scholarly journals Contamination Study of Zirconia on the Densification Process and Properties of Transparent MgAl2O4 Ceramics

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 749
Author(s):  
Yi Li ◽  
Qun Zeng ◽  
Jian Zhang ◽  
Dan Han ◽  
Shiwei Wang
Keyword(s):  
Optical Properties ◽  
Hot Isostatic Pressing ◽  
Magnesium Aluminate ◽  
Sintering Behavior ◽  
Pressureless Sintering ◽  
Densification Process ◽  
Thick Sample ◽  
Anion Vacancies ◽  
Average Grain Size ◽  
Zirconia Content

In this paper, transparent magnesium aluminate (MgAl2O4) spinel ceramics are fabricated through pressureless sintering combined with hot isostatic pressing (HIPing). To investigate the effect of zirconia on sintering behavior, microstructure, and optical properties of transparent spinel ceramics, different contents of zirconia were added. The results show that zirconia can promote the densification process by the formation of anion vacancies. The resulting zirconia exists as tetragonal phase along the grain boundaries. The average grain size of resulting ceramics depends on the content of zirconia and HIPing condition. Small zirconia content did not deteriorate the optical properties of samples. A 5-mm-thick sample with 0.05 wt% ZrO2 pre-sintered at 1500 °C followed by HIPing treatment at 1550 °C achieved a high in-line transmittance of 75.5% at 400 nm and 85% at 1100 nm.

Processing and Properties of Nanocrystalline Tetragonal Zirconia

2007 ◽  
Vol 336-338 ◽  
pp. 2300-2303 ◽  
Author(s):  
Martin Trunec ◽  
Karel Maca
Keyword(s):  
Fracture Toughness ◽  
Pore Size ◽  
Hot Isostatic Pressing ◽  
Tetragonal Zirconia ◽  
Cold Isostatic Pressing ◽  
Pressureless Sintering ◽  
Isostatic Pressing ◽  
Average Grain Size ◽  
Zirconia Nanopowders ◽  
Sintering Behaviour

Zirconia nanopowders (stabilized by 1.5 and 3 mol% Y2O3) with particle size below 10 nm were compacted by cold isostatic pressing. Pressureless sintering and hot isostatic pressing were applied to obtain dense nanocrystalline ceramics. The influence of the pore size in powder compacts on sintering behaviour was investigated. Green bodies pressed at 1000 MPa had a maximum pore size of 5 nm. These bodies were densified to a relative density of over 99.6% with an average grain size about 85 nm by pressureless sintering at 1100 °C. Indentation techniques were used to evaluate the hardness and fracture toughness of zirconia nanoceramics. The decrease in the yttria content from 3 to 1.5 mol% resulted in the toughness increasing from 5.3 to 11.1 MPa m1/2. The differences in fracture toughness of zirconia ceramics prepared with different yttria contents and by different sintering methods were discussed and their possible causes were proposed.

Effect of HIP on the Properties and Microstructure of Transparent Polycrystalline Spinel

2007 ◽  
Vol 336-338 ◽  
pp. 1200-1202 ◽  
Author(s):  
Mu Yun Lei ◽  
Cun Xin Huang ◽  
Jia Lin Sun
Keyword(s):  
Grain Size ◽  
Optical Properties ◽  
Hot Pressing ◽  
Hot Isostatic Pressing ◽  
Magnesium Aluminate ◽  
Magnesium Aluminate Spinel ◽  
Sintering Aid ◽  
Average Transmittance ◽  
Before And After ◽  
Spinel Powder

In this paper, transparent polycrystalline magnesium aluminate spinel was fabricated by hot pressing ultra fine high purity spinel powder using LiF as the sintering aid in vacuum, then hot isostatic pressing (HIPing) the sintered body to improve the optical properties of the sample. The transmittance and the strength of the samples before and after HIPing were measured; morphologies of the fracture surface of the samples before and after HIPing were observed. Following hot pressing, the grain size of the sample is small; the transmission values are low and may varied at different sites in the same sample. After HIPing, the strength of the sample decreased, the grain size increased obviously, and the transmittance and the uniformity of transmittance increased significantly. The panel of transparent spinel up to 200 mm in diameter and 8 mm thick was fabricated by this method; the average transmittance of the spinel is above 80% in the range between 2 μm and 5 μm .

Structural Ceramics Based on Nanosized Si3N4 Powders

2010 ◽  
Vol 65 ◽  
pp. 86-91
Author(s):  
V. Rumyantsev ◽  
Andrey Osmakov ◽  
N. Korableva ◽  
N. Belykh ◽  
L. Stafeckis ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Hot Isostatic Pressing ◽  
Cutting Tools ◽  
Plasma Chemistry ◽  
Decomposition Temperature ◽  
Pressureless Sintering ◽  
Structural Ceramics ◽  
Chemical Corrosion ◽  
Average Grain Size

Ceramics based on nanosized plasma chemistry Si3N4 powder compositions s (30-100 nm) is processed by activated pressureless sintering, hot pressing and hot isostatic pressing. Microstructure characterization of the obtained materials by means o light and scanning microscopy revealed no correlation between microstructure and the bulk consolidation method . Average grain size in all cases was 200-500 nm. Comparative characterization of the physical and mechanical behavior of the analyzed samples showed the following results: relative density - over 99 %, flexural strength – over 700 MPa, Vickers hardness - 16-17GPa, fracture toughness – 6.5-7.4 MPa·m1/2. The activated pressureless sintered samples demonstrated physical and mechanical behavior comparable to the samples consolidated by other methods. Activated pressureless sintering of nanosized plasma chemistry Si3N4 powders led to considerable economic advantages in processing Si3N4 spherical rotation bodies for hybrid roller bearings and cutting tools. Silicon nitride (Si3N4)-based structural ceramics is widely studied and used for over half a century due to its unique properties: low density, combined with high strength and wear-resistance, high decomposition temperature, high oxidation resistance, low friction coefficient and high resistance to chemical corrosion[1].

Effect of TiO2 and MgO on Microstructure of α-Alumina Ceramics and its Sintering Behavior

2015 ◽  
Vol 1112 ◽  
pp. 519-523 ◽  
Author(s):  
Jarot Raharjo ◽  
Sri Rahayu ◽  
Tika Mustika ◽  
Masmui ◽  
Dwi Budiyanto
Keyword(s):  
Mechanical Properties ◽  
Sintering Temperature ◽  
Physical And Mechanical Properties ◽  
Basic Material ◽  
Sintering Behavior ◽  
Pressureless Sintering ◽  
Alumina Ceramics ◽  
Density Measurements ◽  
Technical Alumina ◽  
Platelet Structure

Observation on the effect of adding titanium oxide (TiO2) and magnesium oxide (MgO) on the sintering of α-alumina (Al2O3) has been performed. In this study, technical alumina used as basic material in which the sample is formed by the pressureless sintering/cold press and sintered at 1500°C which is lower than alumina sintering temperature at 1700°C. Elemental analysis, observation of microstructure, hardness, fracture toughness and density measurements were carried out to determine the physical and mechanical properties of alumina. The results indicate a change in the microstructure where the content of the platelet structure are much more than the equilateral structure. At sintering temperature of 1500°C, neck growth occurs at ceramics grain, supported by the results of the density test which indicate perfect compaction has occurred in this process.

Influence of Substrate Temperature on Structural and Optical Properties of Co-Evaporated Cu2SnS3/ITO Thin Films

2022 ◽  
Vol 1048 ◽  
pp. 189-197
Author(s):  
Tippasani Srinivasa Reddy ◽  
M.C. Santhosh Kumar
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Substrate Temperature ◽  
Indium Tin Oxide ◽  
Nir Spectroscopy ◽  
Stoichiometric Ratio ◽  
Tin Sulfide ◽  
Structural And Optical Properties ◽  
Average Grain Size ◽  
Deposited Films

In this study report the structural and optical properties of Copper Tin Sulfide (Cu2SnS3) thin films on indium tin oxide (ITO) substrate using co-evaporation technique. High purity of copper, tin and sulfur were taken as source materials to deposit Cu2SnS3 (CTS) thin films at different substrate temperatures (200-350 °C). Further, the effect of different substrate temperature on the crystallographic, morphological and optical properties of CTS thin films was investigated. The deposited CTS thin films shows tetragonal phase with preferential orientation along (112) plane confirmed by X-ray diffraction. Micro-Raman studies reveled the formation of CTS thin films. The surface morphology, average grain size and rms values of the deposited films are examined by Scanning electron spectroscopy (SEM) and Atomic Force Microscopy (AFM). The Energy dispersive spectroscopy (EDS) shows the presence of copper, tin and sulfur with a nearly stoichiometric ratio. The optical band gap (1.76-1.63 eV) and absorption coefficient (~105 cm-1) of the films was calculated by using UV-Vis-NIR spectroscopy. The values of refractive index, extinction coefficient and permittivity of the deposited films were calculated from the optical transmittance data.

Microstructure and optical properties of transparent aluminum oxynitride ceramics by hot isostatic pressing

2014 ◽  
Vol 81 ◽  
pp. 20-23 ◽  
Author(s):  
Feng Chen ◽  
Fang Zhang ◽  
Jun Wang ◽  
Hailong Zhang ◽  
Run Tian ◽  
...  
Keyword(s):  
Optical Properties ◽  
Hot Isostatic Pressing ◽  
Aluminum Oxynitride ◽  
Isostatic Pressing

scholarly journals Pressureless sintering behavior of injection molded alumina ceramics

2014 ◽  
Vol 46 (1) ◽  
pp. 3-13 ◽  
Author(s):  
W. Liu ◽  
Z. Xie
Keyword(s):  
Detrimental Effect ◽  
Pore Space ◽  
Critical Role ◽  
Solid Loading ◽  
Sintering Behavior ◽  
Alumina Powder ◽  
Pressureless Sintering ◽  
Alumina Ceramics ◽  
Injection Molded ◽  
Full Densification

The pressureless sintering behaviors of two widely used submicron alumina (MgOdoped and undoped) with different solid loadings produced by injection molding have been studied systematically. Regardless of the sinterability of different powders depending on their inherent properties, solid loading plays a critical role on the sintering behavior of injection molded alumina, which greatly determines the densification and grain size, and leads to its full densification at low temperatures. As compared to the MgO-doped alumina powder, the undoped specimens exhibit a higher sinterability for its smaller particle size and larger surface area. While full densification could be achieved for MgO-doped powders with only a lower solid loading, due to the fact that MgO addition can reduce the detrimental effect of the large pore space on the pore-boundary separation.

The Structure-Property-Processing Relationship for Sintered Yttria-Stabilized Zirconia (YSZ)/Alumina Bioceramics

2013 ◽  
Vol 25 (04) ◽  
pp. 1350005 ◽  
Author(s):  
Sea-Fue Wang ◽  
Thomas Chung-Kuang Yang ◽  
Ya-Ting Hsu ◽  
Sheng-Yang Lee ◽  
Jen-Chang Yang
Keyword(s):  
Fracture Toughness ◽  
Relative Density ◽  
Sintering Temperature ◽  
High Hardness ◽  
Solid State Reaction Method ◽  
Sintering Behavior ◽  
Structure Property ◽  
Stabilized Zirconia ◽  
Average Grain Size ◽  
Alumina Addition

The objective of this research is to study the effects of alumina addition on the microstructure-mechanical property relationship and sintering behavior of yttria (3 mol%)-stabilized zirconia (YSZ) ceramics. Well-dispersed YSZ / Al 2 O 3 ceramics containing 10–40 wt.% Al 2 O 3 were prepared by solid state reaction method. The relative density, average grain size, lattice parameters, microhardness, and fracture toughness of YSZ / Al 2 O 3 ceramics system sintered in the temperature range of 1250~1500°C as a function of Al 2 O 3 content were investigated. Experimental results showed that the ceramics with high Al 2 O 3 content and low sintering temperature tended to reveal low bulk densities. But the Al 2 O 3 content dependence on relative density for YSZ / Al 2 O 3 ceramics becomed deminishing when increasing the sintering temperature. Dense ceramics with composition of (80/20) ( YSZ / Al 2 O 3) and sintered at temperature of 1400°C and 1450°C revealed the optimal Vickers hardness and fracture toughness properties. These ceramics with high Al 2 O 3 content tended to reveal small grain sizes. The high sintering temperature governs the slow grain growth and high hardness in materials indicating the good correlation between microstructure of fabricated dense and mechanical properties.

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