EP0126220A1 - Pickling solution for metallic surfaces, and its use - Google Patents

Abstract

These are pickling solutions based on halogenated hydrocarbons, which contain small amounts of phosphoric acid as pickling acid and small amounts of water, a lower alcohol as solubilizer and an inhibitor and, if appropriate, an aprotic component and an aldehyde. They preferably contain soluble zinc, manganese or calcium compounds for the purpose of doping the metal surfaces. The pickling solutions can be used with particular advantage during subsequent phosphating in phosphating baths based on halogenated hydrocarbons.

Description

The invention relates to homogeneous organic pickling solutions based on low-boiling halogenated hydrocarbons as the base component, which contain aqueous phosphoric acid and, if appropriate, additionally sulfuric acid as pickling agents, at least one low-boiling alcohol as solubilizer and at least one inhibitor for protecting the bare metal or for reducing the evolution of hydrogen. The pickling solutions according to the invention can contain further activating, complexing or reducing substances.

The organic pickling solutions are used to remove scale and rust layers, especially on unalloyed steels, before further treatment by phosphating and painting.

It is known to remove scale and / or rusty workpieces from the oxide or hydroxide layers by treatment in aqueous pickling baths in order to obtain completely bare surfaces (W. Rausch, EG Leuze Verlag, Saulgau (1974), "Die Phosphating of metals ", pages 25 to 41). The known pickling baths are generally inhibited, aqueous mineral acids, in particular hydrochloric, sulfuric or phosphoric acid (W. Rausch, EG Leuze Verlag, Saulgau (1974), "The Phosphating of Metals" _, pages 25 to 41 ). It works in the concentration range of about 5 to 20 percent by weight and, depending on the pickling acid, in the temperature range between 20 and 95 ° C. As inhibitors that are intended to inhibit the attack on the bare metal, different classes of substances, such as. B. aldehydes, amines, nitrites, sulfoxides, thioureas, thiosemicarbazides and unsaturated alcohols can be used. The pickling times are usually 10 to 30 minutes.

After pickling, the resulting salts must be carefully rinsed off with water. The workpieces must not dry between pickling and phosphating, as they tend to form rust film when they dry. Flash rust, however, hinders subsequent phosphating and leads to poor corrosion protection. It is therefore usually carried out "wet-on-wet" to ensure perfect aqueous phosphating.

The newer phosphating processes based on organic solvents, as described, for example, in DE-AS 26 11 789 and DE-AS 26 11 790, EP-A 34 842, require both rust-free and scale-free as well as dry workpieces. This requirement is achieved with greased workpieces without further surface contamination by simple degreasing, for example with a solvent in the immersion and / or steam process.

In practice, the requirement for freedom from rust and scale is often not met, despite corrosion protection greasing. In these cases, it is necessary not only to degrease the workpiece, but also to remove the rust and scale in a suitable manner.

Aqueous pickling is unsuitable in such cases, since subsequent solvent-based phosphating cannot be carried out "wet-on-wet" and thus formation of flash rust and a drop in corrosion protection cannot be avoided.

However, other than aqueous pickling systems have so far not become known at all.

It was therefore the task of finding a non-aqueous pickling system based on organic solvents, which can remove rust and scale like an aqueous system, and also for phosphating solvent-based system and does not affect the subsequent phosphating itself.

Another task was to find a pickling system which is sufficiently inhibited to avoid excessive metal attack and excessive hydrogen embrittlement of the metal. In addition, corrosion-inhibiting metals such as Mn and Zn should be incorporated into phosphate layers without being limited to rust-free surfaces and certain phosphating bath compositions.

These tasks have been solved by creating a pickling system according to claims 1 to 19.

The fact that H ₃ PO ₄ -containing halocarbons - especially chlorinated hydrocarbons (CHC) - in the presence of a solubilizer can be used as pickling solutions is particularly surprising because it has previously been assumed that such baths only as phosphating with appropriate Phos _- phatschichtbildung can be used. For example, in DE-PS 12 36 301 homogeneous CHP-based phosphating baths with 0.05 to 7.5% H ₃ PO ₄ as a phosphating agent, 0.001 to 1% of a quinone as a hydrogen acceptor and 1 to 10% of one described lower alcohol as a solubilizer, whereby phosphate layer coatings of about 1 to 2 g / m ² are obtained.

According to US-PS 3,338,754 anhydrous homogeneous as possible be _Phos p _ha ti _erb ä on _the C _KW basis with from 0.05 to 6% H ₃ PO ₄ as phosphatierendem agent from 0.001 to 6% inhibitors, such as nitrobenzene, glacial acetic acid and alkylthioureas, 0.001 to 15% stabilizers such as octylphenol, diisobutylene, diethylthiourea, tert. _- Butylpyrocatechin, and 1 to 35% of a solubilizer, such as lower primary alcohols, halogenated alcohols, acetic acid esters, dimethylformamide, etc., are used, with which layer masses of about 300 mg / m ² to about 27 g / m2 have been obtained.

DE-OS 15 71 767 describes practically water-free homogeneous phosphating baths based on CHC with 0.1 to 6% H PO as a phosphating agent, 0.01 to 6% of an organic nitro compound or 0.1 to 0.5% glacial acetic acid and 1, 5 to 25% of a lower alcohol is described as a solubilizer, with which layer coating compositions between about 270 mg / m ² and over 10 g / m ² are obtained.

According to DE-AS 26 11 789 and DE-AS 26 11 790, homogeneous phosphating baths based on CHC contain up to 1% H ₃ PO ₄ as a phosphating agent, 1 to 6% H ₂ 0, generally up to 25% of a lower alcohol as a solubilizer and various additives to accelerators, stabilizers and aprotic compounds. Coating masses of approximately 50 mg / m ² to 3.4 g / m ² can thus be produced. The phosphoric acid concentration should not be raised significantly above 1%, since then sticky phosphate layers form.

EP-A 34 842 contains water-containing homogeneous phosphating baths based on CH ₂ Cl ₂ with up to 2% H ₃ PO ₄ , with 1 to 10% H ₂ 0, with 10 to 50% of a lower alcohol with the addition of small amounts of anionic or amphoteric surfactants and accelerators, such as dinitrotoluene, urea or thiourea, with which phosphate layers of different quality are produced.

On the basis of the descriptions given, it can therefore be concluded that the treatment of metal surfaces with homogeneous mixtures of a chlorinated hydrocarbon as the main solvent, a lower alcohol as a solubilizer and aqueous H ₃ PO ₄ different water contents with the addition of various additional components always leads to more or less thick phosphate coatings of different quality .

Since the aim of pickling is to remove only rust or scale and, on the other hand, to avoid attacking the bare metal surface and, if possible, not forming a layer on the metal surface, it was not to be expected that mixtures of the aforementioned type in a suitable composition would also be used as pickling baths without significant layer formation can be used.

The pickling baths according to the invention are homogeneous solutions which should consist or may optionally consist of the components mentioned below. The salary information is given in percent by weight.

All halogenated hydrocarbons which are also suitable and known for degreasing and phosphating baths can be used as main solvents, i.e. in particular chlorinated hydrocarbons and chlorofluorocarbons, such as CH ₂ Cl ₂ , CHCl ₃ , CHCl = CCl ₂ , CCl ₂ = CCl ₂ , CH ₃ CCl ₃ , C ₂ H ₃ Cl ₃ , C ₂ H ₂ Cl ₄ , C ₂ H ₄ Cl ₂ , C ₂ H ₂ Cl ₂ , C ₂ F ₄ Cl ₂ , C ₂ F ₃ Cl ₃ , CHF ₂ Cl ₃ , C ₂ F ₂ Cl ₄ and CFC1 ₃ .

It is expedient to use the solvent for the pickling bath which is also used for degreasing and / or phosphating the metal surface. If the metal surface is degreased with -CH ₂ Cl ₂ and with a phosphating bath based on CH ₂ Cl ₂ - such as. B. in DE-AS 26 11 790, EP-A 34 842 - phosphated, then it is appropriate to use CH ₂ Cl ₂ for the pickling bath. The CH ₂ Cl ₂ content, for example, should be between 50 and 85%, preferably between 50 and 75%.

Low boiling alcohols with 1 to 4 carbon atoms, such as methanol, ethanol, isopropanol, propanol, butanol, sec-butanol, tert. -Butanol, their derivatives, such as. B. chloroethanol, and mixtures thereof. Methanol, ethanol or isopropanol are preferably used as solubilizers. The salary of solubilizers should be chosen at least so high that a homogeneous pickling solution is created. The content to be selected depends both on the solubilizer itself and on the acid and water content in the pickling solution. Experience has shown that the content of solubilizers is between 10 and 30%, but can also be up to about 40%.

Either only phosphoric acid or preferably a mixture of phosphoric and sulfuric acid is used as the pickling agent or pickling acid. Other mineral acids and organic acids, preferably formic acid, can also be admixed. The total acidity should be around 2 to 10%, preferably around 3 to 7%. The weight ratio of phosphoric acid to other mineral acid or organic acid should be 1: 2 to 5: 1.

The pickling baths according to the invention also contain water in order to better keep the salts formed in the pickling process in solution. The water content can be both smaller and larger than the total acid content. It is generally between 1 and 10%, preferably about 2 to 6%.

Another necessary component of the pickling baths according to the invention is at least one component acting as an inhibitor, which has the task of suppressing the pickling attack on the bare metal and thus the acid-consuming hydrogen evolution. Thiourea and alkylated thioureas have proven suitable for this. The excellent inhibitory effect of this class of substances in organic pickling baths based on halogenated hydrocarbons is surprising in that this class of substances has already been described in organic phosphating baths based on halogenated hydrocarbons with the opposite effect. For example, DE-AS 26 11 789, DE-AS 26 11 790 and described in EP-A 34 842 urea and thiourea as accelerators to increase the rate of formation of a phosphate coating. In addition, for example in US Pat. No. 3,281,285, US Pat. No. 3,220,890, US Pat. No. 3,297,495 and in DE-AS 12 93 522 alkylated thioureas are also used as stabilizers for organic phosphating solutions and as improvers for the condition of the phosphate layer described. It is therefore completely surprising that this class of substances in the pickling baths according to the invention inhibits the attack on the metal and thus the formation of a phosphate layer. In principle, all known alkylated thioureas have proven to be suitable. N, N '- ethylene thiourea, diethylthiourea and hydroxyethyl-N' - allylthiourea are particularly effective. This substance class is used in a concentration of 0.001 to 0.2%, preferably 0.01 to 0.1%; used. Protection values of over 80% are achieved with these inhibitors, protection value S according to DIN 50 940 as

• mit U = Masseverlust eines rostfreien Werkstückes im Beizbad ohne Inhibitor
• V = Masseverlust eines rostfreien Werkstückes im Beizbad mit Inhibitor

definiert ist.

• with U = loss of mass of a stainless workpiece in the pickling bath without inhibitor
• V = loss of mass of a stainless workpiece in the pickling bath with inhibitor

is defined.

However, other classes of substances are also suitable as inhibitors. Unsaturated alcohols such as allyl alcohol, methallyl alcohol, preferably butynediol or aldehydes such as acetaldehyde, glyoxal, glycol aldehyde are also preferred Formaldehyde, effective, although generally higher contents of about 0.1 to about 1% are used. All inhibitors can also be used in a mixture, which may result in synergistic improvements in the inhibitor effect.

In addition to the above-mentioned main components of the pickling baths according to the invention, these can contain further additives which have a favorable effect on the pickling action, the necessary pickling time and the subsequent phosphating.

For example, the pickling effect is increased by adding aprotic compounds, such as, for example, carboxylic acid esters, preferably methyl formate. The addition amounts are i. a. at about 0.3 to about 3%, but can also be higher. In addition, the pickling baths according to the invention can also contain reducing compounds, such as aldehydes, hydroquinones, preferably formaldehyde. These reducing compounds are particularly advantageous if there is a drying process between pickling and phosphating. This suppresses the formation of flash rust. This protective effect already takes place at concentrations from approximately 0.1%, preferably concentrations between 0.1 and 1% are selected.

Furthermore, soluble zinc, manganese or calcium compounds are added for the purpose of doping the metal surfaces. The concentration of the soluble zinc, manganese or calcium compounds expediently ranges from 0.01 weight percent to the solubility limit.

Orthophosphates, sulfates, formates or alcoholates are preferably used as soluble zinc, manganese or calcium compounds.

The pickling solutions are used to pickle and activate both rusted and stainless steel surfaces simultaneously and to produce a thin Zn or Mn salt film on the stainless surface. The purpose of this measure is to use the metal salt film for doping a phosphate layer to be subsequently applied and thus to improve the corrosion protection properties of the phosphate layer.

The above-described pickling baths are generally used in immersion processes, i. H. scaled and / or rusty workpieces are immersed in the pickling bath until the scale or rust layer is removed. Depending on the selected temperature, which can range from room temperature to the boiling point of the pickling bath, experience shows that depending on the degree of rusting, the pickling times are between about 5 and 30 minutes. In the case of pickling below the boiling point of the pickling bath, it may be expedient to support the pickling removal mechanically, for example by stirring the bath or using ultrasound.

The pickling can also be carried out by spraying, although combinations of dipping and spraying can also be advantageous when it comes to removing particularly stubbornly adhering rust. It has been shown that the oxide layer adhering directly to the metal is easiest to dissolve and the overlying layers also fall undissolved into the pickling bath if the pickling is supported by mechanical forces such as occur when the pickling bath is sprayed and circulated.

In order to achieve good phosphating results, ie to achieve phosphate layers with a high level of corrosion protection, it may be expedient to connect a washing immediately after the pickling, which serves to remove any troublesome addition salts. The washing solutions preferably also consist of the components that are in the Pickling bath are present, but do not contain pickling acids. The washing can be carried out either by immersion or by spraying at room temperature up to the boiling point of the washing solution.

With simultaneous doping, the procedure is to apply the desired metals by dipping or spraying with a suitable metal-containing, corrosion-inhibiting, pickling treatment bath, also called doping bath, before the phosphating as a thin layer on the metal surface and this only after the subsequent phosphating incorporates chemical fixation into the phosphate layer. According to the invention, non-aqueous pickling baths based on low-boiling halogenated hydrocarbon are used as doping baths, but they additionally contain the desired corrosion-inhibiting metals (Zn, Mn etc.) in the form of dissolved compounds. In this way, both rusted and rust-free surfaces can be stained or immersed at the same time in the immersion or spraying process. activated and coated with a foreign metal salt film after the bath has dried.

The advantage of the pickling baths according to the invention and their use is that now scaled and rusted workpieces can also be fed to a phosphating process in a phosphating bath based on an organic solvent, which was previously not readily possible. In addition, these pickling baths can also be used as activation baths for bare metal surfaces, since phosphating after pickling gives better results.

Low-carbon, cold-rolled deep-drawn sheet metal St 1405 with the dimensions 10 x 20 cm, which were greased in a commercially available manner for the purpose of tempered corrosion protection, were used as test workpieces for carrying out the test examples. For the pickling tests, the sheets were first degreased in a commercially available metal degreasing bath and then degreased and then exposed to rust for several days in order to obtain typical rust surfaces with rust layers of 3 to 10 g / m2. For comparative investigations, the same stainless steel sheets were used immediately after degreasing, both for pickling and for direct phosphating. A heated jacket was used as the pickling vessel, which was provided with cooling coils at the upper edge to prevent evaporation losses from the pickling bath and with a lid with a passage for a diving device.

Typical compositions - as explained in more detail in the examples - were selected as pickling baths.

As a rule, after the pickling treatment, the sheets were subjected to phosphating in accordance with German patent application 32 09 828.6 in order to test the influence of the pickling on a subsequent phosphating.

The following examples are intended to explain the pickling baths according to the invention and their use in more detail.

example 1

After degreasing, a series of steel sheets of the type described were exposed to a two- or six-day outdoor weathering in an industrial atmosphere, resulting in all-over rust layers with mass increases of about 3 to 6 g / m ² . After rusting for several days in normal room air, the rusted sheets were subjected to pickling by immersion in a pickling bath boiling at 38 ° C. of the following composition:

70% CH ₂ Cl ₂ , 23% CH ₃ OH, 3, 0% H ₂ 0, 5% methyl formate, ^2, 5% H ₃ PO ₄ , 1% H ₂ SO ₄ and 0, 03% N, N -Ethylene thioharn fabric.

The degree of protection of the pickling bath determined by preliminary tests was 91%.

After a pickling time of 20 minutes, the sheets were rust-free and bare, without a visible phosphate layer having formed. After washing immediately in a washing bath consisting of the components of the pickling bath without the addition of acid and inhibitor, the sheets were phosphated.

In comparison, both non-rusted sheets of pickling and phosphating as well as rusted and non-rusted sheets without pickling were subjected to phosphating. The resulting increases in mass due to the phosphating with formation of appropriate phosphate protective layers are listed in Table 1. The phosphate protective layers were subjected to a water solubility test of the following type: The dried, phosphated sheets were immersed in demineralized water for 10 minutes at room temperature and the decrease in mass was determined by weighing before and after the immersion with subsequent drying.

The table initially shows that rusted metal sheets only provide a defined phosphate coating with a uniform appearance after pickling. Rusted, unpickled metal sheets cannot be phosphated directly. In addition, it follows that pickling leads to a significant increase in the phosphate layer structure with a consistently low water solubility of the phosphate layer. The fact that even stainless steel sheets can be phosphated better after pickling shows that pickling is not necessary for rustproof workpieces, but has a positive effect on phosphating. In this respect, the pickling can also be used as an activating pretreatment for rusted and stainless steels.

Example 2a

Rustproof and rusted metal sheets of the type described in Example 1 were pickled in the boiling pickling bath of the following composition for 15 minutes until rust-free: 50% CH ₂ Cl ₂ , 18% CHCl ₃ , 15% CH ₃ 0H, 10% isopropanol, 2, 8% H ₂ 0, 3% H ₃ PO ₄ , 1% H ₂ SO ₄ , 0, 2% HCHO and 0, 05% diethylthiourea.

The degree of protection determined by preliminary tests was 88%.

The pickled sheets did not have to be washed immediately after pickling as in Example 1, since the addition of aldehyde effectively prevented the formation of flash rust.

After phosphating in accordance with Example 1, the originally rusted metal sheets resulted in phosphate layer coatings of 2.5 g / m ² and the original stainless metal sheets an average of 2.0 g / m ² . The phosphate layers had a uniform gray appearance. The water solubility was below 5%. It is thus shown once again that pickling is necessary for rusted sheets, but pickling is also advantageous for stainless sheets.

Example 2b

In a parallel experiment, the pickling bath of Example 2a was also used in the spraying process for rust removal. The pickling bath was pulsed onto the sheet at 32 ° C at a pre-pressure of 1.5 bar using a diaphragm pump in a circulating process. Rust was reached after 15 minutes. With subsequent phosphating, phosphate layer coatings of about 2.5 g / m ^{2 have been} achieved.

Example 3

Rusted sheets of the type described in Example 1 were pickled in the boiling pickling bath of the following composition until rust-free for 30 minutes: 52.5% 1, 1, 2-trichlorotrifluoroethane, 40% CH ₃ OH, 4.8% H ₃ PO ₄ , 0.4% HCOOH, 2.0% H ₂ 0.0, 3% HCHO and 0.01% hydroxyethyl-N '-allylthiourea.

A degree of protection of 87% was determined by preliminary testing.

After washing, the sheets were phosphated as in Example 1. A uniform gray layer of phosphate on average of 1,600 mg / m ^{2 was} produced. The water solubility of the layer was <5%.

Example 4a

Rusted metal sheets of the type described in Example 1 were pickled in the boiling pickling bath of the following composition until rust-free for 10 minutes: 64.5% CH ₂ Cl ₂ , 22.5% CH ₃ OH, 4.2 H ₂ 0.3% Formic acid methyl ester, 3.5% H ₃ PO ₄ , 1.5% H ₂ SO ₄ , 0.5% butynediol and 0.3% formaldehyde.

A degree of protection of 85% was determined by preliminary testing.

After washing, the sheets were phosphated as in Example 1. A uniform gray layer of phosphate was achieved on average of 1 900 mg / m ² .

Example 4b

In a parallel experiment, the immersion method was also used in the non-boiling pickling bath with the composition of Example 4a rusted sheets stained. Rust resistance was reached after 15 minutes with mechanical stirring of the bath.

Example 5a

Rusted sheets of the type described in Example 1 were pickled in the boiling pickling bath of the following composition until rust-free for 20 minutes: 58% trichlorethylene, 16% C ₂ H ₅ OH, 16% CH ₃ 0H, 4% H ₃ PO ₄ , ¹ % H ₂ SO ₄ , 4% H ₂ 0, 1% methyl formate and 0, 02% N, N '-thylenethiourea.

A degree of protection of 85% was determined by preliminary testing.

After washing, the sheets were phosphated as in Example 1. A uniform gray layer of phosphate on average of 1,600 mg / m ^{2 was} achieved.

Example 5b

In a parallel test, rusted sheets were also pickled using the immersion method in the non-boiling pickling bath with the composition of Example 5a. Rust was achieved after 35 minutes with mechanical stirring of the bath.

Example 6

This example shows the particular advantages of adding soluble Zn and Mn compounds for the purpose of doping. The main experimental and comparative examples are summarized in the form of an overview.

A pickling bath with 70% CH ₂ Cl ₂ , 23% CH ₃ OH, 3, 0% H ₂ 0, 0, 5% methyl formate, 2, 5% H ₃ PO ₄ , 1% H ₂ SO ₄ and 0 was used as the doping bath , 03% N, N'-ethylene thiourea with the addition of 0.1% ZnSO ₄ · 7H ₂ 0 or 0, 1% MnSO ₄ · H20. By comparison, such a pickling bath without additives was also used. The tests with the Zn- and Mn-containing pickling baths were carried out both with rust-free and with rusted metal sheets. The duration of treatment in the boiling pickling and doping baths was a uniform 20 minutes.

In addition, a degreased sheet without prior pickling was subjected to a technically customary zinc phosphating, in which a layer coating of 2,500 mg / m ^2, which was customary for this phosphating, was obtained.

After the pickling or doping treatment, the sheets were coated in the same way as a non-aqueous phosphating and then all the sheets were coated in the same way with a commercially available two-component stoving enamel by spraying.

This was followed by a 1,000 h salt spray test in accordance with DIN 53 167 in conjunction with SS DIN 50 021 for determining the rust penetration, whereby the degree of blistering according to DIN 53 209 and the edge rust according to DIN 53 230 were examined at the same time.

Die Ergebnisse der Tabelle 2 zeigen, daß die beizende Zink- bzw. Mangandotierung gegenüber einer reinen Beizung eine deutliche Verbesserung bei der Rostunterwanderung, aber auch beim Blasengrad und Kantenrost bewirkt. Dabei ist es unerheblich, ob die Prüfbleche vor der Behandlung rostfrei oder angerostet waren.The results of this series of tests are summarized in Table 2. The values in brackets apply to rusted sheets.

The results of Table 2 show that the pickling zinc or manganese doping brings about a significant improvement in the rust penetration, but also in the degree of blistering and edge rust, compared to a pure pickling. It is irrelevant whether the test sheets were rust-free or rusty before the treatment.

An improvement in the infiltration of rust and in a conspicuous manner also in the degree of blistering is also achieved compared to a commercially available zinc phosphating.

Example 7

The procedure was as in Example 6, with the difference that the pickling bath instead of ZnSO ₄ .7H20 now 0.1% Zn (OOCH). 2H ₂ 0 was added.

The results obtained with rust-free and rusted metal sheets after pretreatment, phosphating and painting correspond to those of column 3 in table 2.

Claims (19)

1. Pickling solutions for pickling and activating metal surfaces,
characterized,
that it is organic homogeneous, low-water pickling solutions with halogenated hydrocarbons as the base solvent, aqueous phosphoric acid as the pickling agent, at least one alcohol as a solubilizer and at least one inhibitor to protect the bare metal. 2. pickling solution according to claim 1,
characterized,
that the halogenated hydrocarbon is dichloromethane, trichlorethylene or trichlorotrifluoroethane. 3. pickling solution according to claims 1 and 2,
characterized,
that the base solvent is used in a concentration range between 50 and 85%. 4. pickling solution according to claims 1 to 3,
characterized,
that in addition to phosphoric acid, another inorganic or organic acid is used as the pickling agent. 5. pickling solution according to claims 1 and 4,
characterized,
that the total content of pickling agent is between 2 and 10%, preferably between 3 and 7%. 6. pickling solution according to claim 1,
characterized,
that the alcohols used as solubilizers are low-boiling C ₁ to C ₄ alcohols. 7. pickling solution according to claims 1 and 6,
characterized,
that the solubilizer is used in a concentration range of 10 to 40%. 8. pickling solution according to claims 1 to 7,
characterized,
that substituted thioureas are used as inhibitors. 9. pickling solution according to claims 1 to 8,
characterized,
that unsaturated alcohols are used as inhibitors. 10. pickling solution according to claims 1, 8 and 9,
characterized,
that the inhibitors are used in a concentration range from 0.001 to 1%. 11. pickling solution according to claim 1,
characterized,
that the pickling solution contains water in an amount of about 1 to 10%, as long as the pickling solution remains homogeneous. 12. pickling solution according to claims 1 to 11,
characterized,
that this pickling solution contains aprotic compounds as additives. 13. pickling solution according to claim 12,
characterized,
that the aprotic component is present in a concentration range from about 0.3 to about 3%. 14. pickling solution according to claims 1 to 13,
characterized,
that it contains an aldehyde in a concentration range of 0.1 to 1%. 15. pickling solution according to claims 1 to 14,
characterized,
that soluble zinc, manganese or calcium compounds are added for the purpose of doping the metal surfaces. 16. pickling solution according to claims 1 to 15,
characterized,
that the concentration of soluble zinc, manganese or calcium compounds ranges from 0.01 weight percent to the solubility limit. 17. pickling solutions according to claims 1 to 16,
characterized,
that orthophosphates, sulfates, formates or alcoholates are used as soluble zinc, manganese or calcium compounds. 18. Use of the organic pickling solution according to claims 1 to 17,
characterized,
that they are allowed to act on rusted or scaled steels in the immersion and / or spraying process at room temperature until the boiling point of the pickling solution until the rust or scale layer is removed. 19. Use of the organic pickling solution according to claims 1 to 17,
characterized,
that they are allowed to act on stainless workpieces to activate the surface and improve the phosphatability in immersion and / or spraying processes at room temperature up to the boiling point of the pickling solution.