The Role of the Displacement Reaction in the Production of Surface Composite Layer

2012 ◽  
Vol 729 ◽  
pp. 320-325
Author(s):  
Viktória Janó ◽  
Gábor Buza
Keyword(s):  
Composite Layer ◽  
Ceramic Particle ◽  
Displacement Reaction ◽  
Surface Composite ◽  
Surface Composite Layer ◽  
Structural Applications ◽  
In Situ Processing ◽  
Processing Techniques

Composites of ceramic particle reinforcement (such as alumina) have potential for high temperature structural applications. In contrast to conventional processing methods (e.g. mechanical alloying), in situ processing techniques can be inexpensive and can also lead to unique microstructures, such as very fine dispersions of the reinforcements or interconnecting phases. The feasibility of processing Fe/Al2O3 composites layer by an in situ displacement reaction between Fe2O3 and Al by using laser beam pre-experiments were carried out and the results are presented in this paper.

MICROSTRUCTURE AND WEAR RESISTANCE OF CHROMIUM CARBIDE COATING IN SITU SYNTHESIZED BY VEB

2014 ◽  
Vol 21 (05) ◽  
pp. 1450065 ◽  
Author(s):  
BINFENG LU ◽  
LIPING LI ◽  
FENGGUI LU ◽  
XINHUA TANG
Keyword(s):  
Wear Resistance ◽  
Composite Layer ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Powder Mixtures ◽  
X Ray ◽  
Surface Composite ◽  
Composite Layers ◽  
Surface Composite Layer

In this paper, ( Cr , Fe )7 C 3( M 7 C 3)/γ- Fe composite layer has been in situ fabricated on a low carbon steel surface by vacuum electron beam irradiation (VEB). Three kinds of powder mixtures were placed on a low carbon steel substrate, which was then irradiated with electron beam in vacuum condition. The microstructure and wear resistance of the composite layers has been studied by means of optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM), microhardness tester and tribological tester. The chemical composition of all specimens were carefully analyzed using energy-dispersive X-ray spectroscopy (EDAX) technique. Depending on three different powder mixtures, hypereutectic and hypoeutectic microstructures were obtained on surface composite layers. No pores and cracks were found on the coatings. The amount of carbides formed in the surface composite layer was mainly determined by carbon concentration. The microstructure close to the fusion line was largely primary austenite dendrite. The hardness and wear resistance of the surface composite layer has been greatly improved due to the extensive distribution of carbides.

The Bending Behavior of Surface Composite Layer Ni/WC Fabricated through Vacuum Infiltration Casting

2011 ◽  
Vol 189-193 ◽  
pp. 385-390 ◽  
Author(s):  
Gui Rong Yang ◽  
Wen Ming Song ◽  
Ying Ma ◽  
Yuan Hao
Keyword(s):  
Transition Layer ◽  
Raw Materials ◽  
Processing Condition ◽  
Composite Layer ◽  
Gray Iron ◽  
Vacuum Infiltration ◽  
Casting Technique ◽  
Three Point Bending ◽  
Surface Composite ◽  
Surface Composite Layer

Ni/WC surface infiltrated composite layer was fabricated on gray iron substrate through vacuum infiltration casting technique using Ni-based powder and WC particles with different content as raw materials. The compact infiltrated composite layer was obtained on the condition of appropriate choice of processing condition such as pouring temperature, preheating temperature, thickness of preform and the grain size of powder. The infiltrated layer includes surface composite layer and transition layer, and the thickness of transition layer decreases with the increasing content of WC. Three-point bending tests were performed to investigate the mechanical and metallurgical properties of the surface infiltrated composite layer. It was found that load-holding circumstance appeared for specimen with infiltrated layer during the process of three-point bending, and there was no this circumstance for substrate during bending process. The load and displacement decreased with the increasing content of WC when the load-holding circumstance happened. The fracture extended to the substrate for all specimens with surface infiltrated composite layer, and the fracture form was similar for all specimens with different WC content. The WC particles were the source of micro-crack for surface infiltrated layer, and the graphite was the source of micro-crack for gray iron substrate.

Microstructure and Hardness of Surface Composite Layer Fabricated by Evaporative Pattern Casting Technology

2012 ◽  
Vol 538-541 ◽  
pp. 302-305
Author(s):  
Ran Yang Zhang ◽  
Gang Yao Zhao ◽  
Yue Chen
Keyword(s):  
Electron Microscope ◽  
Cast Steel ◽  
Composite Layer ◽  
Steel Matrix ◽  
X Ray ◽  
Surface Composite ◽  
Casting Technology ◽  
Surface Composite Layer ◽  
Scanning Electron ◽  
Evaporative Pattern Casting

Surface composite layer was fabricated on the cast steel matrix using the evaporative pattern casting (EPC) technology. The pre-coating with WC and Cr-Fe particles as raw reinforcements was reacted with matrix and formed the composite layer. Then, the microstructure and hardness of surface composite layer were investigated by Scanning Electron Microscope (SEM), Olympus Microscope (OM), Energy Dispersive X-ray Spectroscopy (EDAX) and Rockwell Apparatus. The results show that the composite layer can be divided into transitive layer and penetrated layer, and the component analysis shows that the microstructure distribution of the penetrated layer is homogeneous.

Effects of Environmental Exposure on Ductile-Phase Toughening in Niobium Silicide-Niobium Composites

1993 ◽  
Vol 322 ◽  
Author(s):  
Joseph D. Rigney ◽  
Preet M. Singh ◽  
John J. Lewandowski
Keyword(s):  
Electron Microscope ◽  
Composite Materials ◽  
Crack Extension ◽  
Resistance Curve ◽  
Test Results ◽  
Ductile Phase ◽  
Processing Techniques ◽  
Scanning Electron

AbstractA variety of materials have been toughened by incorporating ductile phases. Brittle silicide intermetallics such as Nb5Si3 composited with niobium particles incorporated during in situ processing techniques have realized significant improvements in toughness and stable crack extension. In the present work, toughness tests conducted on Nb5Si3/Nb materials monitored in a scanning electron microscope were instrumental in viewing the role of the deforming niobium particles on the process of toughening. In particular, the behavior of the ductile phase was monitored and related to the toughness values obtained. In an attempt to vary the behavior of the ductile phase, the composite materials were exposed to a variety of gaseous environments and subsequently tested in air. The resulting toughness, resistance-curve behavior, and in situ test results highlight the importance of the behavior of the ductile phase on subsequent properties.

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