The complex-shape gears can be formed by a sinter-forging technology when the sintering temperature is 1600°C and the superplastic forging temperature is 1550°C.

Hot Press Sintering and Superplastic Forming of Fine-Grained Si3N4-Si2N2O Composites

2006 ◽  
Vol 532-533 ◽  
pp. 25-28 ◽  
Author(s):  
Qing Zhang ◽  
Jun Ting Luo ◽  
Kai Feng Zhang
Keyword(s):  
Grain Size ◽  
Complex Shape ◽  
Sintering Temperature ◽  
Superplastic Forming ◽  
Hot Press ◽  
Fine Grained ◽  
Sinter Forging ◽  
Average Grain Size ◽  
Hot Press Sintering

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.

scholarly journals Influence of Steel Grain Size on Residual Stress in Grinding Processing

2010 ◽  
Vol 638-642 ◽  
pp. 2389-2394 ◽  
Author(s):  
Masahide Gotoh ◽  
Katsuhiro Seki ◽  
M. Shozu ◽  
Hajime Hirose ◽  
Toshihiko Sasaki
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Grain Size ◽  
Stress State ◽  
Mechanical Grinding ◽  
Fine Grained ◽  
Residual Stress State ◽  
Analysis Methods ◽  
Average Grain Size ◽  
Fine Grained Steels

The fine-grained rolling steels NFG600 and the conventional usual rolling steels SM490 were processed by sand paper polishing and mechanical grinding to compare the residual stress generated after processing. The average grain size of NFG600 and SM490 is 3 μm and 15μm respectively. Therefore improvement of mechanical properties for such fine-grained steels is expected, it is important to understand the residual stress state of new fine-grained materials with processing. In this study, multi axial stresses of two kinds of specimens after polishing and grinding were measured by three kinds of analysis methods including cos-ψ method. As a result, as for σ33, the stress of NFG was compression, though that of SM490 was tension.

Low temperature sintering of nano-SiC using a novel Al8B4C7 additive

2010 ◽  
Vol 25 (3) ◽  
pp. 471-475 ◽  
Author(s):  
Sea-Hoon Lee ◽  
Byung-Nam Kim ◽  
Hidehiko Tanaka
Keyword(s):  
Grain Size ◽  
Liquid Phase ◽  
Low Temperature ◽  
Sintering Temperature ◽  
Applied Pressure ◽  
Liquid Phase Sintering ◽  
Low Temperature Sintering ◽  
Densification Rate ◽  
Sintering Additive ◽  
Average Grain Size

Al8B4C7 was used as a sintering additive for the densification of nano-SiC powder. The average grain size was approximately 70 nm after sintering SiC-12.5wt% Al8B4C7 at 1550 °C. The densification rate strongly depended on the sintering temperature and the applied pressure. The rearrangement of SiC particles occurred at the initial shrinkage, while viscous flow and liquid phase sintering became important at the middle and final stage of densification.

Effect of Sintering Temperature on Microstructure and Mechanical Properties of WC-16TiC-xTaC-9Co Cemented Carbides

2012 ◽  
Vol 268-270 ◽  
pp. 340-343
Author(s):  
Chong Cai Zhang ◽  
Quan Wang
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Sintering Temperature ◽  
Rupture Strength ◽  
High Energy ◽  
Cemented Carbides ◽  
Average Grain Size ◽  
Comprehensive Performance ◽  
Energy Ball ◽  
Average Size

In this paper, the WC-16TiC-xTaC-9Co and Co are mixed together preparing for WC, (W, Ti, Ta) C. By high-energy ball milling, the powder is cold isostatic pressed and vacuum sintered by 1410°C, 1430°Cand 1450°C.The physical properties and the micrographs of samples are detected. The main conclusions are as following: sintered samples have the best comprehensive performance at 1450°C, the density of the sample is 99.7% and the actual density is 10.91g/cm3. The hardness is 92.8 HRA and the transverse rupture strength (TRS) is 1100MPa. The grain size grows up obviously with the high temperature. The average grain size of WC is 0.7μm and the average size of (W, Ti, Ta)C is 3μm.

Low-Temperature Sintering of 3Y-TZP/Glass Composites as All-Ceramic Dental Materials

2007 ◽  
Vol 336-338 ◽  
pp. 1593-1595
Author(s):  
Zheng Qiu Sun ◽  
Hong Yan Miao ◽  
Guo Qiang Tan ◽  
Ao Xia
Keyword(s):  
Grain Size ◽  
Sintering Temperature ◽  
Dental Materials ◽  
Xrd Analysis ◽  
Cold Isostatic Pressing ◽  
Liquid Phase Sintering ◽  
Glass Composites ◽  
All Ceramic ◽  
Mean Grain Size ◽  
The Mean

3Y-TZP ceramics were fabricated with the addition of 10wt% MgO-Al2O3-SiO2 glass additive by cold-isostatic pressing and afterwards liquid-phase sintering at 1200-1400°C for 2 h. The densities of samples sintered at 1300°C for 2 h reaches 99.1%, but further increase of sintering temperature results in the decrease of densities. XRD analysis showed that the cordierite crystals and a small amount of amorphous phase were presented at the grain junctions, and SEM observation indicated that the mean grain size of ZrO2 with round-shape ranged from 200 to 300 nm, which was below the critical transformation size, and the increase in sintering temperature was accompanied with an increase in the mean grain size. The strength and toughness of samples were kept in the range of 396-528 MPa, 4.4-5.8 MPa·m1/2 respectively, which could meet the need of clinical applications of all-ceramic dental materials.

Microstructures and Mechanical Properties of Y2O3 Ceramics

2017 ◽  
Vol 726 ◽  
pp. 179-183
Author(s):  
Tong Yu Zhu ◽  
Jin Feng Xia
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Sintering Temperature ◽  
High Density ◽  
Average Grain Size ◽  
Basic Performance ◽  
Different Temperatures ◽  
Microstructures And Mechanical Properties

Currently, Y2O3 ceramics are widely used in various fields. The basic performance of Y2O3 ceramics were sintered temperatures are studied in this paper, their phase compositions and microstructure are studied with XRD and SEM. The mechanical properties of Y2O3 ceramics at different temperatures are studied. The sintering temperature of Y2O3 ceramic significantly affected the final grain size and density. It was found that a high density and fine average grain size of Y2O3ceramic can be simultaneously achieved when the sintering temperature was 1600°C. To determine the best sintering temperature, grain size, density, and mechanical properties were considered, and the most suitable sintering temperature was found to be 1600°C.

Nanopowder and Fine-Grained Ceramics for Multilayer PTCR Elements

2008 ◽  
Vol 368-372 ◽  
pp. 453-455 ◽  
Author(s):  
Jun Zhao ◽  
Shu Ping Gong ◽  
Chun Fang Cheng ◽  
Zhi Ping Zheng ◽  
Huan Liu ◽  
...  
Keyword(s):  
Grain Size ◽  
Sintering Temperature ◽  
Boundary Effect ◽  
Sol Gel ◽  
Tape Casting ◽  
Casting Technique ◽  
Fine Grained ◽  
Average Grain Size ◽  
Sol Gel Process ◽  
Different Temperatures

BaTiO3 nanopowders prepared by sol-gel process were used for multilayer PTCR ceramics in order to utilize grain boundary effect and lower sintering temperature. The precursor gel was calcined at different temperatures and the powders were characterized by XRD and TEM. The average grain size was about 26nm when calcined at 800°C for 2h. Effects of acceptor/donor concentration and sintering temperature on PTCR ceramics were also investigated. The optimal concentration of the donor was found to be 0.6mol with the acceptor concentration being 1/8 of the donor. Multilayer PTCR elements were fabricated by tape-casting technique. The jump ratio of PTCR chips sintered at 1240°C was above 103 with the average grain size smaller than 1~2 μm, which is suitable for the multilayer PTCR elements.

scholarly journals Microstructure and Properties of Ultrafine Cemented Carbides Prepared by Microwave Sintering of Nanocomposites

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 507
Author(s):  
Yanju Qian ◽  
Zhiwei Zhao
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Vickers Hardness ◽  
Sintering Temperature ◽  
Microwave Sintering ◽  
Raw Material ◽  
Cemented Carbides ◽  
Microstructure And Mechanical Properties ◽  
Average Grain Size

Ultrafine cemented carbides were prepared by microwave sintering, using WC-V8C7-Cr3C2-Co nanocomposites as a raw material. The effects of sintering temperature and holding time on the microstructure and mechanical properties of cemented carbides were studied. The results show that the ultrafine cemented carbides prepared at 1300 °C for 60 min have good mechanical properties and a good microstructure. The relative density, Vickers hardness, and fracture toughness of the specimen reach the maximum values of 99.79%, 1842 kg/mm2 and 12.6 MPa·m1/2, respectively. Tungsten carbide (WC) grains are fine and uniformly distributed, with an average grain size of 300–500 nm. The combination of nanocomposites, secondary pressing, and microwave sintering can significantly reduce the sintering temperature and inhibit the growth of WC grains, thus producing superfine cemented carbides with good microstructure and mechanical properties.

scholarly journals Effect of ECAP on the Microstructure and Mechanical Properties of a Rolled Mg-2Y-0.6Nd-0.6Zr Magnesium Alloy

Crystals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 586 ◽  
Author(s):  
Shi ◽  
Li ◽  
Hu ◽  
Tan ◽  
Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Room Temperature ◽  
High Strength ◽  
Electron Backscattered Diffraction ◽  
Bar Rolling ◽  
Fine Grained ◽  
Angular Pressing ◽  
Microstructure And Mechanical Properties ◽  
Average Grain Size

A fine-grained Mg-2Y-0.6Nd-0.6Zr alloy was processed by bar-rolling and equal-channel angular pressing (ECAP). The effect of ECAP on the microstructure and mechanical properties of rolled Mg-2Y-0.6Nd-0.6Zr alloy was investigated by optical microscopy, scanning electron microscopy, electron backscattered diffraction and a room temperature tensile test. The results show that the Mg-2Y-0.6Nd-0.6Zr alloy obtained high strength and poor plasticity after rolling. As the number of ECAP passes increased, the grain size of the alloy gradually reduced and the texture of the basal plane gradually weakened. The ultimate tensile strength of the alloy first increased and then decreased, the yield strength gradually decreased, and the plasticity continuously increased. After four passes of ECAP, the average grain size decreased from 11.2 µm to 1.87 µm, and the alloy obtained excellent comprehensive mechanical properties. Its strength was slightly reduced compared to the as-rolled alloy, but the plasticity was greatly increased.

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