WO1997039167A1 - Decalaminage de surfaces metalliques - Google Patents

Decalaminage de surfaces metalliques Download PDF

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Publication number
WO1997039167A1
WO1997039167A1 PCT/GB1997/001045 GB9701045W WO9739167A1 WO 1997039167 A1 WO1997039167 A1 WO 1997039167A1 GB 9701045 W GB9701045 W GB 9701045W WO 9739167 A1 WO9739167 A1 WO 9739167A1
Authority
WO
WIPO (PCT)
Prior art keywords
process according
electrolysis
bath
anodic
metal
Prior art date
Application number
PCT/GB1997/001045
Other languages
English (en)
Inventor
Neil Mcmurray
John Mcdonald Duncan
Sandy Francoise Lancelot
Edward Pugh
Original Assignee
Maysonic Ultrasonics Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Maysonic Ultrasonics Limited filed Critical Maysonic Ultrasonics Limited
Priority to EP97916580A priority Critical patent/EP0894158A1/fr
Priority to AU25190/97A priority patent/AU2519097A/en
Priority to JP9536868A priority patent/JP2000508711A/ja
Publication of WO1997039167A1 publication Critical patent/WO1997039167A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling
    • C25F1/02—Pickling; Descaling
    • C25F1/04—Pickling; Descaling in solution
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling
    • C25F1/02—Pickling; Descaling
    • C25F1/04—Pickling; Descaling in solution
    • C25F1/06—Iron or steel

Definitions

  • the present invention is concerned with the removal of scale from surfaces of metal bodies, such as steel, in the form of steel wires, rods or the like.
  • an applied electric potential causes a current to flow between a pickling solution and a metal surface.
  • the current may be anodic or cathodic and will typically be of a density of 1 to 200 amps dm 2 .
  • the process is carried out with the electrolyte bath at a substantially neutral pH.
  • the process is typically used for removal of scale from steel, which is typically in the form of wire, rod or other continuously formed article.
  • the pulsed electric potential has a current density is in the range 0.1 to 10 amp cm 2 , more preferably in the range 0.5 to 5 amp cm 2 .
  • the non-aggressive electrolyte comprises a solution of an ammonium or alkali metal tripolyphosphate; typically, the alkali metal is sodium.
  • the electric potential may be predominantly anodic or cathodic, typically with an anodic pulse duty cycle of 5 to 95% such as 45 to 75%.
  • Figure 3 is a graph showing cleaning times for removal of oxide from heat scaled carbon steel wire as a function of pH and current density in a process according to the first embodiment of the invention
  • Figure 4 is a graph showing cleaning times for removal of oxide from heat scaled carbon steel wire as a function of pH and current density in a process, not according to the invention, involving no ultrasonic treatment
  • Figure 5 is a 3-dimensional plot showing cleaning times for the same wire in 10% aqueous NaCl solution at 65'C, as a function of the frequency and the anodic duty cycle;
  • Figure 6 is a graph showing the percentage of scale (graphite) remaining at the wire surface, as a function of time, for current densities of 0.5 and 2.5 amps cm" 2 , according to the first embodiment of the present invention
  • Figure 7 is a graph showing the time to clean as a function of current density at pH's of 0, 1 and 7, respectively;
  • Figure 9 is a 3-dimensional surface plot of descaling time as a function of current density and temperature in neutral sodium chloride solution with an anode duty cycle of 95%;
  • Figure 11 is a 3-dimensional surface plot of descaling time as a function of current density and temperature in neutral sodium chloride solution with an anode duty cycle of 95% and interspersed ultrasound;
  • Figure 12 is a 3-dimensional surface plot of descaling time for removal of graphite scale as a function of anodic duty cycle and frequency at 60°C in neutral sodium sulfate with a current density of 1 Acm 2 ;
  • Figure 13 is a 3-dimensional surface plot of descaling time for removal of graphite scale as a function of current density and pH at 60°C in sodium sulfate with an anode duty cycle of 95% and interspersed ultrasound;
  • Figure 14 is a 3-dimensional surface plot of descaling time for removal of graphite scale as a function of current density and pH at 60°C and 1Hz in sodium sulfate with an anode duty cycle of 95% and continuous ultrasound
  • Figure 15 is a 3-dimensional surface plot of the descaling time for oxide heat scale as a function of the anodic duty cycle and frequency at 60°C and 1 Hz in a 10% sodium tripolyphosphate solution at pH7 and 1.6 Acm 2 current density;
  • Figure 17 is a 3-dimensional representation of the descaling time (again for oxide heat scale) vs electrolyte concentration and solution temperature, with data collected under the conditions of pH7, 1Hz at 95% anodic duty cycle;
  • Figure 18 is a 2-dimensional graph of descaling time (again for oxide heat scale)vs anodic duty cycle at 1Hz frequency (for which the cleaning conditions were pH7, adjusted using orthophosphoricacid, 60°C, 10% sodium tripolyphosphate, samples being high carbon Si-Mn wire, pickled and subsequently scaled in air and 900°C for various times);
  • Electrode 3 (in the form of wire) is the sample to be cleaned and electrode 4 is a graphitic carbon counter electrode. Both electrodes were mounted in a beaker 5 of electrolyte 6 which was in turn placed in an ultrasonic bath 7 containing water 10. The bath itself is thermostatically controlled in order to maintain a constant temperature. During the testing, the exposed area of the electrode 3 is submerged in the electrolyte 6. A Luggin capillary 8 was placed in contact with electrode 3 so that a reference electrode 9 could be used to measure the potential of electrode 3. This potential data was fed back to the Data Acquisition card in the computer 1 and recorded continuously.
  • the electrolytic current was applied to the cell using a pulsatile alternating current (a typical waveform being shown schematically in Figure 2).
  • the combined ultrasonic-electrolytic surface cleaning of wires was carried out using the cleaning cell apparatus shown schematically in Figure 1.
  • the wire 3 to be cleaned was suspended in a volume of electrolyte 6 contained within a thermostated ultrasonic agitation bath 7.
  • Electrolytic current was passed between the electrode wire 3 and a graphite counter electrode 4; in all cases the area of the electrode wire exposed to electrolyte was determined, in order to calculate surface current density.
  • the flow of electrolytic current was established using a voltage controlled current source (galvanostat) 2 which was in turn actuated by voltage waveform controller 11.
  • the electrolytic current passed in the cleaning cell was usually in the form of a pulsatile alternating current and a typical current waveform is shown schematically in Figure 2.
  • time is the total time for which the electrolytic current is flowing at the sample surface.
  • electrolytic current was interrupted and followed by a period of ultrasonication to remove any loosened scale immediately prior to visual evaluation of surface cleanliness.
  • anodic duty cycle as defined with reference to Figure 2
  • Figure 3 shows cleaning times for oxide removal from heat scaled carbon steel wire in 10% aqueous sodium sulfate solution at 65°C as a function of pH and current density.
  • Figure 4 shows cleaning times for the same system subject to ultrasound electrolysis.
  • Figure 5 show cleaning times for the same wire in 10% aqueous sodium chloride solution at 65°C as a function of frequency and anodic duty cycle (duty cycle shown as a percentage figure); identical cleaning times were measured for the same system subject to interspersed ultrasound-electrolysis.
  • pH7 neutral conditions
  • Figures 3 and 4 may be seen from Figures 3 and 4 that cleaning time in the sulfate medium decreases with increasing current density and decreasing pH; cleaning times at pH3 were immeasurably long (> 30 minutes).
  • Figures 3 and 4 also show that a synergistic effect exists between ultrasound and electrolysis, in that cleaning times are about 30% shorter in the case of simultaneous electrolysis-ultrasonication.
  • the rate determining step for oxide scale removal was the anodic dissolution of underlying metal.
  • Oxide scale removal, leaving a clean, satin textured, metal surface is possible using combined ultrasound and anodic d.c. electrolysis in aqueous sodium sulfate solutions at pH ⁇ 3.
  • Oxide scale removal, leaving a clean, satin textured, metal surface is possible using combined ultrasound and anodic d.c. electrolysis in aqueous sodium chloride solutions at pH7 but with significant anodic chlorine evolution.
  • Graphite drawing lubricant (aqueous sodium sulfate).
  • Figure 6 shows the percentage of scale (graphite) remaining at the wire surface as a function of time, for current densities of 0.5 and 2.5 amps cm 2 , with and without simultaneous ultrasound.
  • Figure 7 shows time to clean as a function of current density at pH 0, 1 and 7; and Figure 8 shows the influence of anodic duty cycle on the time dependent cleaning curve at pH7 with a current density of 1 amp cm 2 .
  • Figure 6 shows that, although the shapes of the cleaning curves are different for the cases of simultaneous electrolysis-ultrasonication and interspersed electrolysis- ultrasonication, there is no significant influence of simultaneous ultrasonication on time to clean (also see Figure 7).
  • Figure 7 reveals that graphite removal is most rapidly accomplished at low pH but that the influence of pH is reduced a higher current densities.
  • Figure 8 shows that cleaning rates increase markedly with increasing anodic duty cycle; however, it was also found that making the electrolytic current entirely anodic i.e. d.c. resulted in large increases in cleaning time together with significant amounts of anodic oxygen evolution due to water electrolysis.
  • the rate determining step for graphite removal was the anodic dissolution of underlying metal.
  • Oxide heat scale sodium tripolyphosphate
  • a 10% sodium tripolyphosphate bath adjusted to pH 7 and raised to 60°C was set up.
  • the current density for each sample was 1.6 Acm '2 , representing lcm length of metal surface exposed for descaling.
  • the electrical properties were methodically varied, the anodic city cycle adjusted from 5 to 95% and the frequency of pulsed ranging from 0.3 to 1000 Hz.
  • Descaling times obtained were compiled and arranged into a 3-dimensional graph shown in Figure 15. Optimum conditions appear to be obtained with an anodic duty cycle of 45-75% and frequencies 0.3 to 100 Hz. For these particular set of conditions, fastest cleaning times are achieved at an anodic duty cycle of 75% and at the lowest frequency of 0.3 or 1 Hz.
  • Figure 17 shows a 3-dimensional representation of the descaling time results vs the tripolyphosphate concentration and solution temperature.
  • the tripolyphosphate concentration was varied from 1-15% and the temperature of the bath adjusted at 20-60°C.
  • the pH value was kept constant at 7 and the anodic duty cycle fixed at 95 % with a frequency of 1 Hz.
  • Figure 18 visually summarises results obtained on descaling times using sodium tripolyphosphate with varying heat scale thickness.
  • a furnace was allowed to reach the temperature of 900°C before being filled with argon gas. Samples were laid out flat on a ceramic boat, separated from each other, and subsequently left in the furnace for 15 minutes so as to allow them to reach 900°C. The furnace was subsequently flushed through with a fast stream of air for a period of 20 seconds and the samples were left to oxidise for 1-60 minutes. Once sealed for the required period of time, the boat was removed from the furnace and placed on a ceramic fibre mat to cool in air at room temperature. Samples were left to oxidise for 1,5, 10,15,30,45 and 60 minutes, to ensure a considerable increase in the scale thickness obtained.
  • the cleaning solution was raised to 60°C and exposed to ultrasound for a minimum period of 15 minutes prior to experimentation. Electrical properties were set at IA and the current pulse fixed at 1 Hz. The anodic duty cycle was varied between 5-95% and its efficiency testing for the descaling of wire of various oxide thicknesses.
  • Optimum descaling conditions for fastest descaling the metal samples were obtained at high electrolyte concentrations (10-15%) and high temperatures of 50-60°C.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Abstract

L'invention concerne le décalaminage de la surface d'un corps métallique. Le corps métallique est soumis à une électrolyse dans un bain électrolytique et à une agitation par ultrasons. L'électrolyse consiste à appliquer un potentiel électrique pulsé sur le corps métallique immergé dans le bain; l'agitation par ultrasons est effectuée à la suite de l'électrolyse, le corps étant encore mouillé.
PCT/GB1997/001045 1996-04-15 1997-04-15 Decalaminage de surfaces metalliques WO1997039167A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP97916580A EP0894158A1 (fr) 1996-04-15 1997-04-15 Decalaminage de surfaces metalliques
AU25190/97A AU2519097A (en) 1996-04-15 1997-04-15 Descaling of metal surfaces
JP9536868A JP2000508711A (ja) 1996-04-15 1997-04-15 金属表面のスケール除去

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9607810.0A GB9607810D0 (en) 1996-04-15 1996-04-15 Removal of contaminants from steel surfaces
GB9607810.0 1996-04-15

Publications (1)

Publication Number Publication Date
WO1997039167A1 true WO1997039167A1 (fr) 1997-10-23

Family

ID=10792109

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1997/001045 WO1997039167A1 (fr) 1996-04-15 1997-04-15 Decalaminage de surfaces metalliques

Country Status (8)

Country Link
EP (1) EP0894158A1 (fr)
JP (1) JP2000508711A (fr)
KR (1) KR20000005451A (fr)
AU (1) AU2519097A (fr)
CA (1) CA2251782A1 (fr)
GB (1) GB9607810D0 (fr)
PL (1) PL329292A1 (fr)
WO (1) WO1997039167A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001053571A1 (fr) * 2000-01-17 2001-07-26 C-Tech Innovation Limited Procede de traitement electrolytique
GB2386907A (en) * 2002-03-27 2003-10-01 Isle Coat Ltd Forming ceramic coatings on metals and alloys
JP2016183393A (ja) * 2015-03-26 2016-10-20 Ｊｆｅスチール株式会社 電解研磨装置および電解研磨方法
ITPD20150095A1 (it) * 2015-05-08 2016-11-08 Ricerca Chimica S R L Apparecchiatura per il decapaggio elettrochimico di superfici in acciaio inox e procedimento di decapaggio elettrochimico di dette superfici

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106929907B (zh) * 2017-03-30 2018-11-06 浙江康盛股份有限公司 一种在线钢管表面除锈工艺

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1090071A (en) * 1963-04-02 1967-11-08 Burndept Ltd Cleaning by use of ultrasonic vibrations
JPS5075530A (fr) * 1973-11-09 1975-06-20
US4206028A (en) * 1976-12-14 1980-06-03 Inoue-Japax Research Incorporated Electrochemical polishing system
WO1995003439A1 (fr) * 1993-07-21 1995-02-02 Dynamotive Corporation Procede d'enlevement de certains films d'oxyde de surfaces metalliques
US5409594A (en) * 1993-11-23 1995-04-25 Dynamotive Corporation Ultrasonic agitator

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1090071A (en) * 1963-04-02 1967-11-08 Burndept Ltd Cleaning by use of ultrasonic vibrations
JPS5075530A (fr) * 1973-11-09 1975-06-20
US4206028A (en) * 1976-12-14 1980-06-03 Inoue-Japax Research Incorporated Electrochemical polishing system
WO1995003439A1 (fr) * 1993-07-21 1995-02-02 Dynamotive Corporation Procede d'enlevement de certains films d'oxyde de surfaces metalliques
US5409594A (en) * 1993-11-23 1995-04-25 Dynamotive Corporation Ultrasonic agitator

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Section Ch Week 7644, Derwent World Patents Index; Class M11, AN 76-81747X, XP002029248 *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001053571A1 (fr) * 2000-01-17 2001-07-26 C-Tech Innovation Limited Procede de traitement electrolytique
GB2358194B (en) * 2000-01-17 2004-07-21 Ea Tech Ltd Electrolytic treatment
GB2386907A (en) * 2002-03-27 2003-10-01 Isle Coat Ltd Forming ceramic coatings on metals and alloys
US6896785B2 (en) 2002-03-27 2005-05-24 Isle Coat Limited Process and device for forming ceramic coatings on metals and alloys, and coatings produced by this process
GB2386907B (en) * 2002-03-27 2005-10-26 Isle Coat Ltd Process and device for forming ceramic coatings on metals and alloys, and coatings produced by this process
JP2016183393A (ja) * 2015-03-26 2016-10-20 Ｊｆｅスチール株式会社 電解研磨装置および電解研磨方法
ITPD20150095A1 (it) * 2015-05-08 2016-11-08 Ricerca Chimica S R L Apparecchiatura per il decapaggio elettrochimico di superfici in acciaio inox e procedimento di decapaggio elettrochimico di dette superfici

Also Published As

Publication number Publication date
JP2000508711A (ja) 2000-07-11
PL329292A1 (en) 1999-03-15
CA2251782A1 (fr) 1997-10-23
KR20000005451A (ko) 2000-01-25
GB9607810D0 (en) 1996-06-19
AU2519097A (en) 1997-11-07
EP0894158A1 (fr) 1999-02-03

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