EP0145576B1 - Zusatzmittel für eine Wartung von Bädern aus geschmolzenen Salzen für die Behandlung metallischer Werkstücke - Google Patents

Zusatzmittel für eine Wartung von Bädern aus geschmolzenen Salzen für die Behandlung metallischer Werkstücke Download PDF

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Publication number
EP0145576B1
EP0145576B1 EP19840402401 EP84402401A EP0145576B1 EP 0145576 B1 EP0145576 B1 EP 0145576B1 EP 19840402401 EP19840402401 EP 19840402401 EP 84402401 A EP84402401 A EP 84402401A EP 0145576 B1 EP0145576 B1 EP 0145576B1
Authority
EP
European Patent Office
Prior art keywords
make
charge according
bath
regenerating agent
product
Prior art date
Legal status (The legal status 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 status listed.)
Expired
Application number
EP19840402401
Other languages
English (en)
French (fr)
Other versions
EP0145576A3 (en
EP0145576A2 (de
Inventor
Bernard Grellet
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Centre Stephanois de Recherches Mecaniques Hydromecanique et Frottement SA
Original Assignee
Centre Stephanois de Recherches Mecaniques Hydromecanique et Frottement SA
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 Centre Stephanois de Recherches Mecaniques Hydromecanique et Frottement SA filed Critical Centre Stephanois de Recherches Mecaniques Hydromecanique et Frottement SA
Publication of EP0145576A2 publication Critical patent/EP0145576A2/de
Publication of EP0145576A3 publication Critical patent/EP0145576A3/fr
Application granted granted Critical
Publication of EP0145576B1 publication Critical patent/EP0145576B1/de
Expired legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/40—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using liquids, e.g. salt baths, liquid suspensions

Definitions

  • Molten salt baths for the treatment of metal parts generally contain at least one active compound, for example cyanate for nitriding, carbide for cementation, etc.
  • Such treatments by baths of molten salts are aimed in particular, in whole or in part, at improving the resistance to wear, seizure, corrosion and fatigue of metal parts.
  • the subject of the present invention is a feedstock intended to compensate for the losses of a bath of molten salts for the treatment of metal parts with a view to the maintenance of this bath, these losses being due, on the one hand, to the entrainment of molten salts by the parts leaving the bath, on the other hand to the transformation of an active compound into degradation product, this degradation product being capable of becoming again the active compound by reaction with a regenerant admitted into the bath this effect, this filler providing, for the first time, the possibility of maintaining a bath of molten salts for the treatment of metal parts in the form of a single total addition, of allowing its introduction into the bath without gassing harmful and to maintain faithful and constant the active power of the bath, said charge being made from inexpensive materials that are commonly found in commerce.
  • this feedstock is in particular characterized in that it consists of tablets obtained by compacting a mixture of at least two particulate materials, one of these materials being formed from a restocking product of the same composition. as the degradation product, and another material being formed of said regenerant.
  • replenishment material is none other than the imitation degradation product, this material is generally inexpensive.
  • the overall charge according to the invention therefore has the particularity of bringing together, for the maintenance of the bath, two constituents, the first of which corresponds to the ultimate product of degeneration of the bath, while the other, in an original manner, has a regeneration mission which goes beyond the sole needs of the bath, since it is called upon to regenerate not only the bath salts that have become inactive, but also the first constituent itself, admitted at the same time as it in the bath.
  • the regenerant is present in the tablet in the form of at least one granule, and preferably in the form of a multitude of granules, coated with the restocking product.
  • each regenerant granule coated with the restocking product in the tablet is preformed under high compactness before coating and compacting of the tablet.
  • regenerant is localized in the tablet in depth and in a precise manner, which allows an effective and faithful mode of action.
  • the tablet has a slight excess of regenerant, this excess being by weight, of the order of 1% to 5% and of preferably around 2%.
  • the charge acts in the bath in a balanced manner, since the regenerant is in a quantity suitable for ensuring the regeneration both of the imitation degradation product which is admitted with it into the bath, and of the degradation product which s is already there.
  • the active compound comprises a cyanate and the tablets advantageously comprise granules of urea and of urea condensation products, coated with carbonate.
  • the granules advantageously have a dimension of the order of a millimeter, while the tablet preferably has a dimension of the order of several centimeters, which allows great convenience in use.
  • a bath of molten salts, working at around 560 ° C., is provided for a treatment by nitriding of metal parts in order to improve their resistance to wear, seizure, corrosion and fatigue.
  • This bath undergoes losses which are due, on the one hand, to the entrainment of molten salts by the parts leaving the bath, on the other hand, to the degeneration of the active compound cyanate into a less active degraded compound which in its ultimate form of degeneration where it has become totally inactive is a product of carbonate degradation.
  • the carbonate content increases, the nitriding potential of the bath decreases, the melting point of the bath rises and correspondingly, the viscosity of the bath increases, so that the quality of the treatment is not constant.
  • a filler charge according to the invention is used which alone and overall makes it possible to compensate for all the losses of the bath.
  • This charge consists of tablets obtained by compacting a mixture of at least two particulate materials, one of these materials being formed from a restocking product consisting of a similar degradation product, and another material being formed from the regenerant.
  • This regenerant which can itself be a mixture of several compounds, is present in the tablet in the form of at least one granule, and preferably of a multitude of granules coated with the restocking product.
  • the feedstock is presented as the mixture of the imitation product totally degraded by oxidation, in this case alkali carbonates, and of the regenerant, in this case urea, or at least one of its condensation products. , or advantageously a mixture of urea and at least one of its condensation products.
  • regenerant is pressed in the form of very compact granules, having a dimension of the order of a millimeter. Then these granules are mixed with carbonates, these being brought in the form of powder.
  • regenerant is urea
  • its reaction with carbonates can be written as follows:
  • the strict mixture should be 2 kg of urea and 1 kg of carbonates in the form C03z-; but the filler according to the invention advantageously has 1 to 5% and preferably 2% more regenerant than in the formula and its composition is actually 1 kg of alkali carbonates in the form of C0 3 2- and 2.0 kg of urea.
  • a mixture of urea and at least one of its condensation products is used as regenerator.
  • the gassing of ammonia gas and water vapor is limited, according to a reaction of the same type as that described above, which concretely results in the formation of the surface of the parts of layers much more compact, that is to say more resistant to wear.
  • this beneficial effect is only obtained if a precise proportion is compacted between the respective amounts of urea and of its condensation product (s).
  • the weight ratio between the amount of urea and that of its condensation products should be between 1.5 and 2.
  • the mixture according to the proportions of the invention of the regenerant granules and of the powder of the restocking product is compacted under a pressure of several tonnes of square centimeter, in the form of tablets of great compactness, having a dimension on the order of several centimeters.
  • Said compaction pressure must be greater than 2 tonnes per square centimeter and it is advantageously of the order of 5.
  • regenerant granules can be uniform ment distributed in the restocking product, but, preferably, they are concentrated in a central region of the tablet, which allows better progressiveness in the mode of action of the regenerant in the bath of molten salts.
  • the filler according to the invention can be used, not only with baths of molten nitriding salts, but also with any other suitable baths, in particular cementation baths in which the active compound is a carbide degenerating into carbonate.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Cosmetics (AREA)
  • Detergent Compositions (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • Seasonings (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Glanulating (AREA)

Claims (13)

1. Zusatzmittel zum Kompensieren der Verluste eines Bades aus geschmolzenen Salzen für die Behandlung metallischer Werkstücke zur Wartung dieses Bades, wobei die Verluste einerseits daher rühren, dass von den das Bad verlassenden Werkstücken geschmolzene Salze ausgetragen werden, und andererseits daher, dass eine aktive Verbindung zu einer abgebauten weniger aktiven Verbindung degeneriert, die in ihrer degenerierten Endform, in der sie vollkommen unwirksam geworden ist, als Abbauprodukt bezeichnet wird, wobei dieses Abbauprodukt durch Reaktion mit mindestens einem zu diesem Zweck dem Bad zugesetzten Regenerierungsmittel wieder in die aktive Verbindung umgewandelt werden kann, dadurch gekennzeichnet, dass das Zusatzmittel aus Presslingen besteht, die durch Pressen einer Mischung von mindestens teilchenförmigen Materialien erhalten wurden, wobei eines dieser Materialien von einem Auffüllprodukt gebildet ist, das die gleiche Zusammensetzung wie das Abbauprodukt hat, und ein anderes Material von dem Regenerierungsmittel gebildet ist.
2. Zusatzmittel nach Anspruch 1, dadurch gekennzeichnet, dass das Regenerierungsmittel im Pressling in Form von mindestens einem von dem Auffüllprodukt umhüllten Korn vorliegt.
3. Zusatzmittel nach Anspruch 1 oder Anspruch 2, dadurch gekennzeichnet, dass das Regenerierungsmittel im Pressling in Form einer Vielzahl von Körnern, die vom Auffüllmittel umhüllt sind, vorliegt.
4. Zusatzmittel nach Anspruch 3, dadurch gekennzeichnet, dass die Körner des Regenerierungsmittels im Auffüllmittel gleichmässig verteilt sind.
5. Zusatzmittel nach Anspruch 3, dadurch gekennzeichnet, dass die Körner des Regenerierungsmittels in einem Mittelbereich des Presslings konzentriert sind.
6. Zusatzmittel nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass jedes Korn des Regenerierungsmittels, das im Pressling vom Auffüllprodukt umhüllt ist, unter hoher Verdichtung vorgeformt wird, bevor es umhüllt und der Pressling gepresst wird.
7. Zusatzmittel nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass die Verdichtung des Presslings unter einem Druck von mehreren Ton- nen/cmz erfolgt.
8. Zusatzmittel nach Anspruch 7, dadurch gekennzeichnet, dass der Druck beim Verdichten über 2 t/cm2 und vorzugsweise etwa 5 t/cm2 beträgt.
9. Zusatzmittel nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass jedes Korn einen Durchmesser in der Grössenordnung von Millimetern hat, während der Pressling eine Abmessung in der Grössenordnung von mehreren Zentimetern hat.
10. Zusatzmittel nach einem der Ansprüche 1 bis 9, dadurch gekennzeichnet, dass der Pressling einen geringen Überschuss des Regenerierungsmittels im Vergleich zu den Verhältnissen, die der Reaktion zwischen dem Abbauprodukt und dem Regenerierungsmittel entsprechen, aufweist.
11. Zusatzmittel nach Anspruch 10, dadurch gekennzeichnet, dass der Überschuss in der Grössenordnung von 1 bis 5 Gewichtsprozent beträgt.
12. Zusatzmittel nach einem der Ansprüche 1 bis 11, worin die aktive Verbindung ein Cyanat aufweist, dadurch gekennzeichnet, dass die Presslinge Körner von Harnstoff und/oder seinen Kondensationsprodukten aufweisen, die von Carbonat umhüllt sind.
13. Zusatzmittel nach Anspruch 12, worin das Regenerierungsmittel aus einem Gemisch aus Harnstoff und einem oder mehreren Harnstoffkondensationsprodukten besteht, dadurch gekennzeichnet, dass das Gewichtsverhältnis zwischen der Menge des Harnstoffs und der seines oder seiner Kondensationsprodukte zwischen 1,5 und 2 liegt.
EP19840402401 1983-12-09 1984-11-26 Zusatzmittel für eine Wartung von Bädern aus geschmolzenen Salzen für die Behandlung metallischer Werkstücke Expired EP0145576B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8319781 1983-12-09
FR8319781A FR2556367B1 (fr) 1983-12-09 1983-12-09 Charge d'apport destinee a assurer la maintenance de bains de sels fondus pour le traitement de pieces metalliques

Publications (3)

Publication Number Publication Date
EP0145576A2 EP0145576A2 (de) 1985-06-19
EP0145576A3 EP0145576A3 (en) 1985-07-10
EP0145576B1 true EP0145576B1 (de) 1987-08-05

Family

ID=9295052

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19840402401 Expired EP0145576B1 (de) 1983-12-09 1984-11-26 Zusatzmittel für eine Wartung von Bädern aus geschmolzenen Salzen für die Behandlung metallischer Werkstücke

Country Status (7)

Country Link
EP (1) EP0145576B1 (de)
JP (1) JPS60141864A (de)
BR (1) BR8406275A (de)
DE (1) DE3465207D1 (de)
ES (1) ES8702499A1 (de)
FR (1) FR2556367B1 (de)
IN (1) IN161219B (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4030279C1 (en) * 1990-09-25 1992-06-04 Goetz Dipl.-Chem. Dr. 5400 Koblenz De Baum Regenerating molten alkali metal cyanate - by continuous addn. of urea] or polymer or condensate that generates urea, feeding additive into containers in continuous conveyor

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1012625B (de) * 1955-06-10 1957-07-25 Houghton Chemie G M B H Verfahren zur Erzielung zeitweiliger Aufkohlungswirkung bei der Waermebehandlung vonStahl in cyanidfreien Salzschmelzen
FR2214760A2 (en) * 1973-01-23 1974-08-19 Ctre Rech Meca Hydromeca Surface treating ferrous metals - with molten salt bath contg carbonate, cyanate, lithium, potassium, and sodium ions
AR204533A1 (es) * 1973-06-20 1976-02-12 Stephanois Rech Mec Procedimiento de regeneracion de un bano de sales fundidas que contiene cianatos y carbonatos
FR2271307A1 (en) * 1974-05-17 1975-12-12 Stephanois Rech Meca Hyd Centr Stabilising fused cyanate heat treatment baths - by introducing sulphur and carbonyl cpds. to reduce cyanide formation
DE2521550A1 (de) * 1975-05-15 1976-12-02 Daimler Benz Ag Mittel zum regenerieren von nitrierbaedern
DE2542519A1 (de) * 1975-09-24 1977-04-14 Daimler Benz Ag Regenerierungsmittel fuer salzschmelzen auf cyanatbasis
JPS5931861A (ja) * 1982-08-16 1984-02-21 Mitsui Toatsu Chem Inc 金属材料の窒化用塩浴の再生剤

Also Published As

Publication number Publication date
DE3465207D1 (en) 1987-09-10
FR2556367B1 (fr) 1986-09-19
ES8702499A1 (es) 1987-01-01
FR2556367A1 (fr) 1985-06-14
EP0145576A3 (en) 1985-07-10
BR8406275A (pt) 1985-10-01
JPS6354067B2 (de) 1988-10-26
IN161219B (de) 1987-10-17
EP0145576A2 (de) 1985-06-19
ES538372A0 (es) 1987-01-01
JPS60141864A (ja) 1985-07-26

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