MD614Z - Process for chemicothermal treatment of steel products - Google Patents

Process for chemicothermal treatment of steel products Download PDF

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Publication number
MD614Z
MD614Z MDS20120096A MDS20120096A MD614Z MD 614 Z MD614 Z MD 614Z MD S20120096 A MDS20120096 A MD S20120096A MD S20120096 A MDS20120096 A MD S20120096A MD 614 Z MD614 Z MD 614Z
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aqueous solution
solution containing
temperature
carried out
product
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MDS20120096A
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Romanian (ro)
Russian (ru)
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Владимир ПАРШУТИН
Анатолий ПАРАМОНОВ
Эмиль ПАСИНКОВСКИ
Александр КОВАЛЬ
Наталия ЧЕРНЫШЕВА
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Институт Прикладной Физики Академии Наук Молдовы
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Abstract

The invention relates to a process for chemicothermal treatment of steel products and can be used in mechanical engineering and instrument engineering for increasing the corrosion resistance of machine parts, tools and tooling.The process, according to the invention, comprises the anode heating of the product in an aqueous solution containing NH4Cl, NH4NO3 and additionally thiosemicarbazide H2N-CS-NH-NH2, during 1…6 min. The subsequent quenching of the product is carried out in an aqueous solution containing zinc monophosphate Zn(H2PO4)2·2H2O, nickel sulphate NiSO4, manganese sulphate MnSO4, phosphoric acid, H3PO4, sodium nitrate NaNO3 and sodium nitrite NaNO2, at the temperature of 20…40°C during 1…20 min. Afterwards, it is carried out the passivation of the product in an aqueous solution containing sodium hydroxide NaOH and potassium bichromate K2Cr2O7, at the temperature of 85…90°C during 1…5 min.

Description

Invenţia se referă la un procedeu de prelucrare termochimică a pieselor din oţel şi poate fi folosită în industria construcţiilor de maşini şi în construcţia aparatelor pentru mărirea rezistenţei la coroziune a pieselor maşinilor, sculelor şi utilajului tehnologic. The invention relates to a process for thermochemical processing of steel parts and can be used in the machine building industry and in the construction of devices to increase the corrosion resistance of machine parts, tools and technological equipment.

Este cunoscut un procedeu de prelucrare termochimică a suprafeţei oţelului prin încălzire anodică a piesei în soluţii apoase de electroliţi, care conţin compuşi ai azotului, % mas.: 1) NH4Cl 10 şi NH4OH 5; 2) NH4Cl 11 şi NH4NO3 11, la densitatea curentului de 1...2 A/cm2 şi tensiunea de 150...220 V. În procesul nitrurării electrolitul din apropierea nemijlocită a anodului începe să fiarbă şi se separă de piesă printr-o peliculă compactă de vapori şi gaze. O parte din energie este consumată pentru încălzirea anodului (piesei) cu posibilitatea reglării lente a temperaturii în limitele 400...950°C. Ca rezultat are loc difuzia azotului în stratul de suprafaţă a oţelului cu formarea nitrurilor. Răcirea piesei se efectuează sau în electrolit după deconectarea curentului, sau în aer, datorită căreia pe suprafaţă se formează o peliculă de oxizi. Acest tratament duce la o anumită sporire a rezistenţei la coroziune a pieselor [1]. A process of thermochemical processing of the steel surface by anodic heating of the part in aqueous solutions of electrolytes containing nitrogen compounds, % wt.: 1) NH4Cl 10 and NH4OH 5; 2) NH4Cl 11 and NH4NO3 11, at a current density of 1...2 A/cm2 and a voltage of 150...220 V is known. In the nitriding process, the electrolyte in the immediate vicinity of the anode begins to boil and is separated from the part by a compact film of vapors and gases. Part of the energy is consumed for heating the anode (part) with the possibility of slow temperature regulation within the limits of 400...950°C. As a result, nitrogen diffusion occurs in the surface layer of the steel with the formation of nitrides. The cooling of the part is carried out either in the electrolyte after the current is disconnected, or in air, due to which an oxide film is formed on the surface. This treatment leads to a certain increase in the corrosion resistance of the parts [1].

Dezavantajele acestui procedeu constau în aceea că stratul de nitrură obţinut este neomogen şi de o grosime insuficientă, iar pelicula de oxizi are o grosime mică, neuniformă şi o continuitate nesatisfăcătoare. În plus, ea are o aderenţă slabă cu suprafaţa piesei, ceea ce duce la fărâmiţarea acesteia şi la diminuarea rezistenţei la coroziune a pieselor din oţel. The disadvantages of this process are that the nitride layer obtained is inhomogeneous and of insufficient thickness, and the oxide film has a small, non-uniform thickness and unsatisfactory continuity. In addition, it has poor adhesion to the surface of the part, which leads to its crumbling and to a decrease in the corrosion resistance of steel parts.

În calitate de cea mai apropiată soluţie serveşte procedeul de prelucrare termochimică a pieselor din oţel, care include încălzirea anodică a piesei până la temperatura de 400…950°C, timp de 3…5 min, într-un electrolit ce conţine, g/L: NH4Cl 40…60, NH2OH·HCl 0,05…0,10, N2H4·HCl 0,1…1,0, apă - restul, la o tensiune a curentului de 100…220 V şi o densitate de 1,0…2,5 A/cm2, după care piesa se căleşte într-o soluţie apoasă ce conţine 50…100 g/L de hidroxid de sodiu. Datorită acestui procedeu în stratul superficial al piesei se diminuează conţinutul de carbon şi se formează stratul de nitrură şi o peliculă de oxid destul de compactă [2]. The closest solution is the process of thermochemical processing of steel parts, which includes anodic heating of the part to a temperature of 400…950°C for 3…5 min in an electrolyte containing, g/L: NH4Cl 40…60, NH2OH·HCl 0.05…0.10, N2H4·HCl 0.1…1.0, water - the rest, at a current voltage of 100…220 V and a density of 1.0…2.5 A/cm2, after which the part is quenched in an aqueous solution containing 50…100 g/L of sodium hydroxide. Due to this process, the carbon content in the surface layer of the part decreases and a nitride layer and a fairly compact oxide film are formed [2].

Dezavantajul acestui procedeu constă în faptul că stratul de protecţie conţine numai nitruri şi peliculă de oxizi, ceea ce nu întotdeauna permite obţinerea rezistenţei la coroziune necesare a suprafeţei. The disadvantage of this process is that the protective layer contains only nitrides and oxide film, which does not always allow the necessary corrosion resistance of the surface to be obtained.

Problema pe care o rezolvă invenţia constă în sporirea rezistenţei la coroziune a pieselor şi formarea unei pelicule de pasivizare suplimentare, subţiri, compacte şi cu o adeziune bună cu suprafaţa stratului de fosfaţi, care protejează de coroziune. The problem solved by the invention consists in increasing the corrosion resistance of the parts and forming an additional passivation film, thin, compact and with good adhesion to the surface of the phosphate layer, which protects against corrosion.

Problema se rezolvă prin aceea că procedeul de prelucrare termochimică a pieselor din oţel include încălzirea anodică a piesei într-o soluţie apoasă de electrolit, ce conţine, g/L: NH4Cl 110, NH4NO3 110 şi suplimentar tiosemicarbazidă H2N-CS-NH-NH2 0,1…1,0, timp de 1...6 min, iar călirea ulterioară a piesei se efectuează într-o soluţie apoasă, ce conţine, g/L: monofosfat de zinc Zn(H2PO4)2·2H2O 5…12, sulfat de nichel NiSO4 1…6, sulfat de mangan MnSO4 0,8…6, acid fosforic H3PO4 13…30, nitrat de sodiu NaNO3 2…6, nitrit de sodiu NaNO2 0,1…0,3, la temperatura de 20…40°C timp de 1…20 min. După aceasta se efectuează pasivizarea piesei într-o soluţie apoasă, ce conţine, g/L: hidroxid de sodiu NaOH 3…7 şi bicromat de potasiu K2Cr2O7 15…25, la temperatura de 85…90°C timp de 1…5 min. The problem is solved by the fact that the thermochemical processing process of steel parts includes the anodic heating of the part in an aqueous electrolyte solution, containing, g/L: NH4Cl 110, NH4NO3 110 and additionally thiosemicarbazide H2N-CS-NH-NH2 0.1…1.0, for 1…6 min, and the subsequent quenching of the part is carried out in an aqueous solution, containing, g/L: zinc monophosphate Zn(H2PO4)2·2H2O 5…12, nickel sulfate NiSO4 1…6, manganese sulfate MnSO4 0.8…6, phosphoric acid H3PO4 13…30, sodium nitrate NaNO3 2…6, sodium nitrite NaNO2 0.1…0.3, at a temperature of 20…40°C for 1…20 min. After this, the part is passivated in an aqueous solution containing, g/L: sodium hydroxide NaOH 3…7 and potassium bichromate K2Cr2O7 15…25, at a temperature of 85…90°C for 1…5 min.

Rezultatul tehnic al aplicării procedeului este mărirea rezistenţei la coroziune a pieselor datorită creării pe suprafaţa stratului de nitruri a stratului de fosfaţi insolubili de fier, mangan şi zinc şi formării pe ele a unei pelicule de pasivizare subţiri şi continue. The technical result of applying the process is the increase in the corrosion resistance of the parts due to the creation of a layer of insoluble phosphates of iron, manganese and zinc on the surface of the nitride layer and the formation of a thin and continuous passivation film on them.

Exemplu de realizare a invenţiei Example of embodiment of the invention

Probele au fost confecţionate din oţel Ст.3 (compoziţie, % mas.: C - 0,14...0,22, Mn - 0,40...0,65; Si - 0,12...0,30; restul - Fe), în formă de placă cu suprafaţa de 2 cm2. The samples were made of St.3 steel (composition, wt.%: C - 0.14...0.22, Mn - 0.40...0.65; Si - 0.12...0.30; the rest - Fe), in the form of a plate with a surface area of 2 cm2.

Tratamentul termochimic anodic a fost efectuat într-un electrolit, care conţine, g/L: NH4Cl 110 şi NH4NO3 110, în care au fost introduse suplimentar 0,5 g/L de tiosemicarbazidă H2N-CS-NH-NH2, tensiunea la electrozi de 200 V, densitatea curentului de 2 A/cm2, temperatura anodului de 750°C timp de 5 min. The anodic thermochemical treatment was performed in an electrolyte containing, g/L: NH4Cl 110 and NH4NO3 110, in which 0.5 g/L of thiosemicarbazide H2N-CS-NH-NH2 was additionally introduced, the electrode voltage was 200 V, the current density was 2 A/cm2, the anode temperature was 750°C for 5 min.

După deconectarea de la curent a piesei-electrod aceasta a fost transferată imediat într-o baie cu soluţie apoasă de electrolit, ce conţine, g/L: Zn(H2PO4)2·2H2O 8, NiSO4 4, MnSO4 3, H3PO4 18, NaNO3 4, nitrit de sodiu NaNO2 0,2, la temperatura de 30°C timp de 1…20 min. Apoi piesa-electrod a fost spălată şi pasivizată în soluţie apoasă, ce conţine, g/L: NaOH 5, K2Cr2O7 20, la temperatura de 90°C timp de 4 min. After disconnecting the electrode piece from the power supply, it was immediately transferred to a bath with an aqueous electrolyte solution, containing, g/L: Zn(H2PO4)2·2H2O 8, NiSO4 4, MnSO4 3, H3PO4 18, NaNO3 4, sodium nitrite NaNO2 0.2, at a temperature of 30°C for 1…20 min. Then the electrode piece was washed and passivated in an aqueous solution, containing, g/L: NaOH 5, K2Cr2O7 20, at a temperature of 90°C for 4 min.

Tabel Table

Influenţa tipului de prelucrare asupra intensităţii curentului de dizolvare anodică Influence of processing type on anodic dissolution current intensity

(mA) în soluţia apoasă, g/L: NaCl 7,0 şi Na2SO4 7,0 (mA) in aqueous solution, g/L: NaCl 7.0 and Na2SO4 7.0

Tipul de prelucrare Ia, mA la φ=0V Ia, mA la φ=0,4V Ia, mA la φ=1,2V Ст.3, neprelucrat 560,0 600,0 640,0 Ст.3, după prelucrarea termochimică în electrolit, g/L: NH4Cl 110 şi NH4NO3 110 25,6 38,5 69,4 Ст.3, după prelucrarea termochimică conform celei mai apropiate soluţii 17,1 25,8 46,3 Ст.3, după prelucrarea termochimică în electrolitul propus 7,4 11,2 20,1 Ст.3, după prelucrarea termochimică în electrolitul propus + călirea în electrolitul propus 4,8 7,3 13,1 Ст.3, după prelucrarea termochimică în electrolitul propus + călirea în electrolitul propus + pasivizarea în electrolitul propus 3,2 4,1 8,7Type of processing Ia, mA at φ=0V Ia, mA at φ=0.4V Ia, mA at φ=1.2V St.3, unprocessed 560.0 600.0 640.0 St.3, after thermochemical processing in electrolyte, g/L: NH4Cl 110 and NH4NO3 110 25.6 38.5 69.4 St.3, after thermochemical processing according to the closest solution 17.1 25.8 46.3 St.3, after thermochemical processing in the proposed electrolyte 7.4 11.2 20.1 St.3, after thermochemical processing in the proposed electrolyte + quenching in the proposed electrolyte 4.8 7.3 13.1 St.3, after thermochemical processing in the proposed electrolyte + quenching in the proposed electrolyte + passivation in the proposed electrolyte 3.2 4.1 8.7

Din datele prezentate în tabel este clar că oţelul neprelucrat este cel mai nerezistent pentru toate valorile potenţialului. Prelucrarea termochimică în electrolitul, ce conţine NH4Cl 110 g/L şi NH4NO3 110 g/L, reduce intensitatea curentului de dizolvare anodică de 9,2...21,88 ori. După tratamentul termochimic conform celei mai apropiate soluţii intensitatea curentului de dizolvare anodică la potenţialul de 0,0 V se reduce de aproape 1,5 ori. Totodată, prelucrarea doar în electrolitul propus reduce intensitatea curentului de dizolvare anodică la potenţialul de 0,0 V de 2,31 ori (de la 17,1 până la 7,4 mA). Mai mult sporesc rezistenţa la coroziune a oţelului alte două procese propuse: călirea şi pasivizarea, la potenţialul de 0,0 V, de exemplu, intensitatea curentului de dizolvare anodică respectiv a scăzut până la 4,8 şi 3,2 mA, adică, în comparaţie cu cea mai apropiată soluţie la potenţialele 0,0 V şi 0,4 V intensitatea curentului de dizolvare anodică a scăzut de 5,3 şi, respectiv, de 6,3 ori. From the data presented in the table it is clear that the unprocessed steel is the least resistant for all potential values. Thermochemical processing in the electrolyte, which contains NH4Cl 110 g/L and NH4NO3 110 g/L, reduces the intensity of the anodic dissolution current by 9.2...21.88 times. After thermochemical treatment according to the closest solution, the intensity of the anodic dissolution current at the potential of 0.0 V is reduced by almost 1.5 times. At the same time, processing only in the proposed electrolyte reduces the intensity of the anodic dissolution current at the potential of 0.0 V by 2.31 times (from 17.1 to 7.4 mA). Furthermore, two other proposed processes increase the corrosion resistance of steel: quenching and passivation, at the potential of 0.0 V, for example, the intensity of the anodic dissolution current decreased to 4.8 and 3.2 mA, respectively, i.e., compared to the closest solution at the potentials of 0.0 V and 0.4 V, the intensity of the anodic dissolution current decreased by 5.3 and, respectively, by 6.3 times.

Astfel, invenţia propusă permite mărirea considerabilă a rezistenţei la coroziune a pieselor din oţel şi a fiabilităţii lor. Thus, the proposed invention allows for a considerable increase in the corrosion resistance of steel parts and their reliability.

1. Паршутин В., Ревенко В., Пасинковский Е., Шкурпело А., Житару Р. Влияние способа ввода азота на электрохимическое, коррозионное поведение и физико-механические свойства модифицированных поверхностей сталей. Электронная обработка материалов, 2004, № 4, с. 14-33 1. Parshutin V., Revenko V., Pasinkovsky E., Shkurpelo A., Zhitaru R. Influence of the nitrogen injection method on electrochemical, corrosion behavior and physical-mechanical properties of modified steel surfaces. Electronic processing of materials, 2004, № 4, с. 14-33

2. MD 192 Y 2010.04.30 2. MD 192 Y 2010.04.30

Claims (1)

Procedeu de prelucrare termochimică a pieselor din oţel, care include încălzirea anodică a piesei într-o soluţie apoasă de electrolit ce conţine compuşi anorganici ai azotului şi călirea ulterioară a piesei într-o altă soluţie apoasă, caracterizat prin aceea că încălzirea anodică se efectuează timp de 1…6 min într-o soluţie apoasă ce conţine, g/L: NH4Cl 110, NH4NO3 110 şi suplimentar tiosemicarbazidă H2N-CS-NH-NH2 0,1…1,0, iar călirea ulterioară a piesei se efectuează într-o soluţie apoasă ce conţine, g/L: monofosfat de zinc Zn(H2PO4)2·2H2O 5…12, sulfat de nichel NiSO4 1…6, sulfat de mangan MnSO4 0,8…6, acid fosforic H3PO4 13…30, nitrat de sodiu NaNO3 2…6, nitrit de sodiu NaNO2 0,1…0,3, la temperatura de 20…40°C timp de 1…20 min, după care se efectuează pasivizarea piesei într-o soluţie apoasă ce conţine, g/L: hidroxid de sodiu NaOH 3…7 şi bicromat de potasiu K2Cr2O7 15…25, la temperatura de 85…90°C timp de 1…5 min.Process for thermochemical processing of steel parts, which includes anodic heating of the part in an aqueous electrolyte solution containing inorganic nitrogen compounds and subsequent quenching of the part in another aqueous solution, characterized in that the anodic heating is carried out for 1…6 min in an aqueous solution containing, g/L: NH4Cl 110, NH4NO3 110 and additionally thiosemicarbazide H2N-CS-NH-NH2 0.1…1.0, and the subsequent quenching of the part is carried out in an aqueous solution containing, g/L: zinc monophosphate Zn(H2PO4)2·2H2O 5…12, nickel sulfate NiSO4 1…6, manganese sulfate MnSO4 0.8…6, phosphoric acid H3PO4 13…30, sodium nitrate NaNO3 2…6, sodium nitrite NaNO2 0.1…0.3, at a temperature of 20…40°C for 1…20 min, after which the part is passivated in an aqueous solution containing, g/L: sodium hydroxide NaOH 3…7 and potassium bichromate K2Cr2O7 15…25, at a temperature of 85…90°C for 1…5 min.
MDS20120096A 2012-07-03 2012-07-03 Process for chemicothermal treatment of steel products MD614Z (en)

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MD3708F1 (en) * 2007-05-23 2008-09-30 Institutul De Fizica Aplicata Al Academiei De Stiinte A Moldovei Process for enhancing the corrosion resistance of steel
MD192Y (en) * 2009-06-04 2010-04-30 Institutul De Fizica Aplicata Al Academiei De Stiinte A Moldovei Process for thermochemical treatment of steel articles
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MD336Z (en) * 2010-03-03 2011-09-30 Институт Прикладной Физики Академии Наук Молдовы Process for thermochemical machining of metal articles

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Title
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