Reaction Sintering of Transparent Aluminum Oxynitride (AlON) Ceramics Using MgO and Y2O3 as Co-Additives

2016 ◽  
Vol 697 ◽  
pp. 7-11 ◽  
Author(s):  
Shen Qi ◽  
Xiao Jian Mao ◽  
Bao Yan Chai ◽  
Long Zhang
Keyword(s):  
Grain Size ◽  
Optical Properties ◽  
Liquid Phase ◽  
Aluminum Nitride ◽  
Sintering Temperature ◽  
Direct Reaction ◽  
Reaction Sintering ◽  
Aluminum Oxynitride ◽  
Sintering Additives

Transparent aluminum oxynitride (AlON) ceramics have been prepared through a method based on direct reaction sintering of alumina and aluminum nitride powders using MgO and Y2O3 as co-additives. The sintering additives could cause the formation of liquid phase during sintering, which would greatly promote the densification and eliminate pores. The grain size of AlON is about 50-100μm. The influence of different component of Al2O3 and AlN as well as sintering temperature on microstructure and optical properties of AlON have been studied. High transparent AlON ceramics with the in-line transmittance of 80.3% at 2000 nm wavelength have been prepared when the concentration of sintering additives was 0.16wt% Y2O3 and 0.02wt% MgO.

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.

Preparation of Aluminum Nitride and Oxynitride Thin Films by Ion-Assisted Deposition

1987 ◽  
Vol 93 ◽  
Author(s):  
J. D. Targove ◽  
L J. Lingg ◽  
J. P. Lehan ◽  
C. K. Hwangbo ◽  
H. A. Macleod ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Electron Beam ◽  
Aluminum Nitride ◽  
Oxygen Diffusion ◽  
Vacuum Chamber ◽  
Rutherford Backscattering Spectrometry ◽  
Ion Fluxes ◽  
Aluminum Oxynitride ◽  
Nitrogen Ion

ABSTRACTAluminum nitride thin films have been deposited by ion-assisted deposition. Aluminum was electron-beam evaporated onto substrates with simultaneous nitrogen ion bombardment. Rutherford backscattering spectrometry showed that nitrogen-to-aluminum ratios of one or greater could be achieved with sufficient nitrogen ion fluxes. This excess nitrogen apparently degrades the optical properties of the films in the visible. Annealing at 500°C improves the optical properties drastically at the expense of a slight oxygen diffusion into the films. Finally, aluminum oxynitride films were deposited by adding an oxygen backfill to the vacuum chamber during deposition. These films had very similar optical properties to the annealed nitride films.

Effect of Composite Sintering Aids on the Thermal and Mechanical Properties of Hot-Pressed Aluminum Nitride

2014 ◽  
Vol 602-603 ◽  
pp. 561-564
Author(s):  
Jun Yu Fu ◽  
Shang Hua Wu ◽  
Yan Ling Cheng ◽  
Chang Lu Fu ◽  
Ruo Jun Wu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Aluminum Nitride ◽  
Composite System ◽  
Sintered Body ◽  
Boundary Phase ◽  
Thermal And Mechanical Properties ◽  
Sintering Aids ◽  
Sintering Additives

The aim of this work was to determine the effect of composite additives on the thermal and mechanical properties of aluminum nitride (AlN) in detail. The composite system has not been studied in depth before. The hot-pressed AlN was prepared with Y2O3-Dy2O3-YF3 and Y2O3-Dy2O3-CaO as the composite sintering additives. As the result, the thermal conductivities for the sintered body with two composite additives were 171 W/m.K and 152 W/m.K, respectively. The fracture toughness values calculated by the Evans & Clarkes’s equation for both of the samples were 2.34±0.09 MPa.m1/2and 2.63±0.13 MPa.m1/2 at 10 kg load. The toughness difference is the result of comprehensive effect of the grain size, the properties of the boundary phase, its distribution, and also the interactions between different phases.

Hot-Pressed Translucent Aluminum Oxynitride (AlON) Ceramics

2008 ◽  
Vol 368-372 ◽  
pp. 450-452 ◽  
Author(s):  
Jun Ming Xue ◽  
Qian Liu ◽  
Tong Ping Xiu ◽  
Li Li Ma ◽  
Ming Fang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Optical Properties ◽  
Hot Pressing ◽  
Sintering Temperature ◽  
Great Influence ◽  
Optical Transmittance ◽  
Aluminum Oxynitride ◽  
Infrared Transmission

AlON with a composition of Al23O27N5 was prepared by hot pressing at temperatures lower than 1900 °C. The microstructures and final properties, including both mechanical properties and optical properties, of the sintered specimens were studied. The results showed that sintering temperature had a great influence on the densification of specimens and could lead to very different properties, especially the optical transmittance and the maximum infrared transmission.

Sintering temperature-microstructure-property relationships of alumina matrix composites with silicon carbide and silica additives

2017 ◽  
Vol 24 (4) ◽  
pp. 495-500 ◽  
Author(s):  
Apichart Limpichaipanit ◽  
Sukanda Jiansirisomboon ◽  
Tawee Tunkasiri
Keyword(s):  
Fracture Toughness ◽  
Silicon Carbide ◽  
Grain Size ◽  
Fracture Surface ◽  
Sintering Temperature ◽  
Matrix Composites ◽  
Reaction Sintering ◽  
Alumina Matrix ◽  
Powder Mixtures ◽  
Ceramic Samples

AbstractAlumina-based composites were fabricated by reaction sintering from two different sintering powder mixtures: alumina with silica (SiO2) and alumina with silicon carbide (SiC; to allow oxidation to form SiO2). After sintering, SiO2 underwent complete reaction to form alumina/mullite composites. In terms of microstructure, the density and grain size of ceramic samples were investigated. The density of the composites prepared by alumina and SiC was lower than those of alumina and the composites prepared by alumina and SiO2. The grain size increased as the sintering temperature increased. In terms of mechanical properties, fracture surfaces, hardness, and fracture toughness were investigated. It was found that the fracture surface of alumina was rather intergranular, whereas the fracture surface of the composites was more transgranular. The hardness of the composites was higher than that of alumina at the same sintering temperature. However, the fracture toughness of the composites was not significantly different compared to that of alumina.

scholarly journals Effect of starting materials and sintering temperature on microstructure and optical properties of Y2O3:Yb3+ 5 at% transparent ceramics

2020 ◽  
Author(s):  
R. P. Yavetskiy ◽  
A. E. Balabanov ◽  
S. V. Parkhomenko ◽  
O. S. Kryzhanovska ◽  
A. G. Doroshenko ◽  
...  
Keyword(s):  
Grain Size ◽  
Optical Properties ◽  
Sintering Temperature ◽  
Raw Materials ◽  
High Energy ◽  
Reactive Sintering ◽  
Average Grain Size ◽  
Median Particle ◽  
Energy Ball ◽  
Sintering Method

Abstract Y2O3:Yb3+ 5 at% ceramics have been synthesized by the reactive sintering method using different commercial yttria powders (Alfa-Micro, Alfa-Nano, and ITO-V) as raw materials. It has been shown that all Y2O3 starting powders consist from agglomerates up to 5–7 µm in size which are formed from 25–60 nm primary particles. High-energy ball milling allows to significantly decreasing the median particle size D50 below 500 nm regardless of the commercial powders used. Sintering experiments indicate that powder mixtures fabricated from Alfa-Nano yttria powders have the highest sintering activity, while (Y0.86La0.09Yb0.05)2O3 ceramics sintered at 1750 °C for 10 h are characterized by the highest transmittance of about 45%. Y2O3:Yb3+ ceramics have been obtained by the reactive sintering at 1750–1825°C using Alfa-Nano Y2O3 powders and La2O3+ZrO2 as a complex sintering aid. The effects of the sintering temperature on densification processes, microstructure, and optical properties of Y2O3:Yb3+ 5 at% ceramics have been studied. It has been shown that Zr4+ ions decrease the grain growth of Y2O3:Yb3+ ceramics for sintering temperatures 1750–1775 °C. Further increasing the sintering temperature was accompanied by a sharp increase of the average grain size of ceramics referred to changes of structure and chemical composition of grain boundaries, as well as their mobility. It has been determined that the optimal sintering temperature to produce high-dense yttria ceramics with transmittance of 79%–83% and average grain size of 8 µm is 1800 °C. Finally, laser emission at ∼1030.7 nm with a slope efficiency of 10% was obtained with the most transparent Y2O3:Yb3+ 5 at% ceramics sintered.

Wear Property of Superfine Grained Si2N2O-Si3N4 Composites

2008 ◽  
Vol 368-372 ◽  
pp. 917-919
Author(s):  
Jun Ting Luo ◽  
Qing Zhang ◽  
Hong Bo Li
Keyword(s):  
Grain Size ◽  
Wear Resistance ◽  
Silicon Nitride ◽  
Liquid Phase ◽  
Sintering Temperature ◽  
High Hardness ◽  
Liquid Phase Sintering ◽  
Wear Property ◽  
Average Grain Size ◽  
Bearing Ball

Si3N4-Si2N2O composites were fabricated with amorphous nano-sized silicon nitride powders by the liquid phase sintering. The mass loss, relative density and average grain size increase with increasing sintering temperature. The average grain size is less than 500nm when the sintering temperature is lower than 1700°C. Friction coefficient is from 0.35 for sintering temperature 1650°C to 0.74 for 1600°C when the composites were worn by silicon nitride bearing ball. High hardness of 21.5GPa and relative wear resistance of 32 were observed at a sintering temperature of 1600°C. The wear surface are very smooth and no grooving and subsurface fracture, which indicates that they are worn slightly.

Liquid Phase Sintering Behavior of Amorphous Nano-Sized Silicon Nitride Powders

2007 ◽  
Vol 336-338 ◽  
pp. 1069-1071 ◽  
Author(s):  
H.B. Li ◽  
Jun Ting Luo ◽  
Kai Feng Zhang
Keyword(s):  
Grain Size ◽  
Silicon Nitride ◽  
Liquid Phase ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
Sintering Behavior ◽  
Average Grain Size ◽  
Sintering Method ◽  
Amorphous Si3n4

The amorphous nano-sized silicon nitride powders were sintered by liquid phase sintering method. Si3N4-Si2N2O composites were in-situ fabricated. 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 obtained at a sintering temperature of 1650°C and reduced when the sintering temperature increased or decreased, which indicates that the reaction is reversible. The mass loss, relative density and average grain size increase with increasing of sintering temperature. The average grain size is less than 500nm when the sintering temperature is below 1700°C. During the sintering procedure, there is a complex crystallization and phase transition: amorphous Si3N4 → equiaxial α-Si3N4→ equiaxial β-Si3N4 → rod-likeSi2N2O → needle-like β-Si3N4. Small round-shaped β-Si3N4 particles are entrapped in the Si2N2O grains and a high density of staking faults are situated in the middle of Si2N2O grains at a sintering temperature of 1650°C.

Effects of powder bed conditions on the liquid-phase sintering of Si3N4

2002 ◽  
Vol 17 (2) ◽  
pp. 465-472 ◽  
Author(s):  
Sea-Hoon Lee ◽  
Georg Rixecker ◽  
Fritz Aldinger ◽  
Sung-Churl Choi ◽  
Keun-Ho Auh
Keyword(s):  
Liquid Phase ◽  
Vapor Pressure ◽  
Chemical Stability ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
Passive Protection ◽  
Powder Bed ◽  
Sintering Additives ◽  
Protection Mechanisms ◽  
Formation Behavior

The effects of the active and passive protection mechanisms of powder beds on the sintering of Si3N4 were investigated. Shrinkage, density, and coloring behavior of sintered samples were analyzed using different compositions and packing conditions of powder beds based on BN and Si3N4 with different additives. Y2O3 additive in the powder bed influences the weight change and phase formation behavior of the samples, although it has a very low vapor pressure at the sintering temperature. When MgO/Y2O3 was used as sintering additives, the packing density and thickness of the powder bed had a much stronger effect than in the case of Al2O3/Y2O3. For the optimization of the powder bed conditions, the vapor pressure and chemical stability of sintering additives at the sintering temperature has to be considered.

Electron Microscopy of Silicon Nitride-Based Ceramics

1991 ◽  
Vol 49 ◽  
pp. 926-927
Author(s):  
Gareth Thomas
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Silicon Nitride ◽  
World Wide ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
High Temperature Strength ◽  
Sintering Additives ◽  
Glass Forming ◽  
Dense Product

Silicon nitride and silicon nitride based-ceramics are now well known for their potential as hightemperature structural materials, e.g. in engines. However, as is the case for many ceramics, in order to produce a dense product, sintering additives are utilized which allow liquid-phase sintering to occur; but upon cooling from the sintering temperature residual intergranular phases are formed which can be deleterious to high-temperature strength and oxidation resistance, especially if these phases are nonviscous glasses. Many oxide sintering additives have been utilized in processing attempts world-wide to produce dense creep resistant components using Si3N4 but the problem of controlling intergranular phases requires an understanding of the glass forming and subsequent glass-crystalline transformations that can occur at the grain boundaries.

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