Enhanced properties of functionally graded Cu–Cr powder compacts

2009 ◽  
Vol 100 (5) ◽  
pp. 723-729
Author(s):  
Indranil Lahiri ◽  
Sanjeev Bhargava
Keyword(s):  
Functionally Graded ◽  
Enhanced Properties ◽  
Powder Compacts

Combustion Synthesis of Dense Functionally Graded B4C Reinforced Composites

2005 ◽  
Vol 492-493 ◽  
pp. 685-692 ◽  
Author(s):  
I. Zlotnikov ◽  
I. Gotman ◽  
Leonid Klinger ◽  
Elazar Y. Gutmanas
Keyword(s):  
Combustion Synthesis ◽  
Synthesis Method ◽  
Combustion Process ◽  
High Volume ◽  
Functionally Graded ◽  
Powder Blend ◽  
Ni Powder ◽  
B4c Particles ◽  
Powder Compacts ◽  
B4c Powder

Dense FGMs with gradually changing fraction of very hard and light-weight B4C particles were fabricated employing an original Reactive Forging (RF) combustion synthesis method. In RF, a self-sustained reaction (thermal explosion, TE) is ignited by placing a powder blend between preheated press rams and the high temperature achieved is utilized for consolidation of the combustion product. The reported FGMs were prepared by stacking layers of highly exothermic Ti-C-Ni powder blend diluted with varying fractions of non-reacting B4C particles. Only a limited amount of B4C could be added as its diluting action reduces the overall exothermicity of the blend. In some cases, B4C particles were precoated in order to prevent their interaction with Ti during combustion. Temperature evolution in (Ti-Ni-C)-B4C powder compacts corresponding to different FGM layers was measured separately and in the stacked form. The better understanding of combustion process in B4C-diluted blends coupled with well-devised geometrical design allowed us to fabricate FGMs with high volume fractions of B4C in the surface layer.

Amorphous silica coating on α-alumina particles

1995 ◽  
Vol 53 ◽  
pp. 210-211
Author(s):  
J. W. Mellowes ◽  
C. M. Chun ◽  
I. A. Aksay
Keyword(s):  
Amorphous Silica ◽  
Heterogeneous Nucleation ◽  
Homogeneous Nucleation ◽  
Silica Coating ◽  
Full Density ◽  
Optimal Conditions ◽  
Fine Grained ◽  
Alumina Particles ◽  
Complete Mullitization ◽  
Powder Compacts

Mullite (3Al2O32SiO2) can be fabricated by transient viscous sintering using composite particles which consist of inner cores of a-alumina and outer coatings of amorphous silica. Powder compacts prepared with these particles are sintered to almost full density at relatively low temperatures (~1300°C) and converted to dense, fine-grained mullite at higher temperatures (>1500°C) by reaction between the alumina core and the silica coating. In order to achieve complete mullitization, optimal conditions for coating alumina particles with amorphous silica must be achieved. Formation of amorphous silica can occur in solution (homogeneous nucleation) or on the surface of alumina (heterogeneous nucleation) depending on the degree of supersaturation of the solvent in which the particles are immersed. Successful coating of silica on alumina occurs when heterogeneous nucleation is promoted and homogeneous nucleation is suppressed. Therefore, one key to successful coating is an understanding of the factors such as pH and concentration that control silica nucleation in aqueous solutions. In the current work, we use TEM to determine the optimal conditions of this processing.

Dynamic Analysis with Stress Recovery for Functionally Graded Materials: Numerical Simulation and Experimental Benchmarking

2014 ◽  
Vol 2 (1) ◽  
pp. 21
Author(s):  
Carlos Alberto Dutra Fraga Filho ◽  
Fernando César Meira Menandro ◽  
Rivânia Hermógenes Paulino de Romero ◽  
Juan Sérgio Romero Saenz
Keyword(s):  
Numerical Simulation ◽  
Dynamic Analysis ◽  
Functionally Graded Materials ◽  
Functionally Graded ◽  
Stress Recovery ◽  
Graded Materials
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