scholarly journals Effects of Simulation-Guided Microwave Presintering Process on the Preparation and Final Properties of Pure Ceramic Rings: Lower Sintering Temperature and Higher Mechanical Properties

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Xiao Lu ◽  
Tong-Tong Zhou ◽  
Feng-He Zhao ◽  
Xiao-Xiong Wang ◽  
Li-Xiang Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electromagnetic Field ◽  
Relative Density ◽  
Textile Industry ◽  
Microwave Sintering ◽  
Three Dimensional ◽  
Simulation Software ◽  
Gel Casting ◽  
Average Grain Size ◽  
Conventional Sintering

In order to improve the performance and endurance of steel rings used for twisting and winding yarns in the textile industry, a more wear-resistant ceramic version is studied and examined by conducting multiple simulations combined with microwave sintering experiments of the ring preparation process, aiming to reduce manufacturing costs and improve efficiency. The three-dimensional (3D) electromagnetic field simulation software HFSS is used to simulate the electromagnetic field distribution in the microwave sintering cavity and to determine the electromagnetic region with the most uniform electromagnetic field to guide the microwave sintering experiments. The 3Y-TZP ceramic rings are shaped by gel-casting. The effect of presintering on the performance of ceramic rings is investigated by applying conventional sintering and microwave sintering methods. The experimental results show that the simulation-guided microwave sintering process can resolve the deficiency of uneven microwave sintering at low temperatures. Comparing the final sintering temperatures and mechanical properties of the final ceramic-sintered rings obtained by microwave presintering to those obtained by conventional presintering, microwave presintered sample has a final temperature of 1400°C, which is 100°C lower than that of conventional presintering, which is 1500°C; its average grain size of 0.18 μm is dramatically smaller than that of conventional presintering, which is 0.24 μm, with about 80% of the grain sizes present in the range of 0.1-0.2 μm and a relative density of about 99%, as opposed to conventional presintering’s 70% falling between 0.2 and 0.3 μm and relative density of about 98%; the Vickers hardness and fracture toughness for microwave presintered sample reach 1550 kg·f·mm−2 and 9.05 MPa m1/2, respectively, which are both greater than 1431 kg·f·mm−2 and 8.86 MPa m1/2 in the conventional samples.

scholarly journals Ag+, Cu2+ and Zn2+ doped hydroxyapatite/tricalcium phosphate bioceramics: Influence of doping and sintering technique on mechanical properties

2018 ◽  
Vol 12 (3) ◽  
pp. 268-276 ◽  
Author(s):  
Zeljko Radovanovic ◽  
Ðordje Veljovic ◽  
Lidija Radovanovic ◽  
Ilmars Zalite ◽  
Eriks Palcevskis ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tricalcium Phosphate ◽  
Microwave Sintering ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydroxyapatite Ceramics ◽  
Average Grain Size ◽  
Conventional Sintering ◽  
Scanning Electron

Green hydroxyapatite ceramics were obtained by cold uniaxial and isostatic pressing of hydrothermally synthesized powders, pure hydroxyapatite and hydroxyapatite doped with Ag+, Cu2+ and Zn2+ ions. The ceramics were conventionally and microwave sintered and analyzed by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction analysis, and energy-dispersive X-ray spectroscopy. The effect of doping on the mechanical properties of the obtained hydroxyapatite/tricalcium phosphate ceramics was examined by comparing their average grain size, porosity and values of the hardness and fracture toughness. The results showed that doping with Cu2+ ions caused the lowest porosity of the ceramics and the highest values of hardness and fracture toughness. The ceramics obtained from hydroxyapatite doped with Ag+ and Zn2+ ions exhibited worse mechanical properties due to the higher porosity even in the case of microwave sintering, which provide denser ceramics than conventional sintering.

Nanostructure Evolution of ZnO in Ultra-fast Microwave Sintering

2011 ◽  
Vol 691 ◽  
pp. 65-71 ◽  
Author(s):  
Rodolfo F. K. Gunnewiek ◽  
Ruth Herta Goldsmith Aliaga Kiminami
Keyword(s):  
Grain Size ◽  
Zinc Oxide ◽  
Grain Growth ◽  
Microwave Sintering ◽  
High Heating Rate ◽  
Heating Rates ◽  
Grain Sizes ◽  
Average Grain Size ◽  
Conventional Sintering ◽  
Holding Temperature

Grain growth is inevitable in the sintering of pure nanopowder zinc oxide. Sintering depend on diffusion kinetics, thus this growth could be controlled by ultra-fast sintering techniques, as microwave sintering. The purpose of this work was to investigate the nanostructural evolution of zinc oxide nanopowder compacts (average grain size of 80 nm) subjected to ultra-rapid microwave sintering at a constant holding temperature of 900°C, applying different heating rates and temperature holding times. Fine dense microstructures were obtained, with controlled grain growth (grain size from 200 to 450nm at high heating rate) when compared to those obtained by conventional sintering (grain size around 1.13µm), which leads to excessively large average final grain sizes.

Double Inhibitory Actions on WC Grains of Microwave Sintered WC-12wt%Co-VC Alloy

2015 ◽  
Vol 816 ◽  
pp. 715-721 ◽  
Author(s):  
Rui Bao ◽  
Jian Hong Yi ◽  
Jia Min Zhang ◽  
Yi Chun Liu ◽  
Feng Xian Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Positive Impact ◽  
Rupture Strength ◽  
Microwave Sintering ◽  
Inhibitory Effects ◽  
Microwave Exposure ◽  
Microstructure Observation ◽  
Average Grain Size ◽  
Bulk Alloys ◽  
Sintering Method

It is well known that grain-refinement has a positive impact on the mechanical properties of WC-Co cemented carbide. The effect of VC inhibitor and microwave on density, microstructure and mechanical properties of the sintered WC–12wt%Co alloy was investigated in the present study. The ball milled WC-12wt%Co-xVC composites were compressed and fabricated by using microwave sintering method. The experimental results indicate that the microwave sintering cycle was significantly shorter to that of vacuum processing, and the density of bulk alloys increased with VC inhibitor contents and microwave sintering temperatures. Moreover, the microstructure observation of the sintered samples suggests that VC inhibitor had prominent inhibitory action on WC grains in microwave exposure, and the WC average grain size of alloy with 0.7wt%VC inhibitor was 0.43μm when the sintering temperature reached 1420°C. It is also evident that WC-12wt% alloys with an appropriate proportion of VC inhibitor exhibited higher hardness (92.1HRA) and better transverse rupture strength (2380MPa). And finally the mechanism of inhibitory effects on WC grains under microwave irradiation was discussed.

scholarly journals Microwave sintering of nano size powder β-TCP bioceramics

2014 ◽  
Vol 46 (2) ◽  
pp. 185-193 ◽  
Author(s):  
B. Mirhadi
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tricalcium Phosphate ◽  
Microwave Sintering ◽  
Calcium Nitrate ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Precipitation Process ◽  
Average Grain Size ◽  
Nano Size

A nano sized beta tricalcium phosphate (?-TCP) powder was conventional sintered (CS) and microwave sintered (MW), in order to obtain dense ?-TCP ceramics. In this work the effect of microwave sintering conditions on the microstructure, phase composition and mechanical properties of materials based on tricalcium phosphate (TCP) was investigated by SEM (scanning electron microscopy)and XRD(X-ray diffraction) and then compared with conventional sintered samples. Nano-size ?-TCP powders with average grain size of 80 nm were prepared by the wet chemical precipitation method with calcium nitrate and diammonium hydrogen phosphate as calcium and phosphorus precursors, respectively. The precipitation process employed was also found to be suitable for the production of submicrometre ?-TCP powder in situ. The ?-TCP samples microwave (MW) sintered for 15 min at 1100?C, with average grain size of 3?m, showed better densification, higher density and certainly higher hardness than samples conventionally sintered for 2 h at the same temperature. By comparing sintered and MW sintered ?-TCP samples, it was concluded that MW sintered ?-TCP samples have superior mechanical properties.

scholarly journals Yttria- Stabilized Tetragonal Zirconia with Superior Mechanical Properties Prepared Using Gel Casting Technology and a Two-Stage Sintering Process

2021 ◽  
Author(s):  
Jing-Siang Jhan ◽  
Chih-Cheng Chen ◽  
Yu-Chi Liu ◽  
Hsing-I Hsiang
Keyword(s):  
Mechanical Properties ◽  
Relative Density ◽  
Grain Growth ◽  
Tetragonal Zirconia ◽  
Solid Content ◽  
Sintering Process ◽  
Two Stage ◽  
Casting Technology ◽  
Gel Casting ◽  
Superior Mechanical Properties

Abstract Yttria-stabilized tetragonal zirconia (YTZP) ceramics with high densification and superior mechanical properties were obtained using gel casting technology and a two-stage sintering process. Well-dispersed Nano-sized (94 nm) zirconia slurry with high solid content (45vol%) was prepared for gel casting using Dolapix CE64 as the dispersant. As the dispersed slurry was added epoxy monomer (EGDGE) and polymerization initiator (DPTA), Dolapix CE64 promoted gelling, leading to an abrupt increase in the slurry viscosity. As Dolapix CE64 was added into the slurry, its functional carboxyl groups reacted with EGDGE, resulting in a decrease in gelling incubation time and an increase in viscosity, hence, leading to gel casting failure. The addition of hydroquinone (HQ) into the slurry can be used to delay the polymerization and extend the gel casting working time. After gel casting, the temperature was raised to above 60o C to promote the polymerization, leading to an increase in the green strength.A two-stage sintering process was used to control the grain growth. The first stage sintering temperature was chosen at 1300oC, where the relative density reached 83%. In the second sintering stage, the temperature was lowered to 1240°C and soaked for 24 h to inhibit grain growth (mean grain size of 195 nm) and continue densification to a relative density of above 99%. Vickers hardness of 15.2GPa, fracture toughness of 7.8MPa.m1/2, and flexural strength of 771MPa can be obtained for the sample prepared using gel casting technology with a two-stage sintering process.

Unconventional Methods of Sintering Inconel 718 MIM Samples

2016 ◽  
Vol 716 ◽  
pp. 830-839
Author(s):  
Olivier Dugauguez ◽  
Jose Manuel Torralba ◽  
Thierry Barrière ◽  
Jean Claude Gelin
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Heating Rate ◽  
Inconel 718 ◽  
Fine Particle ◽  
Alloy Powder ◽  
Microwave Sintering ◽  
Conventional Sintering ◽  
Unconventional Methods ◽  
Super Alloy

In this investigation, three different ways of sintering Inconel 718 MIM samples are compared. The conventional way of sintering in a furnace will be compared to FAHP and microwave sintering. The difficulty of these two methods is to be able to control the shrinkage of the sample and so its shape. These methods have yet not been investigated with a super alloy powder and so, the effects of a high sintering rate on a MIM sample. By accelerating the sintering kinetics, the thermal behavior may be modified. Hence, the behavior of the Inconel 718 sintered by field assisted and microwave sintering has been investigated. The sintered samples were all injected from a feedstock composed of a fine particle Inconel powder and a binder principally composed of CAB and PEG. They were debinded into water for 24h and put in a furnace at 500°C during 2 hours. The heating rate of the furnace was set to 5°C/min until 1290°C during 2 hours. The heating rate of the FAHP was set to 50°C/min until 1250°C during 15 minutes. The microwave samples were sintered around 1300°C during 1 hour, the temperature was increased progressively by steps of 100°C. The effects of the different process on the microstructure and the mechanical properties are then compared. There was no difference in distribution of pores between the conventional sintering and the FAHP sintering but a finer grain size showed better hardness. The microwave sintering of a MIM sample is more complex and the best properties were not obtained.

Sintering of HA/Zirconia Composite for Biomedical and Dental Applications: A Review

2013 ◽  
Vol 686 ◽  
pp. 290-295
Author(s):  
Kok Fong Lim ◽  
Muchtar Andanastuti ◽  
Rusnah Mustaffa ◽  
Chou Yong Tan
Keyword(s):  
Mechanical Properties ◽  
Microwave Sintering ◽  
Hot Isostatic Pressing ◽  
Medical Application ◽  
Processing Method ◽  
Isostatic Pressing ◽  
Alternative Processing ◽  
Conventional Sintering ◽  
Phosphate Product ◽  
Dental Applications

Hydroxyapatite is a calcium phosphate product that being widely use in medical application due to its excellence biocompatibility. However its application has being limited due to the inferior mechanical properties, many researcher attempted to improve its mechanical properties. HA-ZrO2 composites have great potential because of their advantages from both constituent materials, such as the excellent biocompatibility of HA and the considerable mechanical strength and toughness of ZrO2. The synergy of the two materials provides a new possibility for developing a composite material with better properties than monolithic ZrO2 and HA. In this work, the stages of development, as well as the different sintering and processing methods of HA and ZrO2 such as conventional sintering, solid-state reaction, microwave sintering and hot isostatic pressing were discussed. It can be concluded that hot isostatic pressing processing yield the most satisfying result amount above method, however the use of nano structured material maybe able to provide alternative processing method and yield better result.

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.

3D Electromagnetic Simulation Study for the Distribution of Electromagnetic Field of Microwave Sintering Cavity

2009 ◽  
Vol 79-82 ◽  
pp. 2247-2250
Author(s):  
Li Xiang Chen ◽  
Chu Lei ◽  
Ning Zhang ◽  
Chang Shun Jin ◽  
Yan Sheng Yin
Keyword(s):  
Electromagnetic Field ◽  
Cross Sections ◽  
Microwave Sintering ◽  
Single Mode ◽  
Simulation Software ◽  
Electromagnetic Simulation ◽  
Internal Space ◽  
Electrical Field ◽  
Novel Method ◽  
Key Features

In this paper, we use electromagnetic simulation software HFSS to investigate the distribution of electromagnetic field of microwave sintering cavity, and establish a simulation model for the TE103 single mode cavity. We then obtain the optimal condition for the distribution of electromagnetic field by capturing the contour of distribution of electrical field of cavity through simulation. Our research shows that electromagnetic simulation software HFSS can use color to effectively demonstrate the intensity distribution of electromagnetic field of internal space and various cross-sections within the microwave sintering cavity, which provides a novel method for improving and applying new ways to compute and predict the key features of field distribution. The simulation results by HFSS can guide the practical microwave sintering techniques as well as the design and improvement of the sintering cavity.

scholarly journals Microwave sintering of tungsten heavy alloys

2018 ◽  
Vol 16 (2) ◽  
Author(s):  
G. Prabhu ◽  
M. Sankaranarayana ◽  
T. K. Nandy
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Microwave Sintering ◽  
Microstructural Parameters ◽  
Heavy Alloys ◽  
Tungsten Heavy Alloys ◽  
Conventional Sintering ◽  
Superior Mechanical Properties ◽  
High Tungsten Content ◽  
Full Densification

To understand microwave sintering of heavy alloys with high tungsten content, 93W-4.9Ni-2.1Fe alloy was sintered using a 6 kW, 2.45 GHz microwave sintering furnace at 1783 K (1510˚ºC) and 1793 K (1520˚ºC). The alloy sintered at 1793 K (1520˚ºC) achieved full densification and had improved microstructural features, superior mechanical properties compared to 99.4% densification and relatively inferior properties obtained in the alloy sintered at 1783 K (1510˚ºC). This study also includes a comparison between microwave sintered and conventionally sintered 93W-4.9Ni-2.1Fe alloy (sintered at 1793K (1520ºC)). Contrary to the full densification and superior mechanical properties obtained in microwave sintering, conventional sintering at 1793K (1520ºC) resulted in only 99.6% densification and substantially inferior properties. Analyses of microstructure and fracture surface revealed that key microstructural parameters such as tungsten grain size, tungsten-tungsten contiguity, matrix volume fraction and also the fracture mode were significantly different between the alloys processed by the two routes. Possible reasons behind dissimilar densification, significantly different microstructures and mechanical properties obtained between these two modes of sintering, are also discussed in this study.

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