Cryogenic machining of porous tungsten for dispenser cathode applications

Tarter, J.O.; Effgen, Michael P.; Pušavec, Franci; Jawahir, I.S.

doi:10.1109/ivelec.2008.4556349

Cited by 5 publications

(4 citation statements)

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“…An earlier study by Tarter et al [126] also highlighted similar benefits of cryogenic machining of porous tungsten. Compared with thermal assisted machining, Nee et al [127] found that cryogenic machining, through controlled brittle fracture, produced a far better surface quality in terms of the amount of porosity.…”

Section: Conventional Machining Of Tungstenmentioning

confidence: 75%

Advanced Processing and Machining of Tungsten and Its Alloys

Omole

Lunt

Kirk

et al. 2022

JMMP

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Tungsten is a refractory metal with the highest melting temperature and density of all metals in this group. These properties, together with the high thermal conductivity and strength, make tungsten the ideal material for high-temperature structural use in fusion energy and other applications. It is widely agreed that the manufacture of components with complex geometries is crucial for scaling and optimizing power plant designs. However, there are challenges associated with the large-scale processing and manufacturing of parts made from tungsten and its alloys which limit the production of these complex geometries. These challenges stem from the high ductile-to-brittle transition temperature (DBTT), as well as the strength and hardness of these parts. Processing methods, such as powder metallurgy and additive manufacturing, can generate near-net-shaped components. However, subtractive post-processing techniques are required to complement these methods. This paper provides an in-depth exploration and discussion of different processing and manufacturing methods for tungsten and identifies the challenges and gaps associated with each approach. It includes conventional and unconventional machining processes, as well as research on improving the ductility of tungsten using various methods, such as alloying, thermomechanical treatment, and grain structure refinement.

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Section: Conventional Machining Of Tungstenmentioning

confidence: 75%

Advanced Processing and Machining of Tungsten and Its Alloys

Omole

Lunt

Kirk

et al. 2022

JMMP

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“…Despite the relative discrepancies between theory and experiments, the deformation cutting model explains more adequately the porosity closure phenomenon whose occurrence was consistently reported while performing turning or milling operations on metallic porous materials that were either titanium or tantalum-based [34][35][36][37][38][39][40]. In most cases, porosity closure or 'surface smearing' can be recognized visually without difficulty as a post-machining effect (Fig.…”

Section: Deformation Cutting Theorymentioning

confidence: 97%

Porosity and cutting forces: from macroscale to microscale machining correlations

Tutunea‐Fatan

Fakhri

Bordatchev

2011

Proceedings of the Institution of Mechanical Engineers, Part B:

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Porous metals, typically produced through powder metallurgy, represent a class of relatively new materials with wide industrial applications, lately extending into the microscale domain. Although produced in near-net shapes, most components fabricated from these materials still require some form of secondary machining. Despite the progress made in the field, relatively little is known either on the inherent cutting mechanism or on the behaviour of these materials under micromachining conditions. The present study reviews the main cutting theories proposed in macroscale machining, along with one of the primary parameters used to describe its machinability performances, namely cutting forces. Then, the feasibility of macroscale concepts is discussed in the context of micromachining technology that is characterized by comparable tool and pore sizes. The microslot cutting experiment performed in a porous titanium sample outlined the relative interplay between the magnitude of the cutting force and porosity of the material. Based on this, it was concluded that the impact of structural porosity on cutting forces experienced during micromachining is significant and therefore further in-depth investigations will be required.

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“…Porous tungsten components for dispenser cathode manufacture are traditionally machined by using polymeric or copper infiltrant. These infiltrants act as a support for the pore structure and lubricant (Tarter et al 2008). Tarter et al (2008) and Pusavec (2012) reported that using LN 2 as coolant media in turning porous tungsten not only enhanced machinability by improving the tool life and surface finish, but also eliminates the requirement for infiltrant material.…”

Section: Effect Of Cryogenic Cooling On Surface Integritymentioning

confidence: 99%

“…These infiltrants act as a support for the pore structure and lubricant (Tarter et al 2008). Tarter et al (2008) and Pusavec (2012) reported that using LN 2 as coolant media in turning porous tungsten not only enhanced machinability by improving the tool life and surface finish, but also eliminates the requirement for infiltrant material. In addition, Pusavec (2012) noted that using cryogenic cooling not only improve the surface finish but also prevents smearing on the machined surface and produce less porosity on the machined surface as compared to conventional techniques.…”

Section: Effect Of Cryogenic Cooling On Surface Integritymentioning

confidence: 99%

State-of-the-art cryogenic machining and processing

Shokrani

Dhokia

Muñoz‐Escalona³

et al. 2013

International Journal of Computer Integrated Manufacturing

177

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This paper is a state-of-the-art review of the use of cryogenic cooling using liquefied gases in machining. The review is classified into two major categories namely, cryogenic processing and cryogenic machining. In cryogenic processing also known as cryo-processing the cutting tool material is subjected to cryogenic temperatures as a part of its heat treatment process. The majority of the reported studies identify that cryo-processing can considerably increase cutting tool life especially for high speed steel tools. It also identified that in cryogenic machining a cryogen is used as a cooling substance during cutting operations. The cryogen can be used to freeze the workpiece material and/or cutting tool. The paper concludes that cryogenic cooling has demonstrated significant improvements in machinability by changing the material properties of the cutting tool and/or workpiece material at the cutting zone, altering the coefficient of friction and reducing the cutting temperature.

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Cryogenic machining of porous tungsten for dispenser cathode applications

Cited by 5 publications

References 0 publications

Advanced Processing and Machining of Tungsten and Its Alloys

Advanced Processing and Machining of Tungsten and Its Alloys

Porosity and cutting forces: from macroscale to microscale machining correlations

State-of-the-art cryogenic machining and processing

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