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
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F3/00—Brightening metals by chemical means
  • C23F3/04—Heavy metals
  • C23F3/06—Heavy metals with acidic solutions

Definitions

• the present invention relates to the composition of baths for the chemical polishing of stainless steel surfaces.
• Chemical polishing of metal surfaces is a well-known technique (electrolytic and chemical polishing of metals - WJ Me G. TEGART - Dunod - 1960 - p. 122 et seq.); it consists in treating the metal surfaces to be polished with oxidizing baths.
• baths are generally used comprising a mixture, in aqueous solution, of hydrochloric, phosphoric and nitric acids (patent US-A-2662814).
• suitable additives such as surface-active agents, viscosity regulators and brighteners.
• a composition of a bath for the chemical polishing of stainless steel surfaces comprising, in aqueous solution, a mixture of phosphoric acid, nitric acid and acid. hydrochloric acid, a viscosity regulator chosen from water-soluble polymers, a surfactant and sulfosalicylic acid as a brightening agent.
• polishing baths have the particularity of attacking the metal at very high speed. A polishing treatment of a stainless steel surface with such baths can generally not exceed a few minutes, at the risk of causing local corrosion.
• Phosphoric acid sulfosalicylic acid and an abiotic compound, such as an abietamine.
• the invention aims to provide baths designed to carry out slow and effective chemical polishing of stainless steel surfaces, at working temperatures below 50 ° C.
• the invention relates to baths for the chemical polishing of stainless steel surfaces, comprising, in aqueous solution, a mixture of hydrochloric acid, nitric acid and phosphoric acid, an optionally substituted hydroxybenzoic acid, a abietic compound and an additive selected from perchloric acid and the water-soluble salts of perchloric acid.
• hydroxybenzoic acid serves as a brightening agent. It can be unsubstituted such as salicylic acid or substituted such as sulfosali ⁇ cylic acid. Salicylic acid is preferred.
• the abietic compounds are 0 chemical compounds comprising an abietyl radical of general formula:
• the abietic compound must be soluble in the aqueous solution.
• Abietic compounds which can be used in the baths according to the invention are abietamines.
• Abietamines specially recommended for baths according to the invention are those of general formula: xi
• R * j _ denotes an abiétyle, hydroabiétyle or déhydro ⁇ abiétyle radical defined above,
• - X denotes a hydrogen atom or a radical comprising at least one carbonyl group.
• abietamines which are very suitable in the baths according to the invention, are those in which at least one of the radicals X ⁇ and X2 is a radical of general formula:
• R2 denotes a linear or cyclic alkyl radical, substituted or unsubstituted, saturated or unsaturated, comprising at least one carbonyl group.
• R2 denotes a linear or cyclic alkyl radical, substituted or unsubstituted, saturated or unsaturated, comprising at least one carbonyl group.
• substituted abietamines and the means of obtaining them are described in GB-A-734665.
• abietamines of this type which can be used in the baths according to the invention, are those in which the alkyl residue R2 is selected from acetonyl, 2-keto butyl, 4-methyl 2-keto pentenyl-3, 4-hydroxy 4 -methyl 2-keto pentyl, 2-keto cyclopentyl, 4-hydroxy 2-keto pentenyl-3, 2-keto cyclohexyl, 2,5-diketo hexyl and 2-phenyl 2-keto ethyl.
• the respective amounts of additive selected from perchloric acid and its water-soluble salts, on the one hand, and of abietic compound, on the other hand, should be adjusted to make coadsorption possible. on the surface of the steel to be polished, while avoiding exceeding their solubility product.
• the baths according to the invention contain, per liter, between 0.001 and 0.5 mole of the additive selected from perchloric acid and its water-soluble salts and between 0.005 and 1 g of the abietic compound.
• the adequate weight quantities of the various constituents of the baths according to the invention depend on the grade of the stainless steel subjected to polishing as well as on the polishing conditions, in particular on the profile of the steel object subjected to polishing. its volume, the volume of the bath, its temperature and the agitation to which it is possibly subjected. They must therefore be determined in each particular case by routine laboratory tests.
• baths in accordance with the invention suitable for polishing austenitic stainless steels alloyed with chromium and nickel, at temperatures between 25 and 50 ° C. include, per liter of aqueous solution: between 0.5 and 5 moles of hydrochloric acid (preferably 0.5-3 moles),
• nitric acid preferably
• 0.05-0.5 mole between 0.005 and 1 mole of phosphoric acid (preferably 0.01-0.5 mole), • between 0.0005 and 0.5 mole of the additive selected from perchloric acid and its water-soluble salts (preferably 0.001-0.2 mole),. between 0.005 and 1 g of abietic compound (preferably
• the polishing baths according to the invention may possibly contain additives usually present in baths known for the chemical polishing of metals, for example ° surfactants, alcohols and viscosity regulators. They may in particular include products of the DEHYQUART brand (Henkel), which are surfactants selected from alkylpyridinium salts and quaternary ammonium salts, comprising substituted or unsubstituted alkyl, phenyl or benzyl radicals.
• DEHYQUART brand Hexyl
• the baths according to the invention are suitable for the chemical polishing of all austenitic stainless steel surfaces. They are specially adapted for polishing austenitic steels containing between 16 and 26% by weight of chromium and between 6 and 22% by weight of nickel, such as steels of grade 18/8 and 18/10, free of molybdenum (AISI standard -304 and 304L).
• the baths according to the invention have the particularity of carrying out the polishing of such steels at low speed, generally requiring a contact time of between 2 and 20 hours, generally between 5 and 12 hours. They can be used at all temperatures between 20 ° C and the boiling temperature.
• the baths according to the invention have the additional advantage of performing good quality polishing of welded joints according to the rules of the art.
• the invention also relates to a method for polishing a stainless steel surface, according to which the surface is placed in contact with a chemical polishing bath according to the invention.
• the metal surface can be brought into contact with the bath * - *> in any suitable manner, for example by immersion.
• the contact time of the surface to be polished with the bath must be sufficient to achieve effective polishing of the surface. However, it cannot exceed a critical value beyond which the bath loses its polishing properties.
• the optimum contact time 0 depends on many parameters such as the grade of the steel, the configuration and the initial roughness of the surface to be polished, the composition of the bath, the working temperature, the possible agitation of the bath in contact with the surface, the ratio between the area of the surface to be polished and the volume of the bath; it must be determined in each particular case by routine laboratory work.
• the bath is carried out at a temperature between 20 and 50 ° C, preferably between 35 and 45 ° C, at normal atmospheric pressure, and is maintained the surface to be polished in contact with the bath for a time between 5 and 12 hours.
• the plate was immersed in the polishing bath, kept at a substantially constant temperature and subjected to moderate agitation. At the end of the immersion period 0, the plate was removed from the bath, rinsed with demineralized water and dried. The following parameters were measured:. the average depth of attack of the metal, defined by the relation
• Nd where S denotes the area of the plate (in cm 2 ), d denotes the specific mass of the metal (in g / cm - * - '), ⁇ P denotes the weight loss (in g) of the plate during immersion in the bath, - * - * ⁇ e denotes the depth of attack ( ⁇ m),
• R a arithmetic mean roughness
• Example 1 (according to the invention)
• a polishing bath was used in accordance with the invention, comprising, per liter:. 2.0 moles of hydrochloric acid,. 0.2 mole of nitric acid,. 0.2 mole of phosphoric acid,. 0.1 mole of perchloric acid,. 0.1 g of sulfosalicylic acid,
• RODINE 213 which is a mixture of substituted abietamines, isopropanol and surfactants (RODINE being a registered trademark of Amchem Products Inc.).
• Example 2 (according to the invention)
• a polishing bath was used in accordance with the invention, comprising, per liter:. 1.5 moles of hydrochloric acid,. 0.1 mole of nitric acid,. 0.2 mole of phosphoric acid,. 0.02 mole of perchloric acid,. 0.1 g of salicylic acid,
• Example 2 The test of Example 2 was repeated with a polishing bath not in accordance with the invention, containing neither perchloric acid nor the abietic compound.
• the bath included, per liter: - 1.5 mole of hydrochloric acid,. 0.1 mole of nitric acid,. 0.2 mole of phosphoric acid,. 0.1 g salicylic acid.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• ing And Chemical Polishing (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Chemical Treatment Of Metals (AREA)
• Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)

Priority Applications (7)

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• 1990
  • 1990-02-23 BE BE9000212A patent/BE1003671A3/fr not_active IP Right Cessation
• 1991
  • 1991-02-18 AT AT91903564T patent/ATE111972T1/de active
  • 1991-02-18 WO PCT/BE1991/000011 patent/WO1991013188A1/fr active IP Right Grant
  • 1991-02-18 HU HU9202704A patent/HU212489B/hu unknown
  • 1991-02-18 RU SU915053079A patent/RU2060302C1/ru active
  • 1991-02-18 BR BR919106053A patent/BR9106053A/pt unknown
  • 1991-02-18 PL PL91295790A patent/PL166062B1/pl unknown
  • 1991-02-18 KR KR1019920702014A patent/KR920703875A/ko not_active Application Discontinuation
  • 1991-02-18 DE DE69104188T patent/DE69104188T2/de not_active Expired - Fee Related
  • 1991-02-18 ES ES91903564T patent/ES2065000T3/es not_active Expired - Lifetime
  • 1991-02-18 JP JP3503637A patent/JPH05504171A/ja active Pending
  • 1991-02-18 CA CA002076398A patent/CA2076398A1/fr not_active Abandoned
  • 1991-02-18 EP EP91903564A patent/EP0516652B1/fr not_active Expired - Lifetime
  • 1991-02-19 MY MYPI91000261A patent/MY106554A/en unknown
  • 1991-02-20 YU YU29891A patent/YU47807B/sh unknown
  • 1991-02-22 PT PT96850A patent/PT96850A/pt not_active Application Discontinuation
  • 1991-02-23 CN CN91101198A patent/CN1054277A/zh active Pending
  • 1991-02-25 CS CS91479A patent/CS47991A2/cs unknown
• 1992
  • 1992-08-21 BG BG96809A patent/BG60923B1/bg unknown
• 1995
  • 1995-02-07 SG SG20095A patent/SG20095G/en unknown

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