scholarly journals Tungsten carbide is more oxidation resistant than tungsten when processed to full density

2016 ◽  
Vol 116 ◽  
pp. 67-70 ◽  
Author(s):  
Samuel A. Humphry-Baker ◽  
William E. Lee
Keyword(s):  
Tungsten Carbide ◽  
Full Density ◽  
Oxidation Resistant

Synthesis of full-density nanocrystalline tungsten carbide by reduction of tungstic oxide at room temperature

1996 ◽  
Vol 27 (12) ◽  
pp. 4210-4213 ◽  
Author(s):  
M. Sherif El-Eskandarany ◽  
T. J. Konno ◽  
K. Sumiyama ◽  
K. Suzuki ◽  
M. Omori ◽  
...  
Keyword(s):  
Tungsten Carbide ◽  
Room Temperature ◽  
Full Density ◽  
Tungstic Oxide

scholarly journals Nano-Indentation Properties of Tungsten Carbide-Cobalt Composites as a Function of Tungsten Carbide Crystal Orientation

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2137
Author(s):  
Renato Pero ◽  
Giovanni Maizza ◽  
Roberto Montanari ◽  
Takahito Ohmura
Keyword(s):  
Tungsten Carbide ◽  
Crystal Orientation ◽  
Advanced Materials ◽  
Full Density ◽  
Micro Hardness ◽  
Electron Backscattered Diffraction ◽  
Nano Indentation ◽  
Mixture Modelling ◽  
Small Set ◽  
The Relationship

Tungsten carbide-cobalt (WC-Co) composites are a class of advanced materials that have unique properties, such as wear resistance, hardness, strength, fracture-toughness and both high temperature and chemical stability. It is well known that the local indentation properties (i.e., nano- and micro-hardness) of the single crystal WC particles dispersed in such composite materials are highly anisotropic. In this paper, the nanoindentation response of the WC grains of a compact, full-density, sintered WC-10Co composite material has been investigated as a function of the crystal orientation. Our nanoindentation survey has shown that the nanohardness was distributed according to a bimodal function. This function was post-processed using the unique features of the finite mixture modelling theory. The combination of electron backscattered diffraction (EBSD) and statistical analysis has made it possible to identify the orientation of the WC crystal and the distinct association of the inherent nanoindentation properties, even for a small set (67) of nanoindentations. The proposed approach has proved to be faster than the already existing ones and just as reliable, and it has confirmed the previous findings concerning the relationship between crystal orientation and indentation properties, but with a significant reduction of the experimental data.

scholarly journals Oxidation resistant tungsten carbide hardmetals

2017 ◽  
Vol 66 ◽  
pp. 135-143 ◽  
Author(s):  
Samuel A. Humphry-Baker ◽  
Ke Peng ◽  
William E. Lee
Keyword(s):  
Tungsten Carbide ◽  
Oxidation Resistant

Structural Imperfections in thin Oxide Films Formed on Some Fe- and Ni-Base Alloys

1970 ◽  
Vol 28 ◽  
pp. 510-511
Author(s):  
L. P. Lemaire ◽  
D. E. Fornwalt ◽  
F. S. Pettit ◽  
B. H. Kear
Keyword(s):  
Oxide Scale ◽  
Oxidation Process ◽  
Short Circuit ◽  
Protective Oxide ◽  
Protective Oxide Scale ◽  
Thin Oxide Films ◽  
Diffusion Paths ◽  
Oxidation Resistant ◽  
Structural Imperfections ◽  
Short Circuit Diffusion

Oxidation resistant alloys depend on the formation of a continuous layer of protective oxide scale during the oxidation process. The initial stages of oxidation of multi-component alloys can be quite complex, since numerous metal oxides can be formed. For oxidation resistance, the composition is adjusted so that selective oxidation occurs of that element whose oxide affords the most protection. Ideally, the protective oxide scale should be i) structurally perfect, so as to avoid short-circuit diffusion paths, and ii) strongly adherent to the alloy substrate, which minimizes spalling in response to thermal cycling. Small concentrations (∼ 0.1%) of certain reactive elements, such as yttrium, markedly improve the adherence of oxide scales in many alloy systems.

Morphologies of Nonadherent Al2O3 and Matching Substrate Surfaces

1972 ◽  
Vol 30 ◽  
pp. 524-525
Author(s):  
C. S. Giggins ◽  
J. K. Tien ◽  
B. H. Kear ◽  
F. S. Pettit
Keyword(s):  
Electron Microscopy ◽  
Oxide Scale ◽  
Oxidation Resistance ◽  
Substrate Surface ◽  
Morphological Features ◽  
Thermally Induced ◽  
Oxide Spallation ◽  
Oxidation Resistant ◽  
Induced Stresses ◽  
Substrate Surfaces

The performance of most oxidation resistant alloys and coatings is markedly improved if the oxide scale strongly adheres to the substrate surface. Consequently, in order to develop alloys and coatings with improved oxidation resistance, it has become necessary to determine the conditions that lead to spallation of oxides from the surfaces of alloys. In what follows, the morphological features of nonadherent Al2O3, and the substrate surfaces from which the Al2O3 has spalled, are presented and related to oxide spallation.The Al2O3, scales were developed by oxidizing Fe-25Cr-4Al (w/o) and Ni-rich Ni3 (Al,Ta) alloys in air at 1200°C. These scales spalled from their substrates upon cooling as a result of thermally induced stresses. The scales and the alloy substrate surfaces were then examined by scanning and replication electron microscopy.The Al2O3, scales from the Fe-Cr-Al contained filamentary protrusions at the oxide-gas interface, Fig. 1(a). In addition, nodules of oxide have been developed such that cavities were formed between the oxide and the substrate, Fig. 1(a).

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.

Microstructural and fractographic characterization of B4C-Al cermets tested under dynamic and static loading

1989 ◽  
Vol 47 ◽  
pp. 562-563
Author(s):  
Gyeung Ho Kim ◽  
Mehmet Sarikaya ◽  
D. L. Milius ◽  
I. A. Aksay
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Static Loading ◽  
Carbon Deposition ◽  
Full Density ◽  
Unique Combination ◽  
Strong Component ◽  
Reaction Products

Cermets are designed to optimize the mechanical properties of ceramics (hard and strong component) and metals (ductile and tough component) into one system. However, the processing of such systems is a problem in obtaining fully dense composite without deleterious reaction products. In the lightweight (2.65 g/cc) B4C-Al cermet, many of the processing problems have been circumvented. It is now possible to process fully dense B4C-Al cermet with tailored microstructures and achieve unique combination of mechanical properties (fracture strength of over 600 MPa and fracture toughness of 12 MPa-m1/2). In this paper, microstructure and fractography of B4C-Al cermets, tested under dynamic and static loading conditions, are described.The cermet is prepared by infiltration of Al at 1150°C into partially sintered B4C compact under vacuum to full density. Fracture surface replicas were prepared by using cellulose acetate and thin-film carbon deposition. Samples were observed with a Philips 3000 at 100 kV.

Graphene Supported Tungsten Carbide as Catalyst for Electrochemical Reduction of CO2

2019 ◽  
Author(s):  
Sahithi Ananthaneni ◽  
Rees Rankin
Keyword(s):  
Tungsten Carbide ◽  
Electrochemical Reduction ◽  
Low Cost ◽  
Co2 Reduction ◽  
Platinum Group Metal ◽  
Reduction Reaction ◽  
Metal Carbides ◽  
Depth Study ◽  
Reduction Of Co2 ◽  
Co2 Reduction Reaction

<div>Electrochemical reduction of CO2 to useful chemical and fuels in an energy efficient way is currently an expensive and inefficient process. Recently, low-cost transition metal-carbides (TMCs) are proven to exhibit similar electronic structure similarities to Platinum-Group-Metal (PGM) catalysts and hence can be good substitutes for some important reduction reactions. In this work, we test graphenesupported WC (Tungsten Carbide) nanocluster as an electrocatalyst for the CO2 reduction reaction. Specifically, we perform DFT studies to understand various possible reaction mechanisms and determine the lowest thermodynamic energy landscape of CO2 reduction to various products such as CO, HCOOH, CH3OH, and CH4. This in-depth study of reaction energetics could lead to improvements and develop more efficient electrocatalysts for CO2 reduction.<br></div>

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