BE1025372B1 - ADJUSTING ECOMAIL ON STEEL - Google Patents

Abstract

The invention covers enamel compositions which, in the absence of the known adhesion oxides of the elements Co, Ni, nevertheless give excellent adhesion to iron alloy surfaces. More particularly, the invention relates to new enamel compositions based on oxides of the elements Mo, Sb, Cu, Sn, W and Bi with which good adhesion can be obtained on sheet steel under the normal processing parameters that are customary in the enamel learning process.

Description

BE2017 / 5973 ASSISTING ECOMAIL ON STEEL

FIELD OF THE INVENTION

The invention is in the field of glassy enamel coatings, more particularly of glassy enamel coatings for steels. The invention provides a method for obtaining the adhesion between the coating and the steel, without oxides of the heavy metals Co and Ni. More in particular, the invention relates to an enamel composition with the oxides of Mo, Sb, Cu, Sn, Bi and W as the most important elements for achieving adhesion with the steel.

BACKGROUND OF THE INVENTION

Email has been used as decorative material for more than 4500 years. Enamelling became industrialized in the 19th century. The glassy enamel coatings are mainly used to protect the surface against external damage (corrosion, scratches, etc.) while at the same time having a decorative aspect. Enamel can be classified as a glass because of its composition that is primarily based on silica (> 30%) and a number of other oxides, such as boron oxide, sodium oxide, potassium oxide and other oxides, which are cross-linked to a three-dimensional network. The formulation of the email may differ depending on its use. Moreover, it is well known in the art that glassy enamel has very special properties that differ in many aspects from other coatings.

In general, the enamel process involves applying to the steel object a dark-colored primer that contains at least the Co or Ni bonding oxides. The strong bond between the metal surface and the enamel is the result of complex responses to the phase boundary between metal and enamel during the burn-in, usually at a temperature in the range of 760 ° C to 860 ° C. If a final finish with a white or light color is desired, it is necessary to use a so-called top layer, which consists of white enamel, semi-opaque enamel or transparent enamel with pigments, and which is applied and burnt on top of the dark adhesive base layer.

There is also another industrially used enamel process that uses an electroless nickel-plated steel surface as a base. During firing, an Fe-Ni-Ti type bonding intermetallic layer is formed at the interface between steel and enamel, with Ti coming from the used frit and Ni from the metallic Ni layer on the steel.

To avoid the hazardous substances CoO / Co ₃ O ₄ and NiO / Ni, new enamel coatings have been developed that, without the use of these substances, still lead to good adhesion. The invention includes both ground e-mails which provide adhesion without chemical resistance and are therefore usually used as a base layer above which a chemical-resistant cover e-mail layer is applied, as well as direct e-mails which provide both adhesion and chemical resistance.

BE2017 / 5973 SUMMARY OF THE INVENTION

This invention describes a way to realize the adhesion of enamel on steel or iron alloy substrates without adding the usual adhesion oxides (from Co and Ni) and without having to apply a layer of nickel to the substrate.

More in particular, the invention relates to enamel coatings which are the only adhesive oxides containing one or more of the oxides of Mo, Sb, Cu, Sn, Bi and W.

In particular, the invention relates to enamel coatings in which one or more of the oxides of Mo, Sb, Cu, Sn, Bi and W are added during the melting of the enamel frits which are subsequently used as the main component in the enamel coating.

Enamelling contains 2 heat treatments. The first, which takes place at the enamel producer, involves melting a homogeneous raw material mixture into a glass melt, which is then quenched between cooled rollers (where flakes are obtained) or in water (where granals are obtained). These flakes and grains are also often described as frit, or email frit. This heat treatment is called melting.

The second heat treatment is that at the producer of the enamelled articles. Here, the applied sludge or powder layer, which consists of ground enamel frit and other additives, is burned onto the metal substrate after a drying process, resulting in a homogeneous enamel coating. This heat treatment is called burn-in.

In the invention, the said oxides can thus be added during the first or during the second heat treatment. Or also during both heat treatments.

In particular, this invention says that Mo-containing enamel frits, Mo + Sb-containing enamel frits, Mo + Cu + Sn-containing enamel frits, Mo + Cu + Bi-containing enamel frits and Mo + W-containing enamel frits lead to good adhesion to steel. This adhesion is achieved by using one or more of the aforementioned frits in sludge or powder that, after application on steel, is burned in at the usual temperatures of 760 ° C to 860 ° C and for times of 3 to 8 minutes at these temperatures. Sheet steel from 0.5 to 1.8 mm is used for this. When using thinner or thicker steel objects, the burn-in temperature and burn-in time must be adjusted. For example, it has been found that good adhesion (1 according to European standard EN10209) is already achieved after burning in for 2 minutes at 780 ° C on 0.35 mm steel plate.

More specifically, the invention relates to a Mo-based frit composition, wherein the adhesion between the enamel coating in which this frit is used as the main component, and the steel is established by a reaction of Mo with Fe of the steel.

The reaction can be enhanced by the addition of oxygen-producing oxides, the element Sb being very important. And this in all ratios between Mo-oxide and Sb-oxide. The use of Fe oxides in the frit also promotes the aforementioned reaction, both in combination with Sb oxide as well as without Sb oxide.

BE2017 / 5973 By adding the oxides of Ti and Zr to the frit and / or by using higher levels of Si, a chemically resistant frit can be obtained that can be used not only for adhesion purposes in an enamel coating, but also for obtaining a chemical resistant enamel coating.

This means that this series of email frits of this invention can be used in one-layer enamel coatings for food contact and drinking water contact.

The enamel coatings made with these frits also meet all the traditional quality requirements set by the European Enamel Authority (EEA quality manual).

The addition of compounds (oxidic and others) of Mo, Sb, Cu, Sn, Bi and W in the sludge or powder to which the articles are enamelled leads to a better reaction between the Mo from the enamel coating and the Fe from the steel . The following components that improve the adhesion reaction with Fe can also be used in the sludge or powder: SiB ₆ , Si ₃ N ₄ , AIN, B ₄ C, MgB ₂ , urea, NaNO ₂ , BaNO ₃ . Other components that have an influence on the redox reactions that take place at the interface can also be added.

Microscopically and electron microscopically it could be demonstrated that the excellent adhesion obtained with the invented frits is indeed indeed based on chemical reactions. At the start of the burn-in of the enamel layer on the steel article, an oxidation of the steel surface occurs, and in a subsequent phase chemical reactions occur between the iron of the steel plate, the iron oxides formed during the first phase (and optionally the added iron oxides in the enamel coating), and the added adhesion elements Mo, Sb, Cu, Sn, Bi and / or W in the enamel coating. This results in metallic alloys that develop into dendrites / anchor points at the steel / email interface, in the email coating. This ensures a very good adhesion of the enamel coating. In addition, there is also a mechanical adhesion of the enamel coating with the steel due to the original roughness of the steel surfaces and due to the roughness that results from the oxidation in the first phase of the burn-in.

Both chemical bonding (alloy formation between steel and enamel coating) and mechanical bonding lead to good bonding between the enamel coating of this invention and the steel.

By using higher levels of alkali and alkaline earth elements, by making use of F and by making use of P, the adhesion can be positively influenced, whereby the same excellent adhesion can be achieved when using lower burn-in temperature and / or or shorter burn-in time.

The addition of the oxides of Mo, Sb, Cu, Sn, Bi and / or W in the enamel coating can be done by using the oxides themselves or other compounds of these elements which are wholly or partially during melting or burning in be converted to oxides with a certain valence of the element and / or react with the other components or the steel.

BE2017 / 5973 For Mo, use is preferably made of Mo, MoO ₂ , MoO ₃ , sodium molybdate, calcium molybdate, bismuth molybdate, cerium molybdate, ammonium molybdate, lithium molybdate, barium molybdate, antimony molybdate, tin molybdate sodium antimony molybdate or potassium antimony molybdate or combinations thereof.

Although the use of the frits of this invention provide good adhesion between the enamel coating in which they are used and steel, the addition of the classic adhesion oxides Co and Ni can be used to color in the frits.

The frits of this invention based on the elements Mo, Sb, Sn, Bi and / or W are transparent to semi-opaque. The frits of this invention based on the above elements and Cu are slightly darker and greener. By adding strong-coloring metal oxides, a melt-colored frit can be obtained. The presence of these metal oxides is primarily intended for coloring the frit (eg Co-blue frit). In addition to Co and Ni, other coloring oxides can be added, including the oxides of Mn, Fe, Cr, Ce, Pr, Nd, Er to color in the frit. The influence on the adhesion is a side effect.

The enamel coating can also be colored by using inorganic dyes and pigments during the grinding of the sludge or the powder.

A crystallization of components from the frits of this invention can be used to obtain an opaque frit. The crystallization of TiO ₂ and ZrO _{2 in particular} during the burn-in process is important here.

The sludge or powder can be applied to the metal substrate by all possible methods, in particular by wet dipping, flow coating, spraying, wet electrostatic coating, electrophoretic coating, powdering or electrostatic powder coating (POESTA), or combinations thereof.

The sludge or powder can also be used on a pre-treated steel surface, where both mechanical and chemical pre-treatment can be used. As chemical pre-treatment of the steel surface, particular use is made of degreasing, pickling, chemical conversion layers, metallic coatings and / or solgel layers.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1: SEM image of the interface of a sample of enamelled steel, with the enamel coating as its main component being an Mo + Sb containing enamel frit. The magnification is 1000X. The anchor points stand out clearly and contain Mo, Sb, Fe. The roughness of the steel surface created during the burn-in process is also striking. Both clearly show the strong interactions / reactions between the enamel layer and the steel surface during the burn-in.

BE2017 / 5973 DETAILED DESCRIPTION OF THE INVENTION

As used in this application, the singular forms include the, the, and both the singular and plural references unless the context clearly dictates otherwise.

The terms comprising, including and consisting of, as used in this application, are synonymous with including, containing or containing and are inclusive or with an open end and do not exclude additional unnamed members, elements or method steps. The terms also include consisting of and consisting essentially of, which have well-known meanings in patent terminology.

The indication of numerical ranges with endpoints includes all numbers and fractions that fall within the respective ranges, as well as the stated endpoints.

The terms approximately or approximate, as used in this application when referring to a measurable value such as a parameter, an amount, a duration, and the like, are intended to include variations on and from the specified value, such as variations of +/- 10% or less, preferably +/- 5% or less, more preferably +/- 1% or less and even more preferably +/- 0.1% or less of the specified value, if such variations are appropriate to use in the described invention. It should be understood that the value to which the modifier approximately refers is also specific and preferably described.

Although the terms one or more, one or more or at least one such as one or more members or at least one member of a group of members are per se obvious, the terms include, by way of further explanation, a reference to any member of said members or to any two or more of said members, such as any 2, 3, 4, 5, 6, 7 etc. of said members, and to all said members. In another example, one or more, one or more or at least one may refer to 1, 2, 3, 4, 5, 6, 7 or more.

The discussion of the background of the invention in this application is included to explain the context of the invention. This is not to be considered as admitting that any material referred to has been published, known or part of the general knowledge in any country since the priority date of any of the claims.

Unless defined otherwise, all terms used in describing the invention, including technical and scientific terms, have the meaning as generally understood by one of ordinary skill in the art to which this invention belongs. By way of further guidance, the definitions of the terms are included to better understand the teachings of the invention. When specific terms are defined in connection with a specific aspect of the invention or a specific embodiment of the invention, this meaning is meant to apply throughout this description, ie also within the context of other aspects or embodiments of the invention, unless defined differently.

BE2017 / 5973 In the following passages, various aspects or embodiments of the invention are defined in more detail. Any aspect or embodiment defined in this manner can be combined with any other aspects or embodiments, unless the contrary is clearly indicated. In particular, any feature that is designated as preferred or advantageous can be combined with any other feature or any other features that are designated as preferred or advantageous.

Reference throughout this description to one embodiment, an embodiment means that a specific feature, specific structure or feature described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the terms in one embodiment or in an embodiment at different places throughout this description do not necessarily all refer to the same embodiment, but it could. Furthermore, the specific features, structures or properties can be combined in any suitable manner in one or more embodiments, as would be apparent to one skilled in the art from this disclosure. Moreover, while certain embodiments described in this application include certain features included in other embodiments but others are not, combinations of features of different embodiments are intended to fall within the scope of the invention and to form different embodiments, as would be apparent to experts in the field. For example, in the appended claims, any arbitrary embodiments according to the claims can be used in any combination.

The term frit includes, as used in this application, the grains or flakes obtained by melting (or fritting) the mixed enamel components at a characteristic temperature between 1100 and 1500 ° C at which a glass structure is formed, followed by cooling of said molten glass to room temperature, usually between cooling rolls or with water.

The term enamel includes, as used in this application, the enamel composition obtained by grinding the frit in combination with additives and dyes or pigments.

The terms email, glassy email, porcelain email and email composition are used as synonyms in this application. Enamel is a substantially glassy material, obtained by melting or fritting a mixture of inorganic materials, which is then applied to a metal substrate in the form of a suspension in water or a dry powder, in one or more layers, and is chemically and physically bonded to the metal substrate when heated to a temperature sufficient for fusion to take place (burning). According to EN 1900, enamel is a substance, resulting from the melting or sintering of inorganic constituents, and designed to form a surface layer that is fused or can be fused, in one or more layers, and whose burning temperature is higher than 500 ° C.

The term enamel is the manufacturing process of the enameled object.

BE2017 / 5973 The term burning includes the heating step that allows the enamel to eventually react with and adhere to the surface of the substrate.

This changes the enamel composition from a cake (powder) to a glassy layer. Burning usually takes place in specific types of furnaces, such as chamber ovens, loading ovens, tunnel ovens, ovens with conveyor belts, continuous ovens, with U or L-shaped heating chambers. It is important that the ovens have an even heat distribution in the room, with as few temperature fluctuations as possible as a function of time and position in the room.

Applying the enamel includes all possible techniques for applying enamel to the substrate, such as, but not limited to: wet dipping, coating coating, spraying, wet electrostatic coating, electrophoretic coating, powdering or dipping, electrostatic powder coating (POESTA) or combinations thereof.

The term adhesion includes the durable connection between the enamel layer and its substrate and is the result of complex reactions at the interface between metal and enamel. Testing the adhesive strength of the porcelain enamel and glassy enamel coating should be performed using the methods specified in EN 10209. In essence, such a test determines the damage caused by a weight that falls on the enamelled surface. This damage is assigned a score of 15 between 1 and 5, where 1 indicates very good adhesion and 5 indicates poor adhesion.

The term adhesion oxides includes oxides that provide adhesion between the substrate and the enamel, as a result of reactions during burning of the enamel on the substrate. The classically known bonding oxides are those from Co and Ni. This invention describes that other bonding oxides also exist. In addition to providing adhesion, these oxides can also be used to color the enamel layer. However, if the sole purpose of the oxide is to color the enamel layer, we do not consider it an adhesive oxide.

The term contains as sole adhesion oxides as used herein intends to exclude other adhesion oxides, more specifically the known adhesion oxides Co and Ni. This means that no Co or Ni is added to the frits. Because it cannot be excluded that a frit may accidentally contain a minimal (trace) amount of Co or Ni, the expression is considered to mean that the frit contains less than 0.1% CoO or NiO.

The term adhesion oxides and oxides includes not only the pure oxides of the said elements, but also other compounds of these elements that are added to arrive at the reactions with the substrate that cause the adhesion between steel and enamel.

The term substrate and steel are used interchangeably, and this defines all Fe metals. Lamellar gray cast iron, ferritic stainless steel, austenitic stainless steel and C-Μη steel are generally used for enamelling. For C-Μη sheet steel, use is often made

BE2017 / 5973 made from standard steel that is specially produced for enamelling; standard EN 10209 is most commonly used for this in Europe.

The enamel frit compositions (expressed in oxides) of this invention can be classified into the following groups:

Group 1: Mo / Cu / Sn

These frits contain 0.1-10% (CuO + Cu ₂ O) and / or 0.1-10% (SnO + SnO ₂ ) and 0.1 - 10% MoO ₃ .

In particular, these frits contain 0.5-5% (CuO + Cu ₂ O and / or 0.2-4% (SnO + SnO ₂ ) and 0.2 - 3%

MOO3, such as 1-5% (CuO + Cu ₂ O) and 0.5 - 2.5% (SnO + SnO ₂ ) and 0.5 - 2.5% MOO3.

More specifically, these frits contain 3-5% (CuO + Cu ₂ O) and / or 0.5-1.5% (SnO + SnO ₂ ) and 0.5 1.5% MOO3.

In addition to these ranges that ensure adhesion, the frits contain the following levels of other components.

Oxide m% Oxide m% Oxide m% AI ₂ O ₃ 0.5-10.0 Fe ₂ O ₃ 0.0-5.0 SiO ₂ 30.0 - 60.0 B ₂ O ₃ 0.5-20.0 K ₂ O 0.0-7.0 SrO 0.0-3.0 BaO 0.0-5.0 Li ₂ O 0.0-3.0 TiO ₂ 0.0-6.0 CaO 0.0-6.0 N32O 5.0-20.0 ZnO 0.0-5.0 F " 0.0-7.0 p ₂ 0 ₅ 0.0-7.0 ZrO ₂ 0.0-5.0

This list is not exhaustive. The presence of other levels of these oxides or the presence of other oxides will also lead to good adhesion based on the presence of the oxides of Mo / Cu / Sn.

Group 2: Mo / Cu / Bi

These frits contain 0.1-10% (CuO + Cu ₂ O), 0.1 and / or 15% Bi ₂ O ₃ , 0.1 and 10% MOO3

In particular, these frits contain 0.5-8% (CuO + Cu ₂ O) and / or 0.5-10% Bi ₂ O ₃ and 0.5-8% MOO3.

More specifically, these frits contain 0.5-5% (CuO + Cu ₂ O) and / or 0.5-8% Bi ₂ O ₃ and 0.5-5% MOO3.

In addition to these ranges that ensure adhesion, the frits contain the following levels of other components.

BE2017 / 5973

Oxide m% Oxide m% Oxide m% AI ₂ O ₃ 0.5-10.0 K ₂ O 0.0-7.0 SrO 0.0-3.0 b ₂ o ₃ 0.5-20.0 Li ₂ O 0.0-3.0 TiO ₂ 0.0-6.0 BaO 0.0-5.0 N82O 5.0-20.0 ZnO 0.0-5.0 CaO 0.0-6.0 p ₂ 0 ₅ 0.0-7.0 ZrO ₂ 0.0-5.0 F " 0.0-7.0 SiO ₂ 30.0 - 60.0

This list is not exhaustive. The presence of other levels of these oxides or the presence of other oxides will also lead to good adhesion based on the presence of the oxides of Mo / Cu / Bi.

Group 3: Mo / W

These frits contain 0.1-10% WO ₃ and 0.1 - 20% MoO ₃ .

In particular, these frits contain 0.5-5% WO ₃ and 0.2-3% MoO ₃ .

In addition to these ranges that ensure adhesion, the frits contain the following levels of other components.

Oxide m% Oxide m% Oxide m% AI ₂ O ₃ 0.5-10.0 Fe ₂ O ₃ 0.0-5.0% SiO ₂ 30.0 - 60.0% b ₂ o ₃ 0.5-20.0 K ₂ O 0.0-7.0 SrO 0.0-3.0 BaO 0.0-5.0 Li ₂ O 0.0-3.0 TiO ₂ 0.0-6.0 CaO 0.0-6.0 N32O 5.0-20.0 ZnO 0.0-5.0 F " 0.0-7.0 p ₂ 0 ₅ 0.0-7.0 ZrO ₂ 0.0-5.0

This list is not exhaustive. The presence of other levels of these oxides or the presence of other oxides will also lead to good adhesion based on the presence of the oxides of Mo / W.

Group 4: Mo / Sb

These frits contain 0.1-10% Sb ₂ O ₃ and 0.1 - 10% MoO ₃ .

In particular, these frits contain 0.1-4% Sb ₂ O ₃ and 0.2-3% MoO ₃ .

More specifically, these frits contain 1-3% Sb ₂ O ₃ and 0.5-2.5% MoO ₃ .

BE2017 / 5973

In addition to these ranges that ensure adhesion, the frits contain the following levels of other components.

Oxide m% Oxide m% Oxide m% AI ₂ O ₃ 0.5-10.0 Fe ₂ O ₃ 0.0-5.0 SiO ₂ 30.0 - 60.0 B ₂ O ₃ 0.5-20.0 K ₂ O 0.0-7.0 SrO 0.0-3.0 BaO 0.0-5.0 Li ₂ O 0.0-3.0 TiO ₂ 0.0-6.0 CaO 0.0-6.0 N82O 5.0-20.0 ZnO 0.0-5.0 F " 0.0-7.0 p ₂ 0 ₅ 0.0-7.0 ZrO ₂ 0.0-5.0

This list is not exhaustive. The presence of other levels of these oxides or the presence of other oxides will also lead to good adhesion based on the presence of the oxides of Mo / Sb.

Group 5: Mo

These frits contain 0.1 - 20% MoO ₃ and / or MoO ₂

In particular, these frits contain 0.5-3% MoO ₃ .

In addition to these ranges that ensure adhesion, the frits contain the following levels of other components.

Oxide m% Oxide m% Oxide m% AI ₂ O ₃ 0.5-10.0 Fe ₂ O ₃ 0.0-5.0 SiO ₂ 30.0 - 60.0 B ₂ O ₃ 0.5-20.0 K ₂ O 0.0-7.0 SrO 0.0-3.0 BaO 0.0-5.0 Li ₂ O 0.0-3.0 TiO ₂ 0.0-6.0 CaO 0.0-6.0 N32O 5.0-20.0 ZnO 0.0-5.0 F " 0.0-7.0 p ₂ 0 ₅ 0.0-7.0 ZrO ₂ 0.0-5.0

This list is not exhaustive. The presence of other levels of these oxides or the presence of other oxides will also lead to good adhesion based on the presence of the oxides of Mo.

Group 6: combination group

French fries containing a combination of the compositions from the above groups.

BE2017 / 5973

The enamel coating compositions of this invention are as follows:

Group A: enamel coatings to which no adhesion promoting components are added when grinding:

The applied sludge or powder layer consists of 1 or more enamel frits from the groups described above that are ground / mixed together with the components customary in the enamel sector. After drying, this layer is burned onto the steel and the final composition is obtained.

Other enamel frits which may or may not contain the Co and / or Ni adhesion oxides may also be added during grinding / mixing.

Group B: enamel coatings to which adhesion promoting components are added when grinding:

The applied sludge or powder layer consists of 1 or more enamel frits from the groups described above which together with 0.2 - 2% Sb ₂ O ₃ and / or 0.05 - 0.5% of one or more of the following products: SiB ₆ , Si ₃ N ₄ , AIN, B ₄ C, MgB ₂ , urea, NaNO ₂ , BaNO ₃ , and are milled / mixed together with the usual components. After drying, this layer is burned onto the steel and the final composition is obtained.

Other enamel frits which may or may not contain the Co and / or Ni adhesion oxides may also be added during grinding / mixing.

Below are some non-exhaustive examples.

EXAMPLES

Example 1: KSE29

This frit is a ground enamel based on the Mo / Sb bonding system (group 4). The oxidic composition is:

Oxide m% Oxide m% Oxide m% Oxide m% AI ₂ O ₃ 6.30 F " 4.10 MgO 0.30 Sb ₂ O ₃ 1.90 b ₂ o ₃ 16.80 Fe ₂ O ₃ 3.00 MoO ₃ 1.00 SiO ₂ 33.40 BaO 3.20 K ₂ O 2.70 N32O 13.80 ZnO 2.20 CaO 4.50 Li ₂ O 1.60 p ₂ 0 ₅ 5.10

BE2017 / 5973

This frit was tested without the addition of adhesion-promoting components during grinding (Group A). The milling formula that was used is shown below.

Grinding formula Quantity Sodium aluminate 0.20g Potassium carbonate 0.20g Ultrasil, amorphous silica 0.50 g Clay 4, OOg Quartz 3.00 g Frit KSE29 100.0 g 10 Water 50.0 ml

The sludge obtained was applied by spraying on various grades of sheet steel: DC04EK, DC03ED, and DC06EK (according to EN 10209). In each case, steel plate of 1 mm thickness was used and a layer thickness of 120 µm was applied. Burning in was done in a box oven at 820 ° C for 4 minutes.

Good adhesion (class 1 according to EN 10209) was achieved on all these steel qualities.

Example 2: KSE192

This frit is based on the Mo / Cu / Sn (groupl) bonding system. The oxidic composition is:

Oxide m% Oxide m% Oxide m% Oxide m% Al2 O3 6.30 CuO 4.00 Li ₂ O 1.60 p ₂ o ₅ 5.10 B2O3 16.80 F " 4.10 MgO 0.30 SiO ₂ 33.40 BaO 3.20 Fe ₂ O ₃ 3.00 MOO3 1.00 SI102 1.00 CaO 4.50 K2O 2.70 N32O 13.80 ZnO 2.20

This frit was tested in 2 times formulas:

without the addition of adhesion-promoting components during grinding (group A). The milling formula that was used is shown below.

BE2017 / 5973

Grinding formula Quantity Sodium aluminate 0.20g Potassium carbonate 0.20g Ultrasil, amorphous silica 0.50 g Clay 4.00 g Quartz 3.00 g Frit KSE192 100, Og Water 50.0 ml

The sludge obtained was sprayed onto DC04E and DC03ED sheet steel (according to EN 10209) of 1 mm thickness. A layer of 120 µm was applied and burnt in a box oven at 820 ° C for 4 minutes.

The obtained adhesion was 1 (class 1 according to EN 10209) on both steel grades.

with the addition of adhesion-promoting components during grinding (group B). The milling formula that was used is shown below.

Grinding formula Quantity Sodium aluminate 0.20g Potassium carbonate 0.20g Ultrasil, amorphous silica 0.50 g Clay 4.00 g Quartz 15.00 g B ₄ C 0.05 g Frit KSE192 100, Og Water 50.0 ml

The sludge obtained was applied by immersion on S235 sheet steel (according to EN10025) of 1.8 mm thickness. Both pickled and defatted steel sheets were used. A layer thickness of 180 μm was applied. Burning in was done in a box oven at 850 ° C for 8 minutes.

BE2017 / 5973 The obtained adhesion was 1 (class 1 according to EN 10209).

Example 3: KSE316

This frit is also based on the Mo / Sb bonding system (group 4). The oxidic composition is:

Oxide m% Oxide m% Oxide m% Oxide m ° 4? Al2 O3 0.50 F " 5.10 MOO3 2.10 SrO 1.30 B2O3 7.30 Fe ₂ O ₃ 3.20 N32O 13.60 T102 4.20 BaO 1.60 K2O 1.90 Sb ₂ O ₃ 1.90 ZnO 0.20 CaO 1.10 Li ₂ O 1.15 SiO ₂ 51.90

In addition to good adhesion, this frit also exhibits good chemical resistance to acids and alkalis.

This frit was tested without the addition of adhesion-promoting components during grinding (Group A). The milling formula that was used is shown below.

Grinding formula Quantity Frit KSE316 100.0 g WR68 bluesil from bluestar silicones 0.2 ml

The powder obtained was applied to various grades of sheet steel via electrostatic powder spraying: DC04EK, DC03ED (according to EN10209). Steel plate of 1 mm thickness was used each time. Burning in was done in a box oven at 840 ° C for 5 minutes.

Good adhesion (class 1 according to EN 10209) was achieved on these steel qualities.

Claims (17)

CONCLUSIONS BE2017 / 5973 An enamel coating which is the only adhesive oxides containing one or more of the oxides of Mo, Sb, Cu, Sn, Bi and W. Enamel coating according to claim 1, wherein the oxides of Mo, Sb, Cu, Sn, Bi and W are from the enamel frit. The enamel coating of claim 1, wherein the oxides of Mo, Sb, Cu, Sn, Bi and W are added during the milling / mixing of the enamel sludge or enamel powder used for the enamel coating. The enamel coating of claim 1, wherein the wherein the oxides of Mo, Sb, Cu, Sn, Bi, and W are from the enamel frit and added from components during the milling / mixing of the used enamel sludge or enamel powder. Enamel coating according to claim 2, wherein the adhesion oxide used is a combination of the oxides of Mo. Enamel coating according to claim 5, wherein 0.5 - 3% MoO 3 is used as the bonding oxides Enamel coating according to claim 2, wherein a combination of the oxides of Mo and Sb is used as bonding oxides. Enamel coating according to claim 5, wherein 0.1-4% Sb ₂ O ₃ and 0.2-3% MoO ₃ are used as the bonding oxides. 9. Enamel coating according to claim 2, wherein the combination oxides of Cu, Sn and Mo are used as bonding oxides. Enamel coating according to claim 7, wherein as adhesion oxides 0.5-5% (CuO + Cu ₂ O), 0.2-4% (SnO + SnO ₂ ), 0.2-3% MoO ₃ . Enamel coating according to claim 2, wherein a combination of the oxides of Cu, Bi and Mo is used as bonding oxides. Enamel coating according to claim 9, wherein as adhesion oxides 0.5-5% (CuO + Cu ₂ O), 0.5-10% Bi ₂ O _3; 0.5-3% MoO ₃ is used. Enamel coating according to claim 2, wherein as a bonding oxides a combination of the oxides of Mo and W is used. Enamel coating according to claim 11, wherein 0.5-5% WO ₃ , 0.2-3% MoO ₃ is used as the bonding oxides. Enamel coating according to claims 3 and 4, wherein additional adhesion promoting components are added during the grinding / mixing of the enamel sludge or enamel powder. 16. Enamel coatings that use a combination of frits that contain one or more of the oxides Mo, Sb, Cu, Sn, Bi and W. 17. Enamel coatings that contain other frits in addition to frits that contain one or more of the oxides Mo, Sb, Cu, Sn, Bi and W.