Plasma assisted parts' manufacturing: sintering and surface texturing - part I - influence of sintering time and temperature

Brunatto, Sílvio Francisco

doi:10.1590/s1678-58782010000200005

Cited by 3 publications

(8 citation statements)

References 11 publications

(13 reference statements)

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“…Here, the heating of the part to the sintering temperature is carried out by the fast plasma species bombardment, and the part to be sintered acts as one cathode of the formed hollow cathode discharge. This situation is illustrated in the bottom of Figure 4, in which cylindrical parts to be sintered act as the inner cathode of a typical annular hollow cathode discharge, as presented in references [17][18][19][20][21][22][23]. It is to be noted that, for this configuration, plasma is much more ionized than that obtained in cathode configuration.…”

Section: (B)mentioning

confidence: 94%

“…In hollow cathode configuration, for a gas mixture composed of 80% Ar + 20% H 2 , the pressure range usually varies from 1 (133 Pa) to 9 (1200 Pa) Torr, considering pulse voltages on the order of 450 V [5,6,[17][18][19][20][21][22][23]. Here, the heating of the part to the sintering temperature is carried out by the fast plasma species bombardment, and the part to be sintered acts as one cathode of the formed hollow cathode discharge.…”

Section: (B)mentioning

confidence: 99%

“…For the cathode configuration, the cylindrical external (hollow) cathode was simply removed, thus leading to a heating condition where only one cathode (the central one) was present in the discharge. For more details, the reader can access the references [17][18][19][20][21][22][23]. In all cases, temperature increment can be expected as the switched-on time of the power supply, and thus the mean power transferred to the plasma is increased.…”

Section: Application Of Direct Current Plasma Sintering Process In Pomentioning

confidence: 99%

“…Finally, at 0.6 Torr pressure and a = 9 mm, for example, by using a 720 V pulse voltage, for a specific switched-on time of 140 μs, and considering a square wave period of 200 μs (duty cycle of 70%, see Figure 7c), the cathode temperature is increased from about 500°C, at the cathode configuration heating (CCH) to 1100°C, at the hollow cathode discharge (HCD). Being the interest, the reader can access additional details about the HCD in references [17][18][19][20][21][22][23].…”

Section: Application Of Direct Current Plasma Sintering Process In Pomentioning

confidence: 99%

See 3 more Smart Citations

Application of Direct Current Plasma Sintering Process in Powder Metallurgy

Brunatto¹,

Cardoso²,

NelmoKlein³

2017

Powder Metallurgy - Fundamentals and Case Studies

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Direct current (dc) plasma-assisted sintering of metal parts is a promising and relatively new research and development field in powder metallurgy (PM). In the present entry, it is intended to introduce the reader to the main applications of the dc plasma sintering process in PM. To achieve this goal, the present entry is divided in a brief introduction and sections in which the bases of the dc plasma abnormal glow discharge regime and its influence in the sintering process are carefully treated. In this case, a clear language is purposely used to didactically introduce the reader to this "fascinating glow world", the dc plasma-assisted sintering of metal parts, aiming to put in evidence the main points on physicochemical aspects of the plasma environment, basic knowledge of the plasma heating, and surface-related phenomena during dc plasma sintering of parts.All these aspects are treated considering the main techniques of the dc plasma-assisted sintering process applied to PM. Finally, some results on DC plasma heating, sintering and surface modification are presented.

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Section: (B)mentioning

confidence: 94%

Section: (B)mentioning

confidence: 99%

Section: Application Of Direct Current Plasma Sintering Process In Pomentioning

confidence: 99%

Section: Application Of Direct Current Plasma Sintering Process In Pomentioning

confidence: 99%

See 2 more Smart Citations

Application of Direct Current Plasma Sintering Process in Powder Metallurgy

Brunatto¹,

Cardoso²,

NelmoKlein³

2017

Powder Metallurgy - Fundamentals and Case Studies

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“…Heat transfer mechanisms and cleaning of the particle surfaces in the plasma environment are suggested to be responsible for the enhanced sintering. Despite the plasma reactivity may be prejudicial to sintering if the plasma atmosphere reacts with the ceramic or composite substrate material, as discussed in [6], the plasma reactivity can be advantageous for the metallic materials processing as observed from nitriding [7][8][9][10][11] and carburizing [12,13] treatments, which can be simultaneously carried out during the plasma sintering of powder materials as in linear glow discharge as in hollow cathode discharge [14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Surface state change influence’s theoretical approach of pressed iron on hollow cathode discharge characteristics: first results of plasma heating reproducibility for sintering purposes

Brunatto¹

2022

Surf. Topogr.: Metrol. Prop.

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In this work first results of the plasma heating process reproducibility for sintering purposes of pressed iron powder sample was investigated analyzing changes on the current-voltage characteristics of pulsed direct current (dc) Ar + H2 hollow cathode discharges sequentially carried out. For this purpose, the temperature of a sample acting as central cathode was varied by changing the switched-on time (duty cycle) of the pulse, via plasma species bombardment (ions and fast neutrals), which typically occurs in both cathode cylindrical surfaces that constitute the annular (hollow cathode) glow discharge, and measured by a thermocouple inserted in the central cathode sample holder. After two sequential plasma heating experiments, the third one practically reproduced the measured plasma parameters evidenced in the second heating, and the respective heating curves as a function of the time have led to similar current-voltage characteristics suggesting the iron sample sintering in non-isothermal way. Principles comprising plasma-surface interface and metallurgical-physical-chemical reactions, powder surface aspects, thermodynamic properties, metallurgical transformation of the pressed sample, and hollow cathode discharge properties are presented and discussed. The main points considered in the present approach are related to plasma (oxygen-affected plasma ionization, high ionization and excitation rate, and the intense light radiation of the annular glow discharge), thermodynamics (oxidation-reduction reactions, electron work function, sintering driving force, and surface energy), and powder (particle size distribution, morphology, specific surface, and iron recrystallization). To the best of the author's knowledge, it is the first time that it is brought to the light the changes on hollow cathode discharge characteristics while an iron sample acting as the central cathode of an annular glow discharge is subjected to distinct heating steps on the temperature range of 20 to ~1250 °C, leading it to have its sintering initiated.

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An overview on plasma-assisted thermochemical treatments of martensitic stainless steels^*

Scheuer¹,

Cardoso²,

Brunatto³

2023

Surf. Topogr.: Metrol. Prop.

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Demand for higher wear and corrosion resistance components has attracted increasing interest in surface engineering. This line of research develops alternative processes for improving the surface properties of engineering materials. The traditional route seeks the development of new alloys. However, the cost and time associated with these developments become prohibitive in many cases. Currently, the application of plasma-assisted thermochemical treatments has been a technically and economically viable alternative to extend the lifespan of components exposed to severe environments. In this sense, the tooling industry is one of the oldest and most traditional users of plasma-assisted processes, since forming, injection and/or cutting tools are usually subjected to wear and corrosion degradation. Among the various materials used to make tools, we highlight the martensitic stainless steels, which are used in the manufacture of molds and inserts for injection of chlorinated and fluorinated thermoplastic and thermoset polymers. In these applications, martensitic stainless steels are exposed to severe deterioration conditions due to abrasive wear and corrosion by chloride and fluoride ions. Considering the variety of available plasma-assisted thermochemical treatments whose application allows improving metallic materials corrosion and wear resistance, it is a complex task to select the better process and its execution parameters to ensure the maximum performance in operation. In this work, it is proposed a systematic method to aid the process selection task, focused on thermochemical treatments of martensitic stainless steels, which integrates the processing conditions and the resulting microstructure, properties and performance. For this purpose, working envelop for selecting processes and processing parameters were elaborated, that allow qualify and quantify the correlations among each specific plasma-assisted thermochemical treatment (like nitriding, carburizing, nitrocarburizing, etc.) execution conditions, with the resulting properties and performance for treated martensitic stainless steels.

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Plasma assisted parts' manufacturing: sintering and surface texturing - part I - influence of sintering time and temperature

Cited by 3 publications

References 11 publications

Application of Direct Current Plasma Sintering Process in Powder Metallurgy

Application of Direct Current Plasma Sintering Process in Powder Metallurgy

Surface state change influence’s theoretical approach of pressed iron on hollow cathode discharge characteristics: first results of plasma heating reproducibility for sintering purposes

An overview on plasma-assisted thermochemical treatments of martensitic stainless steels^*

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Plasma assisted parts' manufacturing: sintering and surface texturing - part I - influence of sintering time and temperature

Cited by 3 publications

References 11 publications

Application of Direct Current Plasma Sintering Process in Powder Metallurgy

Application of Direct Current Plasma Sintering Process in Powder Metallurgy

Surface state change influence’s theoretical approach of pressed iron on hollow cathode discharge characteristics: first results of plasma heating reproducibility for sintering purposes

An overview on plasma-assisted thermochemical treatments of martensitic stainless steels *

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Product

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An overview on plasma-assisted thermochemical treatments of martensitic stainless steels^*