scholarly journals 5% PALLADIUM on Activated Alumina Powder

1949 ◽  
Vol 27 (15) ◽  
pp. 1070
Keyword(s):  
Alumina Powder ◽  
Activated Alumina

Effects of Al2O3 Species and Particle Sizes on Properties of Al2O3-Cr2O3 Refractories

2013 ◽  
Vol 745-746 ◽  
pp. 610-615
Author(s):  
Hong Gang Sun ◽  
Peng Tao Li ◽  
Shuang Zhi Yan ◽  
Gang Wang ◽  
Jian Qiang Li ◽  
...  
Keyword(s):  
Pore Size ◽  
Bulk Density ◽  
Size Distribution ◽  
Modulus Of Rupture ◽  
Alumina Powder ◽  
Particle Sizes ◽  
Activated Alumina ◽  
Bimodal Size Distribution ◽  
Lower Porosity ◽  
Shock Resistance

The microstructure of Al2O3-Cr2O3 refractories is an important factor to affect its high temperature performance. The Al2O3-Cr2O3 green bodies were prepared by hot pressing using aluminum oxide and Cr2O3 powder mixture by adding a binder. And then the specimens were sintered at 1650 for 4h in the electric muffle furnace. Properties of specimens with different species of Al2O3 powders were studied, including α-Al2O3 powder, ρ-Al2O3 powder, and fused corundum powder. Moreover, three sizes of α-Al2O3 powder (D50=0.8 μm, 1.4 μm, 4.0 μm) were used as additive. Properties of specimens, including apparent porosity, bulk density, cold modulus of rupture, pore size distribution were tested. The morphology of sintered specimens was analyzed by the Scanning Electron Microscope. The results showed that the specimens adding α-Al2O3 powder had the better properties since α-Al2O3 powder has higher sintering activity, and it was more efficient for Al2O3-Cr2O3 solid solution. The specimens with α-Al2O3 had lower porosity, higher bulk density and cold modulus of rupture, and more uniform pore distribution. There were great differences in sintering activity for specimens with different particle size of α-Al2O3 powder. And the microstructure of Al2O3-Cr2O3 was significantly dissimilar. The specimen with the addition of the activated alumina powder of D50 with the size of 1.4 μm and bimodal size distribution showed the perfect performance, including high density and high flexural strength. The experimental results showed that the microstructure of this specimen was uniform and its pore size was homogeneous. This special microstructure is beneficial for improving the slag resistance and thermal shock resistance of Al2O3-Cr2O3 refractories.

scholarly journals The kinetics of the partial dehydration of gibbsite to activated alumina in a reactor for pneumatic transport

2001 ◽  
Vol 66 (4) ◽  
pp. 273-280 ◽  
Author(s):  
Ljiljana Rozic ◽  
Tatjana Novakovic ◽  
Nadezda Jovanovic ◽  
Ana Terlecki-Baricevic ◽  
Zeljko Grbavcic
Keyword(s):  
Water Content ◽  
Residence Time ◽  
Theoretical Calculations ◽  
Pneumatic Transport ◽  
Alumina Powder ◽  
Order Kinetic ◽  
Activated Alumina ◽  
Two Phase ◽  
Short Residence Time ◽  
Kinetics Of

The dehidration kinetics of gibbsite to activated alumina was investigated at four different temperatures between 883 K and 943 K in a reactor for pneumatic transport in the dilute two phase flow regime. The first order kinetic behavior of this reactionwith respect to the water content of the solid material was proved and an activation energy of 66.5 kJ/mol was calculated. The effect of residence time on the water content is given and compared with theoretical calculations. The water content and other characteristics of the products depend on two main parameters, one is the short residence time and the other is the temperature of the dehydration of gibbsite. The short residence time of the gibbsite particles in a reactor for pneumatic transport prevents crystallization into new phases, as established from XRD analysis data. Reactive amorphous alumina powder, with a specific surface area of 250 m2/g, suitable as a precursor for catalyst supports is obtained.

Research on Carbon-Free Al-Al2O3 Composite Sliding Gate Performance

2012 ◽  
Vol 466-467 ◽  
pp. 8-12
Author(s):  
Jin Bao Li ◽  
Yong Li ◽  
Jun Jie Zhang ◽  
Ya Qin Liu ◽  
Shan Shan Hong
Keyword(s):  
Apparent Porosity ◽  
Modulus Of Rupture ◽  
Alumina Powder ◽  
Activated Alumina ◽  
Crushing Strength ◽  
Al Content ◽  
Cold Crushing Strength ◽  
Sintered Corundum

The Al-Al2O3 specimens of the carbon-free sliding gate are made from sintered corundum, white fused corundum, activated alumina powder and aluminum. The Al contents of the metal Al-Al2O3 composite sliding gate are 3%, 6%, 9%, 12% and 15% respectively. The specimens are treated with three different processes (200°C drying, Nitriding and CO atmosphere). The results show that, the specimen of Nitriding has the best performance. Especially, the specimen, whose Al content is 9% and is treated with Nitriding, has relative lower apparent porosity, higher cold crushing strength and hot modulus of rupture, which makes it posses the superior combination property.

Characterization of microwave-sintered ceramic composites

1993 ◽  
Vol 51 ◽  
pp. 1136-1137
Author(s):  
X. Zhang ◽  
Y. Pan ◽  
T.T. Meek
Keyword(s):  
Matrix Material ◽  
Maximum Output Power ◽  
Ceramic Matrix Composite ◽  
Ceramic Composites ◽  
Processing Technique ◽  
Structure Characterization ◽  
Alumina Powder ◽  
Maximum Output ◽  
Sintered Ceramic

Industrial microwave heating technology has emerged as a new ceramic processing technique. The unique advantages of fast sintering, high density, and improved materials properties makes it superior in certain respects to other processing methods. This work presents the structure characterization of a microwave sintered ceramic matrix composite.Commercial α-alumina powder A-16 (Alcoa) is chosen as the matrix material, β-silicon carbide whiskers (Third Millennium Technologies, Inc.) are used as the reinforcing element. The green samples consisted of 90 vol% Al2O3 powder and 10 vol% ultrasonically-dispersed SiC whiskers. The powder mixture is blended together, and then uniaxially pressed into a cylindrical pellet under a pressure of 230 MPa, which yields a 52% green density. The sintering experiments are carried out using an industry microwave system (Gober, Model S6F) which generates microwave radiation at 2.45 GHz with a maximum output power of 6 kW. The composites are sintered at two different temperatures (1550°C and 1650°C) with various isothermal processing time intervals ranging from 10 to 20 min.

scholarly journals Process characterization and analysis of ceramic powder bed fusion

2021 ◽  
Author(s):  
Kevin Florio ◽  
Dario Puccio ◽  
Giorgio Viganò ◽  
Stefan Pfeiffer ◽  
Fabrizio Verga ◽  
...  
Keyword(s):  
High Speed ◽  
Ceramic Powder ◽  
Integrating Sphere ◽  
Alumina Powder ◽  
Powder Bed Fusion ◽  
Single Track ◽  
Ceramic Powders ◽  
Pure Alumina ◽  
Powder Bed ◽  
Melt Pool

AbstractPowder bed fusion (PBF) of ceramics is often limited because of the low absorptance of ceramic powders and lack of process understanding. These challenges have been addressed through a co-development of customized ceramic powders and laser process capabilities. The starting powder is made of a mix of pure alumina powder and alumina granules, to which a metal oxide dopant is added to increase absorptance. The performance of different granules and process parameters depends on a large number of influencing factors. In this study, two methods for characterizing and analyzing the PBF process are presented and used to assess which dopant is the most suitable for the process. The first method allows one to analyze the absorptance of the laser during the melting of a single track using an integrating sphere. The second one relies on in-situ video imaging using a high-speed camera and an external laser illumination. The absorption behavior of the laser power during the melting of both single tracks and full layers is proven to be a non-linear and extremely dynamic process. While for a single track, the manganese oxide doped powder delivers higher and more stable absorptance. When a full layer is analyzed, iron oxide-doped powder is leading to higher absorptance and a larger melt pool. Both dopants allow the generation of a stable melt-pool, which would be impossible with granules made of pure alumina. In addition, the present study sheds light on several phenomena related to powder and melt-pool dynamics, such as the change of melt-pool shape and dimension over time and powder denudation effects.

Sign in / Sign up

Export Citation Format

Share Document