Kinetics of WC-Co oxidation accompanied by swelling

Lofaj, František; Kaganovskii, Yu.

doi:10.1007/bf00351615

Cited by 80 publications

(49 citation statements)

References 8 publications

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“…In presumed order of importance, these are oxidative wear of WC ( Figures 4 and 6), and the increased brittleness due to the transformation of the WC binder. Lofaj et al [35] and Casas et al [36] reported that when WC reacts with oxygen, its volume expands by about 300% via an oxidation process that generates CO gas in the solid. The pressure of this gas is greater than the fracture strength of the WC and therefore leads to crack formation.…”

Section: Effect Of Wear On Microstructuresmentioning

confidence: 99%

“…The WC binder phase is continuously exposed to severe repetitive conditions due to its contact with the workpiece during FSW. It has been shown that WC exposed to fatigue loading exhibits reduced fracture toughness, erosion resistance and thermal shock resistance [35]. The repetitive cycles of contacts between the tool and material creates fatigue like conditions, resulting in particle fracture in the affected regions.…”

Section: Effect Of Wear On Microstructuresmentioning

confidence: 99%

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Tool Wear Characteristics and Effect on Microstructure in Ti-6Al-4V Friction Stir Welded Joints

Fall

Fesharaki

Khodabandeh

et al. 2016

Metals

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Abstract:In the present paper, tool wear and the rate of wear during friction stir welding (FSW) of Ti-6Al-4V alloy are investigated. A conical tungsten carbide tool was used to produce butt-type friction stir welded joints in two-millimeter thick Ti-6Al-4V sheets. An original design of a movable pin allowed for the examination of the tool damage for each process condition. The influence of tool degradation on the quality of the welded joints and the damage brought to the microstructure are examined and discussed. For this purpose, optical and scanning electron microscopies as well as EDX analyses were used to examine the tool wear and the resulting macrostructures and microstructures. The type and nature of the defects are also analyzed as a function of FSW processing parameters. Important geometry and weight variations were observed on the pin and shoulder for all welding conditions, in particular when low tool rotation and travel speeds were used. Experimental results also show that the radial wear of the pin is not uniform, indicating the presence of important frictional temperature gradients through the thickness of the joint. The maximum wear was measured at a location of about one millimeter from the pin root center. Finally, tool rotation was determined as the most significant process parameter influencing both tool wear and microstructure of the joints.

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Section: Effect Of Wear On Microstructuresmentioning

confidence: 99%

Section: Effect Of Wear On Microstructuresmentioning

confidence: 99%

Tool Wear Characteristics and Effect on Microstructure in Ti-6Al-4V Friction Stir Welded Joints

Fall

Fesharaki

Khodabandeh

et al. 2016

Metals

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show abstract

“…The porosity of this layer is thought to be related to gaseous CO and CO 2 being released at the interface between the cemented carbide and the atmosphere. At higher binder levels, the layer becomes less porous, more compact and consists of the complex oxide CoWO 4 [14][15][16][17].…”

Section: Graphmentioning

confidence: 99%

“…It is because at these temperatures, the oxidation ability of the carbide phase is limited. The situation is reversed at higher temperatures: the oxidation ability of the binder is limited, and tungsten trioxide WO 3 readily forms [14][15][16][17].…”

Section: Graphmentioning

confidence: 99%

Properties and Testing of Cemented Carbides

Kříž¹,

Bricín²

2017

Powder Metallurgy - Fundamentals and Case Studies

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This chapter deals with selected properties of cemented carbides and their testing. It consists of three main sub-chapters. The first one covers the degradation processes associated with grinding of cemented carbides. Among those, the focus is on the effects of thermal loads and reactions with the environment-the atmosphere. The second main sub-chapter describes the origin of residual stresses and their impact on cemented carbide properties. Finally, the third main sub-chapter explores the corrosion of cemented carbides in various environments. The choice of these topics was inspired by the impression that many users have of cemented carbides: indestructible materials in which no degradation takes place either during the production of cutting tools or during their use. As evidenced by the authors' experience described below, which has been acquired over many years in the field, damage in cemented carbides is a very frequent occurrence. Despite that it still receives very little attention, and especially the damage in cemented carbide cutting tools tends to be ascribed to various other factors, such as the applied coatings, the cutting process conditions and the material of the workpiece.

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“…Many studies on the high temperature oxidation of tungsten scraps have also been investigated in various aspects such as swelling kinetics, fracture resistance, and the effect of alloying composition [7][8][9]. However, they did not consider the possible effect of the rotary kiln with oxygen burner to accelerate the oxidation rate of scraps during the oxidation process.…”

Section: Introductionmentioning

confidence: 99%

Extraction Factor Of Pure Ammonium Paratungstate From Tungsten Scraps

Pee

Kim

Lee

et al. 2015

Archives of Metallurgy and Materials

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Typical oxidation process of tungsten scraps was modified by the rotary kiln with oxygen burner to increase the oxidation rate of tungsten scraps. Also to accelerate the solubility of solid oxidized products, the hydrothermal reflux method was adapted. By heating tungsten scraps in rotary kiln with oxygen burner at around 900• for 2hrs, the scraps was oxidized completely. Then oxidized products (WO 3 and CoWO 4 ) was fully dissolved in the solution of NaOH by hydrothermal reflux method at 150• for 2hrs. The dissolution rate of oxidized products was increased with increasing the reaction temperature and concentration of NaOH. And then CaWO 4 and H 2 WO 4 could be generated from the aqueous sodium tungstate solution. Ammonium paratungstate (APT) also could be produced from tungstic acid using by aqueous ammonium solution. The morphologies (cubic and plate types) of APT was controlled by the stirring process of purified solution of ammonium paratungstate.

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Kinetics of WC-Co oxidation accompanied by swelling

Cited by 80 publications

References 8 publications

Tool Wear Characteristics and Effect on Microstructure in Ti-6Al-4V Friction Stir Welded Joints

Tool Wear Characteristics and Effect on Microstructure in Ti-6Al-4V Friction Stir Welded Joints

Properties and Testing of Cemented Carbides

Extraction Factor Of Pure Ammonium Paratungstate From Tungsten Scraps

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